Solar PV Quote seems excessive

groovyf

No problem, Ray.
Here's mine:
NE panels: http://www.groovyf.co.uk/temp/panels-ne.jpg
SW panels: http://www.groovyf.co.uk/temp/panels-sw.jpg

As you can see from the image below (mine;s the right-hand side of the semi-d), the SW-facing roof was the troublesome one for rectangular panels, thanks to the extra hipped roof part of the extending part of the house.
Google Earth view of roof: http://www.groovyf.co.uk/temp/top-view.jpg

Ageing_Stick_Insect

Thanks for that groovy. Nice NE array and the SW looks reasonably enough.

More thinking about the direction of the array. All the experts suggest a south-facing array is best but after 6pm the sun has moved off it. And you're generating more electricity than you might be able to use around noon.

By utilising 3 sides of your roof you'll get power from sunrise to sunset all year and especially those late summer evenings when you will probably be cooking and watching TV.

Or is that too simplistic a thought process?

Martyn1981

Ageing_Stick_Insect wrote: »

By utilising 3 sides of your roof you'll get power from sunrise to sunset all year and especially those late summer evenings when you will probably be cooking and watching TV.

Or is that too simplistic a thought process?

Hiya Ray, that's pretty spot on, but, whilst the FiT is still the major source of income for PV, it does mean that maximising generation is the main goal.

So you start with south and move onto 'less ideal' rooves as a 'making the most of it' compromise/solution.

Without FiT I'd reckon on half SE + half SW being better than all south, even though total generation would be about 10% less. But, end of the day, you have to work with what you've got. You've got a lovely SSW orientation, but it's small and angled. You've got a good fallback of ESE, but it also has an angle and a chimney, and then you have the not so good WNW, also with an angle, but no chimney taking up space. Sod's Law, your best orientation has the worst space, and vice versa.

If you're happy with the triangles (T&S), then plan A 3.7kWp on the two south rooves is ideal, as long as you can get the price down. Then don't bother with the WNW ..... unless the bug has really bit, and you want to go even bigger. Though I think you'll have a problem with the maximum number of panels/voltage on the SolarEdge inverter. I can't remember the max, but it might be 26 or thereabouts.

Last thought, been rabbit'ing away about off-south, but what pitch is your WNW roof? 30d isn't bad, but as it gets steeper, total generation falls off, as shallow panels suit high summer sun, and steep panels suit low winter sun (fine for south facing) - but (of course) low winter sun doesn't reach as far east and west.

Mart.

Ageing_Stick_Insect

Hi Mart,

You're right. You can only work with what you've got and having seen another install today on a hip roof I think mine - especially with Trienergia panels to maximise roof space - will be as good a deal as I can achieve.

Point taken about whether the WNW roof is viable especially as it might exceed inputs to the inverter. I'll see what the installer says tomorrow.

I haven't been in the loft yet with my trusty protractor but the earlier installer reckoned it was close to 35 deg. More or less spot on.

Walking towards my house from the south this morning I have to say I'm very lucky to have such an open southerly aspect with no trees or shadowing likely. Next door's roof is unlikely to cast a shadow except perhaps a couple of weeks around the winter solstice. The chimney is to the north-east of my roof so that won't be a problem.

I did some research today on the ideal location for the inverter. Up to now I was convinced the loft was best but advice on t'internet is that it's best close to the mains outlet for two reasons:-

1) Less loss from a long run of DC cable than AC.
2) Lofts get very hot in summer and cold in winter. Not good apparently.

I have space in my garage very close to the electricity meter inside the house. My main concern here is the routing of the cable(s) from the panels to the inverter. Having had my flat garage roof recovered a couple of years ago I don't really want it drilled to accept cabling. I'd much prefer it was routed through an airing cupboard and into the small enclosure under the stairs where the meter is. Is it safe for 28 cables to be routed that way?

And finally SolarEdge have internet access for monitoring. Are there any other inverters that have this as it's mandatory. It would be even better to utilise a homeplug with ethernet connectivity.

Martyn1981

Ageing_Stick_Insect wrote: »

Hi Mart,

Point taken about whether the WNW roof is viable especially as it might exceed inputs to the inverter. I'll see what the installer says tomorrow.

I haven't been in the loft yet with my trusty protractor but the earlier installer reckoned it was close to 35 deg. More or less spot on.

Yep, this is where it starts to get complicated again. Slapping rectangles on 3 rooves to make up for lost generation from the triangles, also means less panels, so 3 rooves into 1 inverter. But that plan probably falls apart with the multitude of 100Wp and 200Wp T&S'. You could of course go for a second inverter, but then all the cost savings of maximising the single inverter start to fall apart, and the WNW generation 'losses' are no longer being offset by falling install costs.

There are larger SolarEdge inverters, which presumably can cope with more panels, but then you'll need DNO permission to exceed 3.68kW (at the inverter, not the panels) and it gets even more complicated. :eek: I'm not sure I'm helping anymore!!!!

Ageing_Stick_Insect wrote: »

I did some research today on the ideal location for the inverter. Up to now I was convinced the loft was best but advice on t'internet is that it's best close to the mains outlet for two reasons:-

1) Less loss from a long run of DC cable than AC.
2) Lofts get very hot in summer and cold in winter. Not good apparently.

