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Solar Info: The Down Low on Everything Up High

Solar Charger Controller

Rain or shine we get a huge number of calls about solar power each day. We’ll attempt to answer the questions asked most often so we can save you a phone call.

Before we get started, you should know that solar power is not the cure-all for replacing spent energy. For example, some people are trying to recharge batteries for a trolling motor, boat, RV, house, electric scooter, backwoods cabin, etc., and they want it done in very short time, usually in just a few days. Assume you take a discharged 100-amp hour battery and charge it with a 30-watt solar panel under ideal summertime light conditions. After a full week, the battery will be just about fully charged. Using this example, you can see that it will take at least 100 watts of solar power to recharge a 100-amp hour battery in a few days.

Also, keep in mind that it takes direct sunshine on the surface of the panel to produce the maximum-rated power of a solar panel. Conditions such as an overcast sky, shadows, improper mounting angle, equatorial direction or short winter days will reduce the actual solar panel output to below the rated values.


Most solar chargers are designed for 12 VDC, but we do have limited availability on a 24-volt panel. Typically, when 24 volts or greater is needed, solar panels may be wired in series, or we can special order solar panels that are made to deliver more DC Volts such as 24V, 36V, 48V etc.


Solar Charger ControllerAnytime you use a panel that is over 5 watts rated output, we recommend using a solar charge controller. Actually, a charge controller is a good idea in a majority of applications, as it can provide several benefits such as preventing overcharge, improving charge quality, and preventing battery discharge in low or no-light conditions. Some solar panels are made with blocking diodes pre-installed that prevent battery discharge during low or no-light conditions. In most cases where a 6-watt or larger solar panel is installed, the use of a charger controller is highly recommended. In a nutshell, a solar charge controller acts like an on and off switch, allowing power to pass when the battery needs it and cutting it off when the battery is fully charged. Something to be aware of when selecting a controller is that they are typically rated in amps, while photovoltaic panels are typically rated in watts. That means a solar charge controller such as the Morning Star SS6L, 6-amp controller will work with nearly every panel we sell, right up to about 70 watts.


Solar panel for maintaining single and dual batteriesSolar panel manufacturers rate solar output in watts. As a rule of thumb, a rating of 15 watts delivers about 3,600 coulombs (1 AH) per hour of direct sunlight. As an example, the Pulse Tech SP-7 panel can output .33AH per hour of direct sunlight. This is a very popular panel for maintaining single and dual batteries for stand-by and storage applications.


The first thing to remember about solar power is that it is all a matter of numbers. The power you require vs. the power the panel can put out. Before you can even get started when purchasing a panel, you need to know how many amp hours or watts you’ll need to produce in a set period of time. This figure could be measured in hours or days. Since there are 24 hours in a day, we suggest you use that as a baseline. First, determine your total electrical consumption in that time period. Then figure the amount of direct sunlight the solar panel will receive in that time period and come up with a total amount of watt hours needed. You should always err on the side of caution and over-estimate your power needs. Typically we see an average of 4 hours of usable sunlight in the winter, and 6 hours of usable sunlight in summer. Granted, there are exceptions to these averages, but erring on the side of caution creates a more reliable solar system. These averages also help compensate for variables like shade, clouds, panel angle, etc. Once you have a good handle on your power requirements, I suggest you go to our Solar Calculator.


Solar panel ratings are calculated in bright direct sunlight. Conditions such as indirect sunlight, overcast and partial shade conditions will decrease the output. We always recommend over-sizing the size of your solar array, as these conditions occur often. Also, remember that the length of daylight in summer vs. winter can make an impact.

One of the biggest errors commonly seen is when a solar array is designed in summer using summer daylight hours, but then it’s also used in the winter. The first complaint is often related to the batteries no longer holding up under load. This is a gradual process that begins when you lose daylight hours, and you start taking the battery pack beyond a 50% depth of discharge. When this happens, the batteries start to sulfate at a much quicker rate, and begin to no longer hold under load. As you can imagine, this is an expensive mistake! The solution generally involves more panels and new batteries with a higher Amp/Hr reserve. Therefore, we advise our customers to be conservative when accounting for daylight hours. Also, if you plan to utilize a solar array year-round, then you need to factor in your daily solar input for winter.


Foldable / Portable Solar PanelWe carry several foldable/portable solar panels for backpacking that come with a female cigarette lighter adapter. This adapter allows you to power 12v accessories that commonly use a 12v DC plug. In order to connect directly to a panel, the device cannot be sensitive to voltage variation—otherwise they may shut down. To solve this problem, it’s best to use a small battery as a storage vessel for energy that will provide constant source of stable, reliable power. To do this, we recommend using a solar charge controller, Y-connector with a battery inline on one leg, and the female cigarette socket on the other leg.


Nearly all solar panels are designed for outdoor installation, as this is where they will receive the best, most direct exposure to sunlight. Remember that anything less than that will cause the panel to produce less than its full-rated power.


A periodic inspection to remove dirt, debris and check electrical connections is all that is needed. Keeping the panel clear of snow and debris will allow for better results.


Performance from a solar panel will vary, but in most cases guaranteed power output life expectancy is between 3 and 25 years. This guaranteed life expectancy rating is usually 80% of the published rating of the solar panel. Of course, this will vary from manufacturer to manufacturer, and as always, you typically get what you pay for. Watch out for those cheap panels made in Paki-china-nam-istan.


Power InverterMany folks use a DC to AC power inverter to convert 12 VDC to 110 VAC. Since they change power from one form to another, inverters are power-gobbling monsters and should be avoided when possible. If you have a choice of a 12-volt, DC-powered device or 110-volt AC device, go with the 12-volt DC device. There are DC devices on the market that either step down or step up DC power, and these also use significantly more power.

DC to AC via an Inverter Formula Examples

This “rule of thumb” is intended as a general guide for estimating the DC amps required operating a DC to AC power inverter. Since the calculations yield approximate values, an appropriate safety factor should be considered when designing and specifying system components, such as wire, size and length. This basically means “oversize your system.”

12-Volt DC Systems

Formula: 12-volt inverters require approximately ten 10 amps DC input for each 100 watts output power used to operate an AC load.

Example: How many DC amps will a 12-volt inverter require to operate three 500-watt quartz lights, or a 1500-watt electric heater?


  • 1) Total watts = 1500
  • 2) 1500 watts/100 (from formula) = 15
  • 3) 15 X 10 amps (from formula) = 150 amps.

This is the DC current the inverter will use to operate the 1500-watt load. Note: If these 150 amps are drawn from the battery for one hour, 150 amp hours of battery power will be used.

To support 150 amp hours of battery power, 300 amps of battery capacity should be used for maximum battery life and performance.

24-Volt DC Systems

Formula: 24-volt inverters require approximately 5 amps DC input for each 100 watts output power used to operate an AC load.

Example: How many DC amps will a 24-volt inverter require to operate three 500-watt quartz lights, or a 1500-watt electric heater?


  • 1) Total watts = 1500
  • 2) 1500 watts/100 (from formula) = 15
  • 3) 15 X 5 amps (from formula) = 75 amps.

This is the DC current the inverter will use to operate the 1500-watt load. Note: If these 75 amps are drawn from the battery for one hour, 75 amp hours of battery power will be used.

To support 75 amp hours of battery power, 150 amps of battery capacity should be used for maximum battery life and performance.

Ready to harness the power of the sun? Shop for a solar charger and accessories.

Spreadsheet icon Solar Calculator

Whether you need a solar battery charger for boat, solar trickle charger for car battery, or a solar ac charger, we have the right chargers for any application.

Choose Your Solar Charger

162 people commented, TECH, Richard Haubert, Tech, Barry, and 158 others
This article is rated 4.7 out of 5
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  • Richard Haubert
    I've used two different mppt chargers and they won't charge my 140amp gel batteries more than about 80%. My current charger can be adjusted but I'm not sure what to change. This must be a common problem.

    Reply  •  Rated article 5  •  April 3, 2023 at 3:06 pm
    • TECH
      It sounds like the absorption time may be timing out. If allowed, you may need to increase the charging absorption time. If the time is already maxed out, you might need to increase the panel size to get more amperage to the battery faster. Just make sure you check your battery's max current rating to be sure you are not exceeding it. As a general rule, most do not like to be charged with an amp rating more than 25% of the AH rating.

      Reply  •  Rated article 5  •  April 28, 2023 at 9:30 am
  • Barry
    Is there a solar set up that has a 110 plug on it, just to charge hear aid battery for small wattage?

