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Discussion Starter #1
I've just had an estimate from the Energy Saving Trust that I'll generate £260 per year of combined savings & income based on the current generation and export tariffs. On an estimated £6000 up front cost, that's a 23-year payback period. I'd have to be mad. Oh - and their home energy check doesn't recommend solar PV because my roof faces ESE.

So help me here. How can I justify fitting now:
  1. Energy prices are going to rocket, so payback will be quicker?
  2. £260 and £6000 are pessimistic?
  3. We all need to do what we can, even if there's no personal benefit?
  4. When we leave the EU, our eco-warrior government, revelling in the elimination of red tape, will triple the generation tariff? Even for crazy people who are stupid enough and rich enough to have it fitted for no personal benefit...
Or should I wait and hope that things will change?

Final question: if solar PV technology is so much better than it used to be, does that mean we need fewer, cheaper panels for the same generation capacity so installation is much cheaper than it was a few years ago?

Cheers!
 

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We have a 4K PV system connected to an Immersun to give us hot water from the spare electricity that would have gone back to the grid, plus we have a Nissan Leaf charging from them. Our last feed in tariff payment for December to February was £88. If you add the greatly reduced electricity and gas bills our saving is going to be a LOT more than £260. That figure seems very pessimistic. We're in Lincoln so I would think you'd get a similar result.

Also, our system was around £7k, including Immersun and micro inverters on every panel for greater efficiency
 

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PV is a long term investment.. mine is about 20 years with a fairly decent FIT.. without one I wouldn't have bothered. £260 sounds on the low side but without a south facing roof you're limiting the time you can generate anything, so the advice to hold off might well be sound.

I get about £350 a year - varies a lot.. my winter FIT wasn't even worth the both cashing the cheque (It was about £5!).
 

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I have a 4kw array on a south facing roof, it produces just short of 4000 kwh per year, essentially enough to power my car for 16000 miles, or offset the energy used.
Financially it will repay for the costs in about 16 years, probably after I die. But that is not the point. Along with the other measures I have taken to reduce my energy consumption , PV forms part of my commitment to the future.
There is a limit to what Government can do, until every one stops believing in the myth of low taxation environmental concerns will remain at the bottom of this Governments agenda.
It is time to do what is right, not simply to make money.
 

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Mine cost double that but I am on last years FiT and the estimated annual payback (inc. lower bills) was about £750. I haven't had the system a year so can't be sure but I think the saving is likely to be closer to £1k/year.

My reasons were, roughly in order:

1. It makes me feel good because it seems the right thing to do
2. I was about to finish paying off the mortgage(s) and so I could afford the expense
3. The long term ROI just tips the scales from "should I?" to "yeah, why not?"

It's sad that (3) above is no longer the case with the dropped tariffs.

Having the watts to charge the car is a plus but not a primary driver as knowing the seasonal variations and the chances of leaving the car plugged in at home during the day when it's sunny enough are all complicated to be reliable. I am working on some of that, but more as a play project - varying the EVSE max current based on PV output.
 

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I have a 4Kwh system split east/west producing circa 3250 kWh a year with an Immersun connected for hot water and also charge the Leaf when the sun is shining. My FIT receipt for the last 4 quarters was just under £600 and my combined gas & electric bills for the same period came to just over £500. Net result nearly £100 profit for energy.

Via the Immersun the PV gives oodles of hot water during the summer period when the central hearing is not on and offsets some energy use in the winter. It also enables driving the Leaf for practically zero cost charging with the EVSE. PV might not work like that for everyone as it depends on property overshadowing and the present FIT is somewhat reduced now, but for me it's a definite 'no brainer!'
 

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Consider a solar water heating system, it'll cost less to install and will pay for itself a lot quicker.

Yes, you won't be able to run your car off it, but if you're thinking of the environment they are a lot better than all the energy and toxic chemicals to make PV panels.
 

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You need to 'do the right thing' and be clear that you'll not be out of pocket.

It is difficult to fully utilise the solar you generate, even with an EV and immersion diverter. You car won't be there when the maximum sun is available (if you've any sense you'll be driving it), it will be fully charged when sun is available and your water will already be hot (my tank is frequently fully hot after 11am, from cold at breakfast). The idea that you can generate 4000kWh per annum and use all that to charge your car is pure fantasy, and I'm sure that no-one is seriously suggesting that.

I've invested in a 6 amp charge cable for my Leaf, but I'm not going to pretend that I can justify it financially. You also need to compare to economy 7. If you have E7 then you'd need to make sure that any solar PV is providing more than 50% of the charging current to make it economical, and E7 will always charge overnight when you need it.
 

