Business Green: The US solar energy industry has become the latest renewable energy sector to report impressive growth figures for 2009, further underlining the extent to which clean tech industries have defied the economic downturn. According to new figures from the Solar Energies Industry Association (SEIA) released yesterday as part of the trade association’s annual report, the amount of installed solar capacity in the US grew 37 per cent last year to 2,108MW. Solar industry revenue …