Off grid solar car charging

[LymeSimon]

Great to read this. I have a £5k (professionally installed) solar installation and since March I have fed slightly under 500kWh of solar into my car (2,000 miles) which would have cost £45 off peak, £130 at full day rate and £255 petrol at 55 mpg! My charger isn't very smart, but I can download charging session data. I simply limit the car to 16a and use the tried and tested method of pulling the plug if it gets cloudy. I wish I could set charge rate from the app, but it's not a big failure and my MG4 is streets ahead of my old Nissan Leaf (and even older first Nissan Leaf) in so many ways.

It would take a long time for solar panel payback if this were all I did, but I also run my house for almost nothing during the summer and even export quite a bit to the grid.

Solar + Battery + EV = Happiness

 

[Rolfe]

Yeah, we have a very reliable grid in the UK.

We had one significant outage a few years ago when they blew up the local cooling towers and the dust triggered a fire at some local electricity infrastructure.

It was actually the Summer I wanted it for - I didn't want to be missing out on solar because the grid was down for an extended period. With the car it is a great option to just put it in there once the house battery is full.

Once my current teething troubles are sorted I'll probably look into it.

 

[GaryMG4]

I'm finding that using solar and the granny when I'm at home I can add 10-15 kWh at a cost of 20-100p depending how many clouds come over. I'm happy enough with that, much easier than spending my time deciding whether to pull the plug or not.

 

[DaevM]

This sounds similar to something my installer said, that my system (quite conventional) wouldn't power the house in a power cut, however another modification could be added at any time that would permit that. I didn't do it because we don't have prolonged power cuts here, but I still might.

I sometimes wonder how I'd heat the house in a prolonged power cut, and the obvious answer is that dirty great tank in of kerosene in the garden, with whatever I have in the house battery powering it.

...and the car battery of course ?.
Didn't use it in our recent 24hr power cut because MrsM enjoys playing with camping gear and candles, but I was sorely tempted. Maybe next time ?

 

[greenacre]

Just as a matter of interest. I completed my “off grid” solar installation for my car charging. I have harvested 450 miles from the sun since it went live on 4th May, l make that about 9 miles a day on average and given we haven’t had the best of summers so far (I live in Devon) and I’m unfortunately shaded by a big tree, so I don’t get much after 4.00pm even on a sunny day, never the less I’m pretty pleased with that. I know that doesn’t seem like much, but I wanted to see if it were possible.

I had next to no advice from solar installers, in fact all were quite hostile to the fact that dared to do it myself. I’m from an time when we all had a go ourselves. (72 years old). They all quoted many regulations and suggested they did it for me at vast cost (nothing less than £6000) despite my constantly reminding them that this was OFF GRID and not connected to the mains in any way what-so-ever.

Anyway here’s how I did it, if anyone is interested: I got 7 x 200w second-hand solar panels and put them on my workshop roof (wired in series), I bought a new Edecoa 3000w inverter, then got 2 nearly new 24 volt 2600w lithium batteries (wired in parallel). Connected them together and it all worked. At the end of the day I’ve probably spent about £1000.

That's really interesting; I would be keen to do the same as I'm not allowed a permanent installation. A couple of questions: why do you need batteries; and do you run the electricity into and through a 'granny'charger in the car? Thanks

 

[pollenface]

I off grid charge at 1.5-2.4kW when there is good sun.

4.5kW of pv spread between 3 mppts and 3.6kWh of usable battery.

 

[siteguru]

What are mppts?

 

[Ian Key]

What are mppts?

I read that as muppets ?

 

[Coulomb]

What are mppts?

They are Maximum Power Point Trackers, needed because photovoltaic (solar) panels have a non-linear voltage-current characteristic.

 

[Gadget Geek]

I've just checked my stats and I got 538 miles of sunshine in June.

 

[GaryMG4]

I've just checked my stats and I got 538 miles of sunshine in June.

Last august I had similar amounts, in June I added around 700 miles with 60-70% of that being sunshine, on the plus side FiT paid me £113 for what I'd produced.

 

[Rolfe]

...and the car battery of course ?.
Didn't use it in our recent 24hr power cut because MrsM enjoys playing with camping gear and candles, but I was sorely tempted. Maybe next time ?

The difficulty there is how to plug the central heating boiler into the car battery. I could manage a long enough extension lead, but as far as I can see the boiler is hard-wired into the house electrics - it doesn't have a three-pin plug.

 

[DixieTGS]

I think there are some potentially dangerous ways of doing it that I've seen described on a forum, so not suitable most of us.

One possibility is to get an electrician to convert the hard-wired boiler to have a 13A plug instead. Then just swap the boiler between a house socket and car V2L socket as needed.

It's possible car charging ports and earthing requirements may come in to play and scupper that idea though.

 

[GaryMG4]

The difficulty there is how to plug the central heating boiler into the car battery. I could manage a long enough extension lead, but as far as I can see the boiler is hard-wired into the house electrics - it doesn't have a three-pin plug.

Funny enough I was thinking exactly the same, so I checked the boiler details which say it should on a 5 amp fuse. I'm very temped to put a plug top on the wire and replace fused switch with a standard 13 amp socket to be ready. a few years back I bought a small camping gas stove due to the number of multi hour power cuts we were getting but since then I've only used it once, perhaps if I adapt the boiler so I can plug it into the car it will ensure no more power cuts!

 

[Rolfe]

I haven't really investigated as the grid supply to this village seems pretty robust. I don't know where the boiler feeds into the mains and I don't know how to get at it.

However, unless it's very expensive, the adaptation to the battery/inverter installation might be the easiest thing. Unless of course the power cut was very long and the home battery couldn't cope. (At that point I start wondering if there's any way to get power from the car battery into the home battery, but probably not.)

 

[Barrie]

I changed my mains feed to my boiler to a standard plug here in France and it works no problem. The boiler only draws around 100 W for the pump as it's a gas combi. Used my V2L adaptor for it a few times during power cuts with zero issues.

I haven't really investigated as the grid supply to this village seems pretty robust. I don't know where the boiler feeds into the mains and I don't know how to get at it.

However, unless it's very expensive, the adaptation to the battery/inverter installation might be the easiest thing. Unless of course the power cut was very long and the home battery couldn't cope. (At that point I start wondering if there's any way to get power from the car battery into the home battery, but probably not.)

Buy a battery charger and plug it into your V2L lead and it will charge your home batteries via the car. Some have adjustable current so you can feed 1kW-2kW etc from the car to the home batteries. It's the simplest and safest way as your car is not really designed for full V2H or V2G. The car will just see the charger as another 240 V appliance. I have an MG Marvel so have 75kWh to play with !!! I only have a 5 kWh home battery but when the sun goes down or we have a power failure the car just constantly keeps the home battery topped up. So I charge the car via solar all day then plug in the battery charger at night to ensure we get through until morning as sometimes my 5 kWh battery is not enough.

 

[Rolfe]

That's an interesting idea, I didn't know that was possible.

 

[Gadget Geek]

Just finished the solar tracker for my light sensor which switches on the Pilot Signal to my granny charger to charge off the excess solar.

I got the idea from here;



and modified it. It also has a PETG cover to keep the weather out.