Grid connected PW with existing solar PV

Grid connected PW with existing solar PV

Our Setup
* 4 KW Solar array (non-Telsa installer with Solaria panels).
* Solar output on most days is not sufficient to charge the PW (more than 10 kWH) fully.
* Looking into a grid connected PW option
* Northen CA with PG&E

* If we're not planning NOT to go for the ITC (investment tax credit) for PW installation, can we configure our PW to be grid connected?
Idea is to charge the PW during Off-peak hours (Midnight to 3 PM on a EV2A plan at 16 cents at kWH) and discharge during the peak and off-peak hours.

Tesla's own documentation states that if you want the rebate, the PW has to be solar connected. Doesn't dictate that PW has to be solar connected when you've a solar system.
Haven't had any luck to get a definitive answer from PG&E nor Tesla reps.

Thoughts / pointers / comments welcome!
Thank you.

Passion2Fly | December 27, 2019

Utilities in the US don’t want people to do load shifting and beat their rates unless you have solar, since the power is not coming from the grid and it’s self produced... it’s not the batteries, it’s the utilities...
Remember, if you’re grid connected, you need permission to operate from your utilities company...

gregbrew | December 27, 2019

Passion2Fly is correct. Many large utilities in the US have their own schemes to store energy produced during low demand times when it's cheaper, only to release it back to the grid when demand and prices are high. For example, SCE (also in CA) pumps water to higher lakes in the Sierras when energy is cheap, and then lets it flow back down through hydroelectric generators during high demand / more expensive times.

You can't do the same. Utilities don't want the competition.

PapaSmurf | December 27, 2019

"You can't do the same. Utilities don't want the competition."

The utilities are upset about even having to provide net metering and forcing them to purchase our excess solar energy.

From everything I have read, Duke Energy has to provide me a one for one swap per kwh that I send to the grid. Then at the end of the year, if I have a credit balance of whatever number of kwh, they have to send me a check for the amount, at some wholesale rate of what they purchase power for.

Two houses on my street have gone solar already. If this continues, there are going to be large gaps in their customer maps within a few years. They thought they have a monopoly in their service areas. But now they don't and they hate it.

jrweiss98020 | December 27, 2019

The utilities in WA successfully lobbied the legislature to be worse than Duke: We must pay in cash a minimum charge of 53¢/day (~$17.50/month with tax) regardless of production. The utility buys your production at the same rate as they sell it. On Apr 1 every year, any credit that you may have built up is zeroed, so there is NO incentive to produce more than you will use yourself.

Early adopters (prior to 2018) were grandfathered under the old rules where they get paid a premium for produced electricity...

kibhu | December 27, 2019

Thanks, guys.
I understand the logic behind why utilities might not want to allow grid connected battery storage when solar PV energy source is present.

I know folks who have gotten battery storage (PW and other companies like LG) without solar i.e. only grid connected.

So, if PW is allowed to be grid connected without solar, why it is not allowed allowed with solar?

Has anyone actually applied for the configuration and officially been turned down by an utility company like PG&E?

I read another thread on TSLA Mototrs club in last week where a gentleman in AZ actually got his PW working in the same configuration as I want it (existing solar array, but storage is grid connected).

Note: at no point I am thinking of base rate arbitrage i.e. charge during off-peak and discharge to the grid during peak... instead it will be charge during off-peak and discharge for home use during peak hours.
Frankly speaking I don't see any difference between this (charging PW) vs. charging a 75 kwh capacity electric car like M3 during off-peak hours and use that during peak hours.

Please let me know if you do have official documentation or rules that explicitly says that such combination is not allowed.

jrweiss98020 | December 31, 2019

You'll have to look at your local electrical codes (or have an electrician or solar installer explain them). Configuration of transfer switches is one of the touchy subjects, so operation of the Tesla Gateway in a configuration without solar may be an issue.