    Reply  •  Rated article 5  •  August 22, 2022 at 6:16 pm
    • BatteryStuff Tech
      Barry - We don't have an all-in-one solution as we find they rarely meet individual needs from person to person. All-in-one systems typically have a solar panel, solar charge controller, battery, and inverter. All-in-one systems are typially priced higher than if you build a system yourself. We always suggest a person build a system to suit their individual needs, which often allows you to save money and you know it will work for your needs. I would suggest reading our article: Solar Systems the Right Way. This article walks you through the steps necessary to build a system and links to calculators that assist with the build.

      Reply  •  Rated article 5  •  August 23, 2022 at 12:34 pm
  • Carla Daniel
    I have a solar panel that plugs into car lighter only? What is it used for? Please help.

    Reply  •  Rated article 5  •  July 4, 2022 at 4:37 pm
    • BatteryStuff Tech
      The panel is most likely designed to work as a solar maintainer for a vehicle that is not used too often. Panels like these can plug into a cigarette lighter that is still active when the car is turned off and send energy to the battery to help keep the battery fully charged.

      Reply  •  Rated article 5  •  July 14, 2022 at 9:39 am
  • Taylor White
    Do I need to wait until a specific time of day to plug my solar panels into my solar charger?

    Reply  •  Rated article 5  •  October 9, 2021 at 10:51 am
    • BatteryStuff Tech
      No, you can do it any time of day. Just be sure not to cross the lead to create a short circuit.

      Reply  •  Rated article 5  •  November 1, 2021 at 9:26 am
  • Todd H Disraeli
    Great information! I've been spending wayyyyy to much time researching what I'm guessing is a simple answer. Any help is greatly appreciated. 95% of my camping is boon-docking and I use very little battery power; LED lights, small fan, water pump, and charging laptop/camera/drone/phones. My trailer is 30amp and I have two 6 volt batteries. Always camp in the mountains of Idaho and usually have excellent strong sun during the camping season. Would two 50 watt solar panels and a 20 amp controller, directly wired to the batteries d the job? I don't want to re-charge them, just keep them being fed all day. Thanks in advance for your time and reply!

    Reply  •  Rated article 5  •  June 19, 2020 at 1:09 pm
    • BatteryStuff Tech
      Todd it is all a math problem. You pose a 50 watt panel which most likely outputs about 2.9 amps an hour. In North America you can factor on getting about 4 to 6 hours of usable solar input. So, during summer this means you are going to get about 17 amp a day from this panel. Now you simply need to equate that back to your battery capacity. How long do your batteries last you? Simply divide your capacity by the days they last and that should give you an idea. In general our recommendation start with our 100 to 150 Watt Solar RV Kits.

      Reply  •  Rated article 5  •  June 19, 2020 at 1:17 pm
  • Brian
    What type of solar panel do I need to charge 4 - 12 volt batteries in my golf cart? What else do I need to purchase with the panel to connect it to the batteries?

    Reply  •  Rated article 5  •  May 25, 2020 at 6:12 pm
    • BatteryStuff Tech
      As the article says solar is a basically a matter of numbers, so every situation is typically unique to each person. You are more that welcome to use our Solar Calculator, but we do not carry 48v Solar Panels, so I really couldn't speculate what your need would be. In most cases the 48v panels meant for a golf carts are simply there to prevent the cart's batteries from discharging after they have been charge, and are for maintenance purposes only.

      Reply  •  Rated article 5  •  June 15, 2020 at 12:08 pm
  • John Dao-Tran
    i have a solar panel connected to a mppt charger, and 200ah of battery in my van. it has been sunny yesterday, and today, and it's only showing 0w for solar, depth of charge is 100%. today has yield 10wh, yesterday 20wh, 3 days ago 360wh, 4 days ago 320, 5 days ago 330. is something wrong? all i did was climb on the roof and check the connections, i barely touched them. i'm using the van, but have not used any of the battery, and the inverter is off. i might have run the fan for a whole 4 minutes. is it normal to read 0w if the battery is full?

    Reply  •  Rated article 5  •  May 16, 2020 at 2:11 pm
    • BatteryStuff Tech
      If your battery pack is fully charge it is most likely dissipating the solar energy. Some units won't show you any solar input while in float mode because that energy isn't passing through the controller to batteries. I would suggest looking to the manual for your controller and verifying how it renders information. Some of our Samlex units only show you the solar going through the device when it is charging, so if the battery is fully charged and the unit is in float mode it doesn't show any solar input.

      Reply  •  Rated article 5  •  May 18, 2020 at 1:17 pm
  • Virginia Fleming
    Hello, I have a 12 ft aluminum boat and want a solar charger for the trolling motor battery. If you were me, what would you buy? Thank you.

    Reply  •  Rated article 5  •  May 9, 2020 at 6:15 am
  • Richard Defeis
    I have a solar phone charger with out direct sun light would LED lighting put a charge on th charger

    Reply  •  Rated article 5  •  April 20, 2020 at 9:44 am
    • BatteryStuff Tech
      Unfortunately, solar panels need direct sunlight to reach their optimal charging voltage, which a LED light isn't going to do.

      Reply  •  Rated article 5  •  April 20, 2020 at 9:55 am
  • Jackson Blessing
    lease is it possible to charge up lithium battery 6v 12.8amps with 130watts 12v solar panel

    Reply  •  Rated article 5  •  March 13, 2020 at 8:49 am
    • TECH
      Some lithium's can be charged off solar and some cannot. A lot of solar charge controllers are still made for lead acid batteries, so we would recommend talking to the manufacturer of your lithium battery to verify compatibility. The manufacturer is most likely going to give you the charging voltages that are acceptable for the battery, which you can then look to the specification sheets of our solar charge controllers. You most likely will not be able to hook a panel directly to the battery, as most 12v panels have a voltage into the 16v or 17v range. In my experience most 12v lithium batteries need to be charge below 15v, but you best source for information regarding compatibility regarding solar would be the manufacturer of the battery.

      Reply  •  Rated article 5  •  March 20, 2020 at 3:05 pm
  • Ernest Leffler
    I was wondering about my 16 gel batteries interms of charging in the winter. Should the batteries always be charged fully or when they are down to 50% charge to say 75% to reduce the amount of fuel used in the generator? I am concerned about the amount of cycles on the batteries. Thank you

    Reply  •  Rated article 5  •  November 30, 2018 at 8:23 am
    • BatteryStuff Tech
      There are two states with a battery... It is either being charged or naturally discharging. We recommend keeping a maintainer on a battery slow down the sulfation process that occurs within the battery when it is discharging. You can never stop the sulfation process but keeping them topped off is the best you can do. In order to better make your decision I would refer you to the specification sheet for your battery, and there is usually a Depth to Discharge Cycle Life chart.

      Reply  •  Rated article 5  •  November 30, 2018 at 8:51 am
  • Dave
    I have 200 watt 12 volt panel and have 2 different 12 volt batteries hooked up. I have read all the postings and it seems all the batteries should be the same and mixing the size of batteries is a no-no.
    Please confirm.

    Reply  •  June 28, 2016 at 4:59 am
    • BatteryStuff Tech
      What you have been reading is correct! You don’t want to mix and match batteries of different capacity, age, or chemistry. The main reason is batteries of different types charge at different voltages. Batteries of different ages will charge a rates, as one battery will be more sulfated than the other battery. And lastly, batteries of different capacity create a situation for a battery to get overcharged, which can result in a failure.

      Reply  •  January 19, 2017 at 9:10 am
  • Arch
    What equipment do I need to trickle charge my travel trailer, 12 volt deep cycle battery when the unit is in storage? We use shore power 99% of the time when we are traveling, so I just what to trickle charge the battery while it is in storage so we can pick it up and take off. I was thinking about a 5 watt unit, but do I need a controller or a battery tender?

    Thanks much

    Reply  •  Rated article 5  •  June 20, 2016 at 10:38 am
    • BatteryStuff Tech
      I would be cautious at selecting the 5 watt panel unless you can be sure the parasite draw coming off those batteries is less than .5 amps a day. The Battery Tender unit only puts 270 mA (.2 Amps) an hours, so about 1 to 1.5 amps a day if in direct sunlight for 4-6 hrs. I have some customers that can get away with that small panel, but most move at least a 10 to 15 watt per battery if you want a reliable setup. I would check you parasite draw just to be sure… But to answer your question the Battery Tender 5 Watt Panel does have a built in controller.

      Reply  •  January 17, 2017 at 12:21 pm
  • Roger Gregory
    I wish to trickle charge 2 car batteries whilst away for 2 months. I have a 20 watt solar panel wired to a controller, can I run 2 sets of leads from the battery outlet of the controller (1 set to each battery) or should I disconnect one battery and hook them up in parallel with the conections from the controller at each end of the bank?

