What Size Charge Controller Do I Need For Solar Panels?
What size charge controller for a 100 watt solar panel? Or 200w, 300w, or 400 watt solar power system? Or more than that?
(A charge controller installs between the solar panel array and a battery bank)
(description below)
Here’s how to figure out the size charge controller you need (its rating).
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I have completely revamped my original post on this. I used a simple hypothetical 300 watt solar panel example to charge a 12 volt RV battery. The concept of how to figure it out will be similar for other solar panel wattage values.
Ready? Lets go…
Every make/model charge controller has their own unique specifications. I know that sounds pretty obvious. But it’s important to match your solar array (which has its own unique output specifications) with the proper charge controller. And it’s important to match your charge controller with the battery or battery bank.
The primary factors that matter most while choosing the right charge controller are:
- the solar array output voltage (volts) under peak conditions
- the solar array output current (amps) under peak conditions
- your battery bank voltage (12 / 24 / 48 ?)
- your battery bank charge amps requirements
The charge controller input specifications (from the solar array) need to be at least able to handle the maximum voltage and current (amps) from your given solar array.
The charge controller output specifications (to the battery or battery bank) need to match the battery voltage, and enough current (amps) to properly charge the battery (batteries).
There’s no one size fits all answer for this. You need to understand the specifications.
I’m going to give you an example, albeit a fairly simple one. This will give you the concept of what we’re doing…
I will use one 300 watt solar panel (actually I have 12 of them in my array, but I don’t want to get complicated here).
