We have had our 3.4kw system ever since solar was introduced commercially here in Vic. Ours was installed back in Jan 2009. We have 2 strings of 10 x 174w Solartech and Topray panels running into 2 x CMS2000 invertors giving a max of 3.4kw normally. Had no real issues with the set ups at all. I do have a spare CMS2000 but not needed it yet. Both invertors have an small aux fan under the heatsink that comes on when inv reaches 40c powered by a 12v panel.