Solar PV Quote seems excessive

tunnel

Sorry Ray,


But for that price I'd rather look at butt ugly rectangular panels over 3 rooves. Try getting quoted with benQ's/sunpowers(same thing,different name) 327W panels.


Once the panels have been up for a few months you'll change your tune about dog ugly, you tend not to notice them.....honest

Martyn1981

Hi Ray, having some problems with those numbers.

1. Price. It's a lot for 3.5kWp. But, assuming those panels are adding £1k, and the Solaredge system is adding about £800 (that's a lot of PO's), and the scaffolding will be a bit more, and extra work fitting more panels, then I suppose it's comparative to a target of £6k for a regular 4kWp system. But, it's still a lot.

2. Generation. Try it yourself and have a good play on PVGIS. I'm not sure what your panel split will be, but I tried (using general location, and 32d roof) two:

1.4kWp ESE + 0.7kWp SSW + 1.4kWp WNW and got 2,567
1.3kWp ESE + 0.9kWp SSW + 1.3kWp WNW and got 2,598

possibly I need to lower the losses from the default, as the SE kit is pretty good, but I'm missing something to be so far off 2,895. I'm assuming it's me, and need the exact kWp breakdown by orientation.

3. Year 1 income. I'm a little short of £701. Assuming the quote is at pre April rates, then that's:
FiT 2,895 * 14.9p = £431.36
Export 1,447.5 * 4.64p = £67.16
Total (so far) £498.52

That leaves £203 in leccy savings. Ok, it's possible, it's high but not ridiculous but looks like 50% of generation * 15p. I'd err on the side of caution and guesstimate £120 (but hope for more).

So my total would be nearer £620, or 7.9% gross (before any lost interest).

I still think those panels are sexy, but sexy doesn't appear to mean cheap (in this case!)

Mart.

Ageing_Stick_Insect

Gents,

Thanks for your feedback. In his email he says... "I had a good look at the conventional option of 1.0m x 1.65m panels but I could only get a max of 2.75kW due to the shape of the hips and it wasn’t going to give you a return."

That should clear up any possibility that my roof can take rectangulars.

Regarding the output for each roof area he gave this:-

ESE. 5 x 200watt panels and 2 x 100watt. Total = 1.2kW
SSW 4 x 200watt panels and 3 x 100watt. Total = 1.1kW
WNW 5 x 200watt panels and 2 x 100watt. Total = 1.2kW
Grand Total = 3.5kW

I visited a nearby house that had rectangular panels and they had 6 x 250watt on a south roof and 3 x 250watt on an east one. That's 2.25kW on a similar sized house but with a different orientation meaning only 2 roofs were utilised.

If I had a rectangular roof I could fit rectangular panels on it and it would be cheaper. I just don't see how I can utilise my roof space any better. To do that I have to buy expensive square and triangular panels. If I had to stick with rectangulars I'd only get 2.75kW and an ugly install to boot. I'm only 500watts off the max. That's not bad for such an awkward roof.

Regarding the FIT I'll get only 14.4p as it's post 1 April.

He calculated first year savings as follows:-
Estimated annual output = 2895kWh
FIT = 14.4p
Total Generation = £416.88
Energy used on site = 1448kWh
Energy Purchase Cost = 15p
Money Saved = £217
Assumed Sell-Back Rate = £0.046
Number of kWh units = 1448
Total of Sell-Back = £67.

Total for Year 1 = £701.

Does that help clarify the numbers? To be honest I don't think I'm going to get a better deal with my roof shape.

tunnel

Hi Ray,


50% electric use is pretty optimistic if your not including some sort of immersion switch in with the quote. Try 25% and build from that.


probably more £600 total(sorry but true)

Ageing_Stick_Insect

Hi tunnel,

I have asked for an immersion heater to be installed in an existing hot water tank. I'm the sole occupant so have complete control over what is on and when.

If rectangular panels can only generate 2.75Kw and let's suppose they cost £1000 less (optimistic) how much will that change the numbers? At the end of the day this guy is trading his company's reputation on the figures he's quoted me. If he's way out I'm not going to be impressed. He's not a high-pressure salesman. He runs his own company. I feel I can trust his report.

Here is the plan for the panels over the 3 roofs. Given you have to leave space around the hips I'd be interested to hear how many rectangular 1.5 x 1 metre panels you think can be fitted in that space.

Martyn1981

Morning Ray. So glad you posted the pics as it was doing my head in trying to work out how to get that mix of Ts & Ss.

Firstly, you're trying so hard, that I really feel bad being negative, and all of these thoughts are just my opinions and calcs, so plenty of room for error. Right here we go.

