Electric - Run my house off my Tesla

coupleuk

OK, so I haven't got a Tesla, but if I did.....

With Electric prices, maybe I should charge the Tesla at 7.5p hWh during the night and then hook my house up to run off the Tesla during the day hahahaha

Seriously though, other than the £15k upfront cost, what's to stop me having a powerbank battery in the house - charge it cheaply during the night, use it during the day and perhaps even sell some back to the grid.

Could this prove a good deal in an all-electric property?

MWT

Tesla is the wrong place to start as they do not support V2H or V2G at the moment, but in general, the payback time is still a little long but getting better as the prices go up on the electricity. A battery for the home is going to be a better option though.

... but most of the tariffs you would want to be on for using a home battery to time-shift the power do also require you to have an EV.

Best to combine with solar energy as the cost of battery capacity is high, so the solar takes some of the day time load away leaving your battery for when the sun goes down.

coupleuk

OK how about this.........

I have 4 holiday flats all together and they are electric-only.

Guests pay for electric using a coin meter so they only pay for what they use - stops them going off for the day and leaving the heating on full (at least they pay for it if they do).

So, I have 4 x units each with an annual electric bill of around £1,200, making nearly £5k in total.

Could I install battery banks in a private part of the building to store energy and then use in the flats?

If I got power at (let's say) 7.5p kWh and sold it at 17.5p kWh then the guests would benefit from half-price electric (they are now paying 35p kWh).

And my "profit" from doing so would more than cover the cost of the battery bank over time.

* even if I had to find an old knackered EV lol

QrizB

coupleuk said:

OK, so I haven't got a Tesla, but if I did.....
With Electric prices, maybe I should charge the Tesla at 7.5p hWh during the night and then hook my house up to run off the Tesla during the day hahahaha

Yes, you can, but it's a bit Heath Robinson:

https://www.youtube.com/watch?v=2nMs_DwveqA

It's a bit tidier with an Ioniq 5:

https://www.youtube.com/watch?v=kyMdgnSVdT8

[Deleted User]

coupleuk said:

OK how about this.........

I have 4 holiday flats all together and they are electric-only.

Guests pay for electric using a coin meter so they only pay for what they use - stops them going off for the day and leaving the heating on full (at least they pay for it if they do).

So, I have 4 x units each with an annual electric bill of around £1,200, making nearly £5k in total.

Could I install battery banks in a private part of the building to store energy and then use in the flats?

If I got power at (let's say) 7.5p kWh and sold it at 17.5p kWh then the guests would benefit from half-price electric (they are now paying 35p kWh).

And my "profit" from doing so would more than cover the cost of the battery bank over time.

* even if I had to find an old knackered EV lol

Four Powerwall 2s at circa £40k - job done provided each property doesn't use more than about 11kWh/day. Your DNO will also insist that your batteries are islanded in the event of a grid failure.

Sadly, if you are thinking of Octopus' Go tariff, you need to own an EV. Can you legally re-sell electricity that you have purchased at 7.5p/kWh for 17.5p/kWh? 

coupleuk

[Deleted User] said:

Sadly, if you are thinking of Octopus' Go tariff, you need to own an EV. Can you legally re-sell electricity that you have purchased at 7.5p/kWh for 17.5p/kWh? 

There is a potential resale issue.

Perhaps I setup a Company purely for the incoming power and battery storage and then sell (not resell) the power to me.

Trying to find a way to cover the battery cost whilst also reducing the amount our guests have to pay.

QrizB

[Deleted User] said:

Sadly, if you are thinking of Octopus' Go tariff, you need to own an EV. Can you legally re-sell electricity that you have purchased at 7.5p/kWh for 17.5p/kWh? 

No, you can't. There are Rules about that.

MWT

One other factor to consider, the lead time on getting a battery is pretty long, so these are not solutions for this year even if you do have the capital to invest at that sort of scale for a long term payback.

[Deleted User]

The other thing that you need to think about is power output. A single Powerwall 2 will output at a maximum of 5kW: enough to run an oven but not an oven and kettle at the same time.

coupleuk

[Deleted User] said:

The other thing that you need to think about is power output. A single Powerwall 2 will output at a maximum of 5kW: enough to run an oven but not an oven and kettle at the same time.

Just looked at my power for yesterday - highest was 0.74 kWh over a 30 min period, two other half hour periods around 0.65 kWh and all other times below 0.35 kWh (midnight to 5am less than 0.05 kWh per 30 min segment)

QrizB

coupleuk said:

[Deleted User] said:

The other thing that you need to think about is power output. A single Powerwall 2 will output at a maximum of 5kW: enough to run an oven but not an oven and kettle at the same time.

Just looked at my power for yesterday - highest was 0.74 kWh over a 30 min period, two other half hour periods around 0.65 kWh and all other times below 0.35 kWh (midnight to 5am less than 0.05 kWh per 30 min segment)

It's not the 30-minute average that causes problems, it's the spikes.

To have a maximum load of 740W would mean you don't have a kettle, a toaster, a microwave - or any sort of electrical cooking / heating appliance beyond an electric blanket.