Question about generator back up with solar.

[GerryB]

A customer of mine has a 400 amp service, two 200 amp panels. He had a generator set up where they fed the two outside disconnects with no transfer or interlocks, relying on the HO to shut the mains to prevent backfeeding, so the solar company said to do it right. Since he had main breakers in his panels also I put interlock kits on each panel paralleled together to the generator. (this setup has been discussed on this forum, works perfectly, no way to backfeed to the disconnects outside. The generator power can only go as far as the back feed breaker in each panel, which can only be turned on when the main is turned off and the interlock moved accordingly.) Problem is since the solar company already saw it ( there was a bunch of professional looking notes and warnings on his outside disconnects about shutting the mains before turning on the generator), they asked the HO for the inspection release. Needless to say I didn't pull a permit and it was never mentioned as a need. Now I can still pull a permit. It's a small town and I have a good relationship with the inspector.My question is can't these solar guys see that it can't backfeed? What do they do normally when the do an install and the customer has some kind of generator set up? The owner is not getting a battery system which might be a problem.

 

[ggunn]

A customer of mine has a 400 amp service, two 200 amp panels. He had a generator set up where they fed the two outside disconnects with no transfer or interlocks, relying on the HO to shut the mains to prevent backfeeding, so the solar company said to do it right. Since he had main breakers in his panels also I put interlock kits on each panel paralleled together to the generator. (this setup has been discussed on this forum, works perfectly, no way to backfeed to the disconnects outside. The generator power can only go as far as the back feed breaker in each panel, which can only be turned on when the main is turned off and the interlock moved accordingly.) Problem is since the solar company already saw it ( there was a bunch of professional looking notes and warnings on his outside disconnects about shutting the mains before turning on the generator), they asked the HO for the inspection release. Needless to say I didn't pull a permit and it was never mentioned as a need. Now I can still pull a permit. It's a small town and I have a good relationship with the inspector.My question is can't these solar guys see that it can't backfeed? What do they do normally when the do an install and the customer has some kind of generator set up? The owner is not getting a battery system which might be a problem.

Normally with a grid tied system when there is a generator the solar is interconnected outside the transfer switch so that when the grid goes down and the generator starts up there is no danger of the PV system backfeeding the generator. If there is no transfer switch then there is a potential problem if the PV system is inside whatever switch the homeowner throws to disconnect from the grid.

Also, if the solar guys have reason to believe that the system they are to add PV to is not up to code, they may feel vulnerable to being on the hook to remedy that when they get inspected.

 

[jaggedben]

If there's any way to add a further interlock kit such that the generator can't be turned on unless the solar is turned off as well, then that would be in order. That is, unless the solar can be connected line-side of the main breakers as ggunn said.

If it were my company I might ask to waive my warranty on the electrical work.

 

[GerryB]

Thanks for the replies. I will probably just get the permit and be on the safe side. His service he has one meter, double lugs and two 200 amp breakers outside, SER to a first floor 200amp MB panel and a second floor 200amp MB panel. So technically these would be sub panels correct? in which case the grounds and neutrals should be separate. I don't think they are, so it may be a can of worms there. Don't know how that affects the solar, as I said nothing can get past those mains in the panels.