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Tariff for home EV charging and solar panels

5K views 41 replies 17 participants last post by  Flash DaEV 
#1 ·
Hi, we are moving into a new build that will have solar panels installed and are going to be installing a EV charger at home. Does anyone know of any tariffs that combine these to get the best benefits/price?
Thanks!
 
#5 ·
This depends on the size of the Array and the use of the car, A small panel (4kWp) setup will at best trickle charge the car and that assumes the car is at home all day.
I see its a 4 panel array - say 1.2kWp (300w a panel at a guess) so not much use for car charging.
Octopus offer 5p a unit on their go tariff for 4 hours - this will be enough to charge the car usually - depends on how its used, the day rate is reasonable as well.
The Panels can supply the daylight load on the house and any excess be sold to a electricity supplier for 3-5p a unit.
The trouble is adding a battery to shift usage of the unused solar to the evening is expensive and the payback is very slow.
 
#7 ·
This depends on the size of the Array and the use of the car, A small panel (4kWp) setup will at best trickle charge the car and that assumes the car is at home all day.
I see its a 4 panel array - say 1.2kWp (300w a panel at a guess) so not much use for car charging.
Octopus offer 5p a unit on their go tariff for 4 hours - this will be enough to charge the car usually - depends on how its used, the day rate is reasonable as well.
The Panels can supply the daylight load on the house and any excess be sold to a electricity supplier for 3-5p a unit.
The trouble is adding a battery to shift usage of the unused solar to the evening is expensive and the payback is very slow.
Thanks yes - that’s what I was trying to work out. Can you have a tariff like the Octopus one that allows you to charge cheaply overnight and still sell back any electricity generated on the solar panels. I don’t necessarily need the panels to charge the car direct. If that makes sense!
 
#6 ·
If you wish to benifit from solar you need to have your EV at home during the day, unless you have a battery installed , which I doubt as you only have 4 panels, you could go for an EV tariff, such as OCTOPUS GO which alows you to charge for 4 hours at 5p/Kwh
 
#9 ·
Thanks yes, wasn’t looking to charge the car with the panels. Just trying to work out if I can get a suitable tariff with a supplier and still sell / offset any electricity from the panels back to the supplier. They seem to offer a tariff for solar panels and a tariff for EVs but couldn’t work out of you can do both.
 
#10 ·
Octopus have an outgoing tariff. I've no idea what it pays but the output from 4 panels is very unlikely to be enough to warrant picking an incoming tariff based on that.
Trying to use as much of your generation is the most cost effective.

I haven't seen a tariff that's aimed at EV drivers with solar panels. EVs are still a small share of the market, EV drivers with solar panels needing an outgoing tariff will be a very small slice of the market.
 
#11 ·
Octopus have an outgoing tariff. I've no idea what it pays but the output from 4 panels is very unlikely to be enough to warrant picking an incoming tariff based on that.
Trying to use as much of your generation is the most cost effective.

I haven't seen a tariff that's aimed at EV drivers with solar panels. EVs are still a small share of the market, EV drivers with solar panels needing an outgoing tariff will be a very small slice of the market.
Thanks - when I contacted Octopus all they said was “If your are looking to export from the panels, then Outgoing Octopus will be the tariff for that: https://octopus.energy/outgoing/
For your electric vehicle, Octopus Go is best suited: https://octopus.energy/go/

Wasn’t sure if I could have the go tariff and get money off for anything generated by the panels (no matter how small). Seems a waste to have them sitting there.

Thanks for all the advice.
 
#12 ·
How is your hot water heated?

4 panels will not generate a huge amount, even if the highest output panels.

Your best option is to maximise your use of what you generate and try and minimise what you export - use your solar to do laundry / heat water during the day, have an EV tariff for cheap charging at night.

A diverter such as Myenergi's Eddi (several other companies make similar / cheaper devices) will automate the process wrt hot water.
 
#13 ·
You can sell the excess to any company, you are not tied to your supplier. Not sure if Octopus go will allow Octopus outgoing, I have a battery and they do not support outgoing so I sell elsewhere any excess.

