Comments on: Solar Panel Calculator

By: K L Parker

K L Parker — Tue, 17 Sep 2024 18:23:33 -0700

This calculator is awesome. I was right on point with 3 panels and a 300Am battery! thank you! I have shared your link with a good dozen people.

By: Jeff Canton

Jeff Canton — Fri, 06 Sep 2024 10:30:39 -0700

I have 16 panels each 370 watts and im trying to find a proper grid tie inverter 48v dc and total 5920 watts

By: Johan Potgieter

Johan Potgieter — Thu, 30 May 2024 05:33:22 -0700

I want to run a 12v dc pump 160w 14 amps only pumping daytime what would i need to power the pump

By: Daniel deWaard

Daniel deWaard — Tue, 21 May 2024 22:26:11 -0700

we are thinking of running a 12v water pump and 12 v lights at a remote hunting camp, what would we need to set up this system? solar panel size and batteries,etc?

By: William John Miller

William John Miller — Mon, 20 Mar 2023 17:20:47 -0700

I have a 100w mono solar panal 30 amp controller for more panels later and bought a 12v 18ah agm battery that has a initial start up of 5.4 amps will this work . I just need the small battery to hold power to charge phones etc at night after a hunt while camping . Will this battery burn up

By: Sandra Bagg

Sandra Bagg — Tue, 13 Sep 2022 10:40:39 -0700

I would like to power a 240v-980kWh fridge using 12v panels. Would 1 kW of panels be sufficient with a 1kWh battery? Also what other equipment would I need? Please help. Thanks so much.

By: Tony akkari

Tony akkari — Fri, 26 Nov 2021 18:53:56 -0800

Hi there I have in mind 5 solar panels at 360w each to charge 4 x200ah lithium batteries at 48v..what is the qty and specs of regulator needed please

By: Chris

Chris — Fri, 01 Oct 2021 15:16:09 -0700

Excellent calculator but it doesn't allow for PVs with voltages above 16v

By: Allen Hutton

Allen Hutton — Thu, 11 Jun 2020 21:08:13 -0700

A very good page with an easy to use calculator that takes all of the guess work away. Thank you.

By: Louie Langley

Louie Langley — Wed, 29 Apr 2020 19:55:24 -0700

I have a 12 volt refrigerator in my new camper. It says it draws 3-5 amps per hour depending on how much it is opened. What size solar panel can I get to keep the battery charged when not in use

By: Joe

Joe — Fri, 01 Jul 2016 12:25:08 -0700

I love this webpage and have learned a lot reading through the comments and responses. My questions is regarding my dual battery bank on my boat. Battery 1 (12v) is a 1000 cranking amp for starting the engine only. Battery 2 is a DieHard deep cycle 565 CCA for the house (the bilge is on this battery and is set to automatic since the boat sits in the water when not in use). I just want to install a solar panel for each of the batteries to keep them topped off in between runs with the boat. I can go weeks to several months without using the boat at times. I am assuming a 7 to 10 watt panel per battery without a regulator should do the trick. Would you agree? Also, is it okay to keep the panels connected to the battery while the engine is in use? I have read on other websites different opinions about this. Any advice would be greatly appreciated. Thank you.

By: Erick

Erick — Mon, 13 Jun 2016 13:39:48 -0700

I am building a small weather station 12V power system, and was trying to solve for hand calcs for number of panels, I saw there was a mention of line 29 was the total wattage PV over the size of panel. So is that the equivelent of taking line (10 or 11) and dividing it over the product of line (24 and 25). i.e. If my total daily wattage was 4.2 WH or 4.284 WH adjusted do I divide that with the product of the 5 watt panel and the 2.903 Hours of sunlight adjusted. The populated form line 29 has an answer of .393, but my answer was .2951. Just trying to wrap my head around it, could you please help with explaining how to set up to solve for line 29.

By: ka8jmw

ka8jmw — Thu, 02 Jun 2016 11:38:18 -0700

Whats the recovery time in days after the battery bank has been deplete? After 7 days of no sun how many days before the battery bank has been recharged?

By: Ratty

Ratty — Mon, 23 May 2016 23:31:55 -0700

Hi, this is really good, but I am still totally confused, apologies for my lack of experience. I have a hot tub and want to use a solar water panel to add supplementary heat to the water, this requires a small 12v pump to circulate the water, but only when the sun is out, therefore I don’t need any permanent or backup power, only on when sunny. The pump I have purchased is classed as 20-60 watt 12v. I plan to connect this directly to the panel. What size panel will this require? Sorry but I think the calculator only works when sizing systems with batteries, but this is not how I want the system to work, thanks.