Firstly, still having trouble hitting that gen figure. Whilst I don't know your exact location, I am sticking a pin in Cheadle Hulme, so would hope to be in the right ballpark, I now get:
1.2 ESE (-60) 948
1.1 SSW (+30) 932
1.2 WNW (+120) 730
Total 2,610

I'm really not trying to be pedantic, but the difference to 2,895 is 10%, and that's a lot on an install that's costing so much.

I tried lowering the default losses from 14% to 10% and got the figure up to 2,750kWh, but still concerned. Again, hoping it's my error.

Secondly, income. As before, £217 savings may be possible, I don't want to say you can't, I save about £180pa, but generate about 4,250. However, admittedly, my winter generation is appalling, so there are two sides to this.

Also under income, is my first point about generation, if it's less, by 10%, then so will the overall income total.

Thirdly, looks. Ok, this is not nice, but please don't take (too much) offence. As the angle of the triangles doesn't match the angle of the hips (as per your diagrams), I'm not sure if it's going to look quite right. It may well look a lot better than rectangles, but to my eye, something that runs away just doesn't look that pleasing. Also not sure about the SSW layout, it has a slight 'rocket ship/arrow head' look to that top triangle!

Thirdly (cont), I can't do any better with rectangles. Using those layouts as a guide, 1.6m by 1m panels are a bust IMO. I think 1.6m by 0.8m 240Wp Panasonics will squeeze in a bit better, but still can't get an increase in total Wp, especially given the position of the chimney on the ESE.

Can you model (just with paper/card) your roofs, and make scale models of the various panel sizes for a play. You should be able to mix portrait with landscape (but check), however whilst this may improve what can be squeezed in, it may not be pretty.

I'm really looking for something positive to say, and feeling quite bad about this unsupportive post. Sorry.

Mart.

Martyn1981

Couldn't leave it on such a negative.

Right Panasonics (P's). I'm staring at those diagrams, and comparing the squares 1.2m by 1.1m to the P's 1.6m by 0.8m.

Looking at the ESE (since the WNW is slightly better (no chimney)), the bottom row of squares on the pic should be approx 3.3m (3*1.1) at the base. 4 P's would be 3.2m so that would fit. The height at the top LHS of the left most bottom square (say what!) is 1.2m, add on the panel gap of 20mm and the height of the corner of the triangle ~200mm, and you're very close to the necessary 1.6m.

Now, height wise for 2 panels, your diagrams show 2 panels at 2.4m, plus what looks like to me, enough spare space to get two 1.6m panels on 3.2m.

If my guesses work out, then you'd definitely get 4 bottom row and 2 top row, so 6*240W = 1.44kWp. If you could fit 3 top row (questionable at 2.4m when pic shows 2.2m of squares lining up with top of triangle) then you'd have 1.68kWp.

Good news, the WNW should be ok for 7 as you'd gain 1/2 the width of the chimney to shift everything to the left (as you look at it).

Onto the SSW. This is where it falls apart. I think you can fit a row of 3 portrait plus 1 extra in the middle for a second row, giving 960Wp. You can get a landscape row of two, but can you get a second row of two, how about a third row of 1 total height 2.4m? Maybe a row of 3 landscape, plus a second row of 2.

If 5 panels on SSW, then you should have 6 ESE (maybe 7) 7 WNW and 5 SSW, total of 18*240Wp = 4.32kWp.

[Edit: comparing prices, even allowing for 3 less PO's, I reckon the P's would cost ~£700 more. Given the 10% lower FiT rate for exceeding 4kWp, I don't think this is a goer, especially since the aesthetics will also be spoiled. M.]

Yes! I know this is getting silly, but had to give it a try.

Mart.

Ageing_Stick_Insect

Hi Martin,

Thanks for taking the time to post all that info. I have the same results from the PVGIS calculator so I'm going to ask for the 2895 figure to be explained.

Second point is the angle he's showing my roof. It looks close to 45 degrees and I remember him saying that's what he thought the pitch was. In fact it's 32 degrees as I measured it with a protractor. That's a big difference and would certainly affect what can be fitted.

At this stage I won't ask about the rectangular panels. To my eye they still wouldn't be a viable option with all the regs about distance from roof edge... and aesthetics.

Ageing_Stick_Insect

I've just found how he's made his calculations for estimated output. His results are:-

ESE - 942
SSW - 926
WNW - 738

Total = 2606.

Not sure how he gets estimated output per year as 2895kWh.

I've written to him so await a reply.

Ageing_Stick_Insect

Another thing which I find confusing is the quote saying a System Size of 3.5KWp. I took that to mean that's how much I would generate. Wrong! It's actually 2.895kWh but that is under scrutiny as things stand.

My earlier quote of £2K higher was for a 3.7KWp system but only utilising 2 roofs. I think that one was placing panels too close to the hip edges and that wouldn't be within the regs of course.

I'm beginning to think my roof is borderline for solar power generation with a decent return over 20 years.