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Now I've got an EV, I've been looking into solar options. We're away during the day so I'd be looking at solar + battery.

A quote I've got is for a 4.2kWp system + 7.2kW battery, for just over £9k.

I commute 45 miles each way with a Leaf every weekday and charge at night and at work. I went electric to save money on petrol.

I'd likely finance the solar installation by adding the £9k onto the mortgage -- so paying over 20 years or so. Even with that, with estimated savings & FIT tariff, it looks like I would -- at best -- break even each month. If I paid outright it looks like a rough break-even time of at least 15 years.

I have a few questions:

-- It occurs to me that as people switch to EVs, the differential between petrol & electricity prices will have to narrow (read: electricity prices will go up as demand increases). So the solar installation would help to hedge against future rises. Are there any good forecasts out there that estimate future prices for electricity & gas?

-- I'm not sure how to estimate electricity savings. It's obviously not as simple as discounting expected annual generation from my current usage, especially if I reduce gas consumption due to using electricity to heat water. What tools/models are recommended to do the maths?

-- I will eventually move house -- likely within five years. Does anyone have ball-park costs for moving installations? Can I take the FIT with me?
 

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Forget moving a system.

Everything else is just a gamble ......

Given that you are moving, and the waining FIT, I wouldn't gamble that amount - find a competent person to do a non FIT install for a fraction of that price.
 

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Now I've got an EV, I've been looking into solar options. We're away during the day so I'd be looking at solar + battery....
You don't need the battery. Get the cheapest good quality PV system fitted and swap to economy 7. PV and E7 go together really well - the E7 for charging overnight (and washing machine, dishwasher etc) then the PV will offset the more expensive daytime units.

If you have a h/w tank and immersion (bottom fitted or the longest standard top fitted), get a diverter to route surplus solar to the immersion heater.
 

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You cannot move a system and retain the FIT. I'd imagine moving a system would cost upwards of a grand, if not two, due to the cost of two sets of scaffolding. If you are planning to move in 5 years it will not be worth installing PV. The FIT is ending early next year, but is already reduced to the point that it is barely worth it.

As said above, a non FIT install is much cheaper. If you can ground mount it it would be much cheaper to move. Definitely also look into E7.
 

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How much cheaper is a non FIT install?

I'm getting quotes of just over 5k for 4.2kWp at the moment...
The main saving would be from using secondhand panels\inverter, which you can't use if you want FIT. If you can ground mount the panels that would also save on the scaffolding costs
 

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The main saving would be from using secondhand panels\inverter, which you can't use if you want FIT. If you can ground mount the panels that would also save on the scaffolding costs
Can you still be Grid tied if you use second hand panels? Or is it that you still need a aproved panels and approved installer?
 

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I'm not aware of any reason why you couldn't use secondhand equipment, though you would still need an MCS approved electrician to connect it up to the grid, and submit the G83 paperwork to the DNO.

I'm considering doing the same thing myself, to add to the 4kWp I already have.
 

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Interestingly only the new stock panels at Bimble Solar are listed as MCS approved, I'm not sure if this due to used stock often from upgraded solar farms that's already been accounted for under government schemes.
 

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I'm not aware of any reason why you couldn't use secondhand equipment, though you would still need an MCS approved electrician to connect it up to the grid, and submit the G83 paperwork to the DNO.

I'm considering doing the same thing myself, to add to the 4kWp I already have.
MCS accreditation is only required if the FIT is to be claimed.
 

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Doesn't this affect your current FIT payments? I added 2Kw but dump it into a battery bank that I use to only light the house and charge devices. So not Grid connected.
It would only affect FIT if the panels went through the same inverter/generation meter. You can no longer claim FIT for extensions or second installs at the same address. In my case, I'm looking at a completely separate install, though still grid-tied. I'd use secondhand panels to reduce cost (also preventing FIT claim) and ground mount them (to further reduce costs), though I'd get a MCS installer to check over the install, connect it up and fill in the G59 paperwork.

I just have to check with our DNO that they will accept the additional install 'in principal' first.
 

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MCS accreditation is only required if the FIT is to be claimed.
I didn't know that. I assumed the DNO would only accept connection applications from MCS qualified installers.

Even so, you still need a qualified electrician to make the grid connection.
 

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-- It occurs to me that as people switch to EVs, the differential between petrol & electricity prices will have to narrow (read: electricity prices will go up as demand increases). So the solar installation would help to hedge against future rises. Are there any good forecasts out there that estimate future prices for electricity & gas?
We have a rate of return and payback calculator we use for our customers. Until recently for future electricity price increases we used 6.7% (based on a House of Commons report). More recently we have started using 8.4% based on current market averages (e.g. UK Energy Price Rises Report 2017 | MoneySuperMarket).


-- I'm not sure how to estimate electricity savings. It's obviously not as simple as discounting expected annual generation from my current usage, especially if I reduce gas consumption due to using electricity to heat water. What tools/models are recommended to do the maths?
We'd be happy to run the model for you. It will consider savings from the solar and battery on the assumption that the combination allows you to save money equivalent to the amount of solar generated across the year (considering expected solar generation each month, and optional Economy 7 charging of the batteries in the winter). It can't consider variables like how much hot water you might get or use.


-- I will eventually move house -- likely within five years. Does anyone have ball-park costs for moving installations? Can I take the FIT with me?
I wouldn't consider moving the solar - it messes up the FIT, requires scaffolding etc., and isn't worth the trouble. I installed £5k of solar on a buy-to-let house. When we sold it I just added £5k onto the market price, and it was paid in full without quibble.

If the battery system is independent of the solar, like our PowerBanx one, then there is no problem taking the batteries when you move.
 

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You don't need the battery.
He says he's out during the day so he won't get benefit from the solar unless he has a battery. This is particularly true now the FIT payments are so low, so the only way the solar can be paid off is with a battery.

And just a reminder for everyone that the FIT scheme ends next March - and if you're thinking of getting solar I wouldn't wait until February as there will be a mad rush ahead of the deadline like the last time the government messed up the FIT scheme.

Sad to say not just is FIT being cancelled, but the export payments too. Some have argued that should be illegal - your electricity supplier will take your solar but not pay you for it - worse, they will get paid by your neighbours for it. However, this change has been confirmed. Of course, we're hoping it will increase sales of our batteries as there's something particularly galling about you not being able to use something of yours, that others are using for free.

UK home solar power faces cloudy outlook as subsidies are axed
 

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He says he's out during the day so he won't get benefit from the solar unless he has a battery. This is particularly true now the FIT payments are so low, so the only way the solar can be paid off is with a battery.
That's not correct at all.

Surplus diversion to a thermal store/water tank with long or bottom immersion makes very effective use of PV in an unoccupied house - or simple diversion to resistive heating (storage or UF).
 
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