I have space in my garage very close to the electricity meter inside the house. My main concern here is the routing of the cable(s) from the panels to the inverter. Having had my flat garage roof recovered a couple of years ago I don't really want it drilled to accept cabling. I'd much prefer it was routed through an airing cupboard and into the small enclosure under the stairs where the meter is. Is it safe for 28 cables to be routed that way?

Can of worms has just been opened.

Firstly the easy bit, there won't be 28 cables, the panels connect to the PO, but the PO's are all connected to each other, so just one long string.

Lofts and inverters (gulp) sure to start an argument.

Start with the basic assumption that leccy items last longer at lower temps, and lofts get very hot, but nothing is that simple, as you're starting to realise.

Lofts get particularly hot during the day as the sun directly heats the slates/tiles, which in turn heat the loft. So the loft temp can be well above the ambient temp. But, after PV, most of your roof will have thermal shielding (;)) so it's more likely to go up and down with ambient temp, rather than sunlight - hope that makes some sense, not sure I'm explaining it well.

Now, if you've got a nice cool place for the inverter, go for it, but the loft might not be as bad as you think.

Also, the SolarEdge inverters are very efficient and have a massive finned heatsink on the back of them. The more efficient the inverter, the less waste (heat) that it'll put into the loft/cupboard/room etc.

My ESE inverters are in the downstairs toilet. The SB1200 is 91% efficient, and on a really good day will generate about 8kWh, thereby wasting about 720Wh of heat. My SE2200 (WNW) is about 98% efficient, and is in the loft. On a really good day will generate about 12kWh, which equates to about 240Wh of heat through a much larger heatsink. However, I converted my loft a long time ago, so it has insulation on the 'ceiling', so again, only ambient temp rises, and a Velux that can be left partially open.

Your loft will get heated by the sun from the WNW side (assuming no panels) the inverter won't be working as hard at that point, but the loft may get quite hot during the summer months.

TBH, whilst the loft maybe ok, a garage sounds best, assuming it doesn't get too hot. The cupboard might be fine, especially given the SolarEdge efficiency, but you'd need to ask the installer if it's big enough to cope with any heat from the inverter, perhaps add some venting?

Mart.

zeupater

Ageing_Stick_Insect wrote: »

Thanks groovy. Of course you never had the opportunity to get triangular panels as they have only just appeared.

Hi

Sharp had monocrystalline triangular panels to match their standard rectangular European modules in their brochures 3 to 4+years ago but at the time I was led to believe that they were 'special order' items and were relatively expensive .... we didn't need them, but I was interested in how they would be cabled to work with the larger panels ....

Just done a quick search and found this polycrystalline triangular (LH & RH) option over the pond .... http://files.sharpusa.com/Downloads/Solar/Products/sol_dow_ND070ERU_ND070ELU.pdf ... so there's no reason to believe that a similar product couldn't still be available within their range in Europe too .... worth giving one of the larger distributors or installers a call to check ...

HTH
Z

Ageing_Stick_Insect

Gents,

Bit late for a full reply tonight. Thanks for all your help. I'll post tomorrow pm after the visit.

Ageing_Stick_Insect

Hi chaps,

The advisor has just left. It's his own company and I was very impressed with what he had to say and also what he did.

He looked in the loft and garage and asked to see the electricity meter. The first guy did none of that.

He wanted to go away and draw up plans for a couple of options possibly involving the WNW roof but whether that was feasible would become clear after costings had been done.

He knows I'm keen on the Trienergia panels but I accept they do come at a higher price which would extend the time before I break even. I think it all boils down to how many panels I can get across x number of roofs and what it will cost as well as it not being an eyesore.

I asked about micro-inverters as an option and he will cost that. Very impressed with his knowledge. Seems to be a specialist whereas the other company exhibited less enthusiasm and knowledge.

I've measured the roof pitch and the front is 32 degrees. Can't imagine the side (SSW) roof will be any different. It doesn't look it on the photos.

He didn't rule out the inverter in the loft but felt it would be better in the garage. More in a few days.

Ageing_Stick_Insect

I recalculated the efficiency scores based on a 32 degree roof pitch (previously 35). Here are the new ones with the old in brackets:-

ESE 90.97 (90.47)
SSW 96.74 (96.44)
WNW 68.28 (66.49)

Minimal except WNW gets a little boost maybe making it slightly more attractive. At least they went up rather than down!

Ageing_Stick_Insect

Hi all,

Received the quote this evening from a local Cheadle Hulme firm fully accredited.

Using Trienergia panels he could only get up to 3.5kW using 3 roofs - ESE, SSW and WNW. Industry regulations on distance from hip and roof edge means I can't get 4kW.

14 near-square panels
7 triangular panels
SolarEdge inverter (model to be confirmed)
21 SolarEdge power optimisers for individual monitoring.
Schletter black clamp mounting system
DC Isolators (make TBC)
2 x AC isolators
Professional scaffolding service
DNO notification (liaising with the area power supplier)
Full site risk assessment including manual handling, working at height etc
Handover Pack and User Guide
Full site clean down after installation to leave your property spotless.

Annual Energy Output estimated at 2895kWh
Annual Cost Saving £701

Price £7848.75 inc VAT @ 5%.

The inverter has a 12 year warranty and the power optimisers have a 25 year warranty.

It's estimated I will break even during year 9 and be in profit from year 10 onwards.

Looks a pretty good deal. Rectangular panels would severely limit power output and look dog ugly to boot!

Appreciate your thoughts but it looks good to me.