How do I size a solar charge controller?

Selecting the Right Size Controller To size a solar charge controller, take the total watts of your solar array and divide it by the voltage of your battery bank, then multiply by a safety factor of 1.25. This calculation will give you the output current of the charge controller.

How much current does a solar charge controller use?

This calculation will give you the output current of the charge controller. For example, a 1000W solar array divided by a 24V battery bank equals 41.6A. Applying the safety factor, 41.6A x 1.25 = 52A. Therefore, you need a charge controller rated at least 52A.

Can a solar controller overcharge?

If your solar system has a 50A output capacity but the controller is only 30 amps, only 30 amps goes into the system. The rest is wasted. There is no risk of overcharging the controller. The controller is going to restrict the output to what it can handle. However it is going to result in a lot of energy loss.

How do I choose a solar charge controller?

MPPT solar charge controllers are rated in amps (Output Current). To select a charge controller, you’ll need to calculate the maximum amount of current (in Amps) that the MPPT should be able to output.

What size charge controller do I need for a 300 watt solar panel?

So a 300 watt solar panel or array needs a minimum 16.6A charge controller. The nearest available size is 20A which should be enough. The 25% in the calculations is to compensate for energy losses, system inefficiencies, temperature, environment etc. You can set this number lower, but 25% is ideal in most cases.

What happens if a charge controller is too small?

No matter how powerful your solar panels and batteries are, you won’t get peak performance if the controller is too small. So let us dive deep into charge controller sizing and why it matters. If the charge controller is too small for the solar panels, the charging and load output will be limited.