Solar Panel Size Calculator For Battery

Use our calculator to find out what size solar panel you need to charge any capacity, voltage, and type of solar battery in desired charge time.

“Enter the battery specs and desired charge time (in peak sun hours) into the calculator to find out what size solar panel you need to charge your battery”

Solar Panel Size Calculator

Battery Capacity (Amp-hours)
Ah
Battery Voltage
V
Battery Type
Battery Depth of Discharge (DoD)
%
Charge Controller Type
Desired Charge Time (Peak sun hours)
hours

Note: If you already have a solar panel and want to know how long it will take to charge your battery, use this solar battery charge time calculator.

Calculator Assumptions: 

  • Lead-acid Battery Charge efficiency rate: 85%
  • AGM Battery Charge efficiency rate: 85%
  • Lithium (LiFePO4) Charge efficiency rate: 99%
  • PWM charge controller: 80% efficient
  • MPPT charge controller: 98% efficient
  • Solar Panels Efficiency during peak sun hours: 80% (meaning a 100 watt solar panel will produce 80 watts during peak sun hours, i’ll explain why…)
  • Charge controller is the only load connected with the battery

What Size Solar Panel Do I Need To Charge Battery?

To find out what size solar panel you’d need to charge your battery, enter the following info into the calculator (located at the top of this page)

  • Battery Capacity: Enter your battery capacity in amp-hours (Ah). e.g 100 for 100ah battery.
  • Battery Volts: is this a 12, 24, or 48 volt battery?
  • Battery Type: Select the battery type, is this a lead-acid, AGM, or lithium-ion (LiFePO4) battery?
  • Battery Depth of discharge DoD: is the percentage of the battery that has been discharged relative to the total battery capacity. for half discharged battery you’d enter 50, (if the battery is fully discharged which you can achieve on lithium battery, ENTER 100)
  • Charge Controller Type: Are you using a PWM or MPPT charge controller to charge the battery? 
  • Desired Charge time (in peak sun hours): How fast would you like to charge your battery or how many peak sun hours your location receives? (keep reading i’ll explain how you can calculate the number of peak sun hours)  

After entering the information, click “Calculate” button to find the required size for a 200ah battery. 

Attention! Scroll down to the bottom of this page ( or click here ) to find out how you can calculate the size solar panel in future without any need of a online calculator.

Example 

Suppose you have a 12v 50ah lithium battery with 100% depth of discharge and an MPPT charge controller. You want to recharge your battery in one day (during summer days) and your location receives 6 hours of peak sunlight 

What size solar panel to charge 50ah battery

You’d need about 120 watts of solar panel to fully charge a 12v 50ah lithium (LiFePO4) battery from 100% depth of discharge in 6 peak sun hours using an MPPT charge controller.

Read the below post to find out how fast you can charge your battery.

Related Post: Guide: Maximum Charging Current & Voltage For 12v Battery

What Are Solar Peak Sun Hours?

Before explaining peak sun hours and why to use them, first, let’s see how solar panels are rated.

“ Solar panels are designed to produce their rated wattage output under standard test conditions – STC ”

STC includes: 

  • 1000 watts per meter square (1kw/m2) of sunlight intensity hitting the solar panels directly
  • 25oC temperature 

So to calculate the sunlight intensity we use peak sun hour as a reference. 

  • 1 peak sun hour = Average of 1kw/meter2 of sunlight intensity for one hour.

This number will depend on the location to location. To calculate how many peak sun hours your city receives use this PVwatt solar calculator.

Step 1: Enter your full address of just a city name & Click GO

How to calculate peak sun hours

Step 2: Click on results

How to calculate peak sun hours
How many peak sun hours in florida?

Now you’d be able to see the total amount of solar radiation your location receives per day (from month to month)

Note! it would have to place my solar panels all day long under sunlight to get those total solar radiations per day. 

Average Solar Panel Output In Peak Sun Hour 

As we know that solar panels are rated their power under a controlled laboratory environment. But in the real world, there will be some power losses 

These power losses will occur due to various reasons, here are some examples

  • Manufacturer’s output tolerance (+-3%)
  • Dirt and grime on panels (+-5%)
  • DC cable loss (+-3%)
  • Temperature derating (+-10 – 20%)

On average. A solar panel will produce about 80% of its rated wattage output in real-world conditions.

This percentage is based on my personal experience with 400 watt solar panels. I collected the 30 days of total output from the solar panels and divide it by that month’s peak sun hours. 

Yes, there’ll be sometimes when you’ll get 100% output from the solar panel but it’s rarely gonna happen and will last for a few minutes 

I have a detailed post about this topic and shared some tips to get the maximum output from your solar panels.

