What Size Battery for 200 Watt Solar Panel? (Step-By-Step Guide)

Here’s my step-by-step guide on “what size battery you need for 200 watt solar panel.”

For a 200 watt solar panel, you need about 12v 80-120Ah lithium or 12v 170-220Ah lead-acid battery.

What size battery for 200 watt solar panel?

What size battery you need, will depend on the total power production of your solar panels. And the power output of the solar panels will depend on how many peak sun hours your location receives.

Which I’ll explain in a moment. But, if you’re in a hurry…

What Size Battery For 200W Solar Panel – Chart

For your convenience, here’s a chart with recommended battery sizes for a 200-watt solar panel in different states.

StateBattery Size For 200W Solar Panel (Lithium-ion)Battery Size For 200W solar Panel (Lead-acid)
Alabama100ah170ah
Alaska100ah200ah
Arizona120ah220ah
Arkansas100ah180ah
California120ah220ah
Colorado100ah200ah
Connecticut80ah160ah
Delaware100ah180ah
Florida100ah180ah
Georgia100ah180ah
Hawaii80ah150ah
Idaho100ah200ah
Illinois120ah220ah
Indiana100ah180ah
Iowa100ah180ah
Kansa100ah180ah
Kentucky100ah180ah
Louisiana100ah170ah
Maine80ah170ah
Maryland100ah170ah
Massachusetts80ah170ah
Michigan100ah180ah
Minnesota100ah180ah
Mississippi100ah180ah
Missouri100ah170ah
Montana100ah190ah
Nebraska100ah190ah
Nevada120ah210ah
New Hampshire100ah180ah
New Jersey100ah170ah
New Mexico120ah210ah
New York100ah170ah
North Carolina100ah180ah
North Dakota100ah180ah
Ohio100ah170ah
Oklahoma100ah180ah
Oregan80ah160ah
Pennsylvania100ah170ah
Rhode Island100ah170ah
South Carolina100ah170ah
South Dakota100ah200ah
Tennessee100ah170ah
Texas100ah180ah
Utah100ah200ah
Vermont80ah160ah
Virginia100ah170ah
Washington100ah170ah
West Virginia100ah160ah
Wisconsin100ah170ah
Wyoming100ah200ah
Table: What Size Battery For 200-watt Solar Panel

Note: This calculation is based on the number of peak sun hours your state receives in summer. And also considering the fact that there will be at least 20% solar panel inefficiency during peak sun hours.

If you got some time, keep reading… I’ll share some key points and also how you can calculate your peak sun hours, what are peak sun hours and much more.

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calculate battery size for 200 watt solar panel in 3 steps

Follow these steps to calculate the battery size for your solar panel, according to your location.

1- Calculate solar panel output

Formula to calculate the 200 watt solar panel output
Example: how to calculate solar panel output?

The solar panel’s power production will differ from state to state. For example, Alaska receives much less good sunlight per day than Illinois.

“Solar panels are designed to produce their rate wattage output under standard test conditions – STC.” Which include 1000 watts/meter2 sunlight intensity, 25oC Temperature, and Air mass (Am) 1.5.

Peak Sun Hour is equal to an hour in the day when the intensity of the sunlight reaches an average of 1000 watts/meter2.

Use this calculator to find out how many hours of peak sunlight your location receives.

Step 1: Enter your complete address or a city name

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 how many peak sun hours your location receives on a monthly basis.

Note: It’s rarely going to happen when the solar panel will produce its 100% output on a sunny day. You can expect about 70-80% of power output from solar panels during peak sun hours.

Related Post: Solar DC Watts To AC Watts Calculator & Formula

For Example

I live in Florida City, and on average, we receive about 5.8 hours of peak sunlight.

But, to calculate the battery size, make the calculations according to the highest number of peak sun hours

In my case, it’s April (6.95 peak sun hours).

Multiply the peak sun hours by the solar panel wattage (200).

200 * 7 = 1400 watts or 1.4kWh 

Take power losses into account (20%).

1400 * 0.8 = 1120Wh

And this is exactly what I receive from my 200w solar panels on average per day in summer.

Full Article: Solar Panel Output Calculator

2- Convert solar panel output from Watt-hours (Wh) Into Amp-hours (Ah)

Battery capacity is measured in Amp-hours (Ah). So now let’s convert the output of 200W solar panels into amp-hours

Formula: Amp-hours = Watt-hours (Wh) ÷ System Voltage. 

