Photovoltaic Solar Energy
Tuesday, February 9th, 2010One of the more significant emerging technologies with solar energy has been photovoltaic (PV) electricity. Photovoltaics use special materials to convert solar energy directly into electricity. This electricity can be used immediately or stored in a bank of DC batteries.
How photovoltaic panels convert solar energy is a subject of advanced physics. In simple terms we can say they take advantage of new age materials and a phenomenon called the photoelectric effect. Solar energy on the atomic level displaces electrons, which in turn creates the flow of electricity.
Photovoltaics were originally developed as part of the space industry. The long life of the panels combined with no moving parts made them ideal for space bound equipment. Solar energy is much stronger outside the Earth’s atmosphere which also helps.
In recent times photovoltaic panels have been converting solar energy for residential homes in far away places. The cost of a photovoltaic array will often offset the costs of routing power transmission cables from the Electrical Grid. When this distance exceeds 1 mile, then the prospects of converting solar energy with photovoltaics makes more and more sense.
There are two types of radiation that are important and contribute to solar energy. The first is beam radiation, which are the direct rays of the Sun. Beam radiation is the strong warm rays we feel on a clear sunny day.
The second type of radiation is diffuse radiation. Diffuse radiation is scattered radiation, and is what we experience on a fully cloudy day. Diffuse radiation is not very strong, but still contributes to the total overall solar energy.
In order to use photovoltaics wisely, one should be in an area abundant with solar energy. Deserts are obvious candidates, in addition to semi-arid and tropical climates. Northern and coastal climates are tougher decisions due to extensive cloud cover, fog patterns, and rains in the winter. Each case should be considered respectively, however, as not all coastal climates are the same.
Photovoltaic panels come in several sizes and voltage ratings. They should be wired in series or parallel as required to meet the inverter / storage bank power requirements. PV panels have maximum system ratings, and so these should be verified before wiring a large array. New photovoltaic panels will convert solar energy between 12 to 14%, with more cutting edge and difficult to obtain units pushing 20%. Life expectancy will typically exceed twenty years.
One downfall of photovoltaic panels is that they can involve significant up front investment. This is due, in part, to the high purity silicone materials used in their construction. New types of panels are under development, however, and the price of photovoltaics is expected to drop in years to come.
Using photovoltaics to convert solar energy can be a complicated decision. One must consider the cost of local Utility’s rate of electricity, and know the solar energy data for their location. In some cases, as with distant properties and transmission cables, the decision can be easy. But in most cases, an investigation of the payback period will be necessary to know if one is making a cost effective decision. In times of uncertainty and surging fuel costs, the simple piece of mind of energy independent technologies may be well worth the effort.
Walter Hull is a recognized expert in solar power systems. For a limited time you can get his free checklist to solar power from your own backyard.