Combining inverter and EV charger

palm615

SolarEdge has now released their SE 7600 HD-Wave inverter with a built-in level 2 EV charger. This made me wonder about combining an inverter and an EV charger on one circuit. Is there anything in the NEC, or from a safety or engineering standpoint that would prohibit the installation of a 30 amp 240v level 2 charger between a solar inverter and the 40 amp breaker in the panel? My reason for wondering is the same as SolarEdge's description in their literature. It would eliminate finding space in the panel for another 40 amp breaker. In my case I currently have a 9kw pv array, and the non EV SolarEdge SE7600H inverter. I am planning on buying an electric car and level 2 charger in the near future. If the car was plugged in at night, the inverter is off and the EV charger would be pulling 30 amps from the 40 amp breaker. If it was plugged in on a sunny day, the EV charger would pull 30 amps from the 32 amp flow from the inverter and theoretically the remaining 2 amps would be back feeding the panel through the 40 amp breaker. On a cloudy day with the car plugged in, maybe the Inverter is providing 15amps to the EV charger, and it would be getting the remaining 15 amps for EV charging from the panel. 

BB.

For example, if you have a 30 amp solar source, plus a 40 amp breaker utility source, you have >70 amps available to your EV charger (way too much current if there is an EV charger/wiring fault)... If I am understanding your setup correctly (I am guessing).

So--while it would "run" OK, if there is a fault somewhere, then you could have unprotected over current issues. Of course, then you could put a fuse/breaker to your EV charger to limit that current.

Could you do this all and follow NEC/local building codes--I am not sure. Generally, NEC does not lend itself very well to this sort of hodgepodge wiring.

-Bill

palm615

Thanks for the input Bill. I can see that the fused protection would be necessary. I was thinking about it from an efficiency point of view as my 3/4" EMT goes right by where my hard wired EV charger will be. My county electrical inspector that approved my grid tied system seemed pretty sharp. I'll run it by him this week also.

Dave

oil pan 4

What' so horrendous about a normal 240v grid tie setup going rhe theain panel and feeding a normal 240v level 2 charger from the main panel and wiring everything correctly?
I dot see any reason why it would be done any other way, unless the car charger circuit is preexisting and would be a pita run a new circuit for the solar.

mcgivor

Asking the inspector is always a prudent thing to do, my understanding is you want to tap into the branch circuit which the GTI inverters are connected to, which is protected by a 40A breaker. The purpose of the breaker is to protect the conductors, therefore all conductors in the branch circuit must be sized appropriately, a smaller gauge cannot be included in the same branch circuit without reducing the capacity of the branch circuit  breaker to the capacity of the smallest gauge, regardless of its location in the circuit. Including a local convenience disconnect with lockout provision for service is good practice, or may be a requirement, a circuit breaker or fused disconnect should  be utilized, which if limited to 30A, would allow a lighter gauge downstream however the distance would be so short the added conductor cost would be negligible. Some devices state a maximum breaker capacity allowed to protect internal circuitry, in which case the appropriate value should be utilized, otherwise I can't see why this application would be treated differently from any other branch circuit, with the exception of a short circuit at the charger, which would theoretically allow both grid and solars combined output to be added, as @BB. pointed out, this is where the fused disconnect/breaker would protect such an event. It's an interesting subject however without reference to the applicable codes these are just thoughts, which may help to rationalize your intent when asking your authority having juristiction, or your local inspector, if you like.

jaggedben

705.12(B)(1) in the 2017 NEC ('D' instead of 'B' in previous codes) requires a dedicated overcurrent device for the inverter, so you cannot field wire any load onto the same circuit without violating code.  The difference between using the SolarEdge product and field wiring different components on the same circuit is that with the SolarEdge product, presumably, it is designed so that no conductors inside can see more than a safe amount of current for those conductors, and UL has signed off on its design.  Note also that the SolarEdge product has the same wire ampacity requirement for either purpose (40A), whereas if you wire two different devices into the same circuit that might not be true.  I suppose a really obstinate AHJ could question whether the SolarEdge product is even code compliant, but an installer would fall back on "I'm using a listed device according to the instructions." (110.3 B ).   

BTW, if you have seen that SolarEdge has actually 'released' that product and not just 'announced' it  - meaning the are now shipping it to distributors - I would like to know!