Solar PV...Still worth it?

silvercar

Gizmosmum wrote: »

If your boiler is running at 74% you'd be better spending your money in the first instance in replacing that for an A rated boiler and installing adequate controls. This should be enough to take you to a D rating and if you've any cash left you can consider pv. You could wait for the Green Deal to come in and do it through them but the FiT will have dropped to around 12p by then and there's a suspicion that the prices through Green Deal will be inflated. Better to do the boiler before Green Deal IMO.

The boiler is only 6 years old, so I don't see the merit of replacing it.

Your post seems contradictory, if I do the boiler first then the FiT will have dropped.

Gizmosmum_2

silvercar wrote: »

The boiler is only 6 years old, so I don't see the merit of replacing it.

Your post seems contradictory, if I do the boiler first then the FiT will have dropped.

If you were sold a boiler 6 years ago that was 74% efficient then you were sold a dud and I'd be challenging the people that sold you it to see why they sold you a boiler with such a low efficiency. Have you checked it's rating on http://www.sedbuk.com/ I'd expect a 6 year old boiler to be running in the high 80's at the very least.

I'm not sure where the contradiction is - if you've used a lot of your disposable cash to replace the boiler to get near a D rating then you may not have enough money to buy pv as well. As the cost of replacing boilers may well go up when Green Deal comes in and the cost of pv will inevitably go down after the next Fit drop then it's better to do the boiler first and pv second.

I suspect that your 6 year old boiler is much more efficient than 74% which would void my argument but of course none of us knew it was 6 year old

silvercar

Gizmosmum wrote: »

If you were sold a boiler 6 years ago that was 74% efficient then you were sold a dud and I'd be challenging the people that sold you it to see why they sold you a boiler with such a low efficiency. Have you checked it's rating on http://www.sedbuk.com/ I'd expect a 6 year old boiler to be running in the high 80's at the very least.

I'm not sure where the contradiction is - if you've used a lot of your disposable cash to replace the boiler to get near a D rating then you may not have enough money to buy pv as well. As the cost of replacing boilers may well go up when Green Deal comes in and the cost of pv will inevitably go down after the next Fit drop then it's better to do the boiler first and pv second.

I suspect that your 6 year old boiler is much more efficient than 74% which would void my argument but of course none of us knew it was 6 year old

Recheck, it was 8 years ago. Out in by the people who previously owned our house, so I suspect it was the cheapest they could find.

The contradiction was (in my mind) that PVs give a rate of return greater than our savings could make, whereas replacing a boiler doesn't give a financial return other than lower energy bill.

EricMears

silvercar wrote: »

Recheck, it was 8 years ago. Out (presumably Put ?) in by the people who previously owned our house, so I suspect it was the cheapest they could find.

The contradiction was (in my mind) that PVs give a rate of return greater than our savings could make, whereas replacing a boiler doesn't give a financial return other than lower energy bill.

A lower energy bill is of course "a financial return " ! If your boiler really is only 74% efficient and you replace it with something in excess of 90% efficient then you could expect your gas (? oil or electricity if not) usage to drop by around 20%. No idea of course what your annual gas bill is but 20% of that set against the cost of a new boiler (probably less than £1000) could be a reasonable %ROI. Maybe not in the same league as PV installations before last month but perhaps still worth considering.

silvercar

Given FiTs are only going to go down, I would want to the PVs now and replace the boiler in the future.

I have a large south facing roof in Southern England, so ideal in that respect for generating.

Martyn1981

EricMears wrote: »

A lower energy bill is of course "a financial return " ! If your boiler really is only 74% efficient and you replace it with something in excess of 90% efficient then you could expect your gas (? oil or electricity if not) usage to drop by around 20%. No idea of course what your annual gas bill is but 20% of that set against the cost of a new boiler (probably less than £1000) could be a reasonable %ROI. Maybe not in the same league as PV installations before last month but perhaps still worth considering.

I had a good thunk around this issue back when the boiler scrappage scheme came out. Not for the scheme as I've got friends who could do a straight swop in less than a day, and probably for about the £1k you suggest. Rather I was surprised to find that my 13 year old Worcester 28cdi (back then about 11 years old) was classed as low efficiency. I've never got round to it as gas consumption (CH, hot water, and oven) is only about £400pa, so I'm not sure if the savings would be high enough to justify the early death of a working piece of kit. Hard to know?

Earlier I posted that the EST test for EPC gave my house a B with A potential (recommendations - condensing combi and room thermostats). Any idea if that is nonsense? I'd have been happy with a D. I entered house specs for a 1930's semi, with 250mm loft insulation, cavity wall insulation, TRV's, DG, low energy bulbs, boiler type and age, non heated conservatory and 50% roof covered in PV.

I'm getting more and more doubtful of that (estimated) rating. I know it's silly to look a gift horse in the mouth, but I'd prefer honest to flattering.

Mart.

Martyn1981

silvercar wrote: »

Given FiTs are only going to go down, I would want to the PVs now and replace the boiler in the future.

