A common misconception is that panels do not generate electricity when it is cloudy
BY Tullah Stephen
Solar photovoltaic (PV) technologies and solar panels have been around for years and over the past decade, use of solar energy has been growing throughout Africa.
And it is not hard to see why. According to the International Energy Agency, about 585 million people in sub-Saharan Africa have no access to electricity. The World Bank estimates that only 23 per cent in Kenya, 10.8 per cent in Rwanda and 14.8 per cent of the population in Tanzania have access to electricity supply.
While so many people live without electricity, the amount being consumed has been growing at around 6 per cent every year, increasing demand for new energy sources and infrastructure investments to deliver it. But such funding has not been sufficient to keep up with demand.
Solar radiation can be converted into electricity via solar thermal and solar PV technology. Of these two methods, it is the production of electricity using solar PV panels that has been gaining grounds in Africa.
But the use of solar panels to generate electricity is also clouded by misconceptions. For instance when Solarcentury East Africa, an international solar company with a local office in Nairobi, announced plans to construct one of the largest solar projects in the region in Changoi, in Kericho County, sceptics questioned whether this technology is well suited to Kenya.
A common misconception is that solar panels do not generate electricity when it is cloudy and some people have associated solar power with heat from the sun. However, solar panels need daylight to generate electricity, not sunlight, and high temperatures slightly inhibit panel efficiency. At higher temperatures, efficiency decreases.
The solar park in Kericho is a perfect example. It is located in the highlands west of the Rift Valley, an area that enjoys a warm, temperate climate with plentiful sunshine hours, which makes it an ideal location for agriculture and in particular, tea growing, and also, generating solar energy.
Research reveals that solar panels are actually more efficient at cooler temperatures. Some of the coldest geographic locations on earth have the best solar power generation potential. Germany, which receives less sun than most parts of sub-Saharan Africa, is today the world leader in solar power, generating about five times as much as the United States.
Although cloudy conditions reduce the irradiance reaching the solar panels and therefore the output falls, there will still be some output from the solar panels as they generate power in ambient light and even on smoggy or overcast days.
To generate solar electricity, panels convert ultra-violet (UV) light into direct current (DC). The DC is converted to alternating current (AC) which is the power supplied by utility companies to our homes.
While people may think areas like Mombasa or Dar es Salaam that have a tropical climate and are generally hot would be the best places for solar panels to function, this is not quite true. Heat from solar radiation (sunlight) can degrade solar panels more than any other environmental factor. Since solar cells do not generally exhibit any measurable degradation without much heat, it is understandable why panels have a longer life span in slightly cooler climates. This is not to say that solar panels will not produce electricity in places like Mombasa and Dar es Salaam. Indeed there are great opportunities to power businesses in these cities.
Despite these misconceptions, many people now realise the incredible opportunity for solar around the world. It is flexible and highly scalable, which means it can generate electricity at a variety of scales, from the smallest calculators, mobile phone chargers and solar lights, to multi-megawatt utility scale systems in deserts and remote areas.
Solar is now becoming a mature, tried and tested technology, with projects at some scale in virtually every country around the world. Such is solar’s potential, that a US-based organization, the International Energy Agency, has predicted that solar energy could surpass electricity use by 2050.