>> Solar Thermal makes no sense anymore. >> Compare 70% efficiency (ONLY 5 mos of the year) >> for a net of 29% to PV that is 18% year round AND >> when used to drive a Heatpump with a COP of 2.5 >> gives a net "efficiency" of producing "45%" HEAT. >> AND the other 7 months provides COOLING or >> retail value for the electricity.
> I think the word you want is "return on investment"; not "efficiency". Nope. Most people only have so much roof available for solar energy. And it is not enough for our total energy needs. So it is very important how much of that surface area you turn into retail value energy and is very much an "efficiency" determination. > Efficiency measures how much energy you get out > divided by how much energy YOU put in. Yes, how much do you get out VERSUS how much the SUN puts in. > The energy you didn't collect isn't costing you anything, > and it isn't "lost" -- it's doing what it always does and is > heating the environment. I'd rather be getting 15 cents per kWh for evrey square foot I have, than throwing it away on square footage that only produces usable heat for only a few months a year and then wastes it all the rest. > Solar thermal makes sense if you want heat. > It's really GOOD at making heat! Which I dont need 7 months of the year. And which I do need in the winter when it is producing HALF the heat for its size. And which produces DOUBLE the heat in the summer when I need it NOT AT ALL and which I cannot STORE for 6 months until I do. With PV you get full retail value for every kWh every month of they year and you can save 100% of the excess you get in the summer for when you might need it in the winter. And with a heat pump, you get 2 to 4 times the heat that you stored! AND you can charge your EV for free from the excess electricity. You cant do that with heat. Forget it. WIth the 10-to-1 reduction in PV costs over the last decade, it is time to let go of solar thermal. It makes no economical sense for the investment. PASSIVE solar design of buildings does make sense but that is direct sun to the inside. Not Solar Thermal. For solar energy collection, only PV makes sense since it can be used for ANYTHING. Not just heat in the winter. Bob, WB4APR. > Solar PV makes sense if you want electricity. It's not all that efficient > (10-15%); but that's still better than using some other method (wind, > thermal) that then needs a second conversion process to give you > electricity. > -- > Ingenuity gets you through times of no money better than money > will get you through times of no ingenuity. -- Terry Pratchett > -- > Lee Hart, 814 8th Ave N, Sartell MN 56377, [email protected] > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/ > group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150114/afe0413f/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
