# What Size Solar Panel to Charge 100ah Battery

Skip Ahead

If you want to know what size solar panel to charge 100ah battery, you are probably new to green energy. A quick answer to this question is that it takes around 240 watt and more power to charge a 100 Ah battery, assuming you have a good amount of sunlight. However, as the hours of sun change, the required watt also increases or decreases. Moreover, the required size of a solar panel to charge 100ah also depends on the battery’s condition. For instance, a depleted battery will take more time to charge than a fresh one.

Several factors influence the number of solar panels you will need to charge a 100ah battery, and there is no one-liner answer. However, if you would like to learn how to calculate the solar panel size required, you are in the right place. In this article, we will share a straightforward formula that will help you calculate what size solar panel meets your requirements.

## How to Calculate Solar Panel Size for Battery

Before we share the formula for calculating solar panel size and explain what size solar panel to charge 100ah battery, you need to have some information that will make understanding things easier.

Solar panel sizes are measured in Watts, and 1 kilowatt has 1,000 watts.

• W = watts
• kWh = Kilowatts

Battery capacity is measured in mAh or Ah, where the former is a smaller unit of the latter.

• Ah = amp-hours
• mAh= milliamp hours
• 1000 mAh = 1 Ah

The formula for calculation solar panels uses all the units mentioned above.

1. Battery amp hours x battery watts = watt-hours
2. Watt-hours/sunlight available hours = Solar panel watts
3. Solar panel watts + 20% extra power = Required solar panel watt size

With this formula, you can easily calculate how many solar panels you need to charge your battery. However, everything depends on three influential factors: sunlight availability, solar panel efficiency, and charge controller type.

### 1. Solar Panel Efficiency

Even under ideal weather conditions, your solar panel system will take longer than usual to charge your batteries. This is primarily because of the loss of energy while charging since solar panels aren’t capable of 100% converting solar energy into electricity. Moreover, the angle of your solar panel also influences its efficiency. If you place your solar panel 45 degrees in the sun, its performance might be undermined.

However, by placing your solar panel 90 degrees towards sunlight, you can expect increased efficiency. Even so, you can expect your solar setup to charge your battery according to your determined time. Therefore, people always shop for solar panels bigger than their ideal requirement. Somewhere in between 240 and 300-watt solar panel set up will fully charge your 100 Ah battery.

If you are looking for a 300 Watt solar setup to charge your 100 Ah battery, we recommend the Renogy 300Watt solar panel kit.

### 2. Charge Controller Size

Choosing the right charge controller is essential to prolong the life of your solar panel kit. Moreover, your c charge controller needs to be of higher amperage than your solar kit. For instance, if you are using a 240 Watt panel, your charge controller should be 300 Watt.

The higher the charge controller amperage, the better, but you don’t want to exceed the required amperage; otherwise, it would adversely affect your solar panel kit.

### 3. Sun Availability

There are many myths about solar power, but its dependence on sun availability is 100% true. Your solar panel won’t work as efficiently as it would under full sun. Performance lag with solar kits is probably prominent in winter when the sun isn’t as bright. On cloudy days, the solar panel doesn’t work as efficiently. Therefore, its reduced performance will affect how fast your 100 Ah battery charges.

A passing cloud could mess with your charge even on a sunny day, and your battery will start from 0%. However, some solar panels have resume charging functionality which is a lifesaver when a stray cloud passes over your solar panel.

## Best Solar Panels for Charging 100ah Battery

Below we have shared a list of solar panels that can charge your 100ah battery easily. These panels will give you an idea of what you should be looking for.

### Renogy 300 Watt Solar Panel Kit Overview

The Renogy 300 Watt solar panel kit is an excellent purchase for charging a 100ah battery. Its small size packs a punch and can produce sufficient electric energy to satisfy your requirements. Below is a better breakdown of the advantages and disadvantages of this solar panel kit.

#### Pros of The Renogy 300Watt Solar Panel Kit

• The Renogy 300 watt is sufficiently durable considering its component material.
• The soaring glass is a low-tempered piece that can handle substantial amounts of bumps and hits.
• The solar panel is also waterproof, so you don’t have to worry about harsh weather conditions affecting its performance.
• The most impressive thing about the Renogy 300 is its dimensions. The PERC technology (Passivated Emitter Rear Cell) allows efficient energy conversions while reducing its dimensions by a noticeable size.

#### Cons of The Renogy 300Watt Solar Panel Kit

• The build quality is as outstanding as one can expect from a 300 Watt solar panel
• Packing quality can use an upgrade and additional safety materials to deliver the product safely to the customer.

### ACOPOWER 300 Watts Overview

The ACOPOWER is a robust 300 Watt solar panel that can efficiently charge your 100 Ah battery under full sun. However, like all solar panels, this one is also limited to the availability of the sun. Unlike other solar panel kits, the ACOPOWER comes with additional cables and a high-quality charge controller. Moreover, its solar charge controller has user-adjustable settings.

#### Pros of the ACOPOWER 300 Watt

• This solar panel comes with 12V and 24V polycrystalline technology making it suitable for your RV, boat, Van, and backup power system.
• It has an excellent build quality making it tough against harsh weather conditions.
• The ACOPOWER 300 watt has 25 years warranty with a 1-year component warranty.

#### Cons of The ACCOPOWER 300 Watt

• Although it’s a good purchase, it doesn’t include a battery which could be a no-buy for most customers.

### DOKIO 300 Watts Overview

The DOKIO 300 watt is a lightweight, portable solar kit that can be carried anywhere easily on your adventures. You can use this kit to power your 100ah battery or multiple devices. On a sunny day, this solar kit can efficiently charge a 100ah battery without much lag. However, a stray cloud could temper its performance.

#### Pros of The DOKIO 300 Watt Kit

• Its lightweight and easy-to-carry make it an appealing solar kit for most customers.
• It has high efficiency monocrystalline solar cell technology
• The DOKIO 300 Watt is highly reliable and has 2 USB ports

#### Cons of The DOKIO 300 Watt Kit

• It’s lightweight, making it good for carrying; however, it can move during high winds.
• The grommets on fabric are not highly durable and don’t look or feel premium.

## Our Final Thoughts

Knowing what size solar panel to charge 100ah battery is a good first step for going green. Now that you know how to calculate the required number of solar panels and how many watts you need, it will be easier for you to calculate the solar energy needed for bigger batteries.