By: baldbemused

baldbemused — Tue, 12 Apr 2016 06:41:51 -0700

This was a great find – thanks for being there!

By: Dieter

Dieter — Thu, 13 Nov 2014 11:35:00 -0800

I can install my 2 300W solar panels 30 feet from the inverter/battery with about a 30% loss of sunlight hours (5.5 yearly avg.), or 120 feet away at 100%. Any suggestion on cabling size differences, potential power loss and any other consequences? Thanks

By: harish

harish — Sat, 11 Oct 2014 20:27:40 -0700

i want to know the size of a solar panel for supplying a 48V,50A battery. this battery is to be used for a kart.pls do reply soon

By: Tyler

Tyler — Wed, 08 Oct 2014 15:23:24 -0700

The batteries in parallel (field 19) and the batteries in series (field 20) should be multiplied to get the value for total number of batteries (field 21). Right now batteries in parallel is divided by batteries in series to get the total number of batteries. Also I would add the battery voltage as an input and calculate the batteries in series based on that input, right now it assumes 12 volt batteries but your website has 6 volt and even 2 volt available too. Just some suggestions to improve the output.

By: gray

gray — Sat, 04 Oct 2014 06:01:47 -0700

50 watts solar panel + 40 amps battery ist good for running a 32” led and charge some gadgets…

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

By: Frawsen

Frawsen — Tue, 08 Jul 2014 07:53:56 -0700

sorry for my bad english! what I called “Earth Socket” in my inquiry is actually “cesspits”. I sincerely apologize for confusing you! :)
I hope you will be able to respond to my email if you do not think my inquiry fits to the comments in here.
Thank you very much in advance! and I’d like to ask for a quotation for such a solution.
Kindly, Frawsen

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

By: Frawsen

Frawsen — Mon, 07 Jul 2014 18:55:02 -0700

Hi,
Thanks for this calculation tool! It is fantastic!
However, since I’m filling in it for the first time, I would appreciate to compare and assure that I’m doing wright. So please give the end answer (i.e. number of batteries as well as solar panels) if the need is an earth closet with an electrical rotor (25 W-AC with 230 VAC that goes ca 1.5 minutes after each use. Assume 3 uses/day) and an electrical heating motor (of either 255 or 80 W-AC with 230 VAC depending on the temp. The ambient temp shall be 80 degrees Celsius. The use of the earth closet is only summer time – i.e. May to September in southern Sweden, Scandinavia). There is a fan as well, which consumes 25 W-AC and a light bulb with 5 Watts. I guess these two go on when the earth closet is in use.

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

By: Barry

Barry — Fri, 04 Jul 2014 16:13:56 -0700

Thank you for ths this great calculator. I have 4 × 12v 100 amp hour batteries wired in series to 48v. I also have 2.5 kw of solar panels and a 48v 60amp max charger. Total max charge current is 36amps at 48v. Does this mean I have too much charging current going to my batteries? At 12v they have a max recommended charging current of 10amps each. Thanks in advance if you can help me.

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

By: zaks

zaks — Wed, 25 Jun 2014 05:44:54 -0700

Am having a challenge with line 29: to determine the number of solar panels in parallel. Please advise. Thanks.

Zaks

By: David B

David B — Mon, 19 May 2014 11:26:01 -0700

I want a small stand-alone 12 volt DC system to power 2 × 14 watt DC L.E.D outdoor light for 12 hrs/day. Only 1 day of back up needed as I will retain the existing AC light. I entered “20” in field #18 [Battery Amp Rating (20)hr]; 5.6 hrs of sun/day (field #22); 70 watt panel and ended up with a total requirement of 1 battery. Was the Field #18 entry correct?

By: Steve J

Steve J — Sun, 11 May 2014 07:40:59 -0700

First line says total watts per hour is DC Amps x 12 but if I’m running a 24VDC Nemo well pump then wouldn’t it be DC Amps x 24 ? The pump needs 4-4.2 amps at its current depth.

By: David Brown

David Brown — Fri, 12 Jul 2013 12:28:11 -0700

great posting, thanks

By: Peter G

Peter G — Mon, 29 Apr 2013 10:59:32 -0700

What size panel do I need to trickle charge a 12volt battery for a John Deere riding lawnmower?