Related Post: Solar Panel Output Calculator – Average Solar Panel Output?

What Size Solar Panel To Charge 12v Battery?

Here’s a chart about what size solar panel you need to charge different capacity 12v lead-acid & Lithium (LiFePO4) batteries in 6 peak sun hours using an MPPT charge controller.

12v Battery Size (Ah)Battery TypeRequired Solar Panel Size
20AhLead-acid30 watts
50AhLead-acid70 watts
60AhLead-acid80 watts
80AhLead-acid110 watts
100AhLead-acid140 watts
120AhLead-acid165 watts
140AhLead-acid190 watts
150AhLead-acid210 watts
170AhLead-acid235 watts
200AhLead-acid280 watts
220AhLead-acid300 watts
250AhLead-acid345 watts
300AhLead-acid415 watts
350AhLead-acid480 watts
400AhLead-acid550 watts
20AhLithium (LiFePO4)50 watts
50AhLithium (LiFePO4)120 watts
60AhLithium (LiFePO4)145 watts
80AhLithium (LiFePO4)190 watts
100AhLithium (LiFePO4)240 watts
120AhLithium (LiFePO4)290 watts
150AhLithium (LiFePO4)360 watts
170AhLithium (LiFePO4)410 watts
200AhLithium (LiFePO4)485 watts
220AhLithium (LiFePO4)530 watts
250AhLithium (LiFePO4)600 watts
300AhLithium (LiFePO4)730 watts
350AhLithium (LiFePO4)850 watts
400AhLithium (LiFePO4)970 watts

Summary

  • You need around 200-300 watts of solar panels to charge most of the 12V lead-acid batteries from 50% depth of discharge in 6 peak sun hours with an MPPT charge controller
  • You need around 400-550 watts of solar panels to charge most of the 12V lithium (LiFePO4) batteries from 100% depth of discharge in 6 peak sun hours with an MPPT charge controller

What Size Solar Panel To Charge 24v Battery?

Here’s a chart about what size solar panel you need to charge different capacity 24v lead-acid & Lithium (LiFePO4) batteries in 6 peak sun hours using an MPPT charge controller.

24v Battery capacity (Ah)Battery TypeRequired Solar Panel Size
50AhLead-acid140 watts
100AhLead-acid280 watts
120AhLead-acid330 watts
150AhLead-acid415 watts
200AhLead-acid550 watts
300AhLead-acid930 watts
400AhLead-acid1100 watts
50AhLithium (LiFePO4)240 watts
100AhLithium (LiFePO4)480 watts
120AhLithium (LiFePO4)580 watts
150AhLithium (LiFePO4)730 watts
200AhLithium (LiFePO4)930 watts
300AhLithium (LiFePO4)1450 watts
400AhLithium (LiFePO4)1940 watts

Summary

  • You need around 300-500 watts of solar panels to charge most of the 24V lead-acid batteries from 50% depth of discharge in 6 peak sun hours with an MPPT charge controller
  • You need around 600-900 watts of solar panels to charge most of the 24V lithium (LiFePO4) batteries from 100% depth of discharge in 6 peak sun hours with an MPPT charge controller

Full article: What Size Solar Panel To Charge 24v Battery?

What Size Solar Panel To Charge 48V Battery?

Here’s a chart about what size solar panel you need to charge different capacity 48v lead-acid & Lithium (LiFePO4) batteries in 6 peak sun hours using an MPPT charge controller.

24v Battery capacity (Ah)Battery TypeRequired Solar Panel Size
50AhLead-acid280 watts
100AhLead-acid550 watts
120AhLead-acid660 watts
150AhLead-acid830 watts
200AhLead-acid1100 watts
300AhLead-acid1660 watts
400AhLead-acid2200 watts
50AhLithium (LiFePO4)490 watts
100AhLithium (LiFePO4)970 watts
120AhLithium (LiFePO4)1160 watts
150AhLithium (LiFePO4)1460 watts
200AhLithium (LiFePO4)1940 watts
300AhLithium (LiFePO4)2900 watts
400AhLithium (LiFePO4)3880 watts

Summary

  • You need around 800-1000 watts of solar panels to charge most of the 48V lead-acid batteries from 50% depth of discharge in 6 peak sun hours with an MPPT charge controller
  • You need around 1600-2000 watts of solar panels to charge most of the 48V lithium batteries from 100% depth of discharge in 6 peak sun hours with an MPPT charge controller

What Size Solar Panel To Charge 120Ah Battery?

