Solar PV...Still worth it?

Martyn1981

silvercar wrote: »

We are still deliberating.

Hard decisions that you guys may be able to help with:

3kw system against 4kw: obviously the FiTs would be lower, but would it be fair to say that we would use more of the generated electric ourselves, therefore the cost difference overall is not a simple 3:4 ratio? ie can I assume that we would use a higher proportion of the generated electric and so save nearly the same amount on our electric bill.

So I'm thinking that I'm generating 75% of a 4kW system and using say 90% of the 4kW system?

The costs were £7k for the 3kW and for the 4kW it was £9k + assumed £1.3k for tree removal = 10.3k.

Hiya Silvercar. You're right about the electricity savings proportionately dropping off. With 1kWp you'd probably use almost all of it, with 10kWp you'd use very little (as a percentage). But as Eric pointed out the smaller system won't (or shouldn't) save you much price wise as the panels themselves now only account for around half the cost of a 4kWp install.

Can I make a cheeky point. I often ask people on here what they paid, or what their quotes are. I say I'm being nosey, but really it's to help me get a 'gut feeling' of where prices are, since they are moving so fast. Obviously you are in a much (much, much) better position than me regarding your install. But my gut suggests upper figures of £6.5k for 3kWp and £8k for 4kWp. Some recent posts have been for less again, but obviously not everyone's circumstances will allow for the cheapest prices. Might there still be a little negotiating room?

As for your front roof. My wife was a little nervous about our install (rear roof), now doesn't mind at all. However, that said, if you were persuaded to install on the front, and your opinion doesn't change, then 25+ years is a long time to regret it. I think you need to decide if you hate the idea, or are just a little uncertain. Then go with your gut.

Best of luck.

WestonDave, glad it's coming together, have fun. By the way, has anyone suggested what PV is worth points wise on an EPC?

Just being nosey, yet again!

Mart.

WestonDave

Martyn - didn't ask as it wasn't going to be necessary (and I was trying to keep the kids in order whilst also talking to the assessor). The Energy Saving Trust online estimator gives me a score of 68 (D) without solar panels and 74 (C) with - however it simply asks if you have PV or not so doesn't take account of the size of system and therefore presumably isn't accurate. I'm interested to see how close the actual figures come to those estimates.

silvercar

But my gut suggests upper figures of £6.5k for 3kWp and £8k for 4kWp.

So my figures are on the high side

From experience of workmen in general, I would rather pay a little bit extra and get a quality service.

My 4kW quote at £9k includes extra support to the summerhouse roof, cost unknown, so I guess that accounts for something, then again I doubt you need scaffolding to install on the summer house. Plus I've got the cost of the trees. Plus this future maintenance of the summer house, without PVs sitting on the roof, by the time it is no longer viable we could get rid, the kids are 21 and 18, so its need is diminishing. With PVs sitting on it, it would need to be retained and maintained.

WestonDave

Did a bit of online digging as I thought that EPC change was on the low side for PV. Apparently the EPC score actually comes from the estimated energy spend - hence why putting gas central heating will boost the score by much more than many other things. In terms of solar PV, because it takes no account of FIT's, the energy cost saving from installing solar PV is relatively small and so it makes a relatively small difference to the EPC score.

(4kw for £7500 if it helps for reference silvercar - split over two aspects so a higher scaffolding cost, but possibly lower costs for Siliken panels rather than a big brand name).

rogerblack

WestonDave wrote: »

In terms of the summerhouse, its worth bearing in mind that the panels you buy are guaranteed to produce 80% of rated output for 25 years however that doesn't make them a total write off at year 25 - they will go on producing electricity for years after that, albeit at an ever diminishing rate.

After 25 years, there is as I understand it no guarantee that you'll get even the export payment.

So, the only saving may be due to savings of electricity.

EricMears

rogerblack wrote: »

After 25 years, there is as I understand it no guarantee that you'll get even the export payment.

So, the only saving may be due to savings of electricity.

More definite than that I think - NO FIT payments after Y25.

However, at any likely rate of inflation, cost saving of even 70% of today's generation is likely to be a reasonably large sum.

WestonDave

roger - correct but that doesn't mean that after 25 years people are going to be tearing down their panels and shoving them in the nearest skip.

Martyn1981

silvercar wrote: »

So my figures are on the high side

From experience of workmen in general, I would rather pay a little bit extra and get a quality service.

Hiya, hope you didn't think I was trying to rain on your parade. £10k or more would definitely be dear. Less than £7k would be a very good price. So £9k is in the ballpark, it's just that things seem to have changed (yet again) in the last couple of months.

We had the 'beat March the 3rd' rush, then a smaller 'beat the EPC band D' rush. Now there might be a small lull before the 'beat the July rate change' rush?

During each lull we tend to see a price change, and my gut is saying that recent posts on some of these threads may show that one has just occurred / is occuring. That said, £9k is not unreasonable, and quality of work for such a large and long term investment is of course extremely important.

I'm getting a headache just trying to write this down. You must really be having fun!!!

Mart.

Martyn1981

WestonDave wrote: »

Martyn - didn't ask as it wasn't going to be necessary (and I was trying to keep the kids in order whilst also talking to the assessor). The Energy Saving Trust online estimator gives me a score of 68 (D) without solar panels and 74 (C) with - however it simply asks if you have PV or not so doesn't take account of the size of system and therefore presumably isn't accurate. I'm interested to see how close the actual figures come to those estimates.

Cheers Dave. I was curious since PV doesn't actually change your energy consumption in the house, I was wondering how it would score.

Many people seem to be reporting consumption going down through increased awareness, and I'd certainly agree that I've become more aware of waste. Whilst that may be led by PV being installed, it would be cheeky to accredit such savings to PV.

Similarly, home generation avoids distribution losses, and PV will 'avoid' the system losses of burning some fuels to generate electricity. But again, these are outside savings, and I've no idea if these are (or even should) be accounted for with a home EPC score.

Apologies for rambling, just thinking out loud, again!

Edit: Ok, re-think, if replacing an old GCH with a more efficient modern one gains you points for using less gas. Then it's not a complete stretch to look at 1kWh of PV leccy as perhaps off-setting the approx. 2kWh's of gas used to generate, distribute and supply that 1kWh of leccy. Damn 2 posts in a row that have given me headaches!

Mart.

WestonDave

I think the EPC thing is fairly flawed anyway. It would appear to be utterly impossible to get a grade A on my house whatever I do even if in reality I got it to the point where I was using virtually no heating (e.g. passivehaus style). I'm not aware that the assessor measured the size of our windows which are probably more numerous than is typical, and also larger than the little ones they tend to put in new builds.

You also don't get extra points for taking out Gas CH and replacing it with an ASHP system because although the ASHP effectively creates free energy (not in the physics sense!), the electricity used to power it is more expensive than gas! Whether that is just an issue that the criteria need changing now that ASHP is more common I'm not sure because the internal workings of the EPC are closely guarded.

If as I read somewhere EPC's work on energy cost rather than outright energy useage (hence a gas system is considered better than a solar powered ASHP) then it will quickly make itself irrelevant. Its tempting to try chase grades but if the EST sample is correct it would be practically impossible to get above a grade C on our house even if we were using no imported energy because the technologies required to do that don't factor in the assessment.

At some point we need to change our windows as the current pre 2002 DG UPVC ones have serious draught issues on some. Comfort let alone energy saving suggests they are life expired so if we change those and cut down our heating costs (heat recovery interests me as insulation without ventilation strikes me as potentially a bad idea!) we might get within sniffing distance of cost neutrality for energy (i.e. FIT's and export payments cover the cost of imported gas and electricity).