If you have an immersion heater in a hotwater tank than something like an EDDI or Solar iBoost will divert any excess into the heater. This nowadays with condensing boilers and high pressure systems is not always the case though I'm lead to believe.
 
#14 ·
Oh I didn’t know I could sell it to anyone, thank you!!
Not sure what hot water system we have as we haven’t moved in yet - but this is the spec we have from the developer:
‘Gas-fired boiler with wet radiator heating system and domestic hot water provided at mains pressure.’ I’m not very technical on these sorts of things so a bit clueless!
 
#16 · (Edited)
domestic hot water provided at mains pressure
Needs an expert - any plumbers around?
To me this sounds like the hot water is not provided by a traditional loft tank / hotwater cylinder but some form of pressurized system so may well not have an immersion.

On the charger I'd get the builder to run suitable cable to where the charger will be, might save disruption when the charger is installed.
 
#15 ·
Octopus Go is best for power with 4 hour 5p rate at 00.30 - 04.30 to charge your car and any other time delay items - washing machine and excellent price at other times. No associated solar export tariff, so So Energy SEG
is the best place to get a SEG contract.
4 panels will contribute to your use but not enough to be troubled by.
 
#23 ·
Octopus Go is best for power with 4 hour 5p rate at 00.30 - 04.30 to charge your car and any other time delay items - washing machine and excellent price at other times. No associated solar export tariff, so So Energy SEG
is the best place to get a SEG contract.
4 panels will contribute to your use but not enough to be troubled by.
Thank you!!
 
#20 ·
New builds tend to have on demand boilers, so unlikely to have a hot water tank as space is also a consideration.

Best bet is to sell it to the grid and charge the car overnight at a low rate. You then tend to just pay a very low marginal rate for charging your car.

4 panels sounds like a bit of green washing in the UK. Really need 10 or more to make it worthwhile.
 
#37 ·
4 panels sounds like a bit of green washing in the UK. Really need 10 or more to make it worthwhile.
I have to say that I agree here. I've 16 panels for 4kWp on an ex-council terrace. Given that a lot of the cost of install was the scaffolding, wiring and labour which will be the same whether 4 of 16 panels I find it intensely annoying that large building firms put in the minimum possible when the cost of extra panels is a low proportion of the total cost.

That said, there's been some good advice on here. Basically adjust your usage to use what you can, get some timeswitches for the appliances that don't have built in ones, even a slow cooker can be a useful tool in the circumstances. With 4 kW I sometimes use the granny charger for the car if I'm at home, have a full tank of hot water until October now, and at this time of year even have a surplus to use with an oil filled radiator but 1 -1.2 kW is more a useful contribution to keep you load down.
 
#21 ·
Octopus go or go faster for 4-5 hours cheap rate for the car

then for solar consider a zappi charger combined with an Eddi which can divert excess solar generation eg to an immersion heater and try to utilise as much excess as possible as during the day you won’t earn as much by exporting as you would save by using it yourself
 
#24 ·
Considering the output from the panels appear to be low, from OP's POST, I cannot see any advantage in obtaining a ZAPPI, ZAPPI's are for obtaining the best use from SOLAR PV and unless OP is intending to add more, there are more suitable chargers available at more resonable cost, using the timer in the EV to charge at lowest tariff.
If there is a hot water cylinder then the EDDI would be a suitable addition
 
#22 ·
That size array even at peak output will be unlikely enough to even trickle charge. Most of the day you’ll be topping up with grid (and meaning the rest of the house is using grid) which will very quickly get more expensive than just waiting for 5p off peak - don’t think it’s worth even considering the car and solar together for that setup
 
#25 ·
“Mains pressure hot water” could be either a combi or an unvented cylinder like a MegaFlo. All the MegaFlo models come with an immersion.
Whether to get an iBoost or similar depends on the export rate. For those of us on the old FIT/deemed export, it was a no brainier because you get paid for export whether you export or not.

I would expect the OP to be on an SEG so you need to balance the savings on gas to heat water minus the cost of the diverter with the value of exported units. At 70% efficiency between purchased gas and temperature rise in the tank, you’d save between 3.5 and 5p per unit of diverted power. If you can get more than that for export, save the cost of the diverter and sell what you don’t use.
 
