Tesla PowerWall in Ontario

wayner · May 1, 2015

Does this new product make sense in Ontario for people who are on the grid? I have looked into the Microfit program which allows you to install solar panels up to 10kW on your home and sell the power back into the grid for $0.384/kWh for twenty years. Given that is about 3-4X what you pay for power it makes no sense to use this power yourself.

Therefore I don't see why you would want to store power that you generate from solar panels, unless you are off grid.

Or would the PowerWall make sense as a backup source of power instead of a generator?

This may change in the future as I believe the Microfit program is moving to net metering.

SmartElectric · May 1, 2015

Let's first look at this from a consumer angle:

New programs are coming in that with be compatible with installing a battery:
Advantage Power Pricing - A new way to save on electricity

The offpeak price is 4.9c/kWh and peak can be 12/24 and rarely (perhaps 5 times per year) 48 depending on grid requirements.

Charging a Tesla with a long commute overnight would be beneficial at these rate differences.
Having a battery to lower load (perhaps to zero) during the 5 hour peak is also a big deal.

wayner · May 1, 2015

I actually already have a battery - in fact I have the capacity of 8.5 of these PowerWalls. Maybe they should allow us to reverse the HPWC and put power back into my house and/or the grid.

SmartElectric · May 1, 2015

The second angle is what's in it for the Ontario Utility Grid managed by IESO.

They have an energy storage program :
http://www.ieso.ca/Pages/Ontario's-Power-System/Smart-Grid/Energy-Storage.aspx

One of the winners used battery:
BYD Batteries Find Home In 4 MW Energy Storage System In Ontario, Canada

sckor · May 1, 2015

wayner said:
I actually already have a battery - in fact I have the capacity of 8.5 of these PowerWalls. Maybe they should allow us to reverse the HPWC and put power back into my house and/or the grid.

That is exactly what I thought.

It would be ideal for my situation (if I had a Tesla

where the car is often in the garage for most of the day and doesn't need much charge to go for the short hops. Have the car top itself off during off peak hours, then let the battery power the house during On-Peak. But that would cannibalize Tesla's new product.

Sean.

mnx · May 1, 2015

SmartElectric said:
Let's first look at this from a consumer angle:

Hmmm that program looks pretty slick, I wish Horizon offered something like that. 4.9c/kWh is a lot cheaper than the offpeak rate of 8.1c/kWh I'm paying starting today.

As far as it making any financial sense in Ontario...

Say you can sell 7kWh a day back to the utility at peak rates and charge at off peak rates, you could earn: ($0.081/kWh * 7 * 92% efficiency) = $0.52
It would take nearly 16 years to pay off just the cost of the powerwall not including the inverter cost or installation. However you do have 7kWh of backup power which would be very useful in the event of an outage.

SmartElectric · May 1, 2015

mnx said:
Say you can sell 7kWh a day back to the utility at peak rates and charge at off peak rates, you could earn: ($0.081/kWh * 7 * 92% efficiency) = $0.52

Well, the Powerstream program has 12c and 24c peak rates during times that many homes (like mine) do consume 7kWh.
Let's use an average of 18c/kWh for the peak.

Load up the Powerwall at 5c/kWh overnight, and during the peak, use that instead of grid at 18c. Difference is 13c/kWh. Payback is ~10 years.

tesltoronto · May 3, 2015

I think the Microfit program allows a max of 10KW solar panels. Since in Ontario, we get 38.5 Cents for electricity sold to the utility, I think it does not make sense to use the powerwall for household (other than as a backup)

However, let us say you have enough room in the roof and add another 5 KW of panels, can't we use the Tesla Powerwall to store this energy and then use it for home? That way, you would not be paying anything to the utility and you house would be energy self sufficient! My average hydro utility bill is $150/month, and I may save $1800 per year. if the additional panels and the powerwall costs me say $18K, my payback will be 10 years. Wondering if this is possible or allowed?

wayner · May 3, 2015

I am pretty sure that you can do that but the economics may not work. I am not sure of the marginal cost of adding an additional 5kW but they would need a separate connection into your regular meter rather than your "outbound meter". And storing only helps you timeshift and arbitrage the power at different times of day, assuming you are going to be connected to the grid anyway. Then you will save the $.08 differential between peak and off-peak for some of the power generated.

tsarlsy · May 4, 2015

SmartElectric said:
Well, the Powerstream program has 12c and 24c peak rates during times that many homes (like mine) do consume 7kWh.
Let's use an average of 18c/kWh for the peak.

Load up the Powerwall at 5c/kWh overnight, and during the peak, use that instead of grid at 18c. Difference is 13c/kWh. Payback is ~10 years.

