PV Installers in Leeds, West Yorkshire

ed110220

Martyn1981 wrote: »

If you're interested, and 'odd' enough, then I'd definitely recommend spending 10mins playing with PVGIS. Quite an eye opener on off-south generation. Roof pitch is critical eg

random pin in UK map gave me (for 1kWp) for south:
25d = 933kWh
35d = 950kWh
45d = 945kWh

so little difference, but for north:

25d = 602kWh (65% of south)
35d = 578kWh (61% of south)
45d = 438kWh (46% of south)

big differences, so pitch is important.

As you move from south, the numbers improve, as the off-south roof drops off a little whilst the off-north roof, starts to improve (IYSWIM), eg:

30d SW roof = 892kWh
30d NE roof = 594kWh (67%)

Another critical factor is scaffolding. Will an extra roof (or two) just add a £100 'whilst on site', or will the costs multiply.

I find this stuff fun, and very interesting, as the final 'best package' depends on varying costs and efficiencies, leading to varying economics.

Mart.

Hi Mart, I do find it interesting! I am in Bath, so fairly good insolation I think. The roof pitch is 22 degrees and the SSW face is at at azimuth of 10 degrees, NNE at -170.

So for for a 4 kW system on the SSW face it gives 3520 kWh/year and on the NNE face 2550 kWh/year.

The neighbours are closer to SW/NE so if I use the same figures but azimuth of 45 and -135 you get 3410 and 2710 kWh/year.

Ed

Martyn1981

ed110220 wrote: »

Hi Mart, I do find it interesting! I am in Bath, so fairly good insolation I think. The roof pitch is 22 degrees and the SSW face is at at azimuth of 10 degrees, NNE at -170.

So for for a 4 kW system on the SSW face it gives 3520 kWh/year and on the NNE face 2550 kWh/year.

The neighbours are closer to SW/NE so if I use the same figures but azimuth of 45 and -135 you get 3410 and 2710 kWh/year.

Ed

Ed, you've got it.

So to put some numbers onto my ponderings (then I'll go quiet and do some paint stripping, before I fill another thread with numbers):

Assuming situation where rooves are only large enough for 2kWp:

3,410/2 = 1,705 and 2,710/2 = 1,355

Applying initial costs to best roof (not a trick, you'd always go with the best first (unless shading etc etc)), and I think £4k for 2kWp and £6k for 4kWp are reasonable, we get:

£4k for SW 2kWp and 1,705kWh pa = £2k/kWp and £2.35/kWh

£2k for additional NE 2kWp and 1,355kWh pa = £1k/kWp and 1.48/kWh

[Edit: Plus average = £1.5k/kWp and £1.96/kWh. M.]

It looks like a trick, but it's all about fixed v's variable costs, and maximising the economics.

Now where's my paint stripper.

Mart.

groovyf

Woah... that's some info to take in, thanks guys!
Had never thought of the NE facing roof (this actually has space for more panels (maybe an extra 3 or so) than the SE face - but dismissed due to no real direct sun.
Actually the aspect is more SSW and NNE really.

Martyn1981

groovyf wrote: »

Woah... that's some info to take in, thanks guys!
Had never thought of the NE facing roof (this actually has space for more panels (maybe an extra 3 or so) than the SE face - but dismissed due to no real direct sun.
Actually the aspect is more SSW and NNE really.

Just in case you haven't spotted it already, the PV FAQ may be of interest, especially sections 1, 2 and 5 (at this stage):

https://forums.moneysavingexpert.com/discussion/3872445

Mart.

groovyf

I realise I've hijacked a thread here, but as there's lot of figures pertaining to my situation in these recents posts, it makes sense to continue here, given the fact I've now got a couple of quotes.

The first quote is for a 1.68 kWp system on the SSW (9 degrees azimuth) facing roof @ just over £5K (estimated annual generation of 1468 kWh)

The second quote is for a 4 kWp system, with 8 panels on the SSW side and 8 on the NNE @ £6.5K. Predicted annual generation is 2760 kWh

I queried the company from the first quote about the NNE side and they said probably not worth it. For the price difference, I'm thinking otherwise.
Does someone with better knowledge think the estimated output of the 4 kWp system on two sides seems a reasonable assumption?

Finally, I have a 30 degree pitched garden (SSW facing), that could accommodate 6 panels - kind of tempted to use that instead of the NNE facing side of the roof.

Thanks in advance for any further input!

Martyn1981

groovyf wrote: »

I realise I've hijacked a thread here, but as there's lot of figures pertaining to my situation in these recents posts, it makes sense to continue here, given the fact I've now got a couple of quotes.

The first quote is for a 1.68 kWp system on the SSW (9 degrees azimuth) facing roof @ just over £5K (estimated annual generation of 1468 kWh)

The second quote is for a 4 kWp system, with 8 panels on the SSW side and 8 on the NNE @ £6.5K. Predicted annual generation is 2760 kWh

I queried the company from the first quote about the NNE side and they said probably not worth it. For the price difference, I'm thinking otherwise.
Does someone with better knowledge think the estimated output of the 4 kWp system on two sides seems a reasonable assumption?

Finally, I have a 30 degree pitched garden (SSW facing), that could accommodate 6 panels - kind of tempted to use that instead of the NNE facing side of the roof.

Thanks in advance for any further input!

Hiya. First bit, which quote is better, well ...... it sort of shows what I was trying to explain (poorly):

£5k/1468 = £3.41/kWh pa
£6.5k/2760 = £2.36/kWh pa

so the larger system will deliver electricity at a lower cost per unit of generation. But obviously for more capital outlay. The bigger is definitely better, unless you can find better still.

Regarding generation estimate, I tried PVGIS (section 5 of the FAQ), stuck a pin randomly in Halifax, put in 30d roof, 2kWp @ -171d azimuth, and 2kWp @ +9d azimuth and got 1,030kWh pa and 1,730kWh pa ...... then shocked to see that it added up exactly to 2,760kWh. Bit of random luck there, but clearly in the right ballpark.

Lastly not sure what 30d garden means, did you miss something out? But if a lower roof, the SSW almost certainly better than NNE unless there is some shading factor.

Not sure if this is helpful, but my WNW extension was installed by a company based in Rochdale, as I needed a SolarEdge specialiast. Don't know if they are still in business, but PM if you want their details.

Mart.

groovyf

Much appreicated, Mart, thanks - that explains things pretty well in my eyes.
I also stuck the -171 and +9 into PVGIS and came to same conclusion... that the 2nd quote was pretty much spot-on with it's genreal estimate.

As for the garden... well, I have decking outside the rear (the SSW-facing side), and it's sort of on two levels. To get to the bottom level you go down about 20 steps. on either side is garden area - shrubs, bushes, etc - this is what has a rough angle of 30 degrees. Debating how ugly it would look with one side tricked-up with panels

Martyn1981

groovyf wrote: »

As for the garden... well, I have decking outside the rear (the SSW-facing side), and it's sort of on two levels. To get to the bottom level you go down about 20 steps. on either side is garden area - shrubs, bushes, etc - this is what has a rough angle of 30 degrees. Debating how ugly it would look with one side tricked-up with panels

Oh dear, you've been dragged down into the world of PV ponderings. There is little hope for you now!

Ok, I'm intrigued. Trying to put some numbers against that info. Assuming steps aren't too big, possibly 3m drop. If my maths are right, then at 30d, that's about 5m base, and 6m garden (hypotenuse), so plenty of room for panels.

Have a google for ground mounts, there are loads, but generally they place angles onto flat ground, whereas you already have the angle. I suspect you'd just need a way to securely anchor the rails, either with some sort of ground fixings, or possibly to walls on left/right, or top/bottom?

Interesting idea, but I know nothing. However, I'd suspect you wouldn't want the panels to hug the ground, as plants would need managing, and you'd want to prevent animals and birds from nesting under there and chewing cables/kit etc. So probably want to raise panels 0.5m+ which might make them less (or more?) attractive.

If raising panels, might be worth considering going steep, perhaps 50d, as this will reduce summer generation (when you'll have too much anyway) and increase winter gen (when you'll need more) for a negligible drop in annual generation*. But double and triple check shading. The lower the panels, the greater the chance of shading. Now is a perfect time, as the sun is only 1 month from its lowest, and if it's ok now, then should only get better for rest of year.

Lastly, don't rush. There is a tariff drop in April, but it's only 3.5% (14.9p down to 14.4p). Large enough to consider, but not enough to warrant rushing and making a mistake.

*Negligible for south, but steep angles reduce annual generation as you get further from south.

Mart.