I’m assuming that you want to build a 12v solar system. Also, I would take the total energy production per day based on my location (1.1kWh). 

1120/12 = 93Ah 

I would need a 90 amp-hours of battery capacity to store the power of a 200-watt solar panel. Now let’s discuss battery types, their depth of discharge limit (DoD), and the maximum charging current limit.

Full Article: Solar Panel Amps Calculator (Watts To Amps)

3- Select the battery type

Watch this video to understand the basics of a battery

There are different types of batteries available in the market right now. The most common ones are Lead-acid, AGM, Gel, and Lithium (LiFePO4). Every battery type has its depth of discharge limit. 

“What is the depth of discharge (DoD)?” It is the percentage of a battery that has been discharged relative to the total battery capacity.

To maintain battery health, some battery types are not recommended to be discharged below 50%.

Here’s a list of different types of batteries and their recommended DoD limit. 

  • Lithium (LiFePO4): 80-100% depth of discharge limit.
  • Lead-acid: 50% depth of discharge limit.
  • AGM: 50% depth of discharge limit.
  • Gel: 50% depth of discharge limit.

This means you can only use the full capacity of the lithium (LiFePO4) battery. 

Multiply the total solar panel output in amp-hours (Ah) by 2 for a lead acid, AGM, and gel battery type. Or, by 1 for lithium (LiFePO4) battery.

For lead-acid battery: 93 * 2 = 186Ah
For a lithium (LiFePO4) battery: 93 * 1 = 93Ah 

Lead-acid vs lithium (LiFePO4) battery: which is better?

You might be wondering, which type of battery you should go for. Here are some key points that will help to make the decision easy for you.

Lead-acid batteries: Pros and Cons


Pros

  • Cheap


Cons

  • Takes up a large space
  • Heavy in weight
  • Takes longer to get charged
  • Need maintenance from time to time

Lithium batteries: Pros and Cons


Pros

  • Takes up a small space
  • Light in weight
  • Support fast charging
  • Zero maintenance
  • Last 4x longer (Lifespan)


Cons

  • Expensive

Consider Battery Max Charging Current 

200Ah battery specs
200ah lithium battery specs sheet

Every battery type also has a max charging current limit. Charging your battery at a higher rate than what is recommended may increase the charging time. But, will decrease the battery charging efficiency rate and its total lifespan.

Here’s a list of different types of batteries and their recommended max charging limit. 

  • Lead-acid, AGM, and Gel batteries are recommended to be charged at 25% of their total capacity. For example, 200ah Lead-acid battery recommended max charging current will be 50 amps.
  • Lithium (LiFePO4) batteries can be charged with a 50% current (A) input of their total capacity. For example, a 200ah lithium battery can be charged with 100 amps of current.

At its peak performance hours, a 200W solar panel can produce about 16.6 amps of power @ 12 volts after passing through the charge controller.

There’s nothing to worry about but I just wanted to address this. Because nobody talks about it online. This may help you in the future. 

Tip: Also batteries have their recommended discharge rate as well. Which is called battery C-rating. 

Must Read: Maximum Charging Current & Voltage For 12v Battery

Do you really need batteries for 200w solar panels?

in short Yes, you need batteries to store the DC power output from solar panels or later use or in case of an emergency.

But, for a 200w solar panel system, I would recommend you a portable solar power station. Especially, if you need power on the go.

Which is easy to set up and easy to maintain and carry on. it’s like a complete package with a built-in battery, charge controller, and inverter.

For my Renogy 200-watt solar suitcase, I have a jackery explorer 1000.

Review: Jackery Explorer 1000: An Owner’s review

But, “DO NOT” pair a Renogy 200w solar panel suitcase with a Jackery power station. To charge the jackery power station, you’d have to bypass the built-in charge controller from the Renogy solar panel.

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Related FAQs

How many batteries do I need for a 200-watt solar panel?

As the 200w solar panel produces about 60-90Ah per day, you need two 12v 100Ah  lead-acid batteries.

Can a 200W solar panel charge a 100Ah battery?

In short, Yes. A 200W solar panel will fully charge a 12v 100Ah battery from 100% depth of discharge in about 7.5 peak sun hours.

How fast will a 200-watt solar panel charge a 12-volt battery?

A 200-watt solar panel will take anywhere between 5-15 peak sun hours to charge fully charge a 12v battery. The difference will depend on the size and type of battery. 

How many batteries can a 200-watt solar panel charge?

a 200w solar panel can charge one 12v 100Ah or two 12v 50Ah batteries per day under good sunlight.

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