Feeding off solar array

[jmo103]

a customer has a strange scenario. Next to his house, he has a solar field with 6 12 panel arrays. Each of these arrays has an inverter at on the rack and feed into a 200 amp panel located in the solar field on 2p breakers. This panel back feeds the main panel through a breaker in the bottom corner.

The customer wants to add an electric car charging station in the solar field, fed off of that panel. My question is, is that even legal? It seems like a bad idea but I am not sure why.

Thank you in advance for any advise on this.

 

[Joe.B]

If designed correctly I see no issue.

 

[gadfly56]

If designed correctly I see no issue.

Are there charging stations that run directly off straight up inverters designed for grid-tie service?

 

[Joe.B]

I was assuming the sub panel that they are showing could support the addition of a breaker serving a EV charger, similar to what I've seen in residential installations. If there is no load on the EV charger all of the PV production would be back-fed into the grid. If you connect an EV load (during the day) then the balance would be either be back-fed to, or provided by, the grid depending on if the EV load is higher or lower than the EV demand. If you add EV load while there is no PV production it would be all grid. Assuming it is all designed correctly I don't see any code issues with it.

 

[gadfly56]

I was assuming the sub panel that they are showing could support the addition of a breaker serving a EV charger, similar to what I've seen in residential installations. If there is no load on the EV charger all of the PV production would be back-fed into the grid. If you connect an EV load (during the day) then the balance would be either be back-fed to, or provided by, the grid depending on if the EV load is higher or lower than the EV demand. If you add EV load while there is no PV production it would be all grid. Assuming it is all designed correctly I don't see any code issues with it.

I suppose as long as the inverter can supply more power than the EVSE will ever call for this scheme might work.

 

[jaggedben]

a customer has a strange scenario. Next to his house, he has a solar field with 6 12 panel arrays. Each of these arrays has an inverter at on the rack and feed into a 200 amp panel located in the solar field on 2p breakers. This panel back feeds the main panel through a breaker in the bottom corner.

The customer wants to add an electric car charging station in the solar field, fed off of that panel. My question is, is that even legal? It seems like a bad idea but I am not sure why.

Thank you in advance for any advise on this.

There's nothing in the NEC that would prohibit this per se, and it's not a bad idea. However one thing is that by code the sum of the breakers in the panel can't add up to more than the rating of the busbar. The forum has lowered the resoulution of your picture so I can't tell if this is a problem for you. This could be a code violation but it's not a practical or safety issue if there's just one EV charger.

Potential non-NEC issues to check for:
Some utilities require a single disconnect for the PV. If that is upstream of the panel they may have an issue with there being a load on that panel. Similarly, many PV systems have a third party meter to measure production for a lease, PPA, or SRECs, and a load would also mess that up.

 

[Joe.B]

I suppose as long as the inverter can supply more power than the EVSE will ever call for this scheme might work.

With it being grid-tied, wouldn't the grid make up the difference? I'm not saying that with a lot of confidence, so grain of salt etc...

There's nothing in the NEC that would prohibit this per se, and it's not a bad idea. However one thing is that by code the sum of the breakers in the panel can't add up to more than the rating of the busbar. The forum has lowered the resoulution of your picture so I can't tell if this is a problem for you. This could be a code violation but it's not a practical or safety issue if there's just one EV charger.

Good call on the bus bar, that would fall under "assuming it is all designed correctly"

 

[gadfly56]

With it being grid-tied, wouldn't the grid make up the difference? I'm not saying that with a lot of confidence, so grain of salt etc...

Good call on the bus bar, that would fall under "assuming it is all designed correctly"

I'm anticipating they want to charge when they are off-grid, but maybe that's an assumption too far.

 

[jaggedben]

I'm anticipating they want to charge when they are off-grid, but maybe that's an assumption too far.

I didn't get that from anything said, and it wouldn't generally be a good idea. I figured the PV panelboard was more convenient to the parking space and/or the alternatives weren't judged to have the extra capacity.

 

[gadfly56]

I didn't get that from anything said, and it wouldn't generally be a good idea. I figured the PV panelboard was more convenient to the parking space and/or the alternatives weren't judged to have the extra capacity.

Rereading the OP, I'm inclined to agree with you.