Solar power is one of the cleanest alternatives to dirty energy powered electricity generation. The sun bathes the earth with more energy each minute than the world consumes in one year.

Not just for the desert

And while global conditions such as cloud cover, topography, latitude and altitude can play a part in solar energy effectiveness, you don’t have to live in the desert or on the equator to utilize solar energy.

Recent work by the National Renewable Energy Laboratory (NREL) is showing that high levels of solar insolation (the measure of solar radiation energy received on a given surface area in a given time) are not a necessary condition for finding good sites for solar panels. A study involving about 35 utilities found many areas of the country with lower insolation levels that received excellent capacity matches. The same study found that the utility's summer/winter peak load ratio provided a good proxy of capacity contribution, with the higher ratios showing higher contributions.

There are two main types of solar power that can legitimately serve as a substitute electricity source:

1. Photovoltaics (Solar Panels)– Most of us are familiar with these types of solar energy devices made up of interconnected photovoltaic cells that are mounted and positioned to collect sunlight.
2. Concentrated solar power (Solar Thermal) – A solar thermal collector is a solar collector specifically intended to collect heat: that is, to absorb sunlight to provide heat. There are various types of thermal collectors, such as solar parabolic, solar trough and solar towers. These type of collectors are generally used in solar power plants where solar heat is used to generate electricity by heating water to produce steam and driving a turbine connected to the electrical generator.

Photovoltaics

How it works

Solar panels, most commonly utilizing highly purified silicon, convert sunlight directly into electricity. When sunlight strikes the material, electrons are dislodged, creating an electrical current, which can be captured and harnessed. The panels can be several individual solar cells or a single thin layer, which make up a larger solar panel.

In fact, market evaluation studies have shown that solar panels can make a contribution to every utility in every part of the country.

Advantages

• Portable
• Don't need electricity distribution system
• Getting cheaper all the time – some innovators claim as cheap as coal, although that’s yet to be proven
• Often the most cost-effective long-term option for power in remote areas
• Fuel does not have to be delivered or stored at the site, another significant cost savings
• A well-designed PV system doesn’t need to be attended and requires little maintenance, thus saving significant labor costs
• Can be designed for easy expansion, which benefits thus that may expect their energy needs to increase in the future
• Current modules are durable and experience little degradation over time

Disadvantages

• Some of the negatives to solar energy involve the production of the photovoltaic (PV) panels themselves. The PV panels require mining of silicon dioxide and then being reduced when pure silicon is heated, and the materials that are released when this refining takes place are what affect your health, because of the toxicity involved. Yet, some companies reduce their use of silicon by focusing on thin-film solar modules that either use a very thin coating of silicon or use other non-silicon materials, though thin-film PV nodules are typically less efficient than the crystalline silicon ones.
• Copper, which is becoming more expensive, is another material used heavily by the solar industry that involves destructive mining activities.
• There are also some design flaws that can be avoided when using solar power to heat domestic water. The water that is stored can sometimes become moldy and can cause an allergic reaction.
• Costs- Kilowatt-hour for kilowatt-hour, PV energy still usually costs more than energy from local utilities, though much depends on location.
• The initial cost of PV equipment is higher than that of an engine generator, though the cost is almost always recovered through substantial fuel savings over the life of the equipment (15-30 years).

Concentrated solar/solar thermal

How it works

A solar thermal collector is a solar collector specifically intended to collect heat: that is, to absorb sunlight to provide heat. Although the term may be applied to simple solar hot water panels, it is usually used to denote more complex installations. There are various types of thermal collectors, such as solar parabolic, solar trough and solar towers. These type of collectors are generally used in solar power plants where solar heat is used to generate electricity by heating water to produce steam and driving a turbine connected to the electrical generator.

Advantages

• No need to change established infrastructure – instead of coal fired utilities, build solar utilities
• Efficiency is also increasing
• Very high temperatures reached. High temperatures are suitable for electricity generation using conventional methods like steam turbine or some direct high temperature chemical reaction. (reference needed)
• Good efficiency. By concentrating sunlight current systems can get better efficiency than simple solar cells.
• A larger area can be covered by using relatively inexpensive mirrors rather than using expensive solar cells.
• Concentrated light can be redirected to a suitable location via optical fiber cable. For example illuminating buildings, like here (Hybrid Solar Lighting).
• Ability to deliver power during periods of peak demand, a feature that makes it one of the most viable energy choice for the West.
• Much of the equipment now used for conventional, centralized power plants running on fossil fuels can also be used for CSP plants, allowing CSP to be integrated fairly easily into the current electric utility.

Disadvantages

• More limited by sunshine.
• Concentrating systems require dual axis sun tracking to maintain Sunlight focus at the collector.
• Inability to provide power in diffused light conditions. Solar Cells are able to provide some output even if the sky becomes a little bit cloudy, but power output from concentrating systems drop drastically in cloudy conditions as diffused light cannot be concentrated passively.
• The CSP plants themselves uses large amounts of land, though much smaller amount of total land than fossil fuel plants that require a significant amount of land for exploration, mining, and road-building purposes

For More Information

• Solar Electric Power Association: Organization presents industry and environmentalist backed facts on solar energy.
• Green Savvy: Eco friendly organization presents the ups and downs of solar energy.
• Wikipedia: Article on active solar energy and the methods of production.
• Clean Technica: A clean energy group talks about the benefits of concentrated solar power.
• Wikipedia: Article on passive solar uses and instalations.
• IEEE Spectrum Online: Technologies magazine's article on "First Solar's" thin film of cadmium telluride solar panel project.
• New York Times: News paper's article on retailers installing solar panels for cost advantages.
• Clean Technica: Clean energy group discuses a breakthrough in energy capturing when there is no sun.

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