Circuit Breaker Sizing For Solar System

Use this table to decide what size battery to inverter cables and overcurrent devices fuses breakers to use with your inverter.

Circuit breaker sizing for solar system.

This is defined as 20 of the overall home s service rating. From there you d land your inverter s output into a 50a breaker and your done. If we take the example 144 watt 12v panel from the introduction section and look at the short circuit current isc we see it is rated at 8 5 amps. Recommended inverter cable and breaker or fuse sizes.

This works well in a system that is comprised of more than one string inverter or several branch circuits of micro inverters. Remember the fuse and breaker are there to protect your cabling from overheating and potentially catching fire. When downsizing a main breaker is not an option for the site you should consider amp shaving. The main purpose of the fuses and breakers are to protect the wiring.

3 follow the code. They are not necessary for the system to run. Circuit breaker sizing of suitable circuit breakers for inverters under pv specific conditions content the selection of the correct circuit breaker depends on various factors. So for example if you have a 200a service you cannot install more than 40a of solar circuit breakers 200 0 2.

This adds a bit more labor and costs into the mix but it will help get that pv system stuffed into that service panel. A 30a circuit breaker can safely carry the exact 30a current but nec suggests 80 as a safe current limit as compared to the rated current. Sma recommends having a licensed solar contractor or electrician determine the correct conductor and breaker size. Especially in case of pv plants some factors have a stronger impact than in customary electrical installations.

Fuses and circuit breakers are used to protect the wiring from getting too hot and also protect all devices connected in the system from catching fire or getting damaged if a short circuit occurs. There is a code rule nec 690 64 b 2 that s says you must not exceed a certain size circuit breaker for solar. As circuit breakers cbs and overcurrent protection devices ocpd are designed for 100 rated current i e. When sizing this combined fuse breaker we must first determine the worst case current that will flow based on our specific panels.

The size of the wire and circuit breaker must be determined in accordance with local codes and regulations and in consideration of the environmental conditions the equipment will experience. So you always want to be sure your sizing your wire to handle the output of each circuit in the system.