Ideas for a model of solar energy
How solar energy can power our future.Everyday we use the sun. We use it to stay warm. We use it when we tan and enjoy it at the beach. We are vessels of solar energy. Our feet grow lighter in May and are dancing by July. What if we could use the sun to power our homes, to drive our cars, to cook our food and heat our swimming pools? As a matter of fact, we can and we are. More and more people are turning to solar energy to power their homes, offices and heat their water. We are in the midst of a solar revolution, searching for a solution greenhouse gases and global warming. From that search have come several ideas for a model of solar energy. Ideas that will become our future.
The use of passive solar techniques is as old as home building. One of the many reasons that solar power is successful is its predictability. Even the ancient Egyptians understood the value of the sun in their architecture. Today, after many years of ignoring it, we too begin to incorporate the sun into our blueprints. Passive solar is the art of harnessing solar energy without the use of machines or electrical devices. Passive solar is large south-facing windows, sunrooms, skylights and swimming pool covers. Passive solar energy alone cannot power our homes and lives but it does significantly lessen heating needs and can make a formidable dent in electric bills.
Solar photovoltaic (PV) systems are active solar energy systems. Solar panels, usually mounted on the roof of the home, directly convert sunlight to electricity. This electricity is then distributed throughout the house to supply daily power needs. In essence, a solar PV system replaces, or supplements, the conventional grid power system. Solar PV is the most widely used idea for a model of solar energy. According to the Solar Energy Industries Association (SEIA), solar PV grew by 48 percent in 2007 compared to 2006.
PV's rapid growth is due largely to tax incentives from several state governments. The PV model's biggest drawbacks are poor efficiency and storage. Solar PV panels convert sunlight directly into electricity. During this process, however, much energy is lost. Solar PV, the most efficient of active solar technologies to date, converts around 15 percent of sunlight to usable electricity. This increases the cost and space required for solar PV arrays. Thin, more flexible, innovations are being developed and used but to this point have even lower efficiency ratings, despite their aesthetic value.
The other problem with PV is storage. For roof panels on a single-family home this isn't really a problem. But for utility scale, or concentrated, solar power it is a big problem. The sun sets every night, just when cities across the world need electricity the most. That's where solar thermal power comes into play. Solar thermal systems use collectors to absorb the sun's heat which, it turns out, is much easier to store than electricity.
Most solar thermal systems in use today serve to heat and cool homes and commercial buildings. However, recent innovations in storage techniques have pushed solar thermal to the forefront of concentrated solar power research. Solar researchers have realized that mediums, such as molten salt, can store incredible amounts of heat and, when necessary at night, this heat can be converted to electricity and used to power homes even when the sun is not shining.
Solar thermal hot water systems are at this time the most cost-effective way of utilizing solar energy. Solar water heat can be passive or active (use pumps to distribute water). Solar collectors absorb heat and heat water which is either stored in a tank for later use or sent directly to the house. Solar thermal collectors are much more efficient than their PV counterparts but are not practical for producing electricity on a small scale.
All Together Now
At this point in time (and I emphasis the temporal, as solar technologies are constantly evolving) no single idea for a model of solar energy can fulfill our lust for abundant, clean energy. It is more likely to be a solar brainstorm that carries us beyond fossil fuels. The sun, as a resource, is abundant and predictable. It rises and sets everyday. It was humankind's first clock. We used to live by it and now, so it seems, we will live by it once more.