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Would you consider getting solar/battery storage, if it would help charge your electric car?

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  • I already have solar

  • I already have solar + battery storage


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Discussion Starter #1 (Edited)
Hi all, I'm trying to get my head around installing a microgrid at my house of EV charger, Solar array and Battery Storage system.....

But is proving tricky to get reliable info on how everything integrates together, what my payback period would be, what sized array is best etc.

Interested to know if other EV owners have or are looking to get Solar + Battery Storage in the future to help directly charge their EV or feed into the grid and lower their energy bills...?

PS. If you already charge your EV via Solar/Battery Storage please post in the comments below what size array/size battery/yield and savings you're making, so we can all learn from you pioneers! :)
 

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Have you looked at the forum here: https://speakev.com/forums/power/
Lots of discussion of solar, battery banks, and the economics thereof.
I got solar PV installed about 18 months ago - the FIT made it a 7 year payback which seemed reasonable. Personally, I don't think there is an economic case for battery storage, because the total power my panels can generate is so low in winter (30kWh total in December), despite a reasonable level of generation during the rest of the year (my max is 30kWh on a bright summer day, half that in spring/autumn). However, if you want to be off grid, or you have issues with intermittent power, then battery storage might be a good solution for that.
 

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Discussion Starter #4
Thanks @Duncan23 - what brand of PV did you get installed and what sized array? Also where in the country are you based? I'm up in Fife - so less sun than down South and wondering if it's worth it! but then again PV is massive in most of Norway/Sweden - which has similar weather..
 

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We’ve got a 4kW system, it generates about 3600kWh a year - surplus goes into our hot water tank via an immersun or a Leaf when possible. This is via a charger with a solar switch but will probably add a Zappi as well.

Have looked at battery storage but as mentioned payback is pretty long - would like to get one at some point when prices drop.
 

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Our tiny cottage is grade II listed. Installing solar power would be difficult or maybe not possible.

I am following battery storage closely. I'll probably do it when prices come down a little more. Right now the payback time is a little too long.
 

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Discussion Starter #8
Hi @Grier I agree the upfront costs of solar/battery sotrage are high....but I'm of the opinion that energy prices in the UK will continue to rise and rise over the next 5-10 years, as more coal power plants switch off and the UK has to import more electricity wholesale until we can build more renewable energy sources.....so investing in Solar/Battery storage would (hopefully) save me money in the long term?

What do others think?

Here's an energy market outlook from Octopus energy
The state of wholesale energy prices in 2017, and what it means for bills

 

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Thanks @Duncan23 - what brand of PV did you get installed and what sized array? Also where in the country are you based? I'm up in Fife - so less sun than down South and wondering if it's worth it! but then again PV is massive in most of Norway/Sweden - which has similar weather..
I'm in Oxford, we got a ~4k system (think it's 3880 or something) with Autarco panels and inverter. It's a split system - 8 on the one side of the roof and 7 on the other as it's pretty close to East/West.
 

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NB inverter is Sunny Boy, can’t remember panels.

Ref energy prices - yes I’m sure they’ll only go up but reckon storage prices will go down more quickly!

Got a couple of storage quotes last year but my brother decided to sell his Leaf for not dissimilar money (and that has about 20kWh to fill) so now have two of them, and there is often one at home.

Seemed better value - shame we can’t power the house from them (yet!).
 

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I don't think there is an economic case for battery storage, because the total power my panels can generate is so low in winter (30kWh total in December), despite a reasonable level of generation during the rest of the year (my max is 30kWh on a bright summer day, half that in spring/autumn).
We think a key benefit of our PowerBanx system is being able to charge it with Economy 7 through the winter, and to model your home circumstances so you know how much to fill it per month - but anyway, let's keep that discussion to the PowerBanx thread, I don't want to derail this one.
 

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We think a key benefit of our PowerBanx system is being able to charge it with Economy 7 through the winter, and to model your home circumstances so you know how much to fill it per month - but anyway, let's keep that discussion to the PowerBanx thread, I don't want to derail this one.
That's a legit use case, but we don't have Eco7 (should probably look into it), and my wife and I both work office hours, so our power use is low during the day.
I don't think it's necessarily off topic - this thread is about EV + solar +battery, and your use case might apply to the OP.
 

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Discussion Starter #13
@Trevor Larkum agree about economy 7 through winter.

Question Trevor - how easy is it to sell electricity you've stored in your residential battery back to the national grid?

Is there a software platform to connect to that streamlines this process and picks the best time to sell it back to the grid when grid demand is highest - thereby giving you the best ROI?
 

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Battery installation may be more attractive financially to you as you'll be paying less vat and installation costs when installed with PV integrated system.(than me with PV already installed).
I find I could use way more than my 4kw system. Something I would look in to would be a much bigger overall panel capacity on multiple direction roofs and an inverter to limit max output to say 4kw. (these exist apparently)- to satisfy local grid restrictions. The extra panels shouldn't add that much to the cost as most of cost is in installation.
 

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I have a 4 kW south-facing solar array that I got installed in March 2017 (LG panels with a SolarEdge inverter), which has generated pretty much exactly 4,000 kWh over the course of one year - on a sunny summer's day, the system generates around 25 to 27 kWh (I'm based in Oxford). The system is great, but as I'm out at work all day I don't get to use much of the solar energy it generates, so in February I placed an order for a Powerwall 2 which will be installed next month. I looked at both the Powerwall and the LG RESU battery systems, but the much higher capacity of the Powerwall (13.5 kWh vs 9.8 kWh) swung the decision (the two batteries were pretty much the same price). I've worked out that from around late March to October, I should be able to run the house and charge the car purely from stored solar energy, and then in winter I can charge up the Powerwall from Economy 7 electrity. The payback period is very long (I've calculated it to be around 10 years) - but for me, it's not about saving money - I love the idea of being able to use the solar energy that my system generates.
 

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Completely off grid, through necessity rather than choice...
 

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I discussed this in another thread recently.

The payback period for Solar is good, because the government are paying you to generate power.

You get a FIT for your 3600kwh, and you get a export payment for half of that generation, and you also have a saving where your self-consuming that electricity.

The payback for battery storage is much smaller, because the only savings your making is a small reduction in import when you manage to self consume a bit more of your solar.

If, with solar alone, you self consume half your generation, thats 1800kwh your exporting. If you can use a battery to store that 1800kwh and use it yourself, then you save a few hundred quid from not having to buy 1800kwh's worth of power from the grid.

Unfortunately due to the lop-sided ness of the generation curve, you would need a MASSIVE battery to ensure you capture and use all of the summer solar generation, which then goes unused for most of the year. Instead you'd end up fitting a more modest sized battery, and accept you still end up exporting solar during the peak months.

i suspect adding batterys will save you 200quid a year at most. Potentially significantly less (especially if your already using an immarsun or whatever), and when a battery system costs 5grand the payback time is really quite long.
 

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in winter I can charge up the Powerwall from Economy 7 electrity
When you do, look at a zero standing charge tariff - Ebico are the best known - 7.2p/kWh night rate - with your solar, your bills should be negligible at best. My bills for the year are about £170 for a 2 bed house!
 

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That's a legit use case, but we don't have Eco7 (should probably look into it), and my wife and I both work office hours, so our power use is low during the day.
I don't think it's necessarily off topic - this thread is about EV + solar +battery, and your use case might apply to the OP.
We have Eco7 already as we used it to charge our ZOE overnight for half price - and we're close to the point where our EV is half our total consumption so it makes a big difference.
 
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