#26 ·
On the PV consumption side, probably best to get used to programming your dishwasher for a midday cycle (if the house is unoccupied during the week), possibly your washing machine too but staggered and calling it quits.
You are doing your bit by adding to the grid supply (and you paid for that by purchasing the house)
The developer followed national building rules set by government (probably installed the stipulated amount of solar no more no less).
Not worth trying to chase down pennies involved in consuming all your own generation.
 
#27 ·
Yeah, I guess four panels is ~1.2kW. So as good a useless for EV charging. I certainly would not plough money into a Zappi, Eddi etc as you will never see a financial return.

As others have said, get a hot water diverter if you have a tank. I think the one I bought was ~£100 as it is a dumb fit and forget device. If I look at the screen it tells me how much it has put in the tank which is of no real interest. On sunny days cut the grass and run appliances sequentially etc

Instead, get yourself onto a decent electricity tariff like Octopus Go/Go Faster. Great for EV charging, tumble dryer, washing machine and dishwasher etc. For EV charging consider the Ohme as there is nothing cheaper. The days of free chargers are gone I think.

Cheers
 
#28 ·
Zappi is a waste of money for 4 panels, unless you are going for an evse that is similar price anyway.
There are other options that might help use the solar, the EO mini will charge at 1.4kW and there are air to be other charge points that do that.

Does the Ohme have settings to reduce the current or follow the solar generation?
If you use a very cheap overnight rate, like Octopus Go, then the Ohme is a good option as it sounds like it is very flexible and probably cheaper than the Zappi.
 
#29 ·
Get economy 7, charge overnight, drive the car during the day when the sun is out, and let the solar offset the higher cost units.

You don't want to sat around with the car in the drive waiting an age for the solar to charge the car.
 
#30 ·
Economy 7 is rarely worth it unless you do a lot of charging or have significant other overnight usage (breakeven point is when roughly 30-40% of your usage is off peak). Complete false economy for most people and you pay a far higher rate for all your peak usage than the non economy 7 tariff with the same supplier.
Even octopus go is not suitable for many Vs a competitive alternative standard (non time of use based ) tariff.
 
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#31 ·
I found it break-even (from data downloaded from the SmartMeter by a really helpful guy at Ecotricity) by just having the car, at quite low mileage. I was then able to switch other usage - washing machine and dishwasher to the overnight.

I wouldn't claim a profit from E7, but it does mean that I don't have to waste time messing about with very low charge rates, trying to charge on solar in sunny weather when I really should be out driving the car.

EVs should be charged overnight so they are available to be driven during the day (unless you are night shift worker). Solar charging is fundamentally incompatible with this common sense notion.
 
#42 ·
Isn't there a new Law of Boris saying that all new builds have to have air source heat pumps for DHW/central heating ? - it might yet be an ASHP.
Have to say we have fallen into ideal configuration through planning and chance. What's missing from the OPs configuration is more solar panels to produce enough electricity to actually benefit from and a domestic battery.
We currently use Octopus Go to charge EV (30kwh), charge domestic battery and first ASHP DHW heat of the day during the 5p/kwh period. The only big draw during the day then is the 2nd DHW about 12 hours later. By this time we've used a good portion of the battery charged @ 5p and the solar has then kicked in, charged it back to 100% ready for mostly evening use and is covering the rest of domestic daytime requirements. I think (from memory - not at home so can't go count) we've got 14 panels and a 5Kwh battery. - It's all working out very well financially but does get a bit more expensive when there's no sun and more heating required. We are still able to take advantage of the 5p/kwh charge of the domestic battery whatever the time of year / weather - we only realised this this winter after having it for a couple of years, rather than it sitting there for 4/5/6 months waiting for a charge from empty to at least the monthly full charge to keep it borderline healthy, it's getting a daily charge (or two) from 0-90%, which is supposed to help with longevity I believe. (min.70% for 10,000 cycles / 10 years). 2 full cycles a day will still be less than 10000 over 10 years.
We also got in on one of the last Solar FIT deals, with British Gas handling it for us. Not a lot - about a tenth of one of our earlier adopter neighbours, but still more than the 5p/kwh we're paying Octopus for during cheaptime/
 
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