This forum is about wrong numbers in science, politics and the media. It respects good science and good English.
I use the neta site but what I usually quote is the load factor, ie Mw(current)/Mw(total monitored), which is Mw(current)/2662.
This figure is often appalling, sometimes being under 1%.
I might as well add this to the thread. The figures for renewable energy's contribution to Britain's electricity production for 2010 are now available in the March 2011 edition of 'Energy Trends' (available on the link I gave in my earlier post in the thread).
The 2010 figure (page 30 of the report) is that 6.6% of Britain's electricity came from renewables, compared with 6.7% in 2009. So despite adding (I would imagine) a considerable amount of new renewable capacity through more windfarms in 2010, the percentage is actually going slightly down. The figure is just about compatible with Buff Huhne's 7% figure. The report attributes the less than expected renewable generation in 2010 as being due to lower wind speeds and lower rainfall (the latter affecting hydroelectric).
The figures I'm quoting above are based on renewable electricity divided by total electricity generated in the UK, which is the most obvious way of doing the calculation and is called the 'international basis' method of presenting the figures. The report also quotes other methods of giving the renewable energy percentage based on the 2008 EU Renewable Energy Directive, which seems to take account of net imported electricity and subtracts the contribution of pumped storage, but that looks like a less realistic way of presenting the figures to me.
The wind turbines break a lot. From any economic standpoint, we simply can't afford the miserable things.