    Reply  •  June 16, 2016 at 1:34 am
    • BatteryStuff Tech
      Putting batteries in parallel for the sake of charging is not recommend unless the batteries were in parallel to begin with. What you need to find is a two bank solar charge controller. The are available, but based on your location I would source one locally, as the shipping to your location would be about the same price as the unit itself. We carry the Morning Star 12v 25 Amp Dual Battery Solar Controller SSDuo-25RM, maybe you can find a local source in your area?

      Reply  •  January 17, 2017 at 11:31 am
  • Lindsey
    Dear Sir,

    Please help!

    Our family purchased a lot of ten (of what was advertised as) 12V 300Watt solar panels. I connected my share of 2 of the panels, each one to two different battery banks, both wired in parallel with 12/24 charge controllers (the charge controller automatically senses whether 12V or 24V) and they settled on 12V and 12V PSW inverters. A very questionable solar professional told me that there’s no way that my setup can work because the panels are rated at 48V. My setup has been working great for over 18 months so I don’t know what he’s talking about. Further, he said I had to wire my battery banks to 48 as well. I told him my banks had been working fine. He said maybe it’s because I was using MPPT charge controllers….I told him I had just replaced the PWM with the MPPT very recently. This guy I feel is trying to take advantage of my elderly mother. Previous to this new guy, a respectable solar installer who had no dog in the game told me all I had to do regarding the 12V 300Ah panels was to make sure I used a 30Amp charge controller. Can you please advise on this?

    Reply  •  June 11, 2016 at 2:20 pm
    • BatteryStuff Tech
      To begin with you said you had a 12v panel, so i’m not sure how 48v even got into the conversation with the first guy. I would opt to trust the second guy as he was correct in his recommendation regarding a controller for the 12v 300 watt panel… I would also recommend a 30 amp controller.

      Reply  •  January 17, 2017 at 10:15 am
  • Joe Iwen
    I made a cooler radio with a car battery as the power source. I am looking to add some more speakers to the equation. Im worried that the car battery may go dead. I was just wondering what you would recommend solar panel wise.

    Reply  •  June 7, 2016 at 3:11 pm
    • BatteryStuff Tech
      Joe I recommend you read our article: OK, So What Size Panel Do I need? This article will link to our solar calculator, which will tell you what size panel you need. It is a math problem, so you do need to know what you are drawing off the battery in order to use the calculator.

      Reply  •  Rated article 5  •  June 9, 2016 at 11:47 am
  • Honza
    Hi there, loads of excellent advice on here!
    I’ve got a question: my charge controller just died on me and it will be about two weeks before I can get a new one. I’m very off grid and depend on my battery power.
    Can I hook up my 100w solar panel to the battery directly for a couple of hours to get some juice in without a charge controller? battery directly for a couple of hours to get ssome

    Reply  •  June 7, 2016 at 10:44 am
    • BatteryStuff Tech
      The battery would accept some of the charge, but because of the higher voltage it can’t accept it all. It definitely is not recommended as it will start to heat the battery up, which will cause the battery to sulfate faster, and could damage the battery.

      Reply  •  Rated article 5  •  June 9, 2016 at 11:40 am
  • Mike

    I am looking to make the connection from my solar panels onboard my boat. We have 2 panels 1@100w 1@30w. The panels have been mounted and I have run the cables to the battery bank but not made the connections. I was told when we bought the boat that it was a dual bank 1×125ah for engine 2×125ah for leisure. The system is 12v! I have a Rutland Hrdi dual bank controller (for the wind turbine also). I am looking to find out how to wire from the controller to the batteries! As I said the batteries should be 2 banks but they seem to be wired as one. I will try to detail how they are wired in order for you to understand so hopefully you can help! So three batteries all appear to be linked together

    Battery one has 1 positive and one negative (links to bat 2)

    Battery two has 1 positive but takes a link cable from
    battery one & three negative

    Battery 3 has 1 positive and 1 negative (links to bat 2)

    I can forward over pictures of battery bank and the wiring diagram.

    Any help would be greatly appreciated.

    I hope to hear from you!

    Reply  •  June 4, 2016 at 1:05 pm
    • BatteryStuff Tech
      I don’t sell wind turbine controllers, so I’m not sure if they can be used in a solar application. Linking all the batteries together in order to charge isn’t a good idea. I would suggest reaching out to the company who makes the Rutland controller to see if your controller will work for solar, or purchasing a dual bank solar charge controller such as our Morning Star 12v 25 Amp Dual Battery Solar Controller. With this type of controller you would tie both solar panels into the solar section, and then you have two banks available to charge. This controller also allows you to slip the charge 90/10 or 50/50, so that the house bank can get the majority of the charge.

      Reply  •  Rated article 5  •  June 9, 2016 at 11:16 am
  • Nick
    Hi, i’m looking at setting up a solar panel to charge two batteries. They will then power an auto gate opener/closer. My question is where would i be best to have the longest run of cable? From the panel to the charge controller and batteries, or from the batteries to the gate opener control panel. The distance from the solar panel to the gate control panel is approx 20m/65ft. I can locate the batteries at either the solar or gate control panel, so just want to have the least power loss in the cabling. many thanks if you can help.

    Reply  •  Rated article 5  •  June 1, 2016 at 2:55 am
    • BatteryStuff Tech
      Nick I would put your batteries by the gate opener, along with the solar charge controller. The gate opener is going to pull a large amount of amps, so you want that close to the gate opener to minimize loss. The solar panel will have some loss going that distance, but just make sure the solar charge controller is near the batteries. The solar charge controller will regulate the charge as needed, so the closer it is the better.

      Reply  •  Rated article 5  •  June 3, 2016 at 2:30 pm
  • Laurie
    Will a 12v solar trickle charger work to charge an 18v marine battery?

    Reply  •  May 29, 2016 at 5:22 pm
    • BatteryStuff Tech
      Unfortunately it will not work. Most 12v Solar panels output in the 16-18v range when hooked up. The solar charge controller will reduce it to the 14v range in order to charge a 12v battery. For an 18v battery the charging need to be in the 21-22v range, which a 12v panel cannot produce.

      Reply  •  Rated article 5  •  June 3, 2016 at 2:11 pm
  • Tola
    Good day. I want to built a solar system with d following conditions
    1. 1500w 12v inverter
    2. 200AH battery (1 unit)
    3. 300w solar panel(1unit)
    4. Sunshine hour =8hr
    These my questions
    1. Can this system provide 1500watt-hour during the day and another 1500watt-hour during the night
    2. How long would it take the solar panel to fully charge the battery
    3. Is the inverter strong enough to run a water pumb of 1HP.

    Reply  •  May 21, 2016 at 4:33 am
    • BatteryStuff Tech
      Tola, your panel generates approximately 13.8 amps a hour, so in 8 hrs that equates to 110 Amps. To know if this is going to work, how many amps is your pump pulling out of the battery bank. If you don’t know how to calculate back to DC from AC I suggest using our Calculator | DC to AC amperage conversion run through an Inverter.

      Reply  •  May 26, 2016 at 7:27 am
  • Tim
    I’m so frustrated just bought a unit, 200 watt unit with charge controller. Had a buddy help me hook it up run wires! When it came time to run the wires to the batteries he just hooked to the closets 12 volt wire said it would charge threw there? Most of the time it reads the battery voltage sometimes the numbers just bounce. Once it hit 13.2 and stayed there and charged the batteries! Can you run them like this or has to be straight to the batteries with amp breaker??? Thank you

    Reply  •  Rated article 4  •  May 11, 2016 at 9:03 pm
    • BatteryStuff Tech
      The preferred method of hooking up to the battery pack would be the positive at one end of the battery pack, and the negative at the other end of the battery pack. Energy will force up to the other batteries if they are in parallel, however the charge doesn’t equalize as well as connecting to each end of the battery pack.

      Reply  •  Rated article 5  •  May 19, 2016 at 11:45 am
  • Nicole
    I have a pond pump that uses 400watts. I want 12 hours of backup power. I calculated 4800wh I would need. If I’m using 12 volt batteries rated at 105ah, I would need 4 to equal 4800wh? Also if I’m using 130 watt solar panels to charge them (say 5 hours of good sunlight) I would need 8? Does this sound right?

    Reply  •  May 11, 2016 at 8:47 pm
    • TECH
      Nicole, I’m coming up with quite different results. In solar you at minimum want one full day of backup, so your batteries are going to be double what you were expecting, and the panels in turn would be double as well. I would suggest looking at our Solar Calculator before proceeding so you can see the results for yourself. Please keep in mind that you never want to discharge a battery more than 50% or you take life out of the battery.

