2 Powerwalls for whole-house backup

[Dan123]

If an upgrade to a meter main is required for solar, then the best option to prepare for future Powerwalls would be to ensure that the branch circuit breakers are not in the same enclosure as the service disconnect. E.g. the new equipment could be a small meter main with a main breaker and subfeed lugs, along with a feeder to another main breaker panel that houses all the branch circuit breakers. Then when Powerwalls are installed, that feeder could be intercepted and rerouted through the Backup Gateway.

Cheers, Wayne

In our area, the meter is outside the house, and the electrical panel with circuit breakers is inside the house. The electrical panels has a 200amp circuit breaker at the top that disconnects the house. I presume the meter box outside also has some sort of disconnect switch.

In my case, two powerwall would probably not be sufficient for a whole-house backup, because there is a heater with 60amp breaker and an oven with 50 amp breaker. So I would probably need to isolate them in a different panel, between the meter, and the breakers in the 60-50 amp range. So I am thinking of installing a second panel now.

 

[GenSao]

Will your new meter have it's own panel directly attached to the meter? If so, you may not need a separate large load panel and the breakers for your solar inverter and ex. main panel can be directly connected to it. If possible, have your electrician have some extra slack in the conductors to allow for future relocation.

In your case, two powerwalls should be sufficient for a whole-house backup. Both the heater with the 60 amp breaker and oven with 50 amp breaker can be added. You can mange your loads in a backup scenario by limiting the use of one or the other. You should confirm The nameplate rating for your heater to be sure.

Is there another sub panel at or near your heater? In my case I have a 50 A breaker that went to a sub-panel for the AC unit. The sub-panel has a 40 A breaker to the AC unit.

 

[jrreno]

Has anyone used 2 PWs for doing a whole-house backup?

I am installing solar panels, and the installer is not very knowledgeable about PW. They are not yet available is South Florida.

Is it really as simple as connecting two PWs in parralel to the main electrical panel, and installing a gateway between the meter and the electrical panel?

So I had my system installed by Brilliant Harvest. It went online in February. My experience with it so far gives me confidence it will function quite well as a whole house backup. 7.5kwh panels with two Powerwall 2.

 

[Dan123]

Will your new meter have it's own panel directly attached to the meter? If so, you may not need a separate large load panel and the breakers for your solar inverter and ex. main panel can be directly connected to it. If possible, have your electrician have some extra slack in the conductors to allow for future relocation.

In your case, two powerwalls should be sufficient for a whole-house backup. Both the heater with the 60 amp breaker and oven with 50 amp breaker can be added. You can mange your loads in a backup scenario by limiting the use of one or the other. You should confirm The nameplate rating for your heater to be sure.

Is there another sub panel at or near your heater? In my case I have a 50 A breaker that went to a sub-panel for the AC unit. The sub-panel has a 40 A breaker to the AC unit.

AC compressor and the blower have a separate 40amp breaker. The heater is a 10kw resistive heater. So when it runs with the blower, the power is above 10kw.

I think this setup won’t pass electrical review.

As an option I thought about reducing the size of the heater. Or replacing the resistive heater with a heat pump.

 

[turnersteve]

Has anyone used 2 PWs for doing a whole-house backup?

I am installing solar panels, and the installer is not very knowledgeable about PW. They are not yet available is South Florida.

Is it really as simple as connecting two PWs in parralel to the main electrical panel, and installing a gateway between the meter and the electrical panel?

I have a 10.5 KWH system with 2 Powerwalls and it works great. Have had grid power go down only once and I did not even know it happened.

 

[AndreyATC]

Anyone knows if Tesla released beefier gateway?
I have 400A service and only 200A was supported from my last conversation with the team (beginning of the year)

 

[rw99]

I have a 10.5 KWH system with 2 Powerwalls and it works great. Have had grid power go down only once and I did not even know it happened.

Interesting!

Is your backup a whole-house setup, with AC included? Was the AC operating when your power went out?

 

[Ampster]

I have 400A service and only 200A was supported

You must have subpanels that could have been supported or are you looking for whole house backup at 400A?

 

[AndreyATC]

You must have subpanels that could have been supported or are you looking for whole house backup at 400A?

Yes, whole house setup
I dont want all individual breakers pulled out from the existing panels

 

[turnersteve]

Interesting!

Is your backup a whole-house setup, with AC included? Was the AC operating when your power went out?

Yes, to both questions.

 

[JHellow]

We have a 9.2kw solar array and 2 PowerWalls with whole house back-up. The house has to variable speed compressors for the AC on a 50 amp circuit, a 40 amp circuit for the air handlers, a 40 amp circuit for that washer and dryer, a 50 amp circuit for the car charger and various others. No issues so far. You just need to make sure that if the grid goes down at night, you are not demanding more than 60 amperes from the 2 PowerWalls. We lose solar at about 7 pm and even with the air on we have not problem bridging the time to low grid rates at 11 PM with the PowerWalls. When they hit 30%, they stop providing power and we are on grid.

 

[dan martin]

We have 2 PW2's that provide whole home backup on 200amp service. They have worked great for about 1.5 years. The installers took our existing main panel and made it a sub panel. The grid now comes first into their new single 200amp breaker. From there it moves into the aforementioned subpanel with all our circuits (largest of which is 50amps). They then installed a second subpanel (I think called a "generation" panel in Tesla parlance) to the right of the 200amp breaker that has a 40 amp breaker for our level 2 car charger and well as 2x30amp breakers for each of the PW2s. From that second sub panel there are two conduit runs. One leads to the PW2s and the other leads to the SolarEdge solar inverter which in turn goes up to the solar on the roof (about 6kW). I am no electrician, but I believe each of the PW2s is rated to 30amp continuous current which would power up to a 60amp circuit. In power outages I have seen inrush current from things like pumps, wells, pressurizers, etc. fry single inverters in backup mode. I like the 2xPW2 combo because at 60amps total, it is enough to power most circuits in most residential contexts. Even our Level 2 EV charger is only 40amps--more than one PW2 but okay with two of them.