Choosing solar PV panels

2 As and a B · Post by **2 As and a B** » 27 May 2011, 14:24

Any suggestions/recommendations for efficient, reliable, robust panels?

I heard 16% efficiency mentioned recently. Does that come with a high price tag or low reliability?

RenewableCandy · Post by **RenewableCandy** » 27 May 2011, 14:57

Ours are 18% and not superlatively pricey.

Keep a lookout also for "designed for UK climate" or somesuch. These have a higher-than-otherwise sensitivity to blue light, and will perform relatively better on cloudy-but-still-bright days.

Post by **adam2** » 27 May 2011, 15:43

Efficiency does not matter much in most cases as sunlight is free and "wasting" it does not matter unlike the inefficient use of coal or gas.

Of geater importance is the power produced per £ invested, not the power produced per unit area.

Lower efficiency modules will need to be larger or more numerous for a given output, and therefore any racks or supports will be more costly.
The cost of these is normally a small part of the cost.

If only limited roof space is available, then higher efficiency modules will give more power from a limited area.
In most cases the available money is the limit, not the roof space.

caspian · Post by **caspian** » 27 May 2011, 16:21

We've just bought 16 Sanyo panels, which have an efficiency of about 18%. If you use Enecsys microinverters, the overall output of the array can be boosted by 5% to 20% compared to what you'd get with a standard string inverter. The exact figure depends on how of a shading problem you have (i.e. it outperforms a string inverter by a greater degree the worse your shading problem is).

Post by **clv101** » 27 May 2011, 16:52

Area efficiency is not important unless you are largely space constrained.

I'd rather have 1kW of 5% efficient panels for £1000 than 1kW of 15% efficient panels for £2000.

2 As and a B · Post by **2 As and a B** » 27 May 2011, 19:34

Are solar PV panels a uniform size?

The surveyor today said the panels that the company he is subcontracted to put up are 1m by 1½m. They are Zen panels, made in Belgium (apparently) and use self-cleaning Pilkington K glass.

The roof area is some 9m wide by 4m. That includes some areas shaded early in the morning. Area unshaded is probably about 7m by 3m - or space for 14 of the panels that the installation company puts up.

Our annual electricity use has varied. More recently it has been about 4,000kWh (or more). I would hope to be able to get it down to about 3,000kWh (weather permitting) - it used to be about 1,500kWh!

The roof is orientated about WSW (actually +60 degrees from south) and the pitch is some 20 degrees.

biffvernon · Post by **biffvernon** » 27 May 2011, 23:49

foodimista wrote:Are solar PV panels a uniform size?

No. Different manufacturers use different shapes. The ones we have were chosen because our roof is a multiple of their size.