What Size Battery For 100w Solar Panel?

By Matthew Joseph Nandirio •  Updated: 07/12/22 •  8 min read

Many types and sizes of batteries are available on the market, but not all are suitable for 100W solar panels. You will find a handful of options for them.

Choosing the correct battery can be intimidating since much calculation and consideration are involved here. But don’t worry for a bit as I’m here to help.

Solar Inverter
Solar Inverter

I will explain about the battery in the easiest possible term. You’ll also know what batteries are best for 100W solar panels. So, let’s get right in.

What Size Battery will Fit For 100W Solar Panel?

100W solar panels are compatible with 12V batteries. You can choose a 50 amp or 100 amp Lead-Acid or Lithium-ion battery for 100W solar panels. You will have to use a battery double the capacity of your solar panel’s output.

Before everything else, you should also know that a 100W solar panel is compatible with 12V batteries. In other words, you must use 12V batteries with 100W solar panels.

The charging time of this battery depends on a lot of factors. For example, if your battery is completely empty, you will need more time to charge it with a 100W solar panel.

Weather is another factor determining the time your battery will charge fully. The position of the sun and your solar panels also have an impact. But on a sunny day, when the battery is fully drained, a 100W solar panel can take 5 to 8 hours to charge a 12V battery.

Why Does Solar Panel Installation Need a Battery?

The battery is an essential part of a solar energy system. It stores the electricity produced by solar panels. Without it, additional electricity that you are not consuming will be wasted. That’s why people use batteries in most solar installations.

There are three types of solar energy systems: Off-Grid, On-Grid, and Hybrid. The on-grid solar system does not require any battery since it directly sends electricity to the grid, but you will need a battery for an off-grid solar system.

If you live somewhere remote where grid electricity is unavailable, you love road tripping on your RV, on your boat, or you want to install an off-grid solar system in your home, a battery is a must. It will store the electricity and run your devices at night.

How Many Batteries Do I Need Per Solar Panel System?

In order to get an answer to this question, first, you must know how much electricity your house generally consumes. Depending on that, you can determine how many batteries your solar energy system will require to run properly.

Generally, if you want to run your house off-grid and are wholly dependent on the solar system, you will require at least two to three batteries, depending on the output of your solar panels. But if you just want to use solar energy when the grid is down, one battery will be sufficient for a system.

However, in both cases, you must calculate your electricity consumption and determine how many solar panels you require. According to that number, you will know how many batteries will suffice. For example, one 12V battery is enough for a couple of 100W solar panels.

What Types of Batteries Are Compatible With 100W Solar Panel?

We have already learned how important batteries are for a solar energy system. Now it’s time to know more about batteries. We will start by discussing which batteries are compatible with 100W solar panels.  

Since solar panels cannot store electricity on their own, to install 100 watt solar panel, you’ll need batteries. There are two types of batteries you can use with your solar panels. Lead-Acid batteries and Lithium-Ion batteries are compatible with the solar energy system.

For Lead-Acid batteries, you will require almost double the capacity of the output of your solar panel to store electricity. On the other hand, a Lithium-Ion battery just needs a little more capacity than your solar panel’s output to run properly.

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

In the case of a 100W solar panel, a 100Ah and 12V battery will work pretty well. So, you can charge a 100Ah battery with a 100W solar panel. But it will take a significantly large amount of time to do so. A 100W solar panel can produce 100 watt-hour electricity in its best condition.

But for a 100Ah 12V Lead-Acid battery, a 100W solar panel will take about 10 to 12 hours to recharge fully at a 50% discharge rate. A Lithium-Ion battery of the same capacity will take slightly less time to recharge.

Can a 100W solar panel charge a 50Ah battery?

A 100W solar panel can charge a 100Ah 12V battery. So, it will easily charge a 50 Ah 12V battery, and that so at a significantly less amount of time. Generally, a 12V 50Ah auto battery at a 20% discharge rate will take a little more than 2 hours to fully charge.

