Borrowing for reroofing plus PV

tunnel

That's about right but have you taken a look at the Canadian 310W? £156.64 each, 12 off gives 3.72kWp...ok its not 3.96 BUT it is around £1300 cheaper than the benQ's.


Food for thought?

ed110220

tunnel wrote: »

That's about right but have you taken a look at the Canadian 310W? £156.64 each, 12 off gives 3.72kWp...ok its not 3.96 BUT it is around £1300 cheaper than the benQ's.


Food for thought?

Hadn't heard of those before so thanks! Only issue is they are rather large so depends how much clearance we need at the ridge and gutter. There are also some Sunedison 330w going extremely cheap but again they are about the same size size, basically larger standard efficiency panels. I make it 4.1m from ridge to gutter, but may be a little more or less as it's hard to measure.

Ed

ed110220

The 310W Canadian Solar are 1954mm tall so arranged portrait two rows would be 3908mm, so if I've measured correctly (bit difficult to be too accurate as there is quite an overhang at the eaves) that would only leave about 100mm gap at the ridge and gutter, which I suspect is too little?

EricMears

ed110220 wrote: »

The 310W Canadian Solar are 1954mm tall so arranged portrait two rows would be 3908mm, so if I've measured correctly (bit difficult to be too accurate as there is quite an overhang at the eaves) that would only leave about 100mm gap at the ridge and gutter, which I suspect is too little?

The 'planning portal' guidelines are just that no part of the panels is higher than the ridge - hence 100mm (4" in English) should be plenty of clearance at ridge end providing you can access ridge tiles from the other side. In my case, I've had to leave a lot more clearance than that at top of my (shallow) roof since accessing the ridge tiles from the other side would be a major problem.

I'd also think that a 4" gap between bottom of solar panels and bottom of roof surface should be enough to ensure that any water dripping off bottom of panels finishes up in the gutter rather than overshooting it.

Martyn1981

ed110220 wrote: »

The 310W Canadian Solar are 1954mm tall so arranged portrait two rows would be 3908mm, so if I've measured correctly (bit difficult to be too accurate as there is quite an overhang at the eaves) that would only leave about 100mm gap at the ridge and gutter, which I suspect is too little?

Hiya Ed. Can you work landscape instead, does that help at all. 3 panels would be approx 3m 'tall'. If that's too much waste then you can mix, say 2 rows landscape and 1 row portrait, which would be approx 3.6m 'tall'.

If you do mix landscape and portrait, you need to consider aesthetics, both the mix of layouts, and how the ends will match up eg 3 landscape = 4.8m, but 4 (or 5) portrait = 4m (or 5m).

Mart.

ed110220

Hi Eric and Mart, that's interesting, for some reason I'd always thought it was 300mm gap around the edges. But that could open up a lot more (cheaper) options.

Plan is to use Vieozinc roofing which has a ridge cap like this:

The panels themselves can be attached directly to the ridges themselves rather than to rails so they can be closer to the roof, which should help avoid wind lift, problems with birds etc and look better.



This person is Gloucester has managed to cram 14 panels on an identical house, not sure I like the way they sit so high or the trailing cable but it shows some ingenuity!

Martyn1981

ed110220 wrote: »

Hi Eric and Mart, that's interesting, for some reason I'd always thought it was 300mm gap around the edges. But that could open up a lot more (cheaper) options.

This person is Gloucester has managed to cram 14 panels on an identical house, not sure I like the way they sit so high or the trailing cable but it shows some ingenuity!

Generally a gap of about 200mm (to 300mm) works well, which is why you'll have heard of it.

Not sure about that Gloucester house. You need planning permission if panels are higher than the ridgeline. So, if you get too close to the ridge, and you allow for the fact that the panels will be raised about 100mm about slates/tiles (less perhaps for zinc), and you do a little trigonometry, and you can see how easy it is to go above the ridge if you get too close to it.

