Net-Zero in the US with asymmetrical loading on the 120v side and balancing at 240v?

[K W]

From observation, my utility here in SE MI is very difficult to deal with when it comes to grid-tie home solar. I would prefer not to have to deal with them and am considering a net-zero grid-tie system. Grid-tie only for line synchronization while managing my production to never feed the grid.

My question concerns asymmetrical loads. 240vac and common come into my home and 120vac is available between either side of the 240vac to common, as is the case with most homes in the US. Now, if I'm consuming 1KW at 120vac can I feed 1KW at 240vac back into the my CB panel and have the smart meter on the side of my home register 0 watts consumed?

Since the utility meter has four connectors (2 IN & 2 OUT) I assume that there are current transformers on both side of the 240vac coming in. I've heard rumors that my meter doesn't care about current direction, so you are charged for consumed power and exported power as though it were all consumption. Hence, the meter would see my symmetrical outgoing power used to balance my asymmetrical 1KW load, right? And potentially charge me for it, if the meter is set up that way. Yet, on the utilities HV side of the pole-pig (pole transformer), the utility really doesn't see the asymmetry, seeing only net-zero.

So for true net-zero, not utilizing any equipment that belongs to the utility, it seems I'd need a big (I have 200A service) 1 to 1 transformer with a center taped 420vac winding on the house side and the 240vac winding connected to utilities smart meter. The utility meter would never see any asymmetry that way... An autotransformer would work too, I think.

Am I on target here? Comments?

 

[Danner]

There are grid tie inverters that you can install yourself that have NetZero check out Sun GTI l2 on YouTube. Also another one I just saw that's a lot more expensive is sun ark.

 

[JeepHammer]

Part of net metering is a bidirectional meter replacing your current meter.
It's sometimes a pain to get the utility to do this, but if your state allows net metering, eventually they have to by law.

There is no national standard to net metering, it changes by state.
See if your state allows you to 'Bank' higher production and not simply loose it to a zero net consumption at the end of the month.
Some states will let you 'Bank' your over production and draw on it during the short winter months, others the monthly billing cycle is it, any over production is gone with no credit.

 

[K W]

As I said, my utility is difficult to work with and having talked with several solar system owners, including a relative and a good friend and his installer just up the road, that now deal with this utility. The install process, drawn out billing issues, losing paperwork, etc., I have zero desire to recreate their experience. Zero. I'm one to learn from other peoples mistakes.

My aim is zero export, probably with lifepo4 solar charging / backup.

Thanks for the suggestion to GTI I2 inverters, Danner. That is certainly a good approach and one I had considered: One 120v inverter dedicated to each side of the 240v with CT's to eliminate exporting to the grid.

To go a little deeper, I have several good second generation Enphase M210, 240v micro inverters that I would like to put back into service. So that is why I posed the 120v / 240v question.

 

[Elmer Ebersol]

As I said, my utility is difficult to work with and having talked with several solar system owners, including a relative and a good friend and his installer just up the road, that now deal with this utility. The install process, drawn out billing issues, losing paperwork, etc., I have zero desire to recreate their experience. Zero. I'm one to learn from other peoples mistakes.

My aim is zero export, probably with lifepo4 solar charging / backup.

Thanks for the suggestion to GTI I2 inverters, Danner. That is certainly a good approach and one I had considered: One 120v inverter dedicated to each side of the 240v with CT's to eliminate exporting to the grid.

To go a little deeper, I have several good second generation Enphase M210, 240v micro inverters that I would like to put back into service. So that is why I posed the 120v / 240v question.

The Sol-Ark does the zero back feed function really well and also allows you the option of AC coupling the Enphase equipment through the smart load control feature, built in right out of the box ( retails for $6500. )

 

[K W]

Thanks for pointing me towards Sol-Arc, Elmer & Danner. It seems like a pretty nice system that's exactly what I'm looking for. Thanks for pointing out that it can be AC coupled to my Enphase inverters. I'll defiantly be checking them out further!