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Solar Info: The Down Low on Everything Up High.

Solar Info

I am not sure what information most folks think they will find in a solar tutorial. Rain or shine we get a huge number of calls about solar power each day. We will attempt to answer the questions most often asked so we can save you a phone call.

Before we get started we think you need to know that solar power is not the cure all for replacing spent energy. For example some 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 summer time 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. 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.

VOLTAGE RATING

Most solar products offer are designed for 12 VDC, but we do have limited availability on a smaller 24 volt panels. 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 24, 36, 48 etc.

CONTROLLERS

SunForce 7 Amp Charge Controller with RingsAnytime you use a panel that is over 5 watts rated output, we recommend using a solar controller. Actually, a charge controller is a good idea in a majority of applications. A charge controller can provide several benefits such as preventing overcharge, improve charge quality, and prevent 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 case where a 6-watt or larger solar panel is installed use of a charger controller is highly recommended. In a nutshell, solar charge controllersact 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. So the morningstar SS-6, 6 amp controller will work with nearly every panel we sell right up to about 70 watts.

POWER RATING WATTS AND AMPS

SP-5 Solar PanelSolar panels 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 SP-5 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. Typically this power output is stored in a battery for use when the panel is not producing energy. This energy is stored for later use and also allows the battery to act as a filter to prevent damage to any sensitive electronics you may be powering.

HOW DO I FIGURE SOLAR PANEL SIZE

The first thing to remember about solar power is that it is all a matter of numbers. The power you require, vs. 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 will 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, get 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 watts-hours needed. You should always err on the side of caution and over-estimate your power needs. This will 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

OUTPUT CONDITIONS

Solar panels ratings are calculated in bright direct sunlight. Conditions such as indirect sunlight, overcast and partial shade 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 be quite different.

OPERATING A DEVICE DIRECTLY FROM SOLAR PANEL

Joos-Orange Portable Solar ChargerThis can be done as long as the device is designed for such an application and not sensitive to voltage variations. It is best to use a battery as a storage container for energy that will provide constant source of stable, reliable power.

 

ARE SOLAR PANELS WEATHER PROOF

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

DO I HAVE TO MAINTAIN SOLAR PANELS

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.

HOW LONG DO SOLAR PANELS LAST

30 Watt Lightweight Unbreakable Solar Module BSP3012LSS

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 Pakichinastan.

 

USE OF AN INVERTER

SSW-1500-12A Samlex PSW inverter 12v 1500wMany folks use an inverter to convert 12 VDC to 110 VAC. Inverters, because whenever you change power from one form to another, 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 than otherwise.

FORMULA DC to AC via an Inverter

Formulas and Examples for 12 & 24 Volt DC Systems

This “Rule of Thumb” is intended as a general guide for estimating the DC amps required operating a DC to AC inverter. Since the calculations yield approximate values, an appropriate safety factor should be considered when designing and specifying system components, for example: wire, size, and length. This basicly is legalese for "oversise 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?

Answer:

  • 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 five (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?

Answer:

  • 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.

Spreadsheet icon Solar Calculator


 
66 Responses,   4.4 Rating

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  • 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

    Steve
    February 16, 2012 a 9:15 am
    • 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.

      James
      February 16, 2012 a 2:03 pm
    • 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

      David
      March 9, 2012 a 6:16 pm
      • 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.

        James Ville
        March 12, 2012 a 9:08 am
      • 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.

        Derik Denally
        March 23, 2012 a 8:57 am
        • What solar panels do you recommend for NiMH battery packs?? More specifically a 12V 10aH.

          Kat
          April 8, 2012 a 7:03 pm
          • 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.

            Tech
            April 9, 2012 a 9:40 am
          • 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?

            Richard
            April 11, 2012 a 11:05 pm
            • 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 :)

              James Ville
              April 12, 2012 a 9:10 am
              • 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.

                Colleen
                May 4, 2012 a 5:53 pm
              • 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?

                Camimel
                April 12, 2012 a 11:16 am
                • 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.

                  Tech
                  April 12, 2012 a 11:28 am
                • 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?

                  Mickey
                  April 12, 2012 a 9:21 pm
                  • 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.

                    Tech
                    April 13, 2012 a 9:01 am
                  • VERY HELPFULL EASY TO USE, GREAT JOB!!!

                    Dan Oneil
                    April 20, 2012 a 3:05 pm
                    • 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.

                      HS
                      April 21, 2012 a 10:28 am
                    • Hi,
                      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%)

                      Murray
                      April 22, 2012 a 12:32 pm
                      • 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.

