Powering Change


An abundant, renewable, pollution-free source of energy

Two types of technology are used to turn sunlight into electricity.

Concentrated Solar Power (CSP)

CSP systems are used in large-scale (50 megawatt+) projects in areas with high direct sunlight. CSP uses the sun as a heat source to generate steam, which rotates a large turbine, which in turn activates a generator that produces electricity. CSP systems consist of three main types: parabolic troughs, dish engines, and central receiver towers. By generating thermal energy, CSP systems are able to also offer cost-effective energy storage, as well as the ability to produce energy during cloudy periods and after the sun has set.



Webberville on About Solar page - 144 x 108

Photovoltaic Energy (PV)

Solar photovoltaics, also often called "solar panels" or "PV panels", are comprised of cells consisting of one or two layers of a semiconducting material, which is often similar to what is used in computer chips. When light shines on the cell it creates an electric field across the layers, causing electricity to flow. The semiconductor material most frequently used in photovoltaic cells is silicon, an element most commonly found in sand. There is no limitation to its availability as a raw material; silicon is the second most abundant material in the Earth's mass.

Solar PV is the most widely used form of solar technology, and it is used in both residential and commercial-scale installations. Commercial-scale installations are typically located in areas with strong solar resources to ensure maximum electricity production.

PV is used in a wide variety of applications:

Grid-connected domestic systems: This is the most popular type of solar PV system for homes and businesses in developed areas. Connection to the local electricity network allows any excess power produced to feed the electricity grid and to sell it to the utility. Electricity is then imported from the network when there is no sun.

Grid-connected power plants: These systems, also grid-connected, produce a large quantity of photovoltaic electricity in a single point. The size of these plants ranges from several hundred kilowatts to several megawatts. Some of these applications are located on large industrial buildings such as airport terminals or railway stations. This type of large application makes use of already available space and compensates a part of the electricity required by these energy-intensive consumers.

Off-grid systems for rural electrification: Where no mains electricity is available, the system is connected to a battery via a charge controller. An inverter can be used to provide AC power, enabling the use of normal electrical appliances. Typical off-grid applications are used to bring access to electricity to remote areas (mountain huts, developing countries). Rural electrification means either small solar home system covering basic electricity needs in a single household, or larger solar mini-grids, which provide enough power for several homes. More information is available at www.ruralelec.org

Hybrid systems: A solar system can be combined with another source of power - a biomass generator, a wind turbine or diesel generator - to ensure a consistent supply of electricity. A hybrid system can be grid-connected, stand-alone or grid-support. More information is available at www.ruralelec.org

Consumer goods: Photovoltaic cells are used in many daily electrical appliances, including watches, calculators, toys, battery chargers, professional sun roofs for automobiles. Other applications include power for services such as water sprinklers, road signs, lighting and phone boxes.

Off-grid industrial applications: Uses for solar electricity for remote applications are very frequent in the telecommunications field, especially to link remote rural areas to the rest of the country. Repeater stations for mobile telephones powered by PV or hybrid systems also have a large potential. Other applications include traffic signals, marine navigation aids, security phones, remote lighting, highway signs and waste water treatment plants. These applications are cost competitive today as they enable to bring power in areas far away from electric mains, avoiding the high cost of installing cabled networks.



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