By: Dewale

Dewale — Sat, 23 Mar 2013 12:35:57 -0700

Thanks for a very useful tool.
What is the limit of total solar watts that can be connected to a given ah battery? I have a 800 watts, 12V, 200AH inverter system. I have a 500 watts AC load to be powered daily for at least 8 hours. The calculation showed I need 15 nos of 120 watts panel in parallel connection to charge the 200ah battery. At what point do I reach the maximum no of panels (in watts or amp) that can be connected on a given battery?

By: kevin

kevin — Sat, 02 Mar 2013 08:39:40 -0800

hi I have a 60 watt solar panel – i need to run a laptop for 4 hours a day and 3 lightbulbs for 4 hours per day – i have a 88ah/640amp battery and recieve roughly 8-9 hours per day. I have 1000 watt sine inverter i have a new xundel controller which always shows that the battery is fully charged however the controller beeps that battery power is low after only using the laptop for 2 hours- what else do i need.

By: Waseem

Waseem — Sat, 26 Jan 2013 21:27:05 -0800

Dear Tech, its nice to come to know about your such a good and infomative site, great work.

my quesition is
I can get calculation about Solar Panel and Battery bank but I can not see any Information about charge controller to find the exact value? so how to calculate the amperage of charge controller that to be used in the system to charge the battery?

thanks

By: VYAPU

VYAPU — Fri, 04 Jan 2013 21:51:06 -0800

how much amp battery is required for 40 watt solar panel where sunlight
is available for 9 hour. is 5 am battery is suitable for 40 watt solar panel

By: Chris

Chris — Tue, 01 Jan 2013 11:06:11 -0800

What is meant by batteries in parallel and is this absolutey necessary

By: Catprog

Catprog — Thu, 13 Dec 2012 03:33:35 -0800

On figures of 3,24,12,1,40 I get <0.5 battery required. Then when rounded it gets rounded down to 0.

By: Willie

Willie — Sun, 11 Nov 2012 07:11:08 -0800

Hi, most interesting. What is the maximum DOD ( degree of Depletion) would you allow your batteries to drop to on a daily basis, taking into consideration the deeper you go the less cycles you will get out of a set of batteries. I am taking mine down to between 20% and 30 %. Your comments please. I see no mention of any regulation in the comments and questions above? I use a MPPT 40 amp regulator? What do you think of the MPPT from outback or Microcare or any other for that matter.
Willie. Montagu, South Africa.

By: Jermaine

Jermaine — Wed, 07 Nov 2012 22:10:33 -0800

I am new to learning solar power and I\‘ve been doing some research for a school project. I want to design/redesign a solar charger that charges a battery bank thats capable enough to charge a 12 volt car battery but at the same time I want to charge small electronics too. I want to use the battery bank to charge these for later use. How would I go about using solar panels and a battery bank to charge a car battery but not overcharging and burning up small electronic rechargeable batteries? Thanks

By: Adeyemi T

Adeyemi T — Wed, 07 Nov 2012 08:57:17 -0800

Dear Tech
I have 4X160AH battery with a 48V 5KVA inverter,l would like to know how many solar panels i need to get and the charge controller?

By: Micah

Micah — Wed, 24 Oct 2012 03:44:32 -0700

I had a question about the Solar Panel array. If I\‘m sizing a system, and I want just one solar panel for the system with no additional panels in parallel then I would: under item 25 (selecting panel size) I would insert a panel wattage until item 31(rounded number of solar panels) approaches 1?

Thanks in advance for clarifying the situation!

My background: I\‘m doing an undergraduate project where I\‘m building a PV powered Vapor Compression Refrigeration system. I\‘ve estimated that the power consumption is about 300 watts per day, or 12.5 per hour 24 hours a day. It will be running on a 12V system, and its days of backup should be between 1-3 days. I\‘m also limiting the system to 1 battery only. Where I\‘m from, using TMY3 data from our local airport, the average peak sun hours per day is around 5 hours. With this, I\‘m finding I need a panel of 130 watts.

Note: I\‘m only using this calculator as a reference for sizing the system so that I have a ball park of what to expect as I\‘m going along in the design and building process.