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My 4kW panels cost £5750 last Oct incl a Solic 200. Solic means my immersion heater is doing all my hot water so I have now turned boiler off. As this is an ancient- but-reliable non condenser I will cut my annual gas use by appx 25%. Saving would obviously be less if boiler was modern condenser. Solic also wouldn't suit those on-demand boilers which fire up when u turn on hot tap. So that's one extra saving to expect, depending. I also try to charge when sun shines. Am retired so car not driven every day - different if u commute. If I did I'd be tempted to have 2 Ampera's - charge 1 while using the other, and have a spare! You could estimate yr electricity saving as each kWh solar charge saves on grid consumption. What's yr FIT payment per solar kWh generated?
 

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Should have added that my array faces 10 degrees north of due East, on 25 degree unshaded roof. Expected to gen appx 3100 kWh PA. I am actually pleasantly surprised how well it's working. Maxes out at 3kW on a perfect day in May/June, but at the moment it starts chucking out the electrons as soon as sun starts rising. Was making 1 kW at 6 am a few days ago! Peaks at 10:30 to 11, and is declining after 12. At 4 it's maybe a kW. This pattern works well for us as wife likes to do laundry first thing in the morning, and on cold-but-sunny spring mornings I can get the house warm for free using a fan heater. Flatter sloped roofs like mine help if you are east or west facing, don't be put off! Probably the ideal is a mix of half east facing, half west, as you would get more like 1.5 kW from 9 am to 7 pm rather than a high peak around noon like south facers do. Yes you would get less elec, but I think it would be much more useful in practice!
 

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Solar panels seem to be lasting well, Milton Keynes afaik has some from 80's ? still running, replaced some inverters, but the panels themselves haven't degraded as much as predicted. Details elsewhere in this forum, search on "Milton" may find it. I also expect electricity prices to rise over time, so this is a way for me to lock down some energy costs predictably.
 

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Hmm, I think your export tarriff is only paid on half the kWh you generate, so in effect you'll get 4.32 + (4.91/2) p/kWh = 6.775p/unit. So if you generate 3,837 kWh p.a. that's presumably the £260 p.a. saving you've estimated.

Looking at my www.energysavingtrust.org calculator output, it predicts for me 3218 kWh p.a., and I'm actually 20 degrees north of East facing, angled at 25 degrees. My system cost £5750.

I've just re-entered my details into the calculator, except made it face 20 degrees south of East, 25 degree roof, 4kW system "extra-large" size, no or slight shading, Northampton postcode, and it's come up with these figures:
3100 kWh p.a - less than mine - must be because Winchester's a lot further south.
£134 Annual payment from FIT at 4.32p/unit, valid April-end June this year
£62 annual fuel bill savings
$76 annual payment from export tarriff at 4.91 p/unit
= total annual savings £272

which is close enough to your £260 - maybe your roof angle's different or more shaded.
M panels & inverters have a 20 yr g'tee, so if I assume yours is the same, lets assume it's worthless after 20 years.
So your capital of 6000 yields £260 p.a. - that's 4.33%, but your 6000 loss over 20 years is -300 £ per year.
Frankly, I don't think the figures stack up for you! unless you can get good savings on gas - my 25% off my gas bill should work out at about £180 p.a, but even if you matched that, your return isn't going to be great.

Your Merc C350e has 6.2 kWh battery, so this won't take much charging & you're not going to make sizeable savings by plugging it into solar panels, so not a lot of scope there.

In your position I'd invest in a mix of good quality shares, plus some pibs from Nationwide & Principality b socs, and enjoy maybe 5 to 6% interest in my ISA instead!
 

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Discussion Starter #17
@HandyAndy, that's how I see the maths. I'm not sure my eco-tendencies stretch to giving a 20 year interest-free loan to my energy company.

I just checked the situation in Germany having heard about the growth of solar PV in the market. It seems the tariff is similar (€0.09 per kWh), but the panels are half the price they are over here. I guess that's partly to do with stronger sunlight, but most of it appears to be down to a stronger competitive market for panels driving down the prices.
 

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So if you generate 3,837 kWh p.a. that's presumably the £260 p.a. saving you've estimated.
Surely it is £260 in your pocket and as much of the 3837 kWh (approx £400 retail cost) as you can use for free. So generally minimum of 25% if you do nothing or perhaps 100% if you had battery storage (not really economic yet) or 70-80% if you added a hot water diverter and schedules appliances for sunny times.
 

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...
in Germany ... panels are half the price they are over here...
If that's the case, a system like mine should be a bit cheaper than last October. Send an email to Jay Rogerson [email protected] and ask what he can do. He's my supplier, did a cracking job at a good price. If he can't give you a good price, no-one can!
 

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Discussion Starter #20
as much of the 3837 kWh (approx £400 retail cost) as you can use for free. So generally minimum of 25% if you do nothing
It's hard to see how I'll get anywhere near the 25%: the house is empty for most of the time and the car is unlikely to be there. A bit of clothes washing and cooking might be covered, but that's all.
 
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