On the other hand, a 12V 50Ah deep-cycle lead-acid battery at a 50% discharge rate will take up to 4 hours to become fully charged with a 100W solar panel. So, you can understand how easy and fast a 100-watt solar panel can charge a 50Ah battery.

How To Charge A 12v Battery With A 100W Solar Panel?

Charging a 12V battery with a 100W solar panel isn’t very complex. You just have to make some decisions beforehand. Here’s how you will charge a 12V battery using your 100W solar panel.

  • Firstly, determine which battery you are going to use. You can choose from Lead-Acid and Lithium-Ion batteries.
  • Then you have to fix the capacity of your battery. You can either use a 12V 50Ah battery or a 12V 100Ah battery. Always remember, you must use a battery whose capacity is at least twice your solar panel’s output.
  • Finally, connect the battery with the charge controller of your solar panel and check whether it’s correctly working.

How Many Amps Does A 100 Watt Solar Panel Produce?

The output of a 100W solar panel depends on a lot of factors. Condition of your solar panel, the sun’s position, the amount of daylight, etc., heavily influence the output. On a typical day, a 100W solar panel can produce 6 amps per hour when sunlight is at its peak.

This means it can produce up to 30 amp-hour per day. But the same 100-watt solar panel can produce up to 8 amps-hour when every factor is in the best conditions. In total, it can produce up to 40 amp-hour per day.

How Do You Match A Solar Panel To A Battery?

Matching a battery with your solar panel is very important. A large or small battery will not only abrupt the production of electricity, but it might also damage your solar system. So, make sure you select the right battery size and solar panel.

  • Firstly, check the wattage of your solar panel. Generally, it should be known to you.
  • Then you have to check the voltage of your battery. You will find it on the battery.
  • Finally, you will have to divide the solar watt rating by the battery’s voltage. Now you have the battery size. Remember, you need a battery capacity twice as large as your solar panel’s output.

How Many Watts Solar Panel Can Charge 100Ah Battery?

The general rule is to multiply battery amp hours with voltage and then divide it by the number of daylight hours. Say you have a 12V 50 amp battery. So, 12×50= 600. Now, dividing it by 6 will give 100.

So, if you use a 100W solar panel, you can fully charge a 50W solar panel from zero in 6 hours. A lot of other factors are related to it. However, you can also use a 100W solar panel for a 100Ah battery. But, you will need at least two of them for a better result. 

Devices That Can Run Off a 100 Watt Solar Panel

A 100W solar panel can run and charge any small devices and some small appliances. The electricity it produces is enough to charge your smartphone, laptop, watches, iPads, and other smart devices. You can also light up a few blubs and run a couple of fans with it.

This solar panel can also run your TV, WiFi router, lamps, etc. Although it runs a lot of small devices, big appliances like heaters, air conditioners, fridges, etc., will require a large solar panel than one 100W. You can use multiple 100W solar panels for running them.

Final Thoughts

After reading this article, I hope you understand 100W solar panels and the correct battery for them.

100W solar panels are specially designed for portability and ease of use. You can carry them with you quite easily, and you can also use them in your home. No matter where you use it, you won’t get an expected result without the right battery.

References

Chaurey, A., Deambi, S. . (1992 ). Battery storage for PV power systems: An overview. ScienceDirect, 227-235.

Shankar, S., Lokesh, C., Bopaiah, M. S., Shradha. . (2020, July 16). Strategical selection of batteries used for solar energy system and impact of lithium batteries on renewable storage. Retrieved from AIP.Scitation: https://aip.scitation.org/doi/10.1063/5.0004646

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Matthew Joseph Nandirio

Matthew Joseph Nandirio is the Founder of walkingsolar. After graduating from the University of Houston in 2002, matt started working as an electrical and electronic engineer for several multi-national solar energy companies. He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research. He now shares his 20 years of expertise through his articles on the walkingsolar website. Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.

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