Frequently Asked Questions

In this section we try to answer your questions about solar energy and what you need to consider when converting to solar at your home or office.



“Photovoltaic solar electricity generation” and “solar thermal heating” involve two fundamentally different technologies, but both rely on the conversion of energy carried by solar radiation (sun light).
On a sunny day, sun light delivers a powerful stream of energy to the tune of 1 kW per square meter.
  • “Photovoltaic solar electricity generation” involves the one step conversion of radiation energy to electrical energy. The technology required is based on the physical properties of semi-conductor materials like silicon and others.
    The conversion efficiency is approximately 17%, i.e. the amount of energy that can be “harvested” from the sun’s radiation is only about 17% of the energy carried by the radiation.
  • “Solar thermal heating” on the other hand involves a one step conversion from radiation energy to thermal heat. The technologies vary from large scale thermal power plants to household sized Solar Water Heaters and Solar Stoves where radiation is collected and absorbed resulting in the generation of heat.
    The conversion efficiency here lies much higher at 70%. Hence it follows that it is extremely inefficient to heat with solar generated electricity.


The term “photovoltaic” comes from the Greek phos meaning “light”, and the name of the Italian physicist Volta, after whom the volt (and consequently voltage) are named. It means literally of light and electricity.
Photovoltaics describes both the technology of solar cells, and also the field, discipline, and approach of creating electricity that is made possible by solar cells.
SOURCE: (en.wikipedia.org/)


The “photovoltaic effect” is the basic physical process through which a solar cell converts sunlight into electricity.
SOURCE: (encyclobeamia.solarbotics.net)

  • A PV (Solar) Module is made up of an array of photovoltaic (solar) cells, embedded between a multi-layer back sheet and a special high transparency glass. The PV cells form the basis of the technology that allows the conversion of radiation energy to electrical energy.
  • A solar thermal collector of a Solar Water Heater in its simplest form can be a black plastic pipe filled with water and exposed to the sun. Today sophisticated collectors however, consist of an efficient multiflow absorber containing the liquid. They are covered by special glass with a minimum radiation transmittance of 94% and are well insulated.

Open circuit: Potable water is heated by the sun in the collector and is then stored within the tank. The water continuously circulates through the collector and the tank due to the thermosiphon principle. www.emcongroup.com

SOURCE: Code of Practice and Register of Products
for Namibian Solar Energy Technologies




closed circuitClosed Circuit: The potable water is stored in the tank which is surrounded by a jacket that is connected to the collector(s). An anti-freeze liquid is heated by the sun, and again continuous circulation through the jacket and the collector is “powered” by the thermosiphon principle. The heat is transferred from the hot liquid in the jacket to the potable water in the tank.

SOURCE: Code of Practice and Register of
Products for Namibian Solar Energy Technologies


Leave a Reply

Your email address will not be published. Required fields are marked *