 Free power from the sun! What could be more simple and perfect?! It's not perpetual motion, but it is FREE ENERGY! Gathering heat energy from the sun is an age old concept, but collecting electrical power directly from sunlight is a relatively "space aged" idea. Even though the first solar cell was made in 1880 by Charles Fritts, it was NASA in the early 60's that popularized the solar cell by using them on satellites and other spacecraft. Originally, the cost of the technology was so high that only the government could afford to use it. But over the years the price has dropped steadily and about 10 years ago started approaching affordability, at least for the deep-pocketed environmentalist types. Back then, a simple system to power a home would cost over $40,000. Today however, thanks to a number of factors, a basic system can be had for as low as a couple grand, and about $12k to $20k for a system to power a medium sized home (such as the one shown above). With the increased popularity of the industry, growing 15% a year, new companies are coming on line at an extraordinary rate. With each increase in production the price of the technology continues to fall. Also, many state and federal tax incentives actually pay you back for part of the cost of a system! More on that later...
How does a solar cell work?... A basic solar cell is actually a type of transistor, like the ones found in old radios. Two layers of silicon are sandwiched together. One is doped, or coated, with phosphorus and is called the N-layer. The "N" stands for "negative" because it carries an excess of electrons which are negatively charged. Electrons moving in a wire or other conductor is what constitutes electricity. The other layer is doped with boron and is called the P-layer since it has a deficiency of electrons and therefore carries a positive charge ("P" is for "positive"). The junction where the two layers meet is then called the P-N junction. That's all wonderful, but HOW DOES IT GENERATE ELECTRICITY! I'm getting there. :) Light from the sun consists of super small packets of energy called photons. As the photons strike the surface of the N-layer, they knock electrons loose from the outer orbit of their respective atoms and they become "free electrons". Free from taxes, oppression, slavery, disease, death, but most importantly, free to move to the P-layer. The P-N junction acts as a barrier such that the only way for the free electrons to get to the P-layer is through an external conductor. Each solar "cell" puts out about .5 volts of electrical potential. These cells can be added in series or parallel to produce just about any voltage and current desired. A bunch of cells tied together constitutes a solar "panel". Solar panels are rated in watts, which is found by multiplying the voltage times the current, e.g. 17.0 volts times 4.4 amps = 74.8 W, or about 75 watts of power (see the ad for the Astropower 75 watt panel below).
So how much power can solar panels really provide?... It has been calculated that 100 square miles of solar panels placed in a sunny region could provide all of the electrical needs of the United States! Yes, solar can indeed power your home. Solar cells themselves however aren't terribly efficient. Silicon based cells range in efficiency from 12 to 17%. That means, of the 1000 watts/square-meter of solar energy striking the surface of the earth (1kW/sq meter is the average solar insolation in sunny regions i.e. California, Arizona, etc.) only 120 to 170 watts of power can be produced using a solar panel. This of course depends  on the solar radiation being perpendicular to the plane of the solar panel, as well as absence of any shading such as trees or clouds. This efficiency also goes down as the cell heats up. There are other materials and methods being tested that promise better results however. Gallium Arsenide solar cells are known to reach efficiencies as high as 30%. Solar thermal electric generation, using the heat of sunlight to generate electricity, is currently 33% efficient. Newer technologies such as parabolic stirling solar gensets (see left), holographic solar cells, concentrator cells, and cells that extract energy from all the wavelengths of light promise even greater gains in efficiency and in lower cost.
