Inefficent yes, but hooking up 2 wires is a lot easier than building one out of copper, plywood, glass and paint. With solar panels costing only 25 cents per watt (on a good deal) then the investment in 4 panels (800W) is about $275 and totally maintenance free. Where as cobbling together one will only work in the summer, or if you want to use antifreeze, then you have to add pumps and heat exchangers, etc. And will it work 20 years without any attention?
But you are right. You can triple the efficiency with a modern heatpump water heater, BUT then it wont run on DC, so then you have to have 4 times more panels and then do the grid-tie-only-when-running trick, and it simply is not worth it. Better to just bight the bullet and be grid tied. Oh, I assume you have seen the articles that thermal solar hot water heating was dead in 2008 and now is considered dead-dead-dead. It is more efficient and economical to do grid-tie solar and a heatpump water heater. Because since 2005, price of PV panels has dropped ten to one and heatpump water heater is 3 times more efficient. (combined, then is 30 times more cost effective than it used to be. Plus, the biggie, is that for every drop of hot water you do not use, then you still get full 100% retail value for your solar energy. Whereas with thermal solar, unless you use 100% of your hot water every single day, then your thermal panels are doing nothing once the tank is hot. Bob -----Original Message----- From: EV <ev-boun...@lists.evdl.org> On Behalf Of Jan Steinman via EV Subject: Re: [EVDL] Solar off grid with an EV? (DC AC/heatpumps and waterheating) > From: Robert Bruninga <bruni...@usna.edu> > > … using about 4 Solar panels > for the bottom coil in a water heater are a good idea. You need hot > water every day, and so this gives you 100% effectiveness of these 4 > or so panels. Seems like a horribly inefficient way of heating water! Direct solar hot water is a much better use of resources and solar energy. Someone who's handy can easily cobble one up out of copper tubing, plywood, glass, and some flat-black spray paint. Jan _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
