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Joined: Dec 2017
Posts: 2,041 Likes: 71
Talk Morgan Expert
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Talk Morgan Expert
Joined: Dec 2017
Posts: 2,041 Likes: 71 |
I have to ask, what is the purpose of a Powerwall if it doesn't work during a power outage? Up here in the mountains we are prone to power outages from a few hours to possibly days after a heavy snow fall, so we have a propane powered generator that automatically kicks in and supplies the house. I always wondered how efficient it would be and would it run out of propane if we were seriously snowed in, well last year we had 2.5 days of no power and the generator only used 10 gallons of gas which was very comforting. My neighbors who have Solar and batteries ran out of power at the start of day two as the panels were covered in frozen snow and he didn't want to climb on the high roof to clear them.
Bruce 1964 4/4 Series V Comp (Megan) 1994 +8 (Maurice) 2013 M3W (Olga)
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Joined: May 2019
Posts: 386 Likes: 17
Learner Plates Off!
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Learner Plates Off!
Joined: May 2019
Posts: 386 Likes: 17 |
The challenge is complying with all the regulations (mostly created to benefit the power company). For anything to work when the grid is down, it must be on some sort of transfer switch. This prevents your personal power from being able to go across the grid and zap the line workers trying to restore the power. Otherwise you must shutdown when the grid is down.
65 Plus 4 / 4 Seater, car addict
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Joined: Jul 2007
Posts: 26,748 Likes: 419
Member of the Inner Circle
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OP
Member of the Inner Circle
Joined: Jul 2007
Posts: 26,748 Likes: 419 |
Bruce, if they are stand alone they work. I guess you need to decouple completely from the grid. I am no expert but that is how I understand it. At best our batteries store 4.2 kWh when full. In winter I am lucky to generate 5 kWh so most goes to use not the batteries. Today for example we generated 4.8kWh and 2 kWh was stored but that is the best day in 5 days , on the others we stored 0 kWh .
They really come into use in Spring through autumn when normally we buy in 4-5 kWh per day and this falls to 0.6-2 kWh per day.
JohnV6 2022 CX Plus Four 2025 MG ZS EV aka Trigger
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Joined: Dec 2017
Posts: 2,041 Likes: 71
Talk Morgan Expert
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Talk Morgan Expert
Joined: Dec 2017
Posts: 2,041 Likes: 71 |
Bruce, if they are stand alone they work. I guess you need to decouple completely from the grid. I am no expert but that is how I understand it. At best our batteries store 4.2 kWh when full. In winter I am lucky to generate 5 kWh so most goes to use not the batteries. Today for example we generated 4.8kWh and 2 kWh was stored but that is the best day in 5 days , on the others we stored 0 kWh .
They really come into use in Spring through autumn when normally we buy in 4-5 kWh per day and this falls to 0.6-2 kWh per day. Now I understand, many thanks.
Bruce 1964 4/4 Series V Comp (Megan) 1994 +8 (Maurice) 2013 M3W (Olga)
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Joined: May 2019
Posts: 589
Talk Morgan Regular
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Talk Morgan Regular
Joined: May 2019
Posts: 589 |
A Tesla Powerwall 2 stores up to 13.7kWh nominal. It also has features like setting minimum retention charge levels for unexpected power cuts and stormwatch that ensures the battery is automatically recharged at or near capacity before bad weather arrives. It’s not cheap but I guess you “pays your money and takes your chances.” It works without any issues when the grid is down and I can also run the house from a generator if needed.
M3W Brooklands (2015) Moody 41 (2013)
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Joined: Aug 2013
Posts: 15,794 Likes: 14
Formerly known as Aldermog Member of the Inner Circle
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Formerly known as Aldermog Member of the Inner Circle
Joined: Aug 2013
Posts: 15,794 Likes: 14 |
A Tesla Powerwall 2 stores up to 13.7kWh nominal. It also has features like setting minimum retention charge levels for unexpected power cuts and stormwatch that ensures the battery is automatically recharged at or near capacity before bad weather arrives. It’s not cheap but I guess you “pays your money and takes your chances.” It works without any issues when the grid is down and I can also run the house from a generator if needed. Interesting: we have PV panels, plus a 2.5kw Pythontech (SP?) battery. When the power goes out it is pointless and I've no idea if and when it is working. The PV panels have provided about 3500kwh a year, we use about that per day in winter, dropping to about 10% of that in summer. If we turn off non essentials we can cut consumption to about 1.5kwh, so a PowerWall 2 would give us 10 or so hours of essential power to run the gas boiler, internet, fridge and a few lights. So time to look at costs....
Peter, 66, 2016 Porsche Boxster S No longer driving Tarka, the 2014 Plus 8...
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Joined: Apr 2014
Posts: 6,827 Likes: 59
Talk Morgan Sage
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Talk Morgan Sage
Joined: Apr 2014
Posts: 6,827 Likes: 59 |
So time to look at costs.... I looked and the cheapest was £5,500 without installation. I think I'm too old to be able to recoup that!
Best Regards Lang may yer lum reek
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Joined: May 2019
Posts: 589
Talk Morgan Regular
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Talk Morgan Regular
Joined: May 2019
Posts: 589 |
I find between April and October we hardly take any power from the grid for the house and the 6.5kWh solar with the Tesla Powerwall handles everything including the hot water using an iboost.
The ev Mini Cooper is sometimes charged from the grid between April and Oct on cloudy days. The bonus is that having an ev lets us use Octopus Go which is 9p per kWh between 0030 and 0430hrs so any grid use is limited to then.
Our annual electricity bill is around £400.00 including running a car. I estimate payback for the solar/batt system is less than 10years at current rates and I personally believe we are all going to see even higher energy charges in the future so the overall payback period is going to be reducing.
Our heating is split between a gas boiler and an electric storage cooker.
Before interest rates bounced back this looked by far the best investment we could make with a bit of spare cash and now even with the higher interest rates it still feels right.
M3W Brooklands (2015) Moody 41 (2013)
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Joined: Jul 2007
Posts: 26,748 Likes: 419
Member of the Inner Circle
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OP
Member of the Inner Circle
Joined: Jul 2007
Posts: 26,748 Likes: 419 |
Fully agree our system has a payback of sub 7 years. What really winds me up is the standing charge, in summer it is far higher than the cost of electricity.
We also heat hot water before exporting to the grid i.e when the batteries are full we heat the water. When the water is hot we export to the grid.
I don't understand why it shouldn't be law that all new builds have pv systems.
JohnV6 2022 CX Plus Four 2025 MG ZS EV aka Trigger
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Joined: Aug 2013
Posts: 15,794 Likes: 14
Formerly known as Aldermog Member of the Inner Circle
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Formerly known as Aldermog Member of the Inner Circle
Joined: Aug 2013
Posts: 15,794 Likes: 14 |
I...... don't understand why it shouldn't be law that all new builds have pv systems. I agree 100%. It is interesting that on a smallish new development in the village the "social" houses all have PV panels, the free market ones do not. I also agree about the "standing charge" theft. Octopus claim they have the lowest standing charge, but I'd rather just pay for what I use. Electricity prices have but one way to go.......as do gas prices.
Peter, 66, 2016 Porsche Boxster S No longer driving Tarka, the 2014 Plus 8...
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