How To Calculate Circuit Breaker In Solar Pv System

3 follow the code.

How to calculate circuit breaker in solar pv system. A maximum output current of 16a multiplied by a 125 percent safety factor equals 20a. When only one circuit breaker is used this factor equals to 1 increase in nominal current as a result of ambient temperatures of 40 c in the distribution board 1 07 due to the fact that the circuit breakers are rated for 50 c result. There is a code rule nec 690 64 b 2 that s says you must not exceed a certain size circuit breaker for solar. So use a 20a circuit breaker.

This is defined as 20 of the overall home s service rating. Ibn 40 a x 0 9 x 0 77 x 1 07 29 7 a. To calculate the fuse size required between the string and the inverter s dc input you take 9 12 x 1 56 14 7 and round up to the next trade size of 15a. Now these are often included with some inverters but it s a good idea to check.

You calculate the power supplied or calculate a solar energy system output from the panel to the battery using its watts peak and exposure. However if we add our pv breakers into a sub panel that is dedicated to only the pv breakers we can land the sub panel into a 40a breaker in the main panel board 10 4a 21a 31 4a x 1 25 39 25a. Multiply the nominal watts of the solar panel by the numbers of hours of sunshine it is exposed to. When sizing this combined fuse breaker we must first determine the worst case current that will flow based on our specific panels.

A maximum output current of 22a multiplied by a 125 percent safety factor equals 27 5a. Two standard pv breaker examples. This happens to be a standard breaker size. A single phase circuit breaker can t be used for three phase supply voltage levels.

A 3 poles circuit breaker can be used on 3 phase system using either 2 or 3 poles. A 3 poles circuit breaker can be used on 1 phase system only and only if indicated by the markings or instructed by user manual. So manufactures do not supply these with their inverters. The nominal load current of the circuit breaker is calculated as.

So we assumes that rated current can be 1 3 times more than flows in some condition that can beared by wire without insulation damaged. So for example if you have a 200a service you cannot install more than 40a of solar circuit breakers 200 0 2.