Please explain this circuit diagram

Re: Please explain this circuit diagram

Badar wrote: »

anyone, please, explain this circuit diagram.
I have following questions

1: What is the purpose of this shunt? What is shunt in solar?
2: What is importance of Circuit Breaker?
3: Why Fuses are installed on these places? i.e. before and after Charge Controller.

As Badar said, the shunt is just a precision power resistor (very low resistance) used to measure current going into/out of the battery bank. The battery monitor measures the voltage drop across the shunt to figure out current flow (and keep track of how full the battery is).

A circuit breaker (or fuse) is used to prevent excessive current flow in the wiring (to reduce the chance of fire). The battery bank can be capable of very high current flow and each positive wire that leaves the battery bank should have a fuse or circuit breaker to prevent a down stream short circuit from over heating the wire/starting a fire.

Circuit breakers can also be used as On/Off switches, and therefore are sometimes nicer than using a fuse+switch to control power flow (flip breaker to turn of inverter, etc.).

The fuse between the battery and the charge controller should be installed near the battery bank/positive battery bus. This can protect any down stream wiring from short circuit excessive current flow. You can put the fuse next to the charge controller, but then the "up stream" wiring back to the battery bank is not protected.

The fuse between the solar panel and the charge controller is really not drawn in the "right place". Normally, if you have three or more solar panels in parallel, each parallel panel string should have its own fuse (or circuit breaker). This is to protect a shorted solar panel from getting too much current (and over heating wiring) from the other two or more parallel solar panel strings (using a "combiner box" with internal fuses/breakers). Again, fuses or breakers will work, but many people like to use breakers because it is easy to turn off power for servicing/debugging. You should not "turn off" a circuit by pulling the fuses... Sometimes fuse holders will "strike an arc" and actually damage/start a fire in the fuse holders.

-Bill