I want to charge my EV at home by solar - HELP.
Discussion
hi all,
i've been looking all over the webnet, filling in various calculators and the like but nothing can seem to answer my questions.
I have a SE facing roof with 33 square m area at a pitch of 25 degrees - from this i understand i could produce 4kw/hr there abouts.
Domestic charging point @ 3.3kw/hr takes 12 hours from flat which is fine for the weekend but not during the week.
professionally installed charging point (which is what we will have) is 7.7kw and gives us 4.5hour charge from flat.
The car will be used for a daily 140mile commute but this also means during the week it won't be plugged in while the sun is out, only the weekends.
it's pretty obvious the answer is a storage / battery wall type solution but i have a few questions around this...
1) will that be able to supply 7.7kw/hr for 5 hours ?
2) if so, what would be the size and cost of a system
3) and would the PV system that i could accommodate on my roof charge the batteries adequately
4) how long would it take my PV system to charge the power wall in order for it to supply the required energy ?
I have a feeling the answer will be it will cost more for the system than i would save - currently at home i pay 13p per kWh but charging from flat everyday my i3 has a 33kw capacity gives me £4.28 daily charge currently - not to mention using the system for the general household stuff the rest of the time?
any help would be greatly received - i can't be the only one wanting to do this?
i've been looking all over the webnet, filling in various calculators and the like but nothing can seem to answer my questions.
I have a SE facing roof with 33 square m area at a pitch of 25 degrees - from this i understand i could produce 4kw/hr there abouts.
Domestic charging point @ 3.3kw/hr takes 12 hours from flat which is fine for the weekend but not during the week.
professionally installed charging point (which is what we will have) is 7.7kw and gives us 4.5hour charge from flat.
The car will be used for a daily 140mile commute but this also means during the week it won't be plugged in while the sun is out, only the weekends.
it's pretty obvious the answer is a storage / battery wall type solution but i have a few questions around this...
1) will that be able to supply 7.7kw/hr for 5 hours ?
2) if so, what would be the size and cost of a system
3) and would the PV system that i could accommodate on my roof charge the batteries adequately
4) how long would it take my PV system to charge the power wall in order for it to supply the required energy ?
I have a feeling the answer will be it will cost more for the system than i would save - currently at home i pay 13p per kWh but charging from flat everyday my i3 has a 33kw capacity gives me £4.28 daily charge currently - not to mention using the system for the general household stuff the rest of the time?
any help would be greatly received - i can't be the only one wanting to do this?
We had a quote from Eon about their solar offering and we would have been very enthusiastic to take it up.
However, the issue is power storage. The battery that Eon offer is about 1/3 the size of the i3 battery, so basically pointless. I do not believe that there is currently someone offering a domestic battery with sufficient storage to charge a car.
However, the issue is power storage. The battery that Eon offer is about 1/3 the size of the i3 battery, so basically pointless. I do not believe that there is currently someone offering a domestic battery with sufficient storage to charge a car.
As I type, the Leaf is at work with me, charging from the grid.
The battery at home is completely full, so when I plug the car in tonight, it'll discharge into the car.
The roof is generating 0.6kWh at this moment. The house is consuming 0.2kWh, and so the system is sending the remaining 0.4kWh back to the grid. Which I get paid nearly bugger-all for.
The battery at home is completely full, so when I plug the car in tonight, it'll discharge into the car.
The roof is generating 0.6kWh at this moment. The house is consuming 0.2kWh, and so the system is sending the remaining 0.4kWh back to the grid. Which I get paid nearly bugger-all for.
You could also look at a "Zappi" charger that can intelligently alter the car charge rate to make the most out of the solar?..
https://www.youtube.com/watch?v=0EtegQfZQRw
Edit: sorry only just seen the bit about the car wont be plugged in during the day.
https://www.youtube.com/watch?v=0EtegQfZQRw
Edit: sorry only just seen the bit about the car wont be plugged in during the day.
Edited by NeoVR on Monday 26th March 13:42
Ignoring the other benefits of having a solar/battery solution, and being self sufficient, what's the ROI of it vs just paying for the electricity to charge?
It's probably about £3-5 a day to charge? assuming £15k to buy that would give about 8 years to break even, which seems ok if it's got a 20 year life span.
These guys seems to do some interesting solutions
http://www.windandsun.co.uk/products/Batteries/Lit...
