On 28 June 2014 03:44, Kerry wrote: > Still no sources, though. > > Solar energy per square meter, realistically - 380WH / day EEVblog #632 > US energy use - 334,000.000 BTUs/person/year That's 268 kWh/person/day. Or 11+ kW 24/7 for every person. Regardless of how that's used, you are going to have to cut back :-). Average sunshine hours/day =3D ~~~4. 268/4 =3D 67 kW / person of solar capacity Realistic figure in near future is 20% efficient (below current best practice) =3D ~ 200 W /m2 or 800 Wh/day - about double the figure given fro= m EEV blog. That's delivered on site using local solar installations. So each person needs 67/.2 =3D~ 270 m^2 of PV panels . Cover a 1/4 acre section in PV and you'd supply 4 people. The 268 kWh/person/day is an immensely high figure. It may be correct but presumably it covers transport, aircon, street lighting, aviation, ... You're going to have to cut back (he said again) regardless of your energy sources. (So are we :-) ) The above was solar PV. Solar thermal for heating can do marvels. 30% + of home energy uses is hot water. All home hot water for a typical family can easily be achieved using less than the roof area of a typical home. High rise maybe not. FWIW - 5W LED bulbs are amazingly adequate in many situations where I'd have used 100W incandescents 10 years ago. Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .