What Prevents Back Feed Into Solar Controller When Connected to Shore Power or Generator

Question:

How do these solar systems interface with the existing converter/ charger system when you plug into shore power or generator without back feeding power into the solar charge controller?

asked by: Paul H

Expert Reply:

Solar kits and battery chargers are completely separate systems and do not interact with each other aside from making contact with the same battery bank. They do not come into direct contact with one another. The battery charger and solar system both provide charge to the battery bank so there is no back feed.

A battery charger # 331-BCDC1225D regulates the flow of power to a battery bank by measuring the voltage level and slows down charge or stops it according to this value. A solar controller acts in the exact same way by measuring the voltage level and determining how full the battery bank is.

The only time there is a potential risk is in the event of a battery short. However, solar controllers have a built-in diode. Its main purpose is to protect the wire and solar panel(s) from the sudden surge of a battery short. The controller would take the hit and prevent damage from making it all the way to the panel(s). Because the controller needs current flow to and from the battery, there is no way to prevent damage to the controller if the battery short circuits, but as far as every day use, back feed to the controller is not a concern.

On the other hand, a transfer switch # 34264403 is needed in order to protect a power inverter # 34280175 from getting back fed when plugged into shore power because it pulls 12V battery power to create AC power.