It's probably about £3-5 a day to charge? assuming £15k to buy that would give about 8 years to break even, which seems ok if it's got a 20 year life span.
These guys seems to do some interesting solutions
http://www.windandsun.co.uk/products/Batteries/Lit...
NeoVR said:
You could also look at a "Zappi" charger that can intelligently alter the car charge rate to make the most out of the solar?..
https://www.youtube.com/watch?v=0EtegQfZQRw
I've got one of these too. It has a variety of charge options:https://www.youtube.com/watch?v=0EtegQfZQRw
- FAST - which uses anything in the battery and the roof and then tops up from the grid to charge asap. 6kW ish?
- Eco1 - which uses the battery and the roof to charge slowly, only using the grid if necessary
- Eco2 - solely uses the battery and the roof, won't draw from the grid at all.
(I think that's how it works, I confess I've not fully got my head around it.)
Just reading about the Tesla powerwall...
Cost - £6k
Usable Capacity- 13.5 kWh
max continuous - 3.68kW/5kW
So, three powerwalls ?
Single (£6k) - usable capacity (kWh) 13.5 max cont. fig 1 (kWh) 3.68 max cont. fig 2 (kWh) 5
Triple (£18k) - usable capacity (kWh) 40.5 max cont. fig 1 (kWh) 11.04 max cont. fig 2 (kWh) 15
Cost - £6k
Usable Capacity- 13.5 kWh
max continuous - 3.68kW/5kW
So, three powerwalls ?
Single (£6k) - usable capacity (kWh) 13.5 max cont. fig 1 (kWh) 3.68 max cont. fig 2 (kWh) 5
Triple (£18k) - usable capacity (kWh) 40.5 max cont. fig 1 (kWh) 11.04 max cont. fig 2 (kWh) 15
Edited by PixelpeepS3 on Monday 26th March 13:54
Edited by PixelpeepS3 on Monday 26th March 13:56
Edited by PixelpeepS3 on Monday 26th March 13:56
I've 14 panels on my SE-facing pitched roof. Best day of the year so far yesterday generated 22kWh.
Most winter days don't get anywhere near that much.
I think if you're trying to go completely self-generated for a 140 mile/day commute you'll need a very big roof and a very big battery set-up.
And even if you had that, half the year you'll still need a top-up from the grid, of a varying amount.
ETA my commute is 50 miles a day, so requires about 12kWh. Just about within reach of a full Power Wall. But I charge at work as well.
Most winter days don't get anywhere near that much.
I think if you're trying to go completely self-generated for a 140 mile/day commute you'll need a very big roof and a very big battery set-up.
And even if you had that, half the year you'll still need a top-up from the grid, of a varying amount.
ETA my commute is 50 miles a day, so requires about 12kWh. Just about within reach of a full Power Wall. But I charge at work as well.
SpeckledJim said:
I've 14 panels on my SE-facing pitched roof. Best day of the year so far yesterday generated 22kWh.
Most winter days don't get anywhere near that much.
I think if you're trying to go completely self-generated for a 140 mile/day commute you'll need a very big roof and a very big battery set-up.
And even if you had that, half the year you'll still need a top-up from the grid, of a varying amount.
ETA my commute is 50 miles a day, so requires about 12kWh. Just about within reach of a full Power Wall. But I charge at work as well.
That Zappi product is very interesting. Most winter days don't get anywhere near that much.
I think if you're trying to go completely self-generated for a 140 mile/day commute you'll need a very big roof and a very big battery set-up.
And even if you had that, half the year you'll still need a top-up from the grid, of a varying amount.
ETA my commute is 50 miles a day, so requires about 12kWh. Just about within reach of a full Power Wall. But I charge at work as well.
Maybe the answer is not trying to 'fully' charge the car with renewables but at least reduce the amount taken from the grid.
Tesla powerwall2
Solar install
Zappi to control where it takes the supply from.
PixelpeepS3 said:
SpeckledJim said:
I've 14 panels on my SE-facing pitched roof. Best day of the year so far yesterday generated 22kWh.
Most winter days don't get anywhere near that much.
I think if you're trying to go completely self-generated for a 140 mile/day commute you'll need a very big roof and a very big battery set-up.
And even if you had that, half the year you'll still need a top-up from the grid, of a varying amount.
