Letter Re: A Practical PV-Powered Well Pump and Cistern System

James:
I appreciate your web site, lots of good thoughtful info and no armchair commando nonsense. I rarely post on this or related blogs, but I've just installed two complete solar water systems and can perhaps add a bit to the backup-powered water discussion. A solar system is tailor-made for supplying water, IMHO, because instead of storing electricity in batteries for nighttime use, it stores water in a tank for use on demand, no inverters, no batteries, no fuel. Simple and effective. Both systems use Grundfos submersible pumps and two solar panels of about 170 watts each. One system pumps from a lake to a 1-1/2 acre orchard/garden about 500 feet away with no head (lift), and supplies about 4000 gallons per day. The other is for use here at the house and pumps from a well about 100' vertically to a 3000 gallon storage tank, then gravity flows to the house, and supplies from 800-1500 gallons per day depending on time of year (sun angle) cloudiness, et cetera.
The pump and solar panels must be sized according to lift, distance pumped, desired output, and geographic location. I'm located in Central Texas with plenty of sunshine year-round, so solar is a natural. Depending upon pump size and number and power output of the panels, the basic components including a stand for the panels costs around $3000-4000. Add to that about $500 or so for standard pressure tanks, pressure switches, wiring and plumbing and the cost is still less than a windmill and pumps a lot more water. Another beauty of these pumps is that they run on both 12 volt (PV solar) and 220 VAC, which means they can also be powered by a generator or from the electric grid. Just make absolutely certain, I repeat certain, that the 220 breaker is off before engaging the solar panels, as 220 VAC does some fairly spectacular things to a 12 volt DC solar panel.
I don't claim to be an electrician, or plumber either, yet I installed both of these systems practically by myself, so that means it can't be all that difficult. - J.H.