Plus, with slates, if you get too close to the ridge, then the installers might have to remove ridge tiles to lift the slates, so that's added work, hence the 300mm(ish) rule.

[Edit: I reckon Eric's right, a 4" gap at the bottom would probably do for rain. Also, rain from panels above will mostly fall through the 20mm gap between panels, so it's only really an issue for the water landing on the bottom row of panels. M.]

I like zinc roofs, no idea why, just something about them. Each to their own!

Mart.

ed110220

Martyn1981 wrote: »

Generally a gap of about 200mm (to 300mm) works well, which is why you'll have heard of it.

Not sure about that Gloucester house. You need planning permission if panels are higher than the ridgeline. So, if you get too close to the ridge, and you allow for the fact that the panels will be raised about 100mm about slates/tiles (less perhaps for zinc), and you do a little trigonometry, and you can see how easy it is to go above the ridge if you get too close to it.

Plus, with slates, if you get too close to the ridge, then the installers might have to remove ridge tiles to lift the slates, so that's added work, hence the 300mm(ish) rule.

[Edit: I reckon Eric's right, a 4" gap at the bottom would probably do for rain. Also, rain from panels above will mostly fall through the 20mm gap between panels, so it's only really an issue for the water landing on the bottom row of panels. M.]

I like zinc roofs, no idea why, just something about them. Each to their own!

Mart.

I was more interested in the width, that they've fitted seven panels in per row portrait. Not sure why they have put them right up to or above the ridge as there's plenty of room at the gutter edge. But, if it means 14 "normal" sized panels fit, then there are a lot more possibilities using cheaper panels.

They have put rails parallel to the roof corrugations and then put another set of rails on top at 90 degrees to the first to mount the panels on, which has raised them abnormally high above the roof which is why it looks odd.

Ed

ed110220

I think I'm going to have to spend some time in the loft getting a more accurate roof length measurement as I think it's going to be very close whether I can get 14 panels on in portrait layout of two rows.

I've had some good quotes:-

14 x Amerisolar 250W solar panels
1 x Solis 3600TL inverter
1 x Schletter roof mounting kit (2 x 7 in portrait)
1 x All cables, clips, isolators needed for the installation
1 x Full MCS / NICEIC Installation including the EPC and completion of all the paperwork

1 x Scaffolding and access
£3,895 inc VAT

As above but using 14 x Perlight 250W (All Black) panels for £3,995 inc VAT

As above but using 14 x Yingli Panda 275W panels for £4,495 inc VAT

As above but using 14 x Hyundai or LG Electronics 280W (Black Frame) panels for £4,995 inc VAT

As above but using 14 x Seraphim 285W panels for £4,895 inc VAT

As above but using 12 x LG Electronics 300W (Black Frame) panels for £4,995 inc VAT

As above but using 12 x BENQ 330W (Black Frame) panels for £5,995 inc VAT

Not convinced that all will fit, eg the Seraphim 285W are 1064mm wide, so spaced 20mm apart will be 7568mm which is almost certainly wider than the roof - can't see I'd be out by more than half a metre! So I'm going to see if they can quote for the BenQ 285W, which would total 7001mm wide. If it's very close I guess the overhang at the gable could be increased slightly when reroofing (this is the bit that makes it hard to measure, short of getting up on a long ladder).

Ed

EricMears

ed110220 wrote: »

I think I'm going to have to spend some time in the loft getting a more accurate roof length measurement as I think it's going to be very close whether I can get 14 panels on in portrait layout of two rows.

I haven't checked in any great detail what the planning portal says but there may not be any bar to fixing SPs on the roof and overhanging sideways. You couldn't of course expand over somebody else's property but creating an overhang above (say) your own driveway may not be out of the question (and even if not 'permitted' may still be possible with planning permission).

Installers may not be too keen on the idea but it shouldn't be too difficult to support one end (or even both if it's a detached property) of the railings with metal struts fixed to the wall(s). That's not really any different to the way one might build out a canopy for use as a carport, porch etc.