A variety of sources are available for energy collection in natural world. One of the available renewable energy resources is solar energy, which is by far the most abundant. More energy is provided to the Earth by sunlight radiation within one hour than is consumed yearly by the entire human civilisation across the world.
At present, sunlight is being harvested with solar panels. About 90% of solar panels are composed of crystalline silicon. The rest of the overall market is made up of thin-film technologies using cadmium telluride, CIGS (semiconductor material composed of copper, indium, gallium, and selenium) and amorphous silicon. Nano electronics create cheaper and more efficient solar cells which generate more solar energy, with the potential to enhance energy efficiency. They produce a relatively high-efficiency conversion for lower cost compared to traditional solar technologies.
Semiconductor materials that display a photovoltaic (PV) effect, i.e. converting light (“photo”) into electricity (“voltaic”), can be used to convert solar radiation into electricity. Developments in technology and increased manufacturing have reduced the cost, increased the reliability and the efficiency of photovoltaic installations. However, despite these improvements, photovoltaics still only accounts for 0.1% of electricity generation worldwide, a result of the incapacity of existing photovoltaic technologies to produce electricity with an efficiency that fulfils the grid parity set by conventional power-generation routes. Grid parity occurs when an alternative energy source can generate power at a levelised cost of electricity (LCOE) that is less than or equal to the price of purchasing power from the electricity grid. Resources, therefore, have to be channelled for the development of new-generation photovoltaic technologies that operate with improved efficiency at lower cost.
Solar power in South Africa includes photovoltaics with installed capacity expected to reach 8,400 Mega Watts (MW) by 2030. The government has signed power purchase agreements for over 1,450 MW from solar photovoltaic projects. A 50 MW concentrated photovoltaics power plant in Touwsrivier, Western Cape, supplies enough electricity to power 5,000 homes. A 75 MW photovoltaics power plant is situated in Kalkbult, in the Northern Cape. Two other photovoltaics power plant, one located at Linde in the Northern Cape and the other in Dreunberg in the Eastern Cape, together provide power for around 90,000 South African households. The Jasper Solar Energy Project is a 96 MW photovoltaic power station, located near Kimberley, Northern Cape and the project powers up to 80,000 homes. At present more than 590 MW produced from PV plants has been connected to the grid. Installations, in MWp (Mega Watt peak, a measuring unit for the maximum output of a photovoltaic power plant), have grown from 1 in 2011 to 439 in 2015, year on year, accumulating to 1,361. Production has grown to 2,373 GWh in 2015. GWh or Gigawatt hours is a unit of energy representing one billion (1 000 000 000) watt hours. A watt hour is a measure of electrical energy equivalent to a power consumption of one watt for one hour.
“As electricity costs keep rising, solar is becoming an even more viable and cost-effective option for businesses in South Africa. While there is an initial outlay cost, it can be recouped after five to eight years on average. That’s an attractive internal rate of return, especially considering solar electricity is then free after the initial payback period. So solar PV actually offers businesses an attractive savings model.” States Gareth Warner, Managing Director of Solarcentury Africa.
In a report titled ‘Solar PV in Africa: Costs and Markets’, by the International Renewable Energy Agency (IRENA), it was reported that on-grid commissioned and planned utility-scale solar PV projects between 2014 and 2018 in Africa range from around R15.75/W to R64.17/W (R15,750/kW to 64175/kW). Although Africa is currently home to a very small set of utility-scale solar PV projects, costs have been declining over time. The cost range was between R44.50/W and R90.40/W in 2012, declining to R31.45/W to R72.00/W in 2013 and to R26.20/W to R64.20/W in 2014. For 2015 to 2016, the cost range is between R17.00/W and R53.50/W. South Africa, with its strong civil engineering sector and large renewable independent power producer (IPP) programme (which provides investor certainty), has the lowest installed cost for an operating solar PV plant (around R18.35/W for the best project) on the continent.
According to an analysis by the CSIR Energy Centre, renewable energy is cheaper than non-renewable energy. A unit of electricity from Eskom’s coal plants cost about R0,80/kWh, from nuclear R1,00/kWh, while a unit of electricity from solar photovoltaic cost R0,80/kWh and from wind only R0,60/kWh. In addition, there are no input costs for wind and solar energy.
Photovoltaic systems range from small rooftop-mounted or building-integrated systems with capacities from a few to several tens of kilowatts, to large utility-scale power stations of hundreds of megawatts. On 22 December 2016, France instated the world’s first “solar highway”, a road paved with photovoltaic solar panels providing enough energy to power the street lights of Tourouvre. The one kilometre route is covered with 2,800 sqm of electricity-generating panels. The electricity generated should be able to power the street lighting in the village of 3,400 inhabitants. The project cost R68 million. One drawback of the system is that solar panels are more effective when angled towards the sun, typically on slanted rooftops, than when they are laid flat. And the cost question is far from being resolved. Each kilowatt-peak generated by the road currently costs R234, compared with R17.80 for a major rooftop installation.
This new use of solar energy takes advantage of large tracks of road infrastructure already in use to produce electricity without taking up new land. The idea could be beneficial in South Africa if local authorities manage to circumvent the ravages of traffic, weather and thieves. Roadways are utilised by vehicles only around twenty percent of the time providing vast stretches to soak up the Sun’s rays. Photovoltaic pavements and contactless electromagnetic induction circuits built into the road which power suitably adapted vehicles could become a common feature on South African roads (urban and rural) in the future.