Tesla Powerwall home battery power storage – What is it?

Tesla Powerwall home battery power storage is Tesla’s version of a home battery storage usually hooked up to solar.  Other companies make them, but that’s the model I’ve chosen so I’ll call it that, but you can find many other alternatives. This isn’t an ad for Tesla

What does it do?

It’s like a UPS for your home if you’re familiar with that. If the power goes out the battery keeps running, powering most of our house.

What will it power?

It won’t run the really large appliances in our house, but it will power the lights, the furnace, the Internet, tv, microwave, coffee maker and all the rest of the wall plugs in the place. Based on this draw I expect it will power the whole house for about 24 hours. Our power draw doing this is about 500w and the Powerwall holds 13.5kW, so that would say 27 hours.

What won’t it power?

A single Powerwall isn’t going to power our dryer, oven, car charger, heat pump (but the furnace will work), or hot water heater. These will all just stop like a normal house in a normal power outage. If we’d bought a second Powerwall and connected the two then we could have run these as well, but we didn’t think the extra cost was worth it.


We also have solar and are connected to the grid. Many people think if you have solar and the power goes out you carry on as normal but that’s not true. The house is connected to the grid so it has to be cut off when work is being done. If the workers are repairing something they need to know my solar isn’t still on the line, even if the power plant isn’t. So our system shuts down when the grid connection drops.

On a typical day we will make about 50kWH of power. We’ll use half of that and then sell the extra to the power company. At night we have ono solar so we use the power company and buy power back. In effect we’re buying our own power back. We buy and sell power for the same price but they do charge a distribution fee both ways, so we’ll be saving some small amount of money with the Powerwall.

The other big advantage of solar is that it will recharge the Powerwall even if the grid is out. So if there was an extended outage we would use about 10kwh/day (because the stove, car charger, dryer, etc, wouldn’t work our consumption would drop a lot) and the solar would provide more than that. So we’d use solar power throughout the day, run off the battery at night and then refill the battery the next day. Except for the missing appliances we could go on like this for all of the summer. In winter there aren’t enough sunny hours though

Is it a good deal?

No, probably not. Not for $10,000. I know most people hate the fees they pay on their power bill, the distribution fee, the transmission fee, the fee fee, etc, but it’s actually a great value. You can draw almost unlimited power at any time. You might not use much power but the point is you could. Keeping all that infrastructure going is expensive even if you don’t use much power. Buying a battery to do it alone isn’t cost-effective

We will save on distribution fees selling, by reducing the power we sell during the day and back at night. In the event of a power outage we will probably not even notice. There’s something appealing about the whole street being in the dark and us having a movie on the projector in the backyard