      Reply  •  Rated article 5  •  May 12, 2016 at 10:20 am
  • Guy Cox
    Hi – good article and you’re doing a great job answering all these questions!

    I have one myself – I recently installed a small solar system and I wonder if the battery is working ok – the controller says it charges up to 99% very soon after the panels are illuminated and as soon as the sun does down, the charge reduces to around 70% with a 2-3A load (a laptop and a couple of LED lights). This allows me only 3-4 hours of usage at night before the battery discharges down to 50%. The battery is 12V 220Ah and the panels are 100W (2×4.4A x x12V) in a very sunny position.

    Any thoughts or advice welcome –

    Is there a way to test battery charge other than the controller’s display?

    Many thanks, GC

    Reply  •  May 5, 2016 at 3:40 pm
    • BatteryStuff Tech
      It would be a good idea to have the battery tested, and you might want to consider looking at your calculations again. Your panel if rated 4.4 amps each, and two of them should output approximately 35 to 52.8 amps back into the battery pack daily (dependent on sunlight condition). You said your load is only 2-3 Amps? LED lights and Laptop I know don’t draw much, but in my experience this seems low. So is this amp rating taken off a 12v adapter, or are these devices 120VAC (plug into inverter or wall)? If it is a 120VAC device you need to use our Calculator | DC to AC amperage conversion run through an Inverter. In the end we like to see that a system that is capable of putting double your 24hr amp draw back into the system in a 24hr day. That way after a bad day it can more than make up for the daily draw and bring you back to full. Also look into your backup… If your taking the battery to 50% every night given your 24hr. amp draw, then you have no backup for bad weather days built into the system. You may want to consider banking some energy up with a higher capacity bank.

      Reply  •  May 6, 2016 at 7:24 am
  • Abdul Odud
    I have 220ah tuboler battery. I want charge from solar panel. Can I charge from 250 watt 12v solar panel.. or not kindly suggest me. Thank u

    Reply  •  April 22, 2016 at 8:42 pm
    • TECH
      I don’t sell Tuboler Batteries, but assuming your battery is a lead acid battery you could through the appropriate Solar Charge Controller.

      Reply  •  Rated article 5  •  April 25, 2016 at 9:18 am
  • Samarpan Bhattarai
    i wanna know if my 10 watt solar panal can charge 100 ah lead acid battery or not.. if yes.. what are the requirements and limitations..

    Reply  •  Rated article 4  •  April 13, 2016 at 9:51 pm
    • BatteryStuff Tech
      It depends what your are trying to accomplish. A 10 watt panel such as our Solarland 12v 10 Watt Framed Solar Charger SLP010-12U, will only output 2.5 to 4.0 amps a day output (dependent on light conditions). So if there is no draw off the battery and you are trying to keep it maintained, then it could work. But if there is a draw I would only be comfortable with this panel if that draw was less than 1.25 amps in a 24hr period.

      Reply  •  Rated article 5  •  April 14, 2016 at 9:19 am
  • Peter
    Hi guys…thinking about installing ip camera outside of my house and looking for solar panel set up(batery,etc…) to keep my camera going.Camery would be used only few hours a day and some days not at all..Can you please advise what configuration I should be looking for..Will need bigger number of these set ups in future if all works..Thank you very much in advance..Kind Regards Peter

    Reply  •  November 29, 2014 at 4:24 am
    • BatteryStuff Tech
      Solar is a math problem, so I would consider reading our article Solar Systems the Right Way. If you still need help after reading that article feel free to contact our Tech Support.

      Reply  •  December 30, 2014 at 9:19 am
  • Mike
    I have a trolling motor which is 24 volt system. I hook up two twelve volts systems to get the 24 volt. My question is, can I get a solar system to hook up Mt system while using the motor but keeping it charged. Thank you. Mike

    Reply  •  November 12, 2014 at 8:42 pm
  • Mike S
    I have a golf cart using 6 – 6 volt batteries wired in series. Can I charge 2 of the batteries at a time using a single solar panel and still receive a complete charge (& not overcharging) as I would using 3 solar panels in series and a 36 volt charge controller (which is very expensive).

    Reply  •  November 4, 2014 at 10:26 am
    • BatteryStuff Tech
      It is always our recommendation to charge the batteries in a pack as a whole, so a 36v panel would be required for your setup along with a 36v controller. But in theory yes you could have three 12 volt panels and three controllers to regulate the charge to make sure they didn’t overcharge.

      Reply  •  Rated article 5  •  November 19, 2014 at 10:51 am
  • Marc Johnstone
    What would I need to keep my two batteries charged on my boat. They are two regular batteries that I have to start the engine and provide power to the electronic instruments. I want to disconnect the shore power to avoid Galvanic corrosion.

    Reply  •  September 15, 2014 at 12:43 pm
    • TECH
      As specific information would be needed to recommend a product I would suggest you contact our TECH Department.

      Reply  •  September 25, 2014 at 11:15 am
  • Creighton
    Hello, I am a pharmacy school student. I did not receive my loans for school so I sold everything I own and was donated a van to live in. The van has 2 deep cycle batteries and they are charged with two 100w solar panels. The initial set up was running perfect. Charge to 12.9v everyday and I would run it down to 12.5v every night. This lasted a month. Now I can only get a full charge of 12.5v and it runs down to 12.1v every night? Any ideas where I could be losing this power? Thank you.

    Reply  •  September 8, 2014 at 3:03 pm
    • TECH
      As we are leaving the summer months this means less sun. It sounds like you might be drawing more that your panels are able to provide during this time of year. I would highly recommend using our Solar Calculator to verify if your systems is sized properly.

      Reply  •  September 25, 2014 at 10:07 am
  • Admin
    Unfortunately we do not have an article that addresses this. Please email your system specs and question to

    Reply  •  August 22, 2014 at 9:44 am
  • Eric
    Thank you for an informational article! I am a novice to a lot of this. So I am trying to start small. I still need to decide on a inverter for my 100W panel system. One thing I can not find a lot of information on is how to safely store the 12V battery. I’ve been told that my crawlspace is great idea if I use a container. Yet I have also been told this is a very dangerous idea and should be avoided. Can you suggest an article that might point me in the right direction?

    Reply  •  August 21, 2014 at 1:20 am
  • Daniel
    Hi in trying too run a dc water pump every fifteen minutes iv started getting my head around solar power. Is there a controler that has a timer built in? Do you have any recommendations s for moving 60 liters of water every fifteen mins must run in the day does not really need too run at night. I was thinking portable solar powered greenhouse with the pump providing hydroponics yield. Small light weight with a six week harvest schedule could solve alot of farming issues where there is drought.

    Reply  •  August 12, 2014 at 12:11 am
    • Admin
      Due to the fact that we don’t have all the information for your system we would need you to contact us at so that we can ask the appropriate questions, to get you the answer that you may need.

      Reply  •  August 15, 2014 at 2:30 pm
  • Wasti
    sir,i have 374 watts Solar panel 1×200w 1×80w 2×37w and 150ah flat battery and also use 900va inverter. but my problem is after full day battery is not fully charged. as per hydrometter is goes to only 1150 which is need 1250 plz sugges me

    Reply  •  Rated article 1  •  August 10, 2014 at 2:48 am
    • Admin
      Due to the fact that we don’t have all the information for your system we would need you to contact us at so that we can ask the appropriate questions, to get you the answer that you may need.

      Reply  •  August 15, 2014 at 2:29 pm
  • Krishna
    I have two batteries each 12v,150Ah connected in series and 24V inverter of 1150 VA.I purchased four number of tata bp solar panel rated 150W,9A,18V output.Sir, how solar plate connected to charge my batteries in 10 hours.

    Reply  •  Rated article 1  •  July 28, 2014 at 1:28 am
  • Monk
    my system comprises of 2 12v solar panels in series 48 v. baterries are 6 2volts in series 12 volts. I noticed recently my charger controller those not trickle anymore, and the output volts from the panels as reduced to about 4 volts during peak sunny periods. help?

    Due to the fact that we don’t have all the information for your system we would need you to contact us at so that we can ask the appropriate questions, to get you the answer that you may need.

    Reply  •  July 15, 2014 at 5:05 pm
    • Admin
      Due to the fact that we don’t have all the information for your system we would need you to contact us at so that we can ask the appropriate questions, to get you the answer that you may need.

      Reply  •  August 15, 2014 at 2:29 pm
  • Anirudh
    Sir ,
    can you tell me the minimum possible size of a 3v solar panel??