Here’s a chart about what size solar panel you need to charge your 12v 120ah lead-acid (50% depth of discharge) and lithium battery (100% depth of discharge) with different peak sun hours and using an MPPT charge controller.

Charge TimeBattery TypeRequired Solar Panel
4 peak sun hoursLead-acid250 watts
5 peak sun hoursLead-acid200 watts
10 peak sun hoursLead-acid100 watts
15 peak sun hoursLead-acid65 watts
20 peak sun hoursLead-acid50 watts
25 peak sun hoursLead-acid40 watts
4 peak sun hoursLithium (LiFePO4)440 watts
5 peak sun hoursLithium (LiFePO4)350 watts
10 peak sun hoursLithium (LiFePO4)175 watts
15 peak sun hoursLithium (LiFePO4)115 watts
20 peak sun hoursLithium (LiFePO4)90 watts
25 peak sun hoursLithium (LiFePO4)70watts

Summary

  • You need around 200 watts of solar panels to charge a 12V 120ah lead-acid battery from 50% depth of discharge in 5 peak sun hours with an MPPT charge controller
  • You need around 350 watts of solar panels to charge a 12V 120ah lithium battery from 100% depth of discharge in 5 peak sun hours with an MPPT charge controller

Full article: Charging 120Ah Battery Guide

What Size Solar Panel To Charge 100Ah Battery?

Here’s a chart about what size solar panel you need to charge a 12v 100ah lead-acid & lithium battery using an MPPT charge controller with different peak sun hours of sunlight.

Charge TimeBattery TypeRequired Solar Panel
4 peak sun hoursLead-acid210 watts
5 peak sun hoursLead-acid165 watts
6 peak sun hoursLead-acid140 watts
10 peak sun hoursLead-acid80 watts
15 peak sun hoursLead-acid55 watts
20 peak sun hoursLead-acid40 watts
4 peak sun hoursLithium (LiFePO4)360 watts
5 peak sun hoursLithium (LiFePO4)290 watts
6 peak sun hoursLithium (LiFePO4)240 watts
10 peak sun hoursLithium (LiFePO4)150 watts
15 peak sun hoursLithium (LiFePO4)100 watts
20 peak sun hoursLithium (LiFePO4)70 watts

Summary

  • You need around 210 watts of solar panels to charge a 12V 100ah lead-acid battery from 50% depth of discharge in 4 peak sun hours with an MPPT charge controller
  • You need around 360 watts of solar panels to charge a 12V 100ah Lithium (LiFePO4) battery from 100% depth of discharge in 4 peak sun hours with an MPPT charge controller

What Size Solar Panel To Charge 50Ah Battery?

Here’s a chart about what size solar panel you need to charge a 12v 50ah lead-acid & lithium battery using an MPPT charge controller with different peak sun hours of sunlight.

Charge TimeBattery TypeRequired Solar Panel
4 peak sun hoursLead-acid100 watts
5 peak sun hoursLead-acid80 watts
6 peak sun hoursLead-acid70 watts
10 peak sun hoursLead-acid40 watts
15 peak sun hoursLead-acid30 watts
20 peak sun hoursLead-acid20 watts
4 peak sun hoursLithium (LiFePO4)180 watts
5 peak sun hoursLithium (LiFePO4)145 watts
6 peak sun hoursLithium (LiFePO4)121 watts
10 peak sun hoursLithium (LiFePO4)70 watts
15 peak sun hoursLithium (LiFePO4)50 watts
20 peak sun hoursLithium (LiFePO4)35 watts

Summary

  • You need around 100 watts of solar panels to charge a 12V 50ah lead-acid battery from 50% depth of discharge in 4 peak sun hours with an MPPT charge controller
  • You need around 180 watts of solar panels to charge a 12V 50ah Lithium (LiFePO4) battery from 100% depth of discharge in 4 peak sun hours with an MPPT charge controller

Related Post: How Long Will A 50Ah Battery last?

What Size Solar Panel To Charge 20Ah Battery?

Here’s a chart about what size solar panel you need to charge a 12v 20ah lead-acid & lithium battery using an MPPT charge controller with different peak sun hours of sunlight.

Charge TimeBattery TypeRequired Solar Panel
4 peak sun hoursLead-acid40 watts
5 peak sun hoursLead-acid33 watts
6 peak sun hoursLead-acid27 watts
10 peak sun hoursLead-acid16 watts
4 peak sun hoursLithium (LiFePO4)70 watts
5 peak sun hoursLithium (LiFePO4)60 watts
6 peak sun hoursLithium (LiFePO4)50 watts
10 peak sun hoursLithium (LiFePO4)30 watts

Summary

  • You need around 40 watts of solar panels to charge a 12V 20ah lead-acid battery from 50% depth of discharge in 4 peak sun hours with an MPPT charge controller
  • You need around 70 watts of solar panels to charge a 12V 20ah Lithium (LiFePO4) battery from 100% depth of discharge in 4 peak sun hours with an MPPT charge controller

What Size Solar Panel To Charge 150Ah Battery?

