Backfeed Breaker Solar

Article 690 requirements apply to solar pv systems.

Backfeed breaker solar. Nec705 12 b 2 3 b states that where there are two power sources the grid and the solar inverter the sum of their breakers cannot equal more than 120 of the busbar rating of the breaker box. Energizing wiring systems far from your setup like this can damage your equipment and the appliances being powered as well as potential for electrocution to technicians repairing power lines. According to the manual backfeeding is a real grid tie system once the grid is off the backfeeding stops. Circuit requirements are outlined in part ii of this article.

If a 200 a busbar has a 200 a main breaker the code allows adding a up to a 40 a backfeed breaker. The nec allows adding a back feed breaker so that the current supply is up to 120 of the rating of the bus bar. We sometimes see people adding a 60 or 80 a breaker instead. The problem is the backfeeding only happens when battery is fully charged.

The main purpose of the fuses and breakers are to protect the wiring. The transfer switch or interlocked backfeed breaker acts to prevent the connection of the generator while the main breaker for the panel is closed. From there you d land your inverter s output into a 50a breaker and your done. The sizing of back feed breakers is another point of difficulty.

Then looking at that photo again you can see i have a 30a 2 pole breaker at the other end for my solar inverter. So you always want to be sure your sizing your wire to handle the output of each circuit in the system. 690 10 e plug in type back fed circuit breakers connected to a stand alone inverter output in either stand alone or utility interactive systems shall be secured in accordance with 408 36 d. When setting up a generator to backfeed your house power can be pushed out through the main breaker to the transformer and cause unexpected high voltage.