    We would require more information about your situation.  Please contact one of our techs at

    Reply  •  July 13, 2014 at 12:44 am
  • Bab
    I am wanting to keep a 12 volt deep cycle marine battery that powers a backwoods cabin charged. Normally the battery will only be used on the weekends and drained to probably 20% and then have all week to recharge. Do you have any recommendations on what size solar panel I will need in order to come back to a charged battery each weekend? I would like to develop a system that I could leave hooked up full time…

    Due to the fact that we don’t have all the information for your system we would need you to contact us at so that we can ask the appropriate questions, to get you the answer that you may need.

    Reply  •  Rated article 5  •  July 11, 2014 at 8:34 am
  • Bab
    I am wanting to keep a 12 volt deep cycle marine battery that powers a backwoods cabin charged. Normally the battery will only be used on the weekends and drained to probably 20% and then have all week to recharge. Do you have any recommendations on what size solar panel I will need in order to come back to a charged battery each weekend? I would like to develop a system that I could leave hooked up full time…


    Due to the fact that we don’t have all the information for your system we would need you to contact us at so that we can ask the appropriate questions, to get you the answer that you may need.

    Reply  •  Rated article 5  •  July 11, 2014 at 8:33 am
  • BatteryStuff Tech
    It is necessary to use a charge controller on panels over 5 watts. We do not recommend charging old and new batteries together.

    Reply  •  June 27, 2014 at 8:59 am
  • Zareef
    I want to put both 24v batteries sets old and new for charge. Is it ok or i will charge them seprately.

    Secondly I want to charge batteries directly from solar panel with out charge controller. is it ok.

    Reply  •  June 25, 2014 at 1:11 pm
  • Aaron
    This is a bit larger than what I am trying to do but still extremely helpful information, thanks!
    I would like to power a single LED, ideally 24/7. I am trying to come up with an arrangement that would let me do this. 3.3V LED (max 3.6V) with 20mA draw, typical Li-ion rechargeable battery looks to be 3.7V, and I can get solar panels that are 1V, 2V, 4.5V, 6V, 12V etc… Any advice? Will this work?

    Reply  •  June 18, 2014 at 10:08 am
    • BatteryStuff Tech
      Our solar panels are only in 12 or 24 volt configurations and are made for lead acid charging situations.

      Reply  •  June 20, 2014 at 12:02 pm
  • Topcol
    I find all the enquiries and responses very interesting. We live on a narrowboat on the English canal system. We have 2 × 80watt solar panels in parallel on the roof which feed directly to our 12v lead acid starter battery via a Victron MPPT controller. We also have 3 x leisure lead acid batteries in parallel with their negs connected to that of the starter battery. We also have a split charge relay and a Smartgauge display unit. I’ve noticed that the starter battery gets more than its share of the charge from the solar panels whereas we need it mainly for the leisure batteries. Could I connect the MPPT output to the 3 leisure batteries or would this only charge one of them, please? Thanks a lot for your help.

    Reply  •  June 18, 2014 at 2:12 am
  • Bud
    I have a 48 volt system containing 3 banks of 12 volt 100mah batteries, 4 batteries in series, 3 banks parallel totaling 12 batteries. The batteries are about 3 years old and a few of the batteries are dead and a few are marginal. Can I replace just the dead and marginal batteries, or should I replace them all? I want to make sure I don’t shorten the lifespan of the new batteries. Thanks

    Reply  •  June 9, 2014 at 4:16 pm
    • BatteryStuff Tech
      You will want to replace them all.

      Reply  •  June 16, 2014 at 10:55 am
  • Takis
    Hello from Greece.I Have a question.I have a 8watts solar panel for charging my 12v car battery.Its output is about 20Volts in the sunlight.Is there any danger of damaging my battery? Do i need a controller? and if yes how many Ah? Thank you for your time

    Reply  •  June 7, 2014 at 5:48 am
    • BatteryStuff Tech
      It should be fine. We usually will recommend a controller if the panel is over 8 watts, but that is a generalization based on a wide array of battery sizes. For a car battery, if the car battery is over 40AH, then you can use a solar panel up to 10 watts without a controller without any issues.

      Reply  •  June 16, 2014 at 10:29 am
  • BatteryStuff Tech
    You will not damage anything by running the system this way. Thanks

    Reply  •  June 6, 2014 at 8:47 am
  • Jerry
    I have a 60 watt folding solar panel with a GV-10 controler. I have a second battery in my vehicle which runs a 12v fridge. I want to leave the panel/controller connected through a dedicated always on cigarette receptacle. Will I damage my controler if it is left plugged in and sending energy to the battery if the engine is running and also charging the battery? In other words, if I forget to unplug the solar panel when I use the vehicle, will it damage the panel or controler? Thanks!

    Reply  •  June 5, 2014 at 2:54 pm
  • Nelson Erhieguke
    sir my inverter is 24volts can it work with 20watts solar panel?

    Reply  •  May 26, 2014 at 1:32 pm
    • BatteryStuff Tech
      The inverter will run off of a battery bank, not the panel directly. If your bank of batteries is 24 volts, then you can use a 24 volt inverter. This would also require that the solar charging system is 24 volts as well.

      Reply  •  May 27, 2014 at 9:47 am
  • Malzy
    Dear sir, thanks for your fantastic help on your previous answers, i will be gr8ful if you could clear my doubt here. I just bought a 135 watts panel and i want to buy inverter with the batteries. so which batteries is recommended for me to buy?

    Reply  •  Rated article 5  •  May 5, 2014 at 1:57 am
  • Wilson
    Hi, I have an ED4 Exide Deep Cycle Battery (55ah) and I wish to set up a solar system for charging the battery. The battery is used in a boat for lighting and electronics, (sounder and GPs.) The battery would be used for about 8 hours every two weeks.

    What would you suggest please.

    Reply  •  May 3, 2014 at 6:59 am
  • Christina
    I was just curious I was reading up on battery banks that you can connect to solar panels. I was wondering could you connect the battery bank to a house or would you have to connect the solar panel to the house?

    Reply  •  Rated article 5  •  April 30, 2014 at 8:13 am
  • Rebin
    Hi, I have a summer villa and would like to connect 40 outdoor lamps (each one 20W) in 1 cable 500m for lighting around my yard. What solution do I need to setup this network? I have 8 hours of direct sun a day and would like the lighting to work for 8 hours in night.
    I live in Iraq and we have sun all year around.


    Reply  •  April 28, 2014 at 5:55 am
  • David Burk
    Hi, this site has been the most helpful of any I’ve visited, much appreciated information. I have my system pretty well figured out except for the amps that my inverter will use which I never really figured into the equation… I have 3 100w panels (total 300 watts) hooked to a charge controller and 2 6v batteries hooked up to deliver 12V and 225AH… to that I have a 2000w peak 1000w continuous inverter hooked up.

    This set up is designed to run a single 70W HPS light each night for 7 hours… I figured with the ballast that the total wattage used by this light at apx 95w an hour… your calculator shows that I’m right on the money for 7 hours of use every night, never depleting my batteries past 50%, and getting a full recharge each day on 5 hours of sunlight. The problem comes in when I factor in the INVERTER which according to your article would use 10 DC amps per hour in my case, which equates to 120 watts just for the inverter, more that the light is using.

    Am I figuring it correctly? The inverter needs 120w and the light another 95 watts for a total of 215 watts? If thats the case then according to your calcualtor I would need 4 more panels… any insight would be appreciated.

    Reply  •  Rated article 5  •  April 7, 2014 at 8:33 pm
  • Dakotah
    how do you connect a 2.5 solar panel to a battery charger

    Reply  •  April 1, 2014 at 10:29 am
  • Louis Peter
    A friend gave me a Sharp Solar Module with the following nominal ratings:
    Maximum Power 90w
    Open Circuit current 59.8v
    Short Circuit Current 2.62A
    Voltage at point of Maximum 45.4v
    current at point of maximum 1.99A
    Maximum System Voltage 600V
    Maximum Series Fuse 5A.

    My Questions
    1. How efficiently can the solar module be used?
    2. Can it work with 650watt inverter with 2 Heavy duty battery? That’s what is common over here.
    Keep the good work going.

    Reply  •  March 23, 2014 at 5:19 am
  • Col
    Can panels that are 200W with open circuit voltage of 45.50 be used to charge 24 volt batteries?

    Reply  •  February 8, 2014 at 12:19 pm
    • Jeremy
      Yes, though you will need a controller.

      Reply  •  Rated article 5  •  February 10, 2014 at 8:40 am
  • Thaddeus
    am extremly emplaced your info is quite helpfull thanks.