Here’s a chart about what size solar panel you need to charge a 12v 150ah lead-acid & lithium battery using an MPPT charge controller with different peak sun hours of sunlight.

Charge TimeBattery TypeRequired Solar Panel
4 peak sun hoursLead-acid310 watts
5 peak sun hoursLead-acid250 watts
6 peak sun hoursLead-acid210 watts
10 peak sun hoursLead-acid125 watts
20 peak sun hoursLead-acid60 watts
4 peak sun hoursLithium (LiFePO4)550 watts
5 peak sun hoursLithium (LiFePO4)440 watts
6 peak sun hoursLithium (LiFePO4)360 watts
10 peak sun hoursLithium (LiFePO4)220 watts
20 peak sun hoursLithium (LiFePO4)110 watts

Summary

  • You need around 310 watts of solar panels to charge a 12V 150ah lead-acid battery from 50% depth of discharge in 4 peak sun hours with an MPPT charge controller
  • You need around 550 watts of solar panels to charge a 12V 150ah Lithium (LiFePO4) battery from 100% depth of discharge in 4 peak sun hours with an MPPT charge controller

Full article: What Size Solar Panel To Charge 150ah Battery?

What Size Solar Panel To Charge 200Ah Battery?

Here’s a chart about what size solar panel you need to charge a 12v 200ah lead-acid & lithium battery using an MPPT charge controller with different peak sun hours of sunlight.

Charge TimeBattery TypeRequired Solar Panel
4 peak sun hoursLead-acid420 watts
5 peak sun hoursLead-acid330 watts
10 peak sun hoursLead-acid165 watts
20 peak sun hoursLead-acid80 watts
4 peak sun hoursLithium (LiFePO4)730 watts
5 peak sun hoursLithium (LiFePO4)580 watts
10 peak sun hoursLithium (LiFePO4)290 watts
20 peak sun hoursLithium (LiFePO4)150 watts

Summary

  • You need around 420 watts of solar panels to charge a 12V 200ah lead-acid battery from 50% depth of discharge in 4 peak sun hours with an MPPT charge controller
  • You need around 730 watts of solar panels to charge a 12V 200ah Lithium (LiFePO4) battery from 100% depth of discharge in 4 peak sun hours with an MPPT charge controller

Full article: What Size Solar Panel To Charge 200Ah Battery?

What Size Solar Panel To Charge 60Ah Battery?

Here’s a chart about what size solar panel you need to charge a 12v 60ah lead-acid & lithium battery using an MPPT charge controller with different peak sun hours of sunlight.

Charge TimeBattery TypeRequired Solar Panel
4 peak sun hoursLead-acid125 watts
5 peak sun hoursLead-acid100 watts
10 peak sun hoursLead-acid50 watts
20 peak sun hoursLead-acid25 watts
4 peak sun hoursLithium (LiFePO4)220 watts
5 peak sun hoursLithium (LiFePO4)175 watts
10 peak sun hoursLithium (LiFePO4)90 watts
20 peak sun hoursLithium (LiFePO4)40 watts

Summary

  • You need around 100 watts of solar panels to charge a 12V 60ah lead-acid battery from 50% depth of discharge in 5 peak sun hours with an MPPT charge controller
  • You need around 175 watts of solar panels to charge a 12V 60ah Lithium (LiFePO4) battery from 100% depth in 5 peak sun hours with an MPPT charge controller

Full article: What Size Solar Panel To Charge 60Ah Battery?

What Size Solar Panel To Charge 130Ah Battery?

Here’s a chart about what size solar panel you need to charge a 12v 130ah lead-acid & lithium battery using an MPPT charge controller with different peak sun hours of sunlight.

Charge TimeBattery TypeRequired Solar Panel
4 peak sun hoursLead-acid270 watts
5 peak sun hoursLead-acid220 watts
10 peak sun hoursLead-acid110 watts
20 peak sun hoursLead-acid50 watts
4 peak sun hoursLithium (LiFePO4)470 watts
5 peak sun hoursLithium (LiFePO4)380 watts
10 peak sun hoursLithium (LiFePO4)190 watts
20 peak sun hoursLithium (LiFePO4)100 watts

Summary

  • You need around 220 watts of solar panels to charge a 12V 130ah lead-acid battery from 50% depth of discharge in 5 peak sun hours with an MPPT charge controller
  • You need around 380 watts of solar panels to charge a 12V 130ah Lithium (LiFePO4) battery from 100% depth in 5 peak sun hours with an MPPT charge controller

What Size Solar Panel To Charge 140Ah Battery?