I have a large south facing roof in Southern England, so ideal in that respect for generating.

Please, please don't think I'm moralising, as I'm in the same boat as you (though my PV is safe!). Older boiler (see above), but are the savings worthwhile?

Well improving your boiler's efficiency will give an instant improvement to both your financial and CO2 expenditure. However as I said above, if the gains are low, then it's similar to scrapping a good car, for a better car. Tricky!

Since you're seriously thinking about PV, I'd repeat what I said a few days ago and suggest you get a proper EPC done and find out what will (or might) be needed to reach a D, at least you'll have an idea where you stand then. Also worth getting a roofer's opinion - not sure, just throwing that one out there, they'll probably try to sell you the need regardless!!

Lastly, do you know what you can reasonably expect from PV, generation and financially? If not try the generation estimating section on the FAQ's thread. If you don't understand the instructions give me a shout, and some details and I'll run off the numbers for you.

Mart.

silvercar

Martyn1981 wrote: »

Please, please don't think I'm moralising, as I'm in the same boat as you (though my PV is safe!). Older boiler (see above), but are the savings worthwhile?

Well improving your boiler's efficiency will give an instant improvement to both your financial and CO2 expenditure. However as I said above, if the gains are low, then it's similar to scrapping a good car, for a better car. Tricky!

Since you're seriously thinking about PV, I'd repeat what I said a few days ago and suggest you get a proper EPC done and find out what will (or might) be needed to reach a D, at least you'll have an idea where you stand then. Also worth getting a roofer's opinion - not sure, just throwing that one out there, they'll probably try to sell you the need regardless!!

Lastly, do you know what you can reasonably expect from PV, generation and financially? If not try the generation estimating section on the FAQ's thread. If you don't understand the instructions give me a shout, and some details and I'll run off the numbers for you.

Mart.

That calculator website was too much for me.

The roof is 10 degrees off due south towards east. The roof would definitely be big enough for a 4kw output. No trees nearby, just north of London. 1930s detached house, not sure of exact roof angle, but I'd say 35-45 degrees.

OH has commented that the roof gets the odd broken tile each winter, so it's not new, but the survey when we bought said its fine. Internally the roof supports are sound and the roof is totally wood lined ( I assume felt between the roof and the tiles).

To complicate the boiler situation, there are actually 2 boilers, both rating about 74%. One serves the extension which is about half the sisize of the house and one the original part. So any replacement involves considering replacing both of them or not. How an EPC analysiser would fare is anyone's guess, gas engineers have been fooled on initial inspections! On first inspection you see one combi boiler the other one is not easy to spot, but the visible controls, like the room thermostat and the programmer operate the other boiler ( which feeds a totally inaccessible tank).

I suspect anyone doing an EPC could have their work cut out. To complicate the situation further, the extension has cavity wall insulation, the original has solid walls.

Martyn1981

silvercar wrote: »

That calculator website was too much for me.

No probs, and don't worry it gets easier.

I popped in 4kWp, building integrated, slope 35deg, azimuth -10, oh and just to let you know, you now live in Stevenage (close enough?).

the results table was:

Fixed system: inclination=35°, orientation=-10°
MonthEd Em Hd Hm
Jan 3.65 113 1.13 35.1
Feb 5.80 162 1.84 51.4
Mar 8.29 257 2.72 84.3
Apr 12.00 359 4.08 122
May 12.80 397 4.43 137
Jun 13.20 397 4.66 140
Jul 13.60 422 4.84 150
Aug 12.70 393 4.51 140
Sep 10.30 310 3.58 107
Oct 7.28 226 2.42 74.9
Nov 4.40 132 1.39 41.7
Dec 2.79 86.6 0.87 26.9
Yearly average 8.92 271 3.04 92.6
Total for year 3250 1110

It's copied over a little wobbly, but the key bits are the column Em, which give you monthly figures eg Jan 113kWh, and July 422kWh. the total is 3,250kWh.

I left the default system losses at 14% (I have mine at 10% as this seems nearer to actual generation) better to underestimate just in case.

Money wise, if you get the higher rate (for EPC D) then that's approx:
3,250 * 21p = £683.50 (FITs generation payment)
1,625 * 3.2p = £52 (Export rate normally based on assumed 50%)
electricity savings of perhaps £100, less if the house is empty all day, maybe a little more if you try to use as much generation as possible.

Total (estimate) £835pa
Please remember that this is only an educated guess.

EPC - Solid walls are trouble!, But remember the rule is EPC D (including PV element) or after all recommended improvements have been implemented, even if D can't be reached.

Not a simple one me thinks?

Mart.

silvercar

^^^thanks, really appreciated.

About 20 miles south of Stevenage, so pretty accurate.

Got a recommended installer coming on thursday, will see what they say.

I do wonder if installers now have started to employ their own EPC assessors, given the new requirements.

Anecdotally, EPC assessors are a bit rough and ready, so I could be lucky with an assessment. I've just fitted an Eco-flap to the letterbox - any points in that

Thanks again.