Powerwall as backup generator?

Powerwall as backup generator?

I see from recent press reports that Tesla has installed a significant number of Powerwalls across the country and even overseas. I understand that the Powerwall is mainly meant to complement home solar installations, but I was wondering if anyone is using the Powerwall as a source of backup electricity in the event of a power failure?

My home is not suitable for PV cells on the roof, but we have frequent power outages and I have considered purchasing a diesel or natural gas generator. The Powerwall looks like it might work quite well as a backup power source, however, and I was wondering if any of you Powerwall users could share your experiences.

Dramsey | 29 December, 2016

A Powerwall doesn't make much sense as a backup power source, since you can get the same continuous capacity for a small fraction of the price with a standard generator. And if the generator's only used during power outages, the emissions will be minimal. For example, a gas generator that can provide 8kW of power continuously can be had for <$2,000 on Amazon.

A Powerwall is really designed to be used as an adjunct to store energy from, say, solar panels, and to be used almost daily. IMHO.

Dwdnjck@ca | 29 December, 2016

If you have a "time of use" electricity fee, you can use a Powerwall for both cost shifting and backup. It might help pay for itself.

brando | 2 January, 2017

It depends, it is complex, your mileage may vary, you need to do specific calculations for your situation and decide for yourself.

Dramsey is correct, the Powerwall is meant for continuous use. So it may cycle many times during the day as clouds come and go, for example. At least daily when ever the Sun sets or before Sun rise.

bp | 2 January, 2017

Wouldn't the Powerwall essentially be a "backup UPS" for the entire house, able to instantly switch over if external power is interrupted vs. a delay of at least a few seconds before a generator would start supplying power?

SamO | 2 January, 2017

Gas generators are incredibly stupid purchases now that the Powerwall is available for purchase. Why would you buy an inefficient ICE engine to run your house? It requires maintenance, fuel, repairs and is expensive.

Wheres the Powerwall is just expensive. All the other qualities (low maintenance, free fuel and simplicity) favor Powerwall.

Frequent power losses are more than just a dollars and cents decision, it's also about ease of use and simplicity.

Backup gas generator are NOT simple.

Mike83 | 2 January, 2017

Try starting a generator in 10 degree weather while you lose power. PowerWalls are always on and a bargain and much safer. Anyone with a a little thinking ability can see it.

milesbb | 2 January, 2017

so you like the bargain of a Powerwall. Say you house uses 5kW on average. Say the grid goes down for a month. You need 5kW X 24 hr X 31 days = 3600 kWh of battery energy to fill in for the grid for a month. At $5,550 for 14 kWh you will need 257 Powerwall 2 home storage battery's for a total cost of $1.43 million plus installation.


Pay $20k, have a simple 20 kW generator installed with a large fuel tank that can be refueled. Invest $1.4 million in a wind or solar project anywhere in the world so you make a difference in green house gas emissions. Spend the last $10k on a nice party for friends and family.

lilbean | 2 January, 2017

Tesla has not followed up well with my powerwall order. I've given up on it.

bp | 3 January, 2017

In our area, we have periodic brief power outages. While we have a risk of longer outages from hurricanes, the bigger issue is the shorter 5-60 minute power outages we get throughout the year.

If a Powerwall can continue to power the house for these brief outages, without interrupting power, that would be a great solution. And, if we knew there was a risk of a longer power outage due to a hurricane, we'd plan ahead and turn off everything but the essentials to stretch the power longer.

But, Tesla still hasn't provided enough information to determine how the Powerwall actually works in a configuration that doesn't have solar panels.

In a backup power configuration, how often is the Powerwall going to go through a recharge cycle?

How much power is lost when charging the Powerwall?

Will the Powerwall be like the Tesla cars - keep it between 10-90% power most of the time, and only charge to 100% in anticipation of a major outage?

We're considering a Powerwall - but until more information is available, we won't make a reservation and place a deposit.

Rocky_H | 3 January, 2017

@milesbb, Quote: "Say the grid goes down for a month."

No. We're not going to say that because that is ridiculous. If you have month-long power outages, you have other far more serious kinds of problems.

I think the original question is actually kind of backward. If you have solar and are grid tied, why would you even want a Powerwall? Net metering is far better and more cost effective. The Powerwall's primary and best use actually does seem to be as a backup to cover for short term power outages.

irproductions | 29 May, 2019

So I am in Florida and I have had power outages from 1-2 weeks after hurricanes. The biggest issue was no A/C and now I am interested in solar with Powerwall instead of a generator. Is this possible? Would the Powerwall be able to power at least an A/C for the house during the outage? Would the solar full power the house during the day and the Powerwall just the night when no sun is out?

Caio | 16 October, 2019

Maybe this video can help you:

Caio | 16 October, 2019

As backup or RV generator, I also found this article I think it could behelpful to you.