How do I power my home with solar energy?... You must first be aware that over 200,000 homes in this country alone are powered by the sun! The technology and the industry are well established and mature. There are many companies nationwide that specialize in installing solar systems on homes and businesses. SunWater is also trained in this field (anyone wanting to learn how to "do it yourself" can take classes through Solar Energy International). There are two types of PV systems: DC and AC. DC systems (direct current) are the simplest and most inexpensive type. DC system components are: solar panels, batteries, charge controllers, and a load center. They're typically used to power small applications such as stand-alone water pumps or even small cabins. With the advantage being cost, the disadvantages are mainly twofold. Firstly, direct current won't travel very far on wires before it loses most of it's potential, requiring a very short distance between the panels/batteries and the loads. Secondly, it's not easy to find major appliances that will run off DC (although the trucking industry has spawned a whole array of small DC appliances suitable for small cabins). An AC solar energy system to power a home consists of about five basic components: solar panels, inverter, storage batteries, charge controller, and load center. The photo above shows a typical AC system component array. The inverter on the upper-left converts the DC from the batteries into AC household current, compatible with power from the utilities. The charge controllers on the upper-right take the  current from the solar panels and use it to charge the storage batteries. The batteries (left) are deep cycle lead-acid storage batteries. Lead-acid is used mainly because of its cost-effectiveness and recyclability. The load center (not shown) is equivalent to a load center in typical homes. It's where the power from the inverter is connected to the wall sockets of the home. Another type of AC system is called "utility intertie". This is where AC power from the inverter is fed back into the utility grid via a pre-existing utility connection. This allows the owner to "sell back" power to the utility companies and actually have their power meter spin in reverse! A federal law mandates that utility companies must allow such a practice and reimburse owners of such systems for whatever power they put back on the grid. In practice however, utility companies are not very supportive of such practices and in many cases put up so much red tape as to make it impossible to sell back power or even connect to the grid. Many people find this sort of unchecked oppression simply unacceptable and choose to connect to the grid anyways. This practice has been labeled "guerilla solar" by Homepower Magazine. Many utility companies choose to cooperate, albeit half-heartedly. They will credit the owner for the power he/she puts back on the grid, but will only pay them the wholesale price of the power, and if the owner actually sells more than he/she uses, then it's simply zeroed out at the end of the year and the owner has basically been robbed. There is only one utility company that SunWater has heard of that actually sends a check to the owner that produces surplus power, and they're located in Vermont.
Does this mean I can continue to consume power as usual?... NO!! The first thing that is taught in SEI's PV Design and Installation course is how to conserve. The blunt fact is, Americans slaughter electrons like no other country! As a country we are incredibly inefficient users of electricity. In order to make the jump to solar, you will also most likely need to exchange your household appliance inventory for a new lot. First of all is lighting. Incandescent lighting produces only 10% visible light out of the electricity it uses. The rest is lost as heat. Flourescent lighting however only consumes about 1/10th the power, and they are guaranteed for 7-10 years! Other appliances to find alternatives for are: electric heaters, dishwashers, electric water heaters, electric clothes dryers, and conventional refrigerators. Every one of those appliances has a low-consumption counterpart available, many of them using natural gas or propane as the power source (although not zero-emission they're considerably cleaner than coal generated electricity). You can find such appliances from solar energy installation companies such as Real Goods. The initial cost of these appliances is higher, but they pay for themselves quickly in energy savings. Another thing to consider is phantom loading. These are appliances that continue to consume electricity even when switched off! These stealthy little power suckers can be eliminated by implementing commonly available "plug switches" and switching them off when the plug is not in use. By making the above mentioned changes, the average consumer could knock up to 50% off his/her electric bill! It's a good way to make a solid contribution to the environment and your pocketbook without having to shell out lots of "green" for a complete solar power system.
Is solar power cost-effective?... The short answer to that would be "no". Actual payback times where the owner would recoup all the capital costs of the system currently average between 20-25 years. Payback time depends entirely on what the cost of electricity is in your area. In California where utility rates are high, payback time is between 10 and 12 years. In reality however the question itself is flawed. Who buys a car or home based on payback time? The real value in going solar isn't to be found, at least for now, in finances. Solar is completely zero-emission, silent, renewable, and free! Yes, free! After the sytem has  been installed it never again needs fuel. All the power produced is free to the consumer. You'll never pay another utility bill. You won't be contributing to the exploitation of our environment for non-renewable oil, coal and nuclear. And best of all you won't be spewing toxins into our air and poisoning our children (see Air Pollution page). When you consider these factors, a solar power system is worth it, no matter what the cost! This doesn't mean there's no hope for those who insist on cost-effectiveness. As we said, Californians are finding solar more and more cost effective every day. Solar panels are warrantied for 20 years! If you're a business that can't afford blackouts and are worried about high fuel and maintenance costs, solar is the way to go. So many are finding solar to be the best solution, that in fact almost all solar panel supplies have been bought out for the rest of 2001! New plants are coming on line and production is ramping up considerably. As production goes up, prices will come down. It may not be but a few years and solar will be cost competitive with electricity generated from coal, hydro, wind, and nuclear. However, as stated above, SunWater believes the time to go solar is now. Our environment, our children, our future can't wait another day for solar to become "cost-effective"! GO SOLAR TODAY!! The planet will thank you, your children will thank you, and your conscience will thank you.
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