When I was first engaged in a renewable projects investments, I learnt that there are types of solar energy technology namely; photovoltaics and solar thermal. Solar PV is the rooftop solar you see on homes and businesses and it produces electricity from solar energy directly. Solar thermal technologies use the sun’s energy to generate heat, and electricity is generated from that.Solar photovoltaic is an elegant technology which produces electricity from sunlight without moving parts. In a photovoltaic cell, sunlight detaches electrons from their host silicon atoms. Tiny packets of light energy called photons are captured by electrons, and impart enough energy to kick the electron free of its host atom. Finland’s solar energy company LEDin CEO Jussi Palve, a good friend of mine told me that near the upper surface of the cell is a one way membrane called a pn-junction and the pn-junction is formed by diffusing tiny quantities of phosphorus to a depth of about one micrometre into a thin wafer of silicon. He explained that when a free electron crosses the pn-junction it cannot easily return, causing a negative voltage to appear on the surface facing the sun and a positive voltage on the rear surface. The front and rear surfaces can be connected together via an external circuit in order to extract current, voltage and power from the solar cell. Solar cells are packaged behind glass to form photovoltaic modules, which have typical service lives of 25 to 35 years.
Soren Andersen, a danish friend and renewable expert with more than 20 years of experience told me few years ago that in many circumstances, photovoltaic modules mounted on building roofs can produce as much electricity as the building consumes. A typical module will generate about 200kilowatt hours per square meter per year, so a collector area of 25-50m2 is needed to power a reasonably energy-efficient house. Such a house exports more electricity to the grid during the day than it imports at night. An additional 10m2 is required to offset the annual greenhouse gas emissions of a fuel efficient car emitting 0.2kg of carbon dioxide per km and driving 10,000km per year.The African solar market is dominated by photovoltaics, and most of the Photovoltaic market is serviced by crystalline silicon solar cells. Up until now Photovoltaic has found widespread use in niche markets such as consumer electronics, remote area power supplies and satellites.In recent years there have been dramatic falls in the cost of solar Photovoltaic and the industry has expanded immensely. Panel prices are now below $900 per kilowatt and system prices are $1000-2300 per kilowatt. Solar Photovoltaic electricity is now less expensive than both domestic and commercial retail electricity from the grid. It is approaching cost-competitiveness with wholesale conventional electricity in many places.The cost of photovoltaic systems can be confidently expected to continue to decline. Current Africa Photovoltaic module sales are 25-30 gigawatts per year which is approximately equal to the power capacity of the African electricity system. In 2015 about one gigawatt was installed in Africa, and nearly half a million African houses have photovoltaic systems on their roofs.
Demand is expected to grow in 2016 following the extension of subsidies for purchasing panels and will keep a long-term growth trend from 2017 because the cost of solar electricity is well below the retail commercial and domestic tariff everywhere in Africa. The future of Africa’s solar Photovoltaic industry is driven by the fundamental equation that Photovoltaic is little constrained by environmental considerations, material supply, land requirements, security considerations and indeed anything other than price and price is now competitive nearly everywhere with other alternative source of energies like Olkaria geo thermal power production in Kenya which has the country cost of energy come down by 20% over the last one year.Grid parity for photovoltaics at a retail level has already been achieved in South Africa for most of the Africa’s businesses and population. In South African cities, rooftop solar systems typically produce electricity at a cost of half to two thirds of what domestic and commercial retail electricity usually sells for. This is leading to rapid growth in sales in the residential and commercial sectors without the need for subsidies.Some people are concerned that more use of variable renewables like solar and wind power will make it hard for the grid to cope – they provide power intermittently but South Africa’s demand is more constant. This is because many options are available for managing fluctuations in the amount of energy provided by wind and photovoltaics, including shifting demand from night to day, the opposite of what is done at present, using a range of renewable energy technologies and mass storage including pumped hydroelectric storage which is by far the leading energy storage technology in Africa.