Thin film expansion

Just finished installing and connecting up 1.6kW of Sharp NAF-121 panels. They're tandem junction "micromorph" panels, with one layer of amorphous silicon and another layer of micro-crystaline silicon giving them a 9% efficiency. So they're more efficient than plain amorphous panels, but less efficient than poly panels.

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Because of the amorphous layer they're subject to the Staebler–Wronski degrading effect, so the initial rating is 140W which will then degrade to their STC rating of 125W, they come with the standard 80% over 25 year warranty and a 10 year manufacturing warranty from Sharp.

Paid 0.33 Euro/Watt for them in Germany, adding in shipping costs, they came in at about 0.43 Euro/Watt ($0.55/Watt). They're an "old" model, so got them at the price because the supplier was clearing stocks.

I have a lot of roof space, so the efficiency isn't really that much of a concern, all I really care about is Price/Watt in cloudy weather. The existing Yingli panels have done a great job of supplying enough energy during most days and we've only had to run the generator about 15 hours for the whole year. I also plan to increase the loads with more water pumping, hot water heating and perhaps some LED grow lights, so the additional PV is really for opportunity loads and to see us through cloudy days.

I'll be really pleased if we can reduce the gen runtime to 0 through good load management and of course the added capacity of these new PVs.

The mounting structure is the "singlefix" system from Schletter which uses short 45cm mouting rails screwed directly to the sheet metal roof.

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It was really easy and fast to fit since it uses self-drilling screws so the whole structure can be mounted from on top of the roof without having to connect nuts and bolts underneath the beams.
There's a video of the mounting system here: http://www.youtube.com/watch?v=nJj8LGxRmxE