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OK.

Figure it this way.

(Everything depends on your location (higher latitude = less solar incident rays per sq meter than a southern desert test site near Mexico), weather = (compared to a cloudless desert!) will ALWAYS mean you can never get as much power as at this test site , altitude + humidity (anything in the air reduces incident rays on the panel), cleanliness (any dirt or pollution or dust on the surface or in the air reduces incident sunlight.) If you have nearby buildings or trees, they reduce by shading the effective area of the sun's arc that you get usable exposure. If you aren't exposed directly to the south facing sun's arc through the sky all day, you get no power. For me, almost all of my roof is shaded almost all of the day, so I get power only from 11:00 to 1:30 in summer. Less in winter.

They are using a collector (or mirror-like concentrator) so the actual roof area req'd is bigger than the solar area of the cell. So, if your roof was 30 ft x 50 ft, you could cover the entire roof with the concentrator, but the actual cell are might be 50-25% of the collector area.

OK. So this was ideal test site conditions. The news is good (to solar enthusiasts) because previous efficiencies couldn't get over 7-15% in routine production of clean cells, and 20-32% under ideal conditions.

using nominal values, to actually run your a one-story average house from the sun from 9:00 - 3:30 (the maximum actual hours the sun is usably producing power!), you need a cell area about the size of 1/4 - 1/3 your roof - assuming the whole roof faces south at the right angle. To run the house (with "usual" electric loads!) from 6:00 AM to 6:00 pm, you need to add batteries, a DC-AC converter, solar controller (needed anyway really) and a battery system charge controller.

OK. All those converters and controllers reduce efficiency - since you're pulling power from the batteries for half the time, and charging the battery half the time. So you need just about the half the roof to run your house half the day - during daylight hours.

To run solar full time, double the area (less electric power is used at night, but during part of the night almost all of the loads are off. Making up is the greater drain on the batteries and less efficiency of the solar-battery-chemical-DC-to AC conversions.... Daytime hours, much of the solar input doesn't need to get reconverted to battery chemical power first. It's used immediately.

AWhat most (almost all!) solar users do is really eliminate almost all of their electric loads: no AC, high efficiency motors, lights, fewer lights, TV, no instant-on appliances, high efficiency refrigerators, etc, etc. All of these cost a LOT more.

The usual figure for planning is to allow for 4 cloudy and lost days for the storage cvapcaity. That much capacity adds more solar bank req'd to charge it and keep it up - not a lot, but a bunch.

Solar is really only practical (for houses!) where the site is so far from the grid that lines (at 10,000 per mile, if not more) are so expensive that the 25,000 investment is "rational" ....

It makes a nice demo. But you can't run much right now.