PV Installers in Leeds, West Yorkshire

tunnel

I was told that Sunpowers and ben-q's were one and the same, just that sunpowers come with a better guarantee

groovyf

Cheers Ed, most useful.
I do believe the best way forward is for higher-rated panels to make use of the smaller roof space.

Martyn1981

groovyf wrote: »

Cheers Ed, most useful.
I do believe the best way forward is for higher-rated panels to make use of the smaller roof space.

Hiya groovyf. Do you have any other rooves suitable (even if orientation is not great)? Since a lot of costs are fixed, the cost of going bigger, on less suitable rooves, might be worth considering, as the lower generation from such rooves may still be more (proportionately) than the increased costs.

Eg 2kWp south facing £4k, and 4kWp (2 south and 2 north) perhaps £6k. Cost is 50% more, but north generation may be 60 to 70% of south gen.

Happy to waffle and explain, but you can see that both Tunnel and I have gone for some unorthodox orientations, so worth a tiny thought (and PVGIS experimenting), before dismissing.

Have fun and best of luck.

Mart.

ed110220

Martyn1981 wrote: »

Hiya groovyf. Do you have any other rooves suitable (even if orientation is not great)? Since a lot of costs are fixed, the cost of going bigger, on less suitable rooves, might be worth considering, as the lower generation from such rooves may still be more (proportionately) than the increased costs.

Eg 2kWp south facing £4k, and 4kWp (2 south and 2 north) perhaps £6k. Cost is 50% more, but north generation may be 60 to 70% of south gen.

Happy to waffle and explain, but you can see that both Tunnel and I have gone for some unorthodox orientations, so worth a tiny thought (and PVGIS experimenting), before dismissing.

Have fun and best of luck.

Mart.

I'd never thought of that actually and was wondering why a few doors down (identical house) they had eight panels fitted on a south west facing roof slope and another eight on the north east facing one. It seemed rather illogical to me.

Ed

zeupater

groovyf wrote: »

..... My estimates put it at 10m² facing SW and maybe possibly 5m² on a SW facing side also ...

Hi

In which case you're pretty seriously stuffed on a 4kWp or even 3kWp system ....

A typical panel size for high power panels (~220W+) would be around 1.7mx1m, so ~10m² gives you 6panels and ~5m² a further 3. With 250W panels you're therefore area limited to ~2.2kW (with unbalanced strings) ....

I'd seriously look at checking the available roof area.

HTH
Z

groovyf

Indeed - It was the IKEA quote of 20 panels that made me think about panel sizes (and guestimating roof size), and realising I may not get the system size I'd prefer.
Even a smaller system is better than none I believe though

PS: that should have been SE-facing for the smaller roof area.

Once I get a couple of installers on-site to size things up I'll be in a better position to choose (if possible) higher powered panels.

ed110220

zeupater wrote: »

Hi

In which case you're pretty seriously stuffed on a 4kWp or even 3kWp system ....

A typical panel size for high power panels (~220W+) would be around 1.7mx1m, so ~10m² gives you 6panels and ~5m² a further 3. With 250W panels you're therefore area limited to ~2.2kW (with unbalanced strings) ....

I'd seriously look at checking the available roof area.

HTH
Z

Oh, didn't spot that! Roof shape also makes a big difference as the panels are quite large compared with an average roof and can't be cut like tiles ;-)

zeupater

groovyf wrote: »

Indeed - It was the IKEA quote of 20 panels that made me think about panel sizes (and guestimating roof size), and realising I may not get the system size I'd prefer.
Even a smaller system is better than none I believe though

PS: that should have been SE-facing for the smaller roof area.

Once I get a couple of installers on-site to size things up I'll be in a better position to choose (if possible) higher powered panels.

Hi

Then you're not talking unbalanced strings, you'll need an inverter with 2MPPTs (is there one this small ?), or more likely micro-inverters or optimisers.

You really do need to check the available roof area before anyone could give further advice on this forum regarding such a complex solution (area+orientation).

Measure the walls, check the roof angle by taking a digital photo and rotating the image on a computer, then it's simply the case of some basic trigonometry and maths.

HTH
Z

Martyn1981

zeupater wrote: »

Hi

Then you're not talking unbalanced strings, you'll need an inverter with 2MPPTs (is there one this small ?), or more likely micro-inverters or optimisers.

HTH
Z

Hiya. I'm probably a little out of date, as it's a year or so, since I busied myself reading inverter specs (for fun ), and the only one springing to mind is the Stecca 2010+ which is 2kW, with 2 MPPT's, and you can add slave units of 2kW each, the slaves also having 2MPPT's each. But these units don't appear in the retail outlets that I've just looked at, so ....... it's definitely an issue.

You could use a larger, dual MPPT inverter, but that'll mean efficiency losses, and possibly an issue meeting the min voltage on the smaller string.

Long story short (sorry), you are probably right, and micro's or PO's.

If the SW roof suggests a NE roof too, then a SolarEdge system linked to all three rooves (3kW, 3.5kW and 3.68kW inverters available) may be a reasonably good solution, balancing total costs and total generation. Certainly isn't going to be a simple straightforward answer, but what's the fun in that.

[Edit: SolarEdge 2.2kW inverter also available for the two smaller rooves. M.]

Mart.

Martyn1981

ed110220 wrote: »

I'd never thought of that actually and was wondering why a few doors down (identical house) they had eight panels fitted on a south west facing roof slope and another eight on the north east facing one. It seemed rather illogical to me.

Ed

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.