                        Tech
                        April 23, 2012 a 9:23 am
                      • 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

                        Adam
                        May 3, 2012 a 12:55 am
                        • 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.

                          Tech
                          May 3, 2012 a 8:29 am
                        • 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!

                          Seth
                          May 8, 2012 a 2:02 pm
                          • 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.

                            Tech
                            May 8, 2012 a 2:19 pm
                          • 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?

                            John Tennyson
                            May 10, 2012 a 8:06 am
                            • 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.

                              Tech
                              May 10, 2012 a 9:10 am
                            • 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.

                              Thanks

                              Jim
                              May 19, 2012 a 9:12 pm
                              • 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.

                                Tech
                                May 22, 2012 a 10:14 am
                              • 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?

                                Ray
                                May 21, 2012 a 10:57 pm
                                • 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.

                                  Tech
                                  May 22, 2012 a 10:47 am
                                • 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.

                                  Alex
                                  June 3, 2012 a 12:27 am
                                  • 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.

                                    Tech
                                    June 5, 2012 a 11:27 am
                                  • 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.

                                    Norman
                                    June 6, 2012 a 3:47 pm
                                    • 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 tech@batterystuff.com with your questions.

                                      Tech
                                      June 6, 2012 a 4:26 pm
                                    • 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?

                                      Bob
                                      June 28, 2012 a 7:20 pm
                                      • 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.

                                        Tech
                                        June 29, 2012 a 8:35 am
                                      • i have 7 32watts solar panel and i need a electrical drawing on how to connect them to a new system.no grid tie will be on this system.so 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

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

                                          Tech
                                          July 13, 2012 a 4:31 pm
                                        • 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.

                                          Julian
                                          August 18, 2012 a 1:52 am
                                          • 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.

                                            Tech
                                            August 20, 2012 a 11:22 am
                                            • 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.

                                              Julian
                                              August 21, 2012 a 4:34 am
                                              • 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.

                                                Tech
                                                August 21, 2012 a 8:09 am
                                          • 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.

                                            Shahzad
                                            August 19, 2012 a 1:32 am
                                            • 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.

                                              Tech
                                              August 20, 2012 a 11:29 am
                                            • 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?
                                              Thanks.

                                              Teddy
                                              August 26, 2012 a 1:20 pm
                                              • 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.

                                                Tech
                                                August 27, 2012 a 10:34 am
                                              • 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?

                                                Spener F.
                                                October 7, 2012 a 7:59 am
                                                • 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?

                                                  Tech
                                                  October 8, 2012 a 8:42 am
                                                • 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?

                                                  Iqbal Singh
                                                  October 10, 2012 a 12:07 am
                                                  • 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.

                                                    Tech
                                                    October 10, 2012 a 9:50 am
                                                  • 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.

                                                    Franklin Kofi
                                                    November 12, 2012 a 7:25 am
                                                    • 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.

                                                      Tech
                                                      November 12, 2012 a 8:23 am
                                                      • 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

                                                        Franklin Kofi
                                                        November 13, 2012 a 12:03 am
                                                        • 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.

                                                          Tech
                                                          November 13, 2012 a 9:07 am
                                                    • 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.

                                                      Robert Montie
                                                      December 3, 2012 a 7:02 pm
                                                      • Sounds good. Please use our solar calculator to find the correct size solar panel for your plane.

                                                        Tech
                                                        December 4, 2012 a 8:04 am
                                                      • 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.

                                                        Solar Air Conditioner
                                                        December 25, 2012 a 9:48 am
                                                        • Not what I wanted

                                                          Adios
                                                          January 31, 2013 a 11:15 am
                                                          • I‘m sorry to hear about your disappointment.

                                                            Tech
                                                            January 31, 2013 a 11:34 am
                                                          • 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.

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

                                                              Tech
                                                              March 5, 2013 a 9:18 am
                                                            • 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-

                                                              Susan
                                                              March 7, 2013 a 5:38 am
                                                              • 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.

                                                                Tech
                                                                March 7, 2013 a 8:48 am
                                                              • am extremly emplaced your info is quite helpfull thanks.

                                                                Thaddeus
                                                                September 26, 2013 a 12:26 pm
                                                                • Can panels that are 200W with open circuit voltage of 45.50 be used to charge 24 volt batteries?

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

                                                                    Jeremy
                                                                    February 10, 2014 a 8:40 am
                                                                  • 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.

                                                                    Louis Peter
                                                                    March 23, 2014 a 5:19 am
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