Tesla Powerwall viability
Discussion
My missus got chatted up by a solar power salesman at the local county show last week, with him extolling the virtues of the Tesla Powerwall. She now thinks it will be green and economical, but I am more doubful.
We've already got solar panels on the roof - a 4kW system fitted in about 2010.
At roughly £5k for a Powerwall, it isn't a cheap investment, so I'd like to try and work out the potential savings on electricity we could make (rather than use the salesman's no doubt optimistic figures)
Is there a simple way of doing this? Or a website where I can pump in some known figures and it does the math? I had a google but it just returned examples of people i the USA and Australia whose solar panels are pumping out the same sort of KW as Hinckley Point C.
We've already got solar panels on the roof - a 4kW system fitted in about 2010.
At roughly £5k for a Powerwall, it isn't a cheap investment, so I'd like to try and work out the potential savings on electricity we could make (rather than use the salesman's no doubt optimistic figures)
Is there a simple way of doing this? Or a website where I can pump in some known figures and it does the math? I had a google but it just returned examples of people i the USA and Australia whose solar panels are pumping out the same sort of KW as Hinckley Point C.
Battery storage can be a money saver in winter too, or even without any solar power.
I'm on Octopus Go tariff and get cheap electricity (about 1/4 normal price) for 4 hours overnight. I have programmed my batteries to charge from the grid during this period then the house runs on battery power during the day.
This can save you a substantial amount. Rough figures for me are 75p for a full 10kWh charge which would cost around £3 if bought at normal rate. Couple of quid a day doesn't sound like much but it's over £50 per month.
I'm on Octopus Go tariff and get cheap electricity (about 1/4 normal price) for 4 hours overnight. I have programmed my batteries to charge from the grid during this period then the house runs on battery power during the day.
This can save you a substantial amount. Rough figures for me are 75p for a full 10kWh charge which would cost around £3 if bought at normal rate. Couple of quid a day doesn't sound like much but it's over £50 per month.
That seems (too) cheap for a Powerwall 2
A Powerwall 2 is 13kWh, so you could fill it with cheap electricity overnight on a tariff like Octopus Go - you'd be saving £4/day, (40p peak / 7.5p off peak). 3 yr payback, not bad.
Plus whatever you can generate for free from solar would bring the payback down even more..
But I suspect the price will be at least double that (6+ year payback)
A Powerwall 2 is 13kWh, so you could fill it with cheap electricity overnight on a tariff like Octopus Go - you'd be saving £4/day, (40p peak / 7.5p off peak). 3 yr payback, not bad.
Plus whatever you can generate for free from solar would bring the payback down even more..
But I suspect the price will be at least double that (6+ year payback)
You can be sure the sun will continue to set every night for the next few years, but how sure are you that night rate will stay low?
Also, step one is to understand what electricity you are using.
With gas CH and HW and a gas hob, we have lots of days in the 6 to 8kWh area, and some of that is the fridge etc running at night.
So the real savings may only be shifting 5 or 7 kWh to a cheaper tariff, which may not stay so cheap.
Meanwhile, I think batteries will be cheaper in a year or two.
Also, step one is to understand what electricity you are using.
With gas CH and HW and a gas hob, we have lots of days in the 6 to 8kWh area, and some of that is the fridge etc running at night.
So the real savings may only be shifting 5 or 7 kWh to a cheaper tariff, which may not stay so cheap.
Meanwhile, I think batteries will be cheaper in a year or two.
essayer said:
That seems (too) cheap for a Powerwall 2
A Powerwall 2 is 13kWh, so you could fill it with cheap electricity overnight on a tariff like Octopus Go - you'd be saving £4/day, (40p peak / 7.5p off peak). 3 yr payback, not bad.
Plus whatever you can generate for free from solar would bring the payback down even more..
But I suspect the price will be at least double that (6+ year payback)
The 5kWh version is £5k, the 13.5kWh version is £9900. A Powerwall 2 is 13kWh, so you could fill it with cheap electricity overnight on a tariff like Octopus Go - you'd be saving £4/day, (40p peak / 7.5p off peak). 3 yr payback, not bad.
Plus whatever you can generate for free from solar would bring the payback down even more..
But I suspect the price will be at least double that (6+ year payback)
CharlieCrocodile said:
Good luck getting hold of a powerwall!
The guy said installation would be in six weeks if we ordered there and then. Pretty sure there is only one size of Tesla PowerWall at 13kw - guessing they are quoting another provider for the 5kw.
On the Tesla PowerWall note the below hints on a new version :-
https://www.teslarati.com/new-tesla-energy-product...
Caveated that there have been rumours of PW3 for a long time.
Personally I couldn't make the man-maths work any which way a year ago, going to re-run the numbers with the current prices.
Two year horizon there seems to be a view electricity prices will come back down so might be solving for a short term problem - but who knows, energy prices were due to come down in Jan/Feb this year from the peak Sept/Oct last year and look what happened.
On the Tesla PowerWall note the below hints on a new version :-
https://www.teslarati.com/new-tesla-energy-product...
Caveated that there have been rumours of PW3 for a long time.
Personally I couldn't make the man-maths work any which way a year ago, going to re-run the numbers with the current prices.
Two year horizon there seems to be a view electricity prices will come back down so might be solving for a short term problem - but who knows, energy prices were due to come down in Jan/Feb this year from the peak Sept/Oct last year and look what happened.
I’ve been looking at batteries as an extra when installing a solar system and can’t see any way to justify it financially within ~10 years, even at current electricity prices. The only way I’ve been able to justify it is as a battery backup when there are power cuts. We don’t get many of those where I live so it’s really a “just in case” if/when things get bad regarding the UK grid in the current winter given what’s going on. Of course, with rampant inflation a possibility (I remember what happened in the 1970s), the cost of electricity may go through the roof in which case the battery (already paid for) may then justify itself.
I wouldn’t trust the electricity companies currently offering ridiculously cheap electricity in a small window overnight to continue offering it in future. In the US the companies that do this also have very high peak rates for power so while benefitting at night you get hit in the day.
I wouldn’t trust the electricity companies currently offering ridiculously cheap electricity in a small window overnight to continue offering it in future. In the US the companies that do this also have very high peak rates for power so while benefitting at night you get hit in the day.
southerndriver said:
The only way I’ve been able to justify it is as a battery backup when there are power cuts. We don’t get many of those where I live so it’s really a “just in case” if/when things get bad regarding the UK grid in the current winter given what’s going on.
Not sure they work that way without additional complication? I remember an old Fully Charged episode about Robert Llewellyn's power wall set up and he needed some sort of auto switching to isolate his place in a power cut, to prevent power going from his place back into the grid while engineers were trying to fix the problem. I don't think batteries provide entirely 'off grid' power as standard.Happy to be proved wrong...
doesthiswork said:
southerndriver said:
The only way I’ve been able to justify it is as a battery backup when there are power cuts. We don’t get many of those where I live so it’s really a “just in case” if/when things get bad regarding the UK grid in the current winter given what’s going on.
Not sure they work that way without additional complication? I remember an old Fully Charged episode about Robert Llewellyn's power wall set up and he needed some sort of auto switching to isolate his place in a power cut, to prevent power going from his place back into the grid while engineers were trying to fix the problem. I don't think batteries provide entirely 'off grid' power as standard.Happy to be proved wrong...
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff