Grid tie PV with Generator back up/

jaggedben said:
Ggunn is just saying that it's a lot simpler to put the PV on the supply side of any such setup than to deal with PV and generator both on the load side.
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Can you also help explain how the ATS is relatively cheap, for residential retrofits ?
 
ramsy said:
Can you also help explain how the ATS is relatively cheap, for residential retrofits ?
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Moving the PV interconnection to the line side of the main breaker and putting a standard interlock kit on the panel would be pretty cheap and it would protect the generator. Most of the generators I have seen on residences, however, have used AT switches. When someone decides to buy a PV system and a generator he has already decided to spend a significant amount of money.
 
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ggunn said:
Moving the PV interconnection to the line side of the main breaker and putting a standard interlock kit on the panel would be pretty cheap and it would protect the generator. Most of the generators I have seen on residences, however, have used AT switches. When someone decides to buy a generator he has already decided to spend a significant amount of money.
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Yes, that makes the most sense.

Especially since those 3-switch solar interlock kits may get red tagged for NRTL no longer certified, per post #10.

And, since service-rated equipment, designed for line-side solar, are available to the panel flippers.

In either case, for those preferring ATS, can you point us to some equipment examples?
 
ramsy said:
Yes, that makes the most sense.

Especially since those 3-switch solar interlock kits may get red tagged for NRTL no longer certified, per post #10.

And, since service-rated equipment, designed for line-side solar, are available to the panel flippers.

In either case, for those preferring ATS, can you point us to some equipment examples?
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Not really. I could google it, but so can you. FWIW, some generators ship with an ATS included.
 
Sierrasparky said:
What is the proper way to add a portable generator to a home with PV grid tie Don't want the PV back-feeding the genny. Someone said add a Normally closed relay on the PV tie to the main panel that opens when the Generator is run?
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This has generated a lot of discussion that may have gone off in directions that are not all that helpful. So let's get back to the question. You don't provide much information so I have to make some assumptions here.
It sounds like since you are specifically indicating a portable generator that tells me you don't want to make any changes to the existing wiring and it would be unusual to want to have a whole house backup with a portable generator. If you wanted to add a permanently installed generator then much has been said previously about the extensive wiring changes that would be needed. If the goal is to just run a few loads off a portable generator when the power is out then you are looking at running some extension cords from those loads to your portable generator outside. Easy enough to do and no danger of connecting the PV to the generator.
 
Most (all?) places you must have some sort of interlock to keep the generator separated from the grid, if for no other reason than not to do so presents a small but non zero risk of electrical workers unexpectedly encountering energized conductors when they are working to repair an outage. If a customer wants to risk equipment damage by not protecting their generator from a PV system, it is their own business.
 
ron said:
We put the PV connection on the utility side of the transfer switch, so when the generator is connected, there is no connectivity to the utility or PV.
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Maybe a dumb question but is there an issue with back feeding the utility if its tied to line side?
 
Dale lee said:
Maybe a dumb question but is there an issue with back feeding the utility if its tied to line side?
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In general, no. The PV inverters in this application are specifically designed to prevent backfeed to a dead grid. Think of the line interactive PV inverter analogous to a grid connected induction generator. The line interactive inverter can only feed power to the grid if the grid is first present to supply 'excitation' to the local source. If the grid goes down, then the line interactive PV inverter is not capable of supplying power to the grid.

-Jonathan
 
Dale lee said:
Maybe a dumb question but is there an issue with back feeding the utility if its tied to line side?
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There really is no difference whether the PV is connected on the line side or load side of the OCPD. The grid, the PV system, and all the loads are a parallel circuit.
 
While I
Sierrasparky said:
What is the proper way to add a portable generator to a home with PV grid tie Don't want the PV back-feeding the genny. Someone said add a Normally closed relay on the PV tie to the main panel that opens when the Generator is run?
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Depending on the budget, you could replace the existing inverter with something like this, which solves your problem of making your generator, and your existing PV system coexist. https://eg4electronics.com/categories/inverters/eg4-12kpv-all-in-one-hybrid-inverter/

Add a battery to it as well for a truly reliable system. The nice thing about adding a battery, is that it will power your house, and you can charge your battery with your generator using this type of inverter. Once battery charge reaches the SOC (state of charge) you set, then generator is automatically turned off, and battery runs the house. Until grid and/or solar power return.

If you have a Tesla Powerwall and Gateway/Backup Switch system, there is no reason why you couldn't have an ATS with the generator on the one side, and the output of your Powerwall into the "grid" side of the ATS. While Powerwall supplies power during an outage, generator doesn't run. Once Powerwall reaches it's max discharge level, the ATS senses power loss, and turns on generator. Powerwall remains off, and the Tesla Gateway/Backup Switch keeps from back feeding the generator power. This is the system that I currently have installed, and it works quite nicely. Though, thinking about adding the EG4 inverter and another battery, so that I can charge the 2nd battery with my generator, to minimize how long it has to run during an outage after my Powerwall3 depletes.
 
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