Home made solar cells - is this real?

To power something directly, or to charge a battery which will power something.

"Don Lancaster" wrote in message news: snipped-for-privacy@individual.net...

It's been a while since I read the paper on your site, but some things to consider:

Panels these days can be bought for less then $5 US per watt. I've heard rumors as low as $3 per watt. This is with paying distribution costs (think of the markup at each middle man, transportation and the end distributor), wages, manufacturing costs, mining, materials refinement, administration costs, packaging, warranty claims and other customer support, energy used, R and D, engineering, taxes each step of the way, licensing, while still breaking at least a modest profit (or they wouldn't bother making the panels).

A comment about your comment about the companies making the panels are not likely to use PV for making PV panels yet - Right now those panels can be sold for much more then the payoff would provide. Making and installing a Mw (which I would expect to be on the right order of magnitude) worth of PV would put a large damper on shipping profitable PV panels so that the plant would be self sustaining. That would currently put most companies under. Kinda like lets work full steam ahead for 1/2 to 1 full year, but sell nothing during that period (killing revenue and allowing competitors to gain a major footing), for a payoff that will not happen until 5 to 10 years. Not likely in this economy. Add to the fact that the company will likely change many things during this time, such as production rates, space needed, processes (these are likely changing continuously, as PV is not a mature product). Add to the fact that industrial power is significantly cheaper, and has a immediate payback (product can be sold right away). As electricity prices increase, and production rates are increased to meet market demand, processes are matured, then PV will likely start to produce PV.

Assuming a need for 20 kWh per day, which is pretty typical for the average household, with typical "turn things off" when you leave attitudes, with typical modern appliances (and emerging appliance efficiency is much better - eg IRF's iMotion technology).

Assuming 6 hours of direct sunlight average per day. Assuming the rest of the light during the day is going to account for losses, lower then rated output, etc. Slapping a largish 4000 W PV array on your house would give 24 kWh of energy per day, likely more, dependant on location. That would cost $16,000 US (assuming $4 a watt). Assuming $1000 for wiring and installation, and $2000 for an grid tie inverter (which are not mass produced by the millions so cost is currently high), this would come out to $19,000. Actually, this cost is potentially thousands lower on new house, since the panels can be used to displace roofing materials and labor.

Assuming electricity is $0.12 US per kWh, the house would cost $876 US to run per year. The PV would produce $1051.20 per year of energy. With net metering the utility would owe $175.20 to the customer per year (this would likely be eaten up in "licensing fees" by the utility, basically protecting them selves as they have to buy the electricity for the same price as it's sold for - the cost will not be calculated in these calculations, as it has nothing to do with energy (other then make the grid more efficient due to lower transmission losses)). Assuming some inflation, it would take 20 to 25 years to pay it off assuming you had $19000 to invest in an system. Going out and borrowing the money from a bank, the payback would likely be 50% longer - not good.

Places close to the equator with lots of sun like the Arizona dessert would likely have an output 50 to 100 % higher (heat could be a problem - lower output)

Lets assume sunny California gets 50% more useable energy, and the price per kWh is $0.35 (it may or may not be anymore, and could be only during peak hours - which the sun shines) - this same $19000 array would generate $4599 US worth of electricity per year. So a 5 to 6 year payback, and under a 10 year payback if borrowing the money. Not bad.

This has been proven in California with high electricity prices, and panels at $5 a watt, payback periods as low as 6 - 8 years have been calculated for installed systems a few years ago (add a year or two if the government subsidies were not in place). As shown above, they likely will not have a problem achieving those payback periods ether.

Efficiency of the panels can be increased by cooling them, possibly with water, which could/is then used for heating. This has been done on a small, mostly experimental/academic scale.

Now assume the house in question uses more efficient light, power management, and appliances, and cuts their loads in half, then the system costs about half as much, for a little "environmentally conscious" change in life style. For the PV investment, and some small, needed lifestyle changes, the payback period is much shorter. This is commonly done, and allows arrays in the size of 2000W to be used. Granted the "environmentally conscious" change in life style is something that can be done right now, so it's not a completely fair comparison.

The panels them selves produce a net *energy* gain, even if it takes 5 to 10 years (likely much shorter) for the break even point in modest light (6 hour). The useful lifetime for a solar panel is greater then 25 years, even the warranties are typically 20 or 25 years long (also guaranteeing 90% minimum output at this time). I wouldn't be surprised if a panel lasted 50+ years, as long as the seals held up, which shouldn't be a problem with modern manufacturing, epoxies and silicones. Therefore a panel is much better at making electricity with a net gain then gasoline, since 1/4 of gasoline produced (from your statements) is consumed in getting more gasoline. With a PV panel it only needs 10 to 20% of the energy (assuming above BEP), and the panel is still likely useable with no pollution, and assuming 6 hours of useable light on average per day, for every 1 watt of PV installed, 2.2kWh would be produced per year. Looking at that number, A 100W panel would generate 220 kWh in one year. I doubt that 220 kWh would be needed to produce a 100 W panel. That is a lot of energy to produce something.

PV currently: reduces pollution, gives energy security, known costs - who knows what a kWh will be worth in 10 years, reliability by adding a small emergency backup battery to a grid tie system, reduces dependence on fossil fuels and large utilities, all for the cost of a fairly cheap new car, which won't hold it's value for long. The big drawback with PV is it only produces energy during daylight, which beneficially just happens to be the time when the grids electrical loads are the greatest. As more and more PV is added to the electrical grid, the peak load will eventually match the base load, and then invert. Other RE such as wind, geothermal, water, biomass, etc can and will likely slowly replace the base load generated with non renewables. Grid tie is nice, since people who can't or don't want to bother with generating their own power benefit from RE. It also allows a gradual transition.

Adding a small turbine (not dependant on sun for output) to a PV system can dramatically reduce payback periods, as the PV array can be much smaller. Allow the cost of a kWh to increase substantially, and the break even period will greatly reduce - oh wait this has already happened in California - where it is economical to have PV. Add to the fact that PV is slowly dropping in price.

PV could be made to look even better by powering a car with it - A typical car electric car uses about 100 Wh per 1 km (often less). A typical round trip commute is 40 to 60 km per day. The car would therefore use 4 to 6 kWh per day. Throw an additional 1 kW array on top of an roof with 6 h of good light to generate 6 kW per day. The 4 to $5,000 investment to cover the PV installation would be paid back within 3 years, with the current cost of gasoline, which is not likely to get cheaper. The excess energy sold back to the grid with net metering would easily pay for gas for a small generator used for long trips - humm looking at the likely modest efficiency of the Honda EU2000 (which is too small, but good enough to use it's efficiency numbers since a larger more optimized generator should be more efficient), this will give 2000W for 7 h on 1 gallon of gas, which would give an efficiency of about 90 miles to the gallon! The cost of battery replacement is easily offset with the lack of need for any maintenance to the drivetrain, not to mention the much simpler, and cheaper car that would result with an electric. Problems, however, as big car companies found out when they had to destroy the EV's they produced; they don't consume stuff like exhausts, spark plugs, oil, timing belts, filters, etc, or more importantly gasoline. Electricity for cars is likely hard to tax, electricity needed to charge all the cars on the road could not be supplied by the current grid or generators. Big oil companies would be upset as gasoline consumption keeps rapidly dropping instead of it's current trend of ever more consumption, therefore, hence the proposed "hydrogen economy".

If you ignore the life of the organic matter that created it...

Only the on-the-books part of the economy matters.