Feedback on Vehicle to Grid (V2G) trial: cost savings and future green tech plans


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Hi,

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.

 

V2G usage

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.

 

Energy bills

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.

 


5 replies

Userlevel 7

Some really great stats and great to hear such a positive de-carbonising story, @richb99999.

 

Just gonna tag a few other V2G/ASHP/Solar users here as I’m sure they’d be interested to compare experiences - @Sean T, @Jequinlan, @Jason lewis, @nealmurphy, @M.isterW, @PeterR1947 😊

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@richb99999 great write up - thank you.

We are in the ASHP trial so can give feedback on our system in the year we have had it. Overall I think we are paying more than with gas - about 20-30%, however we are running the ASHP four times longer than the old gas system so we are getting much more for our money. Total hot water and heating kWh is lower than gas, but the house is so much warmer. Very happy with the system performance and efficiency.

We have been running weather compensation since early March, having run the ASHP more like a conventional boiler for ten months prior. Finding weather comp is more efficient way of running it but had to do a lot of tinkering to set the curve just right. Likely we will need to tinker more mid winter this coming year.

What manufacturer did you opt for? Who did the install and what has your SCOP/COP been like? Any other experiences?

There is masses of experience on the trial and we are a friendly bunch and happy to help if you need it. Best advice I can give is to look up Heat Geeks on YouTube and on their web site - you will learn a lot from those guys.

Cheers

 

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Oh @richb99999 i forgot to say, my i3 goes back in November and I am looking at V2G/H so any advice you can share would be much appreciated. 

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We have an 11.2 kW Ecodan. I think the unit is good, but our installers (Allseasons) didn’t do a fantastic job. They seemed to be more obsessed with squeezing the external pipework into some neat PVC ducting than they were in insulating it well, or sealing the hole in the wall! I ended up fixing it using the best practise info on the Ovo heatpump forum (https://forum.ovoenergy.com/your-smart-home-139/heat-pump-pipe-insulation-energy-efficiency-starts-with-the-pipes-9477). I am going to be monitoring it using the open source system being developed by the engineers/programmers/enthusiasts at Open Energy (https://guide.openenergymonitor.org/applications/heatpump/), but I have not got it working yet, so I don’t have an accurate SCOP. My target is to tinker until it is as cheap to run as mains gas. I was going to set up the weather compensation initially. Then I was going to rig up some small computer fans to blow air through the radiators, to see how much the the flow temperature can be dropped, whilst maintaining heat output. In retrospect, I should have insisted that the installers fitted the biggest available radiators that would fit in our house. They did upgrade almost all the downstairs radiators, but I have since found out that they designed for a flow temperature of 50 degC on a -3 degC day. The new rads are only slightly bigger than the original ones, which strikes me as a bit daft. In retrospect, I should have got them to minimise the flow temperature by fitting the biggest balanced set of radiators that could physically fit in our house. It would have increased the radiator cost slightly, but would have dropped the running costs.

 

Thanks for the info about Heat Geeks – the videos look really helpful.

 

Regarding V2G/V2H, the best link I have found is https://www.flexi-orb.com/electric-vehicles/vehicle-to-grid/. I don’t know if there are any commercial V2G offerings in the UK yet. I would recommend trying to get on one of the trials if you can (not sure how many are still taking on new participants). I got a Leaf, because that was the only option if you wanted to join the Ovo trial, but the website above is suggesting a much bigger range of cars/vans are now possible. I think most cars will be compatible soon (Fully Charged did an episode from Utrecht recently which looks really hopeful https://www.youtube.com/watch?v=L_BYDKz3_Jg). My experience is that V2G really complements heat pumps.

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Oh @richb99999 i forgot to say, my i3 goes back in November and I am looking at V2G/H so any advice you can share would be much appreciated. 

Indra have opened their V2H trial and excepting applications. It does require an investment from you for the equipment (no idea how much) but I’d take a look at that. The equipment is solid and very capable.

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