Introduction To Solar Power Generation

Photovoltaic Solar Panels

Photovoltaics (PV) literally means "light-electricity," and is the process of converting sunlight into electricity. The term "photo" comes from the Greek word "phos" or light, and "volt" was derived from Volta (1745-1827), a pioneer in the study of electricity.

How does it work?

When some materials are exposed to sunlight, they release small amounts of electricity giving off what is known as the "photovoltaic effect." Sunlight is composed of photons, or particles of solar energy that contain various amounts of energy corresponding to the different wavelengths of the solar spectrum. When photons strike a PV cell, the energy of the photon is transferred to an electron in a cell's atom. The cell is made of a semiconductor material.

With its newfound energy, the electron escapes from its normal position on the atom and becomes part of the current in an electrical circuit. When this happens, the electron creates a "hole." Special electrical properties of the PV cell, specifically a built-in electric field, provide voltage that drives the current through an external load, such as a light bulb, a hairdryer or a television set.

The components of PV systems

Photovoltaic modules are the basic building blocks of solar electric power systems. PV modules can be made from several different materials, which vary in cost and conversion efficiency. Modules are combined to create panels. Panels are combined to form arrays. Solar electric power systems may also have batteries, charge controllers, and inverters, which convert the direct current generated by PV system into an alternating current, the type of electricity sold by utilities and required to run most appliances and electronic devices.

Types of Solar Modules

There are two major categories of solar modules, Crystalline and Thin Films. There are a couple types of each and each has its positive and negative factors.

Source: Center for Sustainable Energy

 

Solar Thermal

Solar thermal uses the heat of the sun to produce energy instead of converting light into electricity. By focusing heat with mirrors onto a tube of liquid (usually some kind of oil or water), solar thermal produces steam. The steam then turns turbines to produce clean electricity. This technology has been used reliably for more than twenty years, but for a long time PV cells took the spotlight. Now some innovation has put Solar Thermal (also called Concetrated Solar Power or CSP) back into the spotlight, and utility-scale investors are building new CSP plants at an amazing rate.

Why so popular? Because it's efficient, cheaper, and you can store heat for use when the sun isn't shining. In fact, one method of heat storage uses molten salt. Some people even think that solar thermal could one day become cheaper than fossil fuels. A whole housing development has even been built to utilize the technology in Canada (the cold weather doesn't effect CSP).

New Innovations in Solar Technology

Building Integrated Photovoltaics (BIPV's) are a relatively new area of solar technology. BIPV's combine building materials with photovoltaic cells that can produce power from sunlight. Examples of BIPV's include solar shingles and solar powered glass.