    Reply  •  Rated article 5  •  September 26, 2013 at 12:26 pm
  • Susan
    Recently, we have been swapping our deep cycle batteries out for gel batteries.
    We were told that solar panels do not work with these kind of batteries? Any truth? It does seem like we are fighting our system more and more! It is a mixed system with gels and deep cycles, but it sounds like i should pull out the gels and make them one separate bank that I charge from the generator and keep the deep cycles charged from the panels. Any suggestions are appreciated-

    Reply  •  March 7, 2013 at 5:38 am
    • BatteryStuff Tech
      Gel batteries are generally made for deep cycle applications. They are more fragile, therefore require chargers/controllers that are compatible. Connecting a solar panel to a gel battery directly will fry the battery. But if you use a gel compatible controller in between, then it is safe to use solar on these batteries. Same goes for the generator. Please use a gel approved battery charger.

      Reply  •  March 7, 2013 at 8:48 am
  • Bosunj
    How long do I have from the time I mount the panels to when they must be attached to the batteries? One hour? One day? Perhaps the better question is will the panel burn out if there is no battery hooked to it. Thank you.

    Reply  •  March 4, 2013 at 7:46 pm
    • BatteryStuff Tech
      There is no harm done to the panel if it is not connected to a battery.

      Reply  •  March 5, 2013 at 9:18 am
  • Adios
    Not what I wanted

    Reply  •  January 31, 2013 at 11:15 am
    • BatteryStuff Tech
      I‘m sorry to hear about your disappointment.

      Reply  •  January 31, 2013 at 11:34 am
  • Solar Air Conditioner
    Most of us are not fully aware about the real fact of the sunlight needed for these panels. Like said it here it takes direct sunshine on the surface of the panel to produce the maximum rated power of a solar panel. The manufacturers or distributors has never pointed out this information while describing their products.

    Reply  •  December 25, 2012 at 9:48 am
  • Robert Montie
    Hi, I am building a Cedar Strip Canoe. I plan on using a Eletric Trolling motor, my plane is to use a solor powered battery charger to keep my power supplied. Any Ideas which Soloor pannel I should use and hook up Ideas. I am thinking of suspending pannel like a spoiller above the back of the boat.

    Reply  •  December 3, 2012 at 7:02 pm
    • BatteryStuff Tech
      Sounds good. Please use our solar calculator to find the correct size solar panel for your plane.

      Reply  •  December 4, 2012 at 8:04 am
  • Franklin Kofi
    Very educative here. I have an inverter of 3.5KVA of 48V, I never charged with panel but through your explanation, i would like to give it a try. How many panels do i need and what and what can i use on it?? And if the Amperage is low or high which is good ?, i need more explantion about that.

    Reply  •  November 12, 2012 at 7:25 am
    • BatteryStuff Tech
      If you have a 48 volt system, you need the solar panels to also equal 48 volts. Our panels are 12 volts nominal, so you will need a minimum of 4 panels in series to create 48 volts. The size of the solar system depends entirely on your battery configuration and the amount of load your system takes. Please have a look at our other tutorials and calculators for the information you‘re looking for.

      Reply  •  November 12, 2012 at 8:23 am
      • Franklin Kofi
        Thanks for your time and explanations. Am trying to learn to keep my inverter in good safe. 1) Thats it mean the tally voltage of the batteries should equal that of the voltage of inverter?? I have six 100amps batteries. 2) the amperage that comes out should it be lesser or greater than the one coming in??? I tried your tuturial but could not get the exact explanation. Thnks. Franklin Kofi

        Reply  •  November 13, 2012 at 12:03 am
        • BatteryStuff Tech
          Whatever the input voltage is for the inverter, you need your batteries to have that nominal voltage. Your inverter is rated in watts, which is equal to volts x amps. If your load is in 120 VAC, use this number and multiply it by the amp load from your device (not the batteries). This number is power going through the inverter and it should be less than what the inverter is rated for.

          Because battery voltage is less than 120, the amperage from the batteries will have to be much higher than the AC amperage, but the total power will be the same because of Ohm‘s Law. Volts x Amps = Watts.

          Reply  •  November 13, 2012 at 9:07 am
  • Iqbal Singh
    can u tell me that a commonly known as 100 watt 12 volt solar panel has 100 watts as peak value or this value is some other value. i want to know that a 100 watt solar panel at 1000w/m2 insolation and 25 deg centigrade temprature produces 100 watts of power or not?

    Reply  •  October 10, 2012 at 12:07 am
    • BatteryStuff Tech
      A 100 Watt solar panel is the maximum power the panel can produce. The voltage and amperage will vary depending on the strength of the sunlight, but the ratio of volts x amps will always equal up to 100 Watts, but never more. Solar panels can vary in efficiency when you consider age, weather, angle, etc. If you need guaranteed at least 100 watts, I recommend using a higher rated panel to be on the safe side.

      Reply  •  October 10, 2012 at 9:50 am
  • Spener F.
    Thank you for your information here. It is VERY helpful. If you have a minute to help me, I would appreciate it. I am getting ready to do my Science Project for 8th grade. I am making a motor and then powering it with various battery sources (of different voltages) then seeing how the motor speed reacts. I am ready to do that, but I want to add more to the project. I am thinking about also trying to run the motor with a solar panel. I was thinking that I would buy a small solar panel, then leave it in direct sunlight for 3 different times (like 6, 8 ,12 hours) and test the motor speed with the solar panel charged for each length of time. Does that sound possible? Or like a realistic thing to do? Or do you have a better suggestion?

    Reply  •  October 7, 2012 at 7:59 am
    • BatteryStuff Tech
      I‘m glad you found our information useful. A solar panel does not store energy. That is what a battery is for. Solar panels are often used as a way to recharge a battery. But if you connect to a solar panel in sunlight, it will only give you LIVE energy as the panel received sunlight. No sun, no power. It‘s as simple as that. A 12 volt solar panel (in direct sunlight) can reach as high as voltage as 22 volts. This is caused by the sunlight‘s own variation in UV rays throughout the day. Maybe this would be something worth testing, the variation in the strength of sunlight?

      Reply  •  October 8, 2012 at 8:42 am
  • Teddy
    Hi, installing many solar panel systems, this is a question about battery chargers. Most systems are the same, several panels, a solar charger, batteries (12V system), inverter.
    Now most people for whom I install also have a water pump that they run with the help of a generator, some of them have 12v output, some gennies Do Not!
    To augment the charging process (esp in days of no sun) all clients would like to be able to use their gennie aswell as the regular solar setup!
    What system (charger) do you recommend? Options? Is there a DC/AC input charger or is manual switching necessary ????
    Not quite sure what is needed?

    Reply  •  August 26, 2012 at 1:20 pm
    • BatteryStuff Tech
      We do not carry a charger that switches AC/DC input with a switch. If your generator outputs at 120 AC, then you may use a regular AC battery charger. As soon as the generator is off, then the solar system will take over. Please only use one or the other as both charging systems running at the same time will throw off the readings of the micro processors in the chargers. This is what I recommend.

      Reply  •  August 27, 2012 at 10:34 am
  • Shahzad
    I have 500 watts solar panels with 24 volts. Is there any inverter/ amplifier which amplifies it to 1500 watts to run an AC load? By the way solar inverter are only inverter or amplifier also ?? I need solar inverter+amplifier. Which take 24volts and 500 watts solar power and amplifies and inverts it to 1500watts to run AC load.

    Reply  •  August 19, 2012 at 1:32 am
    • BatteryStuff Tech
      I am not sure about “amplifier”. If you need 24 VDC into 115 VAC, that‘s not a problem. We have inverters to do that. But to go from 500 watts to 1500 watts requires more input. There is no device that can take power and simply turn it into more power. It‘s not like volume. As a matter of fact, when you connect your solar to an inverter (which should only be done with a bank of batteries in between), you will actually have ~15% inefficiency loss at each connection. You will loose power, not gain it. If you want 1500 watts AC, you will need a lot more solar power and/or battery power in the form of a battery bank.

      FYI, a battery bank to run a load of 1500 watts for 1 hour through an inverter should be no less than 24 volts, and 180 AH.

      Reply  •  August 20, 2012 at 11:29 am
  • Julian
    I bought a Powerfilm F15-600 10W folding panel to power my Maha PowerEX C401FS (12V DC)battery charger to charge my AA/AAA NiMH Eneloop batteries. Would a Powerfilm solid state MOSFET controller interfere with the ability of the Maha charger to properly charge my Eneloop batteries? The Maha is a smart charger after all (is it redundant), or could an overcharge from the panels damage the Maha charging unit? Should I use the Powerfilm controller? Thanks in advance, Julian L.

