Solar Panels

moredeadthanalive

I have been looking at the installation of solar panels for a month or so and have had 2 companies round for quotes. Both seemed competent and answered my questions well. I have a SW facing roof which is good, live near south coast which is good but have some shade from trees so they knocked off 20%.

One quoted for 9x245 (2,2kWh) at £10400 and the other 8*240 (1.92kWh) at £10800. The second dropped this to £8995 if we had a board outside for 10 weeks (money back from referrals) and the other could drop to £10000 only. I then phoned Tesco who can do 9x230 (2.07KWh) for £7839 on their 20% off promotion. I only have roof space for 8 or 9 panels.

First 2 companies gave references who I spoke to and they gave good reports of the installation and panel performance.
Comparing the panel outputs with the SAP reduction (-20% anyway, -20% for shade, 997 for location)

output yearly income payback in years
2.2 1403kW £700 14.2
1.92 1224kW £610 14.7
2.07 1320kW £659 11.9

I am aware that with energy prices rising and RPI increasing the FIT, these durations will decrease slightly.

So I am now confused. With such a variance in price, what do I risk with going for the cheapest system? My thinking at the moment is that all you are paying for is the installation of commodity items - panels and inverter and cables etc.

How about efficiency of panels and their variance? I was told that Sharp panels have thinner glass and so are more flimsy. Does this matter? I was also told that Suntech were best value for money. Fronius inverters come with a 20 year warranty until end October.
How much significance should I put on the design of the system such as matching the panels with the inverter and the location of panels, connections and inverter. Tesco value deal is what is says on the tin. Panels and inverter are a given. Would you need a specific inverter most suited to the output and type of the panels? Could I just ask for a deal with Suntech 245 with Fronious and go for the cheapest.

I have seen several comments implying I could expect to get 2.2kWh for between £6.5k and £7k.

Am I realistically going to get a good system for this much or should I be prepared to pay more?

Lots of questions but I am sure someone will shed light on them.

Cardew

If you go to the 'Green' forum on MSE there are several threads and some real experts contributing.

Cut & Paste is your friend!

UncleZen

20% discount because of shading?
When a panel is shaded, even a little bit, the effectiveness of the whole panel is reduced, if that panel is in series (they often are), then the wole string of panels can be affected.

Personally, I'd avoid shading at all costs, also what will happen when those trees grow?