our V2G system has been fully functioning for a year, so I thought it might be useful to share our experiences. We have quite a lot of green tech installed – first solar, then a Leaf (mainly to access the V2G trial), and this winter an ASHP. It seemed like the right thing to do for the environment, but I had nagging doubts that we might be shooting ourselves in the foot financially, in terms of running costs, maintenance & deterioration. But having gone through all our bills for the last 12 months, it is working out to be very cheap to run the house & car, when the V2G credit is included. Long may it continue!
Leaf battery deterioration with V2G
It’s a 62 kWh Leaf bought 31 Jan 2020. So it’s about 2 years 2 months old. It has done 20500 miles. About half the mileage is tootling around town. The other half is tootling on motorways (I usually tuck in behind trucks or coaches to maximise range). We mostly charge at home with only an occasional fast charge on the motorway.
Leaf Spy Pro is showing State-Of-Health as 95.44%. I have only been tracking SOH for the last 5 months. Over that time period, it looks like the battery has been deteriorating at about 0.58% per year.
According to https://storage.googleapis.com/geotab-sandbox/ev-battery-degradation/index.html
Leaf deterioration at 2 years 2 months is 95.7%. Some sites plot against age and some against mileage. I guess in reality it’s a mixture of both.
There seems to be a lot of scatter in the data on the internet, so I’m not sure much can be concluded from just my experience. On face value, maybe there’s a tiny bit of extra deterioration due to V2G, but it appears pretty negligible to me. I am encouraged that the rate of battery deterioration appears to be pretty low at the moment – only about 1.4 miles range per year. So it looks like there’s a good chance that the battery will outlast the car, and still be useable for grid backup afterwards.
Over the last year, the car imported an average of 17.7 kWh/day, with 12.2 kWh/day exported from the car. We both cycle to work, so the car is typically plugged in more than 20 hours per day.
We also have a 4 kW peak array of solar panels on the roof which generate 4000 kWh/year.
The V2G payments vary quite a lot, but average out at £140/month.
So far, we have found the V2G very beneficial, both financially and environmentally. Our 20 year old gas boiler packed in last September, so we replaced it with an air source heat pump. We had previously switched from gas to electricity for cooking, so we could disconnect the gas supply. This cost about £100, but we should save about the same amount every year on the standing charge. The whole system of electric car + V2G + ASHP + solar seems to fit together really neatly. The car charges over-night on generally lower carbon electricity. On cold winter evenings, the V2G provides enough power to run the ASHP, so we are not boosting the demand for coal or gas (sorry Mr Putin). In summer, we run hot water & dishwashers etc off the solar panels, and the V2G rebates mean our energy bill goes negative, which is a novel experience. There’s a guy who charges his car on our drive after driving up from London, once a week for a course at Derby University. We charge him cost price for the electrons. Taking that into account, over the year, it costs about £300 for heating, hot water & electricity for running the house & car, which is a lot less than we used to pay. It’s a 1940’s 4 bed semi. We have gradually improved the insulation over the years, and it’s now a “B” on the EPC. But it’s definitely no passivhaus, so £300 per year strikes me as really cheap.
The FIT has paid off the installation of the solar, and is now making us a tidy profit. The RHI payments are not so generous, but will pay off the extra cost of installing an ASHP rather than a gas boiler. The V2G was free.
The car fuel costs are peanuts. The tax is zero. Maintenance appears to be a bit cheaper than for an ICE car. The battery is definitely deteriorating, but much slower than I was expecting.
The solar has had no maintenance in 11 years. The panels are supposed to deteriorate slowly over time, but I cannot see any drop off in generation.
I have not been able to do a direct comparison of the cost of heating with mains gas versus heating with an ASHP. But our total energy bill is really low, so my original fears that the ASHP might be considerably more expensive appear to have been unfounded, so far. I guess it just depends on what happens to tariffs over the next few years. We have not had the ASHP long enough to be able to comment on maintenance. It’s a complicated bit of kit. I think it should be possible to tweak the settings to improve the efficiency, but I have not had time yet.