What Size Solar Panel Do I Need To Charge A 100AH Battery?

If you want to install the solar power system in your home or commercial space, you need to install not only a solar panel but also a battery and inverter. Therefore, you need to have some idea of what size solar panel, battery, and solar inverter you need.

Today we’re going to know about what size of solar panel do you need to charge a battery system in the simplest way possible. I am going to give you a certain watt-hour charge load, and we’re going to figure out what size solar panel and how many solar panels we need to charge the battery with a certain number of days of autonomy or what size solar array will charge that battery in a decent amount of time.

Let’s think, you have a 12-volt 100AH battery.

That means you need 100 amp to charge the battery within hours. But most probably in Australia, you will get 10–12 hours of sunlight for your solar array. We think that your solar panel will get sunlight on average of 10 hours every day.

So, let’s calculate how many amps we need to charge the battery fully within a 10-hour solar array.

If We have a 100AH battery, let’s divide it by the total hours of the solar array.

100/10=10 amp

We need a total of 10 amp from the solar panel to fully charge the battery in 10 hours of the solar array.

Now convert the AMP into the solar panel watt. We need 10 amp.

We know that,

Watt= AMP X Volt.

(Here Amp=10, Volt=12, and Watt= unknown)

So, Watt= 10 X 12

= 120 Watt.

So, we need to use one 120 watts solar panel or two 100 watts solar panels to fully charge the battery in 10 hours.

On the other hand, if you have a 300 AH battery, you will need (300/10=30 AH) 30 amp per hour to fully charge the battery. Indeed, the calculation will be the same. For this 300 AH battery, you need Watt= 30 X 12= 360 watts. That indicates that you need four 100-watt solar panels to charge the battery.

Also, if you have a 24-volt battery, you need 2x energy/watt to fully charge the battery.

So, this is the way where you can easily calculate or size your solar panel for your desired battery.