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Solar cell roof panels and so on are now available that will supply the average home with power to run all our toys provided the system is part of the mortgage package.
Finannng a solar system at 5 0r 6 percent apr via home mortgage versus financing the same system through personal loans or credit cards at 14 percent plus makes the difference.
I doubt many home lenders are ready to do this.
Many obscure regulations probably exist barring the batteries needed for one thing;neither lead nor cadmium or supposed to be in homes in many cities.

We are really a nation of laws now;too darn many if you ask me.

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.

The price per watt is still probably high, but this is a huge improvement. The average solar cells people have on their roofs now are only about ten to fifteen percent efficient if they've purchased them in recent years, worse if older. Cells with efficiency of 10% will produce about a hundred watts of power per square meter during peak sunlight hours. Sunlight at ground level is supposedly the equivalent of one kilowatt of electricity per square meter. Panels that are 100% efficient would generate one kilowatt per square meter during peak sun hours, or something like five or six kilowatt hours per day depending on how much sun they get in the area where the panels are set up. Cells that are 40% efficient would then put out around 400 watts per square meter during peak sun hours. That means with 40% efficient panels we can produce four times as much power per square meter of panels than we would get with standard 10% efficient panels still common today. It probably also means a reduction in price, since less materials will be necessary to set up the two or three or more kilowatts worth of solar panels people like to set up for home power. Costs for solar panels and other equipment you need to set up a solar power system for your home have slowly but surely been going down, and efficiency of the panels is going up. Big strides in efficiency like this hasten the day when solar power systems will be providing a big part of the electricity homes and businesses need. It will be a while before that happens but in the mean time you're going to see more and more solar power being utilized for small gadgets, remote equipment that needs power, maybe cheap solar panels for your work truck to keep your power tools charged, and so on. I remember being amazed by solar powered calculators, and things like the solar powered school zone signs with the flashing lights, and seeing solar panels at gas wells. As efficiency improves and price goes down we'll see a lot more innovative uses for solar power in addition to seeing more solar panels on homes and businesses for supplementing power from the grid.

Where solar can have biggest impact on energy usage is air conditioning during the summer.

Also note the multijunction flexible product put out by 'UniSolar':

http://www.uni-solar.com/index.asp

They put out a flexible peel and stock roll (feels like linoleum) that can easily confrom to almost any roof. They also put out a shingle product. They presently warrantee their product for 25 years.

In the solar biz, the weakest link is the AC-DC Converter, but they are getting better with longer warranties (> 5 years to now greater than 10 years).

Batteries are a problem in more ways then one.

But looking at grid loads during the summer, air conditioning is a huge percentage of load and if solar systems can take up that load, then oil and other fossil fuel markets will definitely feel it.