By: Abdullah Hasan Al ghaya

Abdullah Hasan Al ghaya — Sat, 20 Oct 2012 00:44:50 -0700

Gentlemen: Greetings I have loads electrical capacity of 15,000 watts which is about lambs ,fans and conditioners and fans Laptops and small mills Please help me choose a system capacity of the solar system works? As I hope that you know all the machines and equipment that will be used in the system in terms of quantity and number .. Thanks

By: iqbal singh

iqbal singh — Mon, 08 Oct 2012 03:07:43 -0700

i need information about a small household project. i m having a 1000watts A.C load and the A.C voltage is 220V. i need this load to be run continuously for 10 hrs a day without any backup. can u please do the calculations for the number of batteries and 100 watts solar panels i would need to install. invertor efficiency is about 90% and sun is available for 6 hrs a day. i want this system to fully rely on solar panels and no other source of power.

By: Jon

Jon — Thu, 04 Oct 2012 03:27:03 -0700

Hi
I am completely new to all these conversions and solar panels etc. I am trying to complete a very small diy project where I want to run a small aquarium air pump for 18hours a day. The pump is rated at 3.5w 240v ac. Are my calculations right in that this could be done with a small 30w panel. Bearing in mind I need to use an inverter as I can‘t source an adequate 12v dc pump .

By: Balakrishna

Balakrishna — Mon, 01 Oct 2012 10:11:30 -0700

I had a confusion with below items can some please explain

19 Actual # batteries wired in parallel Raw number number (gives 2.13 for my specifications)
20 Batteries wired in series Relates to system voltage number (gives 4.00 for my specifications)
21 Rounded number of Batteries Always rounded up number (gives 1 for my specifications)

By: craig

craig — Wed, 29 Aug 2012 18:48:53 -0700

I have a hunting cabin and I just need lights. I have 3 50 watt dc lights that I need to be on for about 6 hours at night for at most 3 days in a row I am in Minnesota with about 6 hours of sunlight in early November. I have a deep cycle battery 12 volt 130ah and a 18 watt solar charger. Will this work? Or what would be the cheapest fix.

By: Rocket

Rocket — Thu, 23 Aug 2012 10:02:27 -0700

Hi, this may sound a little stupid, but i am trying to get my head around 12v power Inverters and deep cycle Batteries. i tried to use your calculations, but came up with more questions that answers.

If I need 8amps (2500watts)per hour under full load (1 to 2 hrs daily) for cooking and about 1-2amps for lighting and radio 24/7.
I will be operating a 2500/5000w modified sine inverter, with a 140AH battery. Will this battery be capable of running this system? I was also looking at a 40watt solar panel through a 30amp regulator for recharging and a 2kva gen-set for use during the cloudy days, or will I need a larger AH battery and larger panel?
There is an average of 10 hours daylight (tropical climate),

If the calculation is correct, I will need 4 × 40watt panels.
It may be the numbers I entered,
line # and figures
3 = 100 (8amps x 12 rounded up)
6 = 7 (60 / 8 average)
12 = 12v system
14 = 1 backup (gen-set)
18 = 1 × 140AH battery
22 = 10 daylight (conservative 9closer to 12)
25 = 40 watt panel

told me I needed 4 × 40watt panels in line 31.

cheers for any advise,

By: Jasir

Jasir — Sat, 04 Aug 2012 06:24:25 -0700

thank you for your help. what does the 18th line mean? and how can i calculate or find this?. still i\‘m getting the wrong rounding at both battery and solar panel numbers, so i sent screenshot of the calculator to your e-mail: tech@batterystuff.com please check and help me about the wrong fields. my estimated watt demand is the device consumption from device data sheet not calculated by the formula DC Amps x 12 and system voltage is 48VDC.

By: Jasir

Jasir — Thu, 02 Aug 2012 03:52:52 -0700

my watt demand is 300w/h but i make 400 to increase the backup power is that is right sir? line 14: # of days backup power required, is that means the needed backup in whole week when we say 24*7= 168 hours and I have direct sun 10 hours daily which means 10*7 = 70hours sun light in week, so i need a backup of 168-70 = 98hours or 4.08 days is that is right sir?. line 19 Actual # batteries wired in parallel and rounded at line 21 to 2 so where is the problem in here. the same manner in solar panel, line 29 Number of solar panels in parallel 2.409 is calculated and rounded to 10 at line 31.

