Should you buy a Tesla Powerwall?

At US$3,000, is it worth the cost?

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When Tesla announced the Powerwall last year, it was touted as a revolution in battery-based energy storage. Tesla promoted it as a convenient way for homeowners to store their solar energy and take their homes off the grid, have backup power for emergencies or offset electricity prices in places where there’s time-of-day pricing.

Now a Canadian company called NRStor plans to bring the Powerwall to Canada sometime this summer, according to the Globe and Mail. While there’s no official price tag and an exact arrival date isn’t given, estimates from within NRStor suggest that with installation, it’ll come in at about twice the American cost of US$3,000.

Is this technology anything more than an expensive piece of interior decoration? We crunched some numbers in order to break the Powerwall down and answer questions you may be wondering.

Can I save by offsetting peak electricity prices?

Ontario is the only province in Canada that uses time-of-day pricing, where electricity becomes more expensive during “peak” times and cheaper during “off-peak” hours. The theory goes that you’ll be able to charge the Powerwall when electricity costs less, and use that power when electricity becomes expensive. The difference in prices amounts to savings that can be used to pay off the Powerwall. Residents in other provinces without time-of-day pricing won’t see this opportunity.

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Let’s see if this theory holds true in Ontario. Toronto Hydro sets a price of $0.18 per kilowatt hours (kWh) during peak hours, and $0.087 per kWh during off-peak hours. That comes to a difference of $0.093 per kWh. In order to get a real-world estimate, we multiply that number by the average household electricity usage in Ontario, which StatsCan tells us is 22kWh per day. What that amounts to is a price difference of $2.04 a day. Of course, it costs money to charge the Powerwall’s 6.4 kWh daily capacity during the off-peak hours—$0.55 to be exact. After that deduction, your savings come to $1.49 a day, or around $543 a year.

That’s not bad. But using those savings, it would take 11 years to break even on the $6,000 price tag. Just remember, the Powerwall has a warranty of only 10 years.

Can I use it to take my house off-grid?

It’s every homeowner’s dream to never see an electricity bill again. If you’re looking to run off solar power or other renewable energy, you might want to consider battery alternatives other than the Powerwall. A daily cycle for the Powerwall provides 6.4 kWh. Meanwhile, StatsCan shows that the average household electricity usage for Canadians is around 30 kWh per day. So unless you’re willing to severely cut back on your electricity usage, or pay for several Powerwalls (yeah, right!), you’ll need to look for other options.

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Can I use it as backup power for emergencies?

The Tesla Powerwall is viable, just not ideal, for backup power. Most households look to backup generators that run on either natural gas or propane. Portable generators can produce between 3 kilowatts (kW) to 8 kW, while stationary generators can produce between 5kW to 20 kW.

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Contrast that with the Powerwall, which can only produce 3.3 kW at any one moment. That may be a problem when Toronto Hydro lists the approximate wattage for a central air conditioning unit at 3.5 kW, an oven at 5 kW and a water heater at 3.5 kW. If you’re just looking for something to keep the lights on during an emergency, the Powerwall might suffice—just don’t plan on doing any laundry at the same time because the it can’t handle too much of a load.

3 comments on “Should you buy a Tesla Powerwall?

  1. The savings that were calculated due to offsetting peak pricing seem to be incorrect.
    The Powerwall can only store 6.4 kWh at a time and therefore the maximum savings per day would 6.4 * $0.093 = $0.60 which assumes you fill it up during “off-peak”hours and use all that energy during “on-peak” hours. During the weekend all prices are off-peak (http://www.ontario-hydro.com/current-rates) and therefore there are only savings for weekdays. As a result the maximum savings would be $3/week or $156/year which would mean it takes more than 38 years to pay for the Powerwall.

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  2. I just read the Globe and Mail story. The price in Canada is not double the US price. The $3000 US price doesn’t include installation and the inverter. The Canadian price does.

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  3. To calculate Time Of Use Savings you use 22kWh per day, but to calculate how long the charge will last you use 30 kWh per day. It seems that on each case the author chose the number that would provide the lest favorable result.

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