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Adding additional powerwalls to existing 2

Adding additional powerwalls to existing 2

I've had solar for over a year and recently installed 2 powerwalls to go along with it.

For some reason, the installer couldn't do a partial house backup (we have various stuff on different subpanels throughout the house), so it had to be full house backup. The house is 100% electric, with heatpumps, a pool and a couple of electric cars, meaning we often go above the 10kw that the 2 powerwall can supply. Would have been nice to have figured that earlier, but that's where we are...

I was wondering what the cost is to add a couple of powerwalls to my existing setup... I'm expecting some of the one time installation costs are not needed this time around... Right? Permitting, installation cost should all be minimal too, or am I too optimistic?

Tesla-David | 15 January, 2020

@MattV, we installed 2-PW2's in June 2018 to complement our 13.2 kWh solar PV system and have been operating in self-powered mode since installation, also charging two Tesla's (MS and M3). To get around the 10 kW limit, we stagger the charging and generally limit the charging to 40 W, and it has worked out for us over that span to stay within the PW2 limits. I would agree having two additional PW2's would certainly help to defuse your anxiety and concerns.

lilbean | 15 January, 2020

I think you are being too optimistic.

adam.lippiatt | 15 January, 2020

Does anyone know how many Powerwall 2's one Gateway 2 supports?

Patrick | 15 January, 2020

Recent Powerwall market pricing in the US seems to be running around $8-9K per unit including installation. Might be a little cheaper if you add them to an existing installation with an existing gateway. We just paid $9K each in December.

As I recall up to 9-10 Powerwalls can be installed together into a single array. The number is somewhere in the specs.

PapaSmurf | 12 February, 2020

We have two powerwalls PW2 already (installed 16.38 kW system Nov 2019) and I inquired about adding two more to the system. The Tesla service guy came back to deal with a minor issue I was having and I asked him while he was here. He said based on the equipment already installed, he was sure at least one more would work with no other upgrades. But he had doubts about adding the fourth. Each PW2 requires a certain amount of room on one of those outside boxes and he said mine was not scaled for 4 of the PW2s.

He was sure a third PW2 will fit, so I might just limit myself to a third PW2 for now. That will enable us to reach 15 kW continuous draw. Our house is also fully electric, no natural gas. So electric water heating, electric cooking/oven, electric dryer, electric heating, etc. Florida based.

Patrick | 13 February, 2020

Papa - FWIW it sounds like your “generation breaker panel” might be out of space for more Powerwall breakers - it could have room for one more breaker but not two.

If that’s the issue, depending on your setup, it might be relatively easy to replace that panel with a larger one. Did the tech mention this?