ETA my commute is 50 miles a day, so requires about 12kWh. Just about within reach of a full Power Wall. But I charge at work as well.
That Zappi product is very interesting. Most winter days don't get anywhere near that much.
I think if you're trying to go completely self-generated for a 140 mile/day commute you'll need a very big roof and a very big battery set-up.
And even if you had that, half the year you'll still need a top-up from the grid, of a varying amount.
ETA my commute is 50 miles a day, so requires about 12kWh. Just about within reach of a full Power Wall. But I charge at work as well.
Maybe the answer is not trying to 'fully' charge the car with renewables but at least reduce the amount taken from the grid.
Tesla powerwall2
Solar install
Zappi to control where it takes the supply from.
TBH I'm not completely convinced on the financial argument at the moment at least. If electricity gets more expensive from the grid though, then it'll pay back more quickly.
It's not really practically possible to have the equipment necessary to charge the car on a dark winters day, and if you did, you'd be generating so much juice on a sunny summer's day that you'd just be sending it cheaply back to the grid.
It's a shame the feed-in tariffs aren't more fairly priced in terms of out:in otherwise the battery wouldn't be necessary - you could just fill the roof with panels and use the grid itself as your mechanism for de-coupling production and consumption.
Also, an early Leaf is £5k, and comes with c.20kWh battery, and a whole car attached.
Which makes £6k for 13kWh of Power Wall look a bit expensive, IMO.
Edited by SpeckledJim on Monday 26th March 15:33
I have a 7.5 kW solar system, SSW facing near Nottingham. It will only kick out max kWs for a short time in the middle of summer. Most of the time you don't get to the maximum rating.
My car has a 10 kWh battery. Yesterday was sunny - peaking at about 5.5 kW generation with 33 kWh generated during the day. I managed to charge the car 1 and a half times, but that's because it could charge when the sun was out. I am lucky and work from home most of the time, as the days get better, this will become the norm.
In winter there are many days where I am lucky to see 10 kWh generated, maximum in summer is ~ 50 kWh & annual is about 6 MWh The only way to use all the solar power would be by battery. I keep looking, but the cost is far too high at the moment to make it worth while.
If you consider a 14 kWh Powerwall costs £6k and you fill and use all the power every day, that's ~ £1.40 worth of electricity or about 12 years to get your money back. You are not going to fill it every day though, so better estimate may be 24 years! They also have limits on discharge rates.
Have a watch of this > https://www.youtube.com/watch?v=nWLzlrGGuxQ
The Zappi charger looks to work well, mopping up power before export, similar to how the Iboost water heater works. If had a choice i would have got one, but i didn't, so I make do with setting the charge rate, depending on rate of generation.
My car has a 10 kWh battery. Yesterday was sunny - peaking at about 5.5 kW generation with 33 kWh generated during the day. I managed to charge the car 1 and a half times, but that's because it could charge when the sun was out. I am lucky and work from home most of the time, as the days get better, this will become the norm.
In winter there are many days where I am lucky to see 10 kWh generated, maximum in summer is ~ 50 kWh & annual is about 6 MWh The only way to use all the solar power would be by battery. I keep looking, but the cost is far too high at the moment to make it worth while.
If you consider a 14 kWh Powerwall costs £6k and you fill and use all the power every day, that's ~ £1.40 worth of electricity or about 12 years to get your money back. You are not going to fill it every day though, so better estimate may be 24 years! They also have limits on discharge rates.
Have a watch of this > https://www.youtube.com/watch?v=nWLzlrGGuxQ
The Zappi charger looks to work well, mopping up power before export, similar to how the Iboost water heater works. If had a choice i would have got one, but i didn't, so I make do with setting the charge rate, depending on rate of generation.
herewego said:
It seems more logical for employers to install a solar roof over the parking area so that cars can be charged directly from solar input during the day and would then have the option of running the household demand during the evening before picking up a top up in the early hours.
That would indeed be logical in terms of the energy timings and requirements. I'd rather charge for free from the roof at work and let my own roof charge my home battery for my own evening and morning requirements.
The hurdles are 'who pays?' and 'who is liable?'
JD said:
Have you thought about moving?
probably the most cost/environmentally effective plan.
That might be the best environmental plan, but the stamp duty and other costs of a home move would cover the capital requirements of a roof full of panels and a battery, and thereafter you're saving £,£££ a year.probably the most cost/environmentally effective plan.
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