An Introduction to Solar Power Generation

 

There are three main types of solar power energy:

• Photovoltaic Solar Power
• Concentrating Solar Power
• Solar Thermal Energy

 

Photovoltaic Solar Power Technology

Photovoltaic solar power results from electricity generated by solar cells by converting sunlight directly into electricity.  The basic solar principles (i.e. that certain materials can produce small amounts of electric current when exposed to light) were initially developed by Alexandre Edmond Becquerel in 1839, but up until 1954 little, if any progress was made in applyingthese principles to developing power.

A major breakthrough came in 1954 when physicists at Bell Labs discovered that a Silicon semiconductor could convert light into electricity with 4-6 percent efficiency in contrast to earlier materials which were less than one percent efficient. This led to extensive research and development work with silicon semiconductors that were treated by a process known as “doping.” Doping simply mixes an additional chemical element with the silicon to create either a positively charged or negatively charged layer of silicon; allowing for two oppositely charged layers of treated silicon:

• The bottom layer is positively charged (P-type), and
• The top layer is negatively charged (N-type).

The two layers form an electric field between them which allows the electrons to flow from the P-type silicon to the N-type silicon. When the solar power energy cell is connected to an external circuit, it will generate solar electricity as light strikes the top silicon surface.

 

Concentrating Solar Power Technology

Concentrating solar power (CSP) uses solar energy to generate heat which is then used to generate electricity. Unlike photovoltaic methods that directly create electricity, concentrated solar power is actually a utility-scale solar solution that can provide hundreds of megawatts of electricity to the existing electric grid. Concentrated solar power can potentially provide a large-scale, sustainable alternative to fossil-fuel power plant. The heat it generates is used to drive a turbine, which in turn, powers a generator which produces electricity.

 

Solar Thermal Energy

There are several solar applications that a homeowner can use to take advantage of solar thermal energy directly, including:

• Solar space heating – Solar space heating uses solar thermal energy to heat the space inside a building. Heating with solar energy can lower a home’s heating bills and reduce dependence on fossil fuels such as oil, propane, and natural gas.
• Solar water heating – Solar water heating uses solar thermal energy to heat household water. Households typically have15-30 percent of energy use applied to hot water heating.
• Solar pool heating -. A solar pool heating system will generally pay for itself in two to five years when replacing gas or electric pool heating systems.
• Solar thermal cooling – Solar thermal cooling is primarily used in commercial settings, but it is becoming more common in residential applications. There are two applications suitable for residential settings where solar thermal energy is used to drive the cooling process. These include:
  • Solar Absorption Cooling, which uses solar-heated water to drive an air conditioner. The air conditioner uses a liquid that consists of an absorbent and a refrigerant. Solar heat is used to separate the absorbent and the refrigerant from each other. The refrigerant is then compressed and evaporated to create a cooling effect for your home. The evaporated refrigerant is then recombined with the absorbent to go through the process again.
  • Solar Desiccant Cooling doesn’t really cool the air, but instead it removes moisture from the air which decreases the relative humidity. The moisture is removed by passing the air through a desiccant. As the desiccant absorbs the moisture from the air, it becomes saturated and loses its ability to continue absorbing moisture. At this point, the desiccant is then regenerated, or dried, with solar heat which evaporates the moisture into the outside air.