By: irfan ul haq

irfan ul haq — Tue, 10 Jul 2012 12:32:46 -0700

sir my load is 750 watts two coolerado units, i have ten 150 watts solar panels and eight batteries of 100AH each an inverter charge controller ,sun light is available for 6 hours.is it adequate system

By: suntamer

suntamer — Mon, 02 Jul 2012 19:23:10 -0700

Most of the comments address small loads over long periods of time. I am trying to powers a gate opener which operates five times a day for one minute cycles each time using 5.5 amps 110 volts and 500 watts at the peak of operation. I need a battery to support this. Currently I am using a 20 watt 12 volt panel with a 33 amp hour battery. This gives me about one cycle per per day then its done. Living in the tropics I get almost 10 hours of strong sunlight. I just can‘t get it figured. To complicate issues, the gate opener draws 0.05 amps and 5.5 watts when not operating to power proximity sensors. Do I need a serious battery bank for this power surge.

By: Tarek

Tarek — Sat, 16 Jun 2012 03:31:52 -0700

very useful…..thanks to the creator….

By: Don

Don — Tue, 12 Jun 2012 13:54:53 -0700

Filled out the calculator properly, I think, but if I put 2 days backup power, the rounded number of batteries comes up as 0. For 3 days, it comes up as 1. I am confused, shouldn‘t I always need at least one battery?

By: Amy

Amy — Wed, 30 May 2012 21:01:42 -0700

I have a attic exhaust fan that has a 38 volt motor. What is the optimum wattage for it to run? Thank you in advance.

By: Jesus

Jesus — Fri, 04 May 2012 16:56:59 -0700

I‘m trying to run a 2 amp(max draw)DC bilge pump 24/7, and have a 3 cloudy day reserve. Just got a 60W panel, and a new 115 Ah 12V deep cycle battery. Do I really need (3) 60W panels in series with (3) 115 Ah batteries to run a little tiny bilge pump constantly. I did calculations on my own before I found this site and bought the parts. Not sure how I came up so short. I get 7 hours a day of direct sunlight on the panel.

By: enriv

enriv — Sun, 15 Apr 2012 05:49:16 -0700

I have two-10 W solar panel and two-12 V small 12AH/20HR Battery bank. What is the best wiring diagram for my panels? is it parallel or in series to compensate a 5 hrs full-charging.

By: abdulla

abdulla — Tue, 27 Mar 2012 04:05:49 -0700

i need to figure out how many panels it will take to charge a 165ah, 12 V battery ?

By: Phil

Phil — Wed, 07 Mar 2012 17:43:01 -0800

Hi, I got a bit confused with the answers provided in blocks 29-31 of the calculator. It says in block 29 I need just over 7 panels in parallel. Block 30 says I need just 1 if in series. But block 31 says I need 8 total panels. ??? My plan was to just have a panel to keep a 90 aH deep cell battery charged in series. Well, 1 vs 7 is going to save me a lot of money. Can you clarify? Thanks!

By: Sean OBrien

Sean OBrien — Wed, 22 Feb 2012 15:34:55 -0800

By: Sean OBrien

Sean OBrien — Wed, 22 Feb 2012 15:32:57 -0800

HI
I just bought an energizer(84020 12V All-In-One Jump-Start System with Built-In Air Compressor and Power Inverter) as I am in sales and constantly on the road. I wanted to charge the battery with solar since I am in solar sales and I like to walk the walk. Its a 12v 18AH SLA but is expecting AC as the charge. I was wondering how many watt panel might supply an adequate recharge if I strap it to the roof of my FJ as I have latops phones and other sales tools plugged in to the unit. I ma guessing Ill need a small inverter and charge controller as well. Thanks in advance!

By: bill

bill — Mon, 20 Feb 2012 10:41:40 -0800

Very very helpful. I used it to size a backup panels and batteries for my refrigerator after a Hurricane. In 2005 locally some lost power for 3 weeks, this helped me calculate what I needed for refrigeration for me. The only question I have is could take a battery to 50%? Is that in Volts or AH?

By: abdullah al ghaya

abdullah al ghaya — Sat, 11 Feb 2012 04:17:40 -0800

thank you too much about good knowldge .

By: abdullah al ghaya

abdullah al ghaya — Wed, 08 Feb 2012 08:20:17 -0800

i am very thanks

By: Mike

Mike — Mon, 30 Jan 2012 15:18:38 -0800

what size solar trickle charger would I need for at jeep wrangler. It is the tow vehicle for my class a motorhome

By: Back pain relief

Back pain relief — Tue, 24 Jan 2012 18:25:15 -0800

I‘m not an expert when it comes to this. Didn‘t even know this was possible. Useful read, appreciate your posting this.