I have a March 809 pump controlling circulation through the solar panel (open-loop system). It's driven by a PV panel - no sun, no circulation -- and has worked well for just over 4 years, but started getting intermittent recently. On inspection, the brushes were down to nubs and the entire motor body was filled with brush dust. No problem, right? Just replace the brushes. Wrong. March claims they're not replaceable and don't offer them as parts, but several vendors claim they've got them, for only about $30 per brush. Either way, I'm looking for another solution. Enter ITT, with something called the Laing ecocircÂ® D5 Solar pump. It's a spherical motor pump (a new thing for me) intended for direct connection to PV panels, with microprocessor controlled optimization of pump output as a function of PV panel output. They claim "maximum performance at any given insolation." On paper, it looks great. I've got one coming and will report back on it, but has anybody already blazed that trail?