Solar energy is the utilization of the radiant energy from the sun. Solar power is used interchangeable with solar energy but refers more specifically to the conversion of sunlight into electricity by photovoltaics and concentrating solar thermal devices or by one of several experimental technologies such as thermoelectric converters, solar chimneys and solar ponds.

Photovoltaic (PV) or solar modules are made up of solar cells that are connected in series. The most common commercial cells are made from purified Silicon (Si). The Silicon cell is essentially a p-n junction that utilises the energy from the sunlight to generate electron flow from the p-type Si (via an external resistance) to the n-type Si. A typical solar module comprises of 36 cells connected in series to produce an operating voltage of 12V.

PV systems often include a battery bank for energy storage, and a charge controller that regulates the power flow into and out of the battery bank. Battery banks are typically sized in order to provide energy during days of no or limited sunshine (cloudy/rainy days).

Solar Electricity

Sunlight can be converted into electricity using photovoltaics (PV), concentrating solar power (CSP), and various experimental tec hnolgies. PV has mainly been used to power small and medium-sized applications, from the calculator powered by a single solar cell to off-grid homes powered by a photovoltaic array. For large-scale generation, CSP plants like SEGS have been the norm but recently multi-megawatt PV plants are becoming common.

According to SESSA (Sustainable Energy Society of South Africa), it has been estimated that after reflection and absorption in the earth’s atmosphere, the total radiation reaching the land area of South Africa amounts to roughly 1 kilowatt per square meter at noon on a sunny day.

South Africa has great potential for solar energy, as we have a high rate for annual sun and one of the best climates for such technology. However, due to the cost and availability of solar technologies and appliances, few people are tapping into the industry, even though the initial cost is paid back over time.

Photovoltaics

A solar cell is a device that converts light into direct current using the photoelectric effect. It is made up of from a semiconductor material, usually silicon. The silicon is chemically treated so that the upper and lower layers are oppositely charged. Sunlight or photons strikes the surface of semiconductor materials, in this case the silicon, and energy penetrates the cell and dislodges electrons from the material’s atoms. Certain chemicals added to the materials composition create a path for the freed electrons and this is how the electric current is created.

Placed metallic contacts on the grid, at the bottom and top of the cell, enables the current to flow through to an external circuit and be “caught” or “captured” for commercial use. As the sun moves across the sky, it is generally advised that solar panels have the same movement, similar to how a sun-flower continuously faces the sun for maximum exposure.

SESSA’s states that if you are more then 5 kilometres away from the grid, solar panels becomes a cost-effective option. Accordingly one 50w panel produces approximately 250 Wh/day. The more panels you have in your system, the more electricity can be generated.

Due to the large amount of power that thermal applications such as stoves and geysers use, it is not recommended that photovoltaics solar panels are used to power such applications. However there are other alternative energy options that could be used to supply such devices with energy.