I used my last year's utilization data from Powerstream and calculated payback in about 13 yrs (Powerstream Advantage Pricing). I didn't include installation costs yet so expect payback to be longer. Payback is much much longer with the current TOU rates. The Powerwall will be a no-go for me.

wayner · May 4, 2015

One thing that comes to mind when talking about time shifting power usage to reduce peak demand -

Shouldn't we be discouraging the recharging of electric vehicles during the peak period?

Yet if you have an office complex where you have free charging statoins then you are economically incented to charge during prime time rather than overnight at home. I charge my car at home starting at 0430 - but if I wanted to I could sign up for a slot where I work and charge from 1200-1400. Does that make sense?

wayner · May 5, 2015

There is a story about the PowerWall in today's G&M http://www.theglobeandmail.com/repo...attery-pack-coming-to-canada/article24244093/

They seem to agree with me when it comes to homes with solar panels:

The Powerwall, launched last week by Tesla chief executive officer Elon Musk, is designed to allow homeowners to store electricity generated by solar panels during the day, then use it at other times when the sun is not shining but electricity consumption is higher.

In Canada, however, that is not likely to be the main application.

That’s because most solar electricity generated by Canadian homeowners’ rooftop panels is sold into the power grid through Ontario’s “feed-in tariff” system. There is no incentive to save the power for personal uses, because homeowners get high prices for the electricity they deliver.

Peter_M · May 5, 2015

Does anyone know the actual regulations for electricity storage in Ontario, or where I could find them? The two applications I'm thinking of are:

Install a PowerWall, charge it in off-peak times and discharge it in mid-peak and on-peak times.
Install a FIT solar generation system with say 100kW DC of panels and 50kW AC of inverters, charge the battery whenever solar production exceeds 100kW and discharge it and sell the energy into the grid later in the day?

I don't know if these applications make economic sense yet; I'm just wondering if there are rules preventing them.

EDIT: I can answer my own question for #2: The FIT contract does not allow any kind of storage. This is to prevent people from buying energy at regular rates and then re-selling it back at higher FIT rates. But maybe in a net-metering scenario (post-FIT), it may be possible to do this. I still don't know about #1 though.

wayner · May 5, 2015

I don't think the differential between peak and off-peak is enough. I believe that differential is currently $.061/kWh and peak lasts for six hours per day. I will do the calculations on the 7 kWh model as that is the daily cycle unit. So assuming that you could make the differential on the full 7kWh every day that would give you a profit of $0.43/day. Thats $111.80 per year assuming 5 days per week and 52 weeks per year. Given the purchase price of C$3600 that would be a 32 year payback period.

Aren't my calculations correct? (I might be slightly off by not including stuff like HST and other surcharges/taxes that are a percentage of the rate in my price differential)

To even get this to a 10 year payback period would require a differential of 3X what it is today or $0.18/kWh.

mnx · May 5, 2015

wayner said:
I don't think the differential between peak and off-peak is enough. I believe that differential is currently $.061/kWh and peak lasts for six hours per day. I will do the calculations on the 7 kWh model as that is the daily cycle unit. So assuming that you could make the differential on the full 7kWh every day that would give you a profit of $0.43/day. Thats $111.80 per year assuming 5 days per week and 52 weeks per year. Given the purchase price of C$3600 that would be a 32 year payback period.

Aren't my calculations correct? (I might be slightly off by not including stuff like HST and other surcharges/taxes that are a percentage of the rate in my price differential)

To even get this to a 10 year payback period would require a differential of 3X what it is today or $0.18/kWh.

Ahh your calculations are better than mine upthread. I foolishly used a 365 day year. As of May 1 the OEB energy rates have a 8.1c differential FWIW. You left off the 92% round trip charging efficency of the powerwall. It's still a very long payback, I did a quick calc and got somewhere around 26 years, quite possibly longer than the battery (and inverter) will last!

wayner · Nov 20, 2015

The differential between peak and off-peak has increased in Ontario so that is shortening the payback if you were to use a Powerwall to arb the peak/off-peak differential. It is now $0.092/hour. That's up from $0.081 over the summer and $0.073 last winter (my data from Toronto Hydro). I think the analysis I did in post 14 was off since I used a differential of $0.061 rather than $0.081 and I didn't include HST on the differential.

My calcs now show that the peak to off-peak differential is $0.092 before tax and $0.104 after 13% HST. The Powerwall for daily cycle is a 7kWh unit. So you can save on 7kW/day. That saves you $0.728 per day. Assuming 260 weekdays per year gets you to an annual savings of $189. Assuming a price of $3600 (which may now be too low as the C$ continues to slide) would give you a 19 year payback. And that's ignoring the cost of installation and other required hardware, like an inverter. Hopefully it is economical in 19.5 years when my microFIT program expires and I start using the power that I generate from my solar cells.

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