# The Role of Renewable Energy Sources and Industry 4.0 Focus for Africa: A Review
## 3 Renewable Energy