    Reply  •  August 18, 2012 at 1:52 am
    • BatteryStuff Tech
      A 12 volt panel can reach as high as 21 volts in direct sunlight. This can harm sensitive 12 volt devices. That is why I recommend connecting the panel to a deep cycle 12 volt SLA battery (the controller will prevent overcharge to the battery) and the battery will provide the safe and steady supply of 12 VDC that your NiMH charger needs.

      Reply  •  August 20, 2012 at 11:22 am
      • Julian
        Thank you for your time and reply. There‘s an inline fuse in the Maha DC car adapter rated for 1.5A. Will the fuse protect against high voltage, or does it just protect against high current? I‘m looking for an extremely portable solution, would a portable battery with a built-in BMS (battery management system) prevent the need to purchase a bulky power controller? Thanks Again.

        Reply  •  August 21, 2012 at 4:34 am
        • BatteryStuff Tech
          The fuse is rated for current. 1.5 amps at 12.5 VDC roughly equates 18.75 Watts. A 10 watt panel should be fine to use with that controller. I do not have enough information about batteries with built-in BMS to verify if not using a controller will be safe.

          Reply  •  August 21, 2012 at 8:09 am
  • Denelle Sammy
    i have 7 32watts solar panel and i need a electrical drawing on how to connect them to a new grid tie will be on this i have started on researching material needed like morningstar ss6 controller
    I need about 20 amps for 8 hours a day 220volts A/C.load 1200btu a/c and 2 lights 1 television Can you send a line drawing for this system the battery and inverter needed and the size or awg of the wire.

    I live in a tropical island and have limited resources on solar equipment so if you can send a link to buy the items needed

    Reply  •  July 13, 2012 at 1:09 pm
    • BatteryStuff Tech
      I‘m sorry. Providing detailed installation diagrams is beyond the scope of the technical assitance we can offer.

      Reply  •  July 13, 2012 at 4:31 pm
  • Bob
    Can you help answer a question on switches? I have an 85 watt solar panel mounted on my rv. when I store the rv I remove the batteries. I need to install a switch between the panel and the controller.
    My Kyocera panel puts out 18.8 volts max.
    Can I use a 12v switch for this, or would a 24 volt switch be appropriate?

    Reply  •  June 28, 2012 at 7:20 pm
    • BatteryStuff Tech
      A 12 volt switch is recommended for a 12 volt system. If you believe 18.8 volts is too high, you can place the switch after the controller, which lowers the voltage from the panel to a safer 14.4-14.8 volts.

      Reply  •  June 29, 2012 at 8:35 am
  • Norman
    I want to run about 50 watts of continuous power 24/7. Do you think it‘s possible and if yes what sort of solar panel would I require?. I have a 10amp charge controller and a 1200w inverter since. my 50 watts of power are ac. I had planned on fixing the solar panel to the battery which in turn will be attached to the inverter.

    Reply  •  Rated article 5  •  June 6, 2012 at 3:47 pm
    • BatteryStuff Tech
      Have you tried using our calculators yet? With your information, you can figure out how many amps DC you draw from a 12 volt battery per hour. Then you can determine what size battery to give you continuous power by using that draw amount, and the duration (24+ hours). Finally, we have a calculator for sizing a solar panel to your system, based on your draw amount, battery size, and hours of direct sunlight in your area. Give our calculators a try, and if you‘re still having trouble, please email with your questions.

      Reply  •  June 6, 2012 at 4:26 pm
  • Alex
    Great article thanks.
    I have 210 watts of mixed 12v solar panels (1×130w, 1×60w, 1×20w) running into an MPPT charge controller, 2 6v 232ah deep cycle batteries from Interstate hooked together to make 12v 232ah. The 232ah is sufficient to run what I need daily but I'd like more. The mppt charge controller show on screen that in full sun during the Bulk stage I can get upto 9amps total and something like 130 watts going into the battery bank. The problem is when the battery gets to around 12.6-8 Volts the Charge controller switches to Float mode and only charges the batteries 1-3 amps. At that point i‘m loosing watts. Do I need a bigger battery bank so that it doesn‘t go into float as fast? I never get a charge more then 13.4 volts because of this float mode.

    Reply  •  June 3, 2012 at 12:27 am
    • BatteryStuff Tech
      If the batteries are reading 12.8 volts, that‘s fully charged. It‘s true that you can get up to 13 volts, but most of it is surface charge. Fresh batteries from the factory can also reach this voltage. But once the batteries reach 12.6-12.8 volts, you don‘t want to pump them with too much power. It takes time for the absorption stage, and then the float. Your controller sounds like a 3-stage charging unit. But more batteries will not solve the issue. Either change the settings on the controller, or get a new one. If you‘re having too many un-used watts from the solar panel, you may simply have a much larger solar system than what your application requires.

      Reply  •  June 5, 2012 at 11:27 am
  • Ray
    The frustration I have is looking at a home that is powered by AC AMPS and the individual circuit loads are usually 15-20 amps (greater for HD devices). Trying to envision that in watts or volts and then decifer if it is AC or DC makes it very confusing. What is required to configure a solar array that will deliver the equivalent of one 15amp ac and one 20 amp ac supply?

    Reply  •  May 21, 2012 at 10:57 pm
    • BatteryStuff Tech
      Most homes run AC. Here in the US, it‘s usually 115 volts. To find the wattage rating, multiply the amps by the volts. a circuit breaker up to 20 amps would have a 2300 Wattage rating. Solar panels are usually rated for 12 volts DC. A 15 watt solar panel will deliver roughly 1 amp DC. They‘re great for charging UPS batteries for emergencies or small cabins. But if you‘re looking for solar to assist or replace your traditional AC power, a grid tie inverter would be needed and then some. If you have a local solar outfit in your town, they should be able to set you up with a home system. Our solar kits are designed for RV/Marine applications, maybe a shed.

      Reply  •  May 22, 2012 at 10:47 am
  • Jim
    Why do some solar panels come with male cigarette plugs and talk about use with an inverter? Im assuming for a vehicle, you would plug the panel w/plug into one socket, then run the inverter off another? for a cycle of power supply (solar panel) and a usage point (inverter)?? I actually use 2-7watt panels for charging my boat batteries (hooked up directly to battery), hoping that is correct, instructions were very useless.


    Reply  •  May 19, 2012 at 9:12 pm
    • BatteryStuff Tech
      All of our solar panels can also be used with alligator clips or ring terminals. The cigarette light adapter is nice because it‘s less intrusive, doesn‘t require access under the hood, and it‘s easy to unplug. But you have a point, you cannot use a single cigarette port for the solar panel and the inverter. At that point, I recommend you use the inverter for what you need, and when you‘re finished, switch back to the solar panel to replenish the battery. Or connect the solar panel directly tot he battery and free up the port for the inverter. Likewise, some inverters can connect directly to the battery as well. And even some vehicles that have more than one port can have both connected via cigarette adapters at the same time. I hope this information helps.

      Reply  •  May 22, 2012 at 10:14 am
      • Jimmie Colon
        Can I connect a 100 watts solar panel through a 30A PMW charger controller directly to my truck’s battery?

        Reply  •  Rated article 5  •  May 19, 2016 at 6:06 am
        • BatteryStuff Tech
          It is preferred to connect solar panel to controller, and then controller to the battery. The original question here was about going through a cigarette lighter outlet… However with a 100 watt panel, I would only recommend going to the battery directly as you may exceed the fuse rating through the cigarette lighter.

          Reply  •  Rated article 5  •  May 19, 2016 at 1:17 pm
  • John Tennyson
    Have frig rated at 1.2 amps@ 115 volts, have 2 135 Kyocera panels feeding 4 deep cycle marine batteries{wal-marts biggest] why does it struggle on startup? Ive installed new start gear on compressor, still struggles, new inverter is Pure sine wave 400 watt/ 800 watt max, any ideas?

    Reply  •  Rated article 3  •  May 10, 2012 at 8:06 am
    • BatteryStuff Tech
      The fridge pulls about 12 amps from the batteries an hour. Your solar inputs around 20 amps an hour, but only during sunlight. Unless you get 15 hours of direct sunlight, you‘re pulling more than you‘re putting back into the batteries during a 24 hour period.

      Reply  •  May 10, 2012 at 9:10 am
  • Seth
    I‘m a solar novice, but am trying to power a 12V DC, 4.3 amp fan directly with a solar panel. My question is, if the panel is rated for a maximum wattage of 135 at at 17.7 volts and 7.63 amps, do I risk damaging the fan? I called the fan manufacturer and they didn‘t know the answer to this question. Or do I need a charge controller, or some other hardware, for this application. Thanks!