Here’s a chart about what size solar panel you need to charge a 12v 140ah lead-acid & lithium battery using an MPPT charge controller with different peak sun hours of sunlight.

Charge TimeBattery TypeRequired Solar Panel
4 peak sun hoursLead-acid290 watts
5 peak sun hoursLead-acid230 watts
10 peak sun hoursLead-acid115 watts
20 peak sun hoursLead-acid60 watts
4 peak sun hoursLithium (LiFePO4)510 watts
5 peak sun hoursLithium (LiFePO4)410 watts
10 peak sun hoursLithium (LiFePO4)200 watts
20 peak sun hoursLithium (LiFePO4)100 watts

Summary

  • You need around 290 watts of solar panels to charge a 12V 140ah lead-acid battery from 50% depth of discharge in 4 peak sun hours with an MPPT charge controller
  • You need around 510 watts of solar panels to charge a 12V 140ah Lithium (LiFePO4) battery from 100% depth in 4 peak sun hours with an MPPT charge controller

Full article: What Size Solar Panel To Charge 140ah Battery?

How To Calculate Number Of Solar Panels Required For Battery?

This is the most accurate way to calculate the required number of solar panels to charge any size battery.

Steps

1- Multiply the battery amp-hours (ah) by battery volts to convert the battery capacity into watt-hours (Wh). let’s suppose you have a 12v 50ah battery

Battery capacity in Wh = 50 * 12 = 600wh

2- Multiply the battery watt-hours to the battery depth of discharge limit.

lead-acid, AGM, and gel batteries come with a depth of discharge limit of 50%, and lithium batteries with 100% DoD. let’s suppose you have a 12v 50ah lead-acid battery

Discharged Battery capacity in Wh = 600 * 0.5 = 300wh

3- Divide the battery capacity after DoD by the battery’s charge efficiency rate ( lithium: 99%; Lead-acid: 85%; )

Power required to charge the battery = 300 / 85% or 300 * 1.15 = 345wh

4- Divide the battery capacity value (after charge adding efficiency factor) by the desired number of charge peak sun hours. let’s suppose you want to recharge your battery in 5 peak sun hours

Solar power required in peak sun hour = 345 / 5 = 69 watts

5- Divide the solar power required in peak sun hour by the charge controller efficiency ( PWM: 80%; MPPT 98%; ). let’s suppose you’re using a PWM charge controller

Solar power required after charge controller = 69 / 80% = 86.25 watts

6- Add 20% to the solar power required after controller to cover up the solar panel inefficiency

Solar panel Required = 86.2 + 20% = 103 watts

What Size Charge Controller Do I Need To Charge The Battery?

The job of the charge controller is to regulate the voltage coming from the solar panels to safely charge the battery and prevent the battery to be overcharged.

To select the right size charge controller according to your solar panel size. Follow these 2 steps

  1. Divide the solar panel rated wattage by battery volts (e.g by 12 for 12v battery and so on…)
  2. Now add an extra 25% to the result value to keep the system safe in case of any fluctuations.
  3. Now the value will be the size of charge controller you’d need with your particular solar panel size to charge the battery.

For Example

let’s suppose you have a 100-watt solar panel and a 12v battery. the calculation will look like this.

100 / 12 = 8.3A
8.3+ 25% or 8.3 * 1.25 = 10.4A

you’d need a 10A charge controller with a 100-watt solar panel to charge a 12v battery.

PWM Vs MPPT

– PWM Charge Controller

will only decrease the voltage coming from the solar panels and will not increase the amps (current).

which as a result will cause power losses and which makes the PWM charge controllers 20-30% less efficient.

The formula to power is… ( Watts = amps * volts )

Note! a 12v solar panel will produce about 18 volts under direct sunlight conditions… and the amps will be lower.

– MPPT Charge Controller

An MPPT charge controller will not only decrease the voltage coming from the solar panel to charge the battery but will also increase the amps to cover up the losses.

which makes them 98-99% more efficient than a PWM charge controller.

Pro Tip: if your solar panel system is higher then 100 watts then i would suggest using an MPPT charge controller.

Related Post: How Many Watts Can A Charge Controller Handle?

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I'm an experienced Sales Consultant with a demonstrated history of working in the renewables and environment industry. Skilled in Photography, Customer Service, and Sales.

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