    Reply  •  May 8, 2012 at 2:02 pm
    • BatteryStuff Tech
      12 volt solar panels will have a range of voltage output, and it‘s uneven. This can cause some voltage sensitive applications to malfunction. I don‘t know about a fan, I would think maybe not. A controller would regulate the voltage, but these units are not simple “regulators”. They are designed to connect to a battery. They “read” the voltage input from the battery in order to determine what output voltage to let pass from the solar panel. Having a controller and no battery would not work. For the safest scenario, I recommend using a 12 volt, deep cycle battery with enough capacity to power your fan, and use the solar panel to recharge the battery daily.

      Reply  •  May 8, 2012 at 2:19 pm
  • Adam
    Sir/ma, Please, when inverter is power by ac supply how can i know that the inverter is fully charged, so that i can quickly switch it off. thanks

    Reply  •  May 3, 2012 at 12:55 am
    • BatteryStuff Tech
      Inverters cannot be fully charged because they are not batteries. They channel and change voltage, usually 12 volts DC goes into the inverter, and 120 volts AC comes out. If your inverter is also a charger, hopefully it is a 3-stage automatic charger, which will taper charge off automatically when the battery is full. If not, you can measure the voltage of your battery to determine if it is fully charged or not. Read our battery tutorials for this info.

      Reply  •  May 3, 2012 at 8:29 am
  • Murray
    I‘d like to run 16W of LED lights from a smallish battery that will be charged by a solar panel. What size panel and what size battery would be suitable to give me 3hrs of light per day for 3 days without charging the battery. In addition how long will it take the panel you suggest to charge the battery you suggest.
    Thanks very much. (My basic calc. suggests a 20W panel and a 35 Ahr battery? assuming the battery shouldn‘t discharge more than 50%)

    Reply  •  April 22, 2012 at 12:32 pm
    • BatteryStuff Tech
      Your basic calculations are pretty good. If you feel the need for more confirmation, you can run your numbers through our online calculators. I‘m sure you‘ll find similar recommendations. A 20 Watt Panel will deliver roughly 1.3 amps of charge an hour. A good 6-7 hours of direct sunlight will produce 7.8 – 9.1 amps of charge a day. How effective that is depends on how much capacity is remaining on your battery.

      Reply  •  April 23, 2012 at 9:23 am
  • HS
    Hi there- I‘m installing a 36000BTU multi split inverter air condition system in my home. The specs I see from on the ac unit is that it will operate at 2600W at 220VAC. I‘m hoping to be able to run this unit completely off grid as energy prices are quite high. In my area, I get approximately 6 to 8 hours of good sunlight. I expect that my air condition will be in operation Mon to Fri for 6 hours per day and on Saturday and Sunday 14 hours per day for a total of 58 hours per week. I‘m looking to use deep cycle batteries which are rated at 145ah. My hope is to use solar to recharge the batteries. My question My question is- how many batteries would I need to run this ac unit and how many solar panels would I need as well? Can you recommend which solar panels I should use? Thanks in advance.

    Reply  •  Rated article 5  •  April 21, 2012 at 10:28 am
  • Dan Oneil
    span class="caps">VERY HELPFULL EASY TO USE, GREAT JOB!!!

    Reply  •  Rated article 5  •  April 20, 2012 at 3:05 pm
  • Mickey
    can I run a 220 volt one half horse submersable pump from a solar aray using a 220 volt inverter and two deep clcle battaries? The pump is in a spring and is located fifty foot from a possible solar source. Is pump start up a problem with a inverter? Should I use a 24 volt system?

    Reply  •  April 12, 2012 at 9:21 pm
    • BatteryStuff Tech
      I‘m not quite sure how your system is set up. First of all, I would suggest running your pump off batteries, not from solar panels. Next, is your pump rated to draw 220 volts? If so, using an inverter is fine as long as the inverter is rated to handle the maximum load that the pump will pull from the batteries at any one time (Wattage rating). If your batteries are configured for 12 or 24 volts, make sure your inverter is also properly rated, as well as the solar panels. Everything has to match up.

      Reply  •  April 13, 2012 at 9:01 am
  • Camimel
    I have a 24v battery system: two 12 v batteries connected in series. But I have a 12 v solar panel. If I hook up that solar panel to one of the 12 v batteries, will it charge both batteries?

    Reply  •  Rated article 5  •  April 12, 2012 at 11:16 am
    • BatteryStuff Tech
      No, connecting your solar panel to one battery will only charge that one battery. But like series for batteries, you can connect another solar panel of the same rating to give you the 24 volts you need. It‘s very important that voltage systems match.

      Reply  •  April 12, 2012 at 11:28 am
      • Lance Lindskog
        If I use the 12v solar panel to charge the 24v battery system, will it still trickle charge in the long run?long

        Reply  •  June 23, 2014 at 2:20 pm
        • BatteryStuff Tech
          No, it will do, effectively, nothing. The charger and the battery must be in the same voltage system to work at all.

          Reply  •  June 25, 2014 at 9:08 am
  • Richard
    I want to use a solar system to recharge a deep cycle battery used to power cabin lights, heater blower, radio in my camper at night, when camping several days at a time, not re-charging by daily driving. I believe typical draw down of at most 25% of battery capacity each night. I am considering a 50 watt panel and a 4 amp charge controller. Do you think this will suffice for most normal situations?

    Reply  •  April 11, 2012 at 11:05 pm
    • Colleen
      You will need a couple more batteries if you want to power the heater blower-it takes a lot of energy. We are using a 125 Watt solar panel that we mounted to the roof of our camper trailer two years ago. At night it will power the lights/radio without losing too much battery charge. New L.E.D. lightbulbs replaced our most-used lights at night and have tested with little voltage loss (.1-.2 volts) with five lights on using 8 L.E.D. bulbs, Versus .8 volts decrease in battery power with 3-4 lights of 2 incandescent bulbs a piece. We can run CD player, run pump & charge a laptop using an inverter during middle of the day, no problem. Just have to conserve at night.

      Reply  •  May 4, 2012 at 5:53 pm
    • James Ville
      You have not provided enough information for me answer your question. Please use our solar calculator, entering your battery information, average draw amount, and number of hours of sunlight in your area. I believe you can find the answer for yourself :)

      Reply  •  April 12, 2012 at 9:10 am
  • Kat
    What solar panels do you recommend for NiMH battery packs?? More specifically a 12V 10aH.

    Reply  •  April 8, 2012 at 7:03 pm
    • BatteryStuff Tech
      Most of our panels are designed to charge lead acid battery types. Our Orange Joos solar charger has adapters for common cell phones and USB adapters. Otherwise, you can also use our Sunlinq foldable panels if you have a 12 volt cigarette lighter adapter for your battery pack. Otherwise, there is nothing else specifically designed for custom NiMH battery packs.

      Reply  •  April 9, 2012 at 9:40 am
  • Derik Denally
    The Solar Panel Support can be used to support solar panels on virtually any roofing system – from flat roofs to roofs sloped up to 2 in 12. Seismic and High-Wind applications are available for the system.

    Reply  •  March 23, 2012 at 8:57 am
  • David
    i am wonting to hook a solar battery tender to my game camera it takes a small 12v battery could you tell me what would work and what i would need to do this thanks

    Reply  •  March 9, 2012 at 6:16 pm
    • James Ville
      Our 12 volt rated solar panels will work for your camera 12 volt battery only if the battery is a lead acid chemistry. We do not recommend our solar panels if you have a lithium, NiCD, or NiMH battery pack.

      Reply  •  March 12, 2012 at 9:08 am
  • Steve
    Is there a distance that you have to maintain in cord length between the solor panel and the batt. being charged?
    changing our automatic gate opener batt each year. the tech said that the solor panel was not getting enough sun so he moved it about 40/50 feet. does the resistance in the wire reduce the effectivness of the ammount of emf that is being conducted by the solor panel to the batt.?
    steve loxahatchee, Florida

    Reply  •  Rated article 2  •  February 16, 2012 at 9:15 am
    • James
      Every connection you make, from panel, to battery, to inverter, etc will result in about a 15% energy loss at each point. If the panel was moved with a new set of longer cable, and not just an extension after extension, that would be the best thing to do. Other than that, 50 feet of cable is about the maximum I would recommend. There is a loss of energy due to distance, but within 50 feet it’s nothing to worry about. If your panel is receiving more sunlight in this new location, that would offset any loss due to cable length.

      Reply  •  Rated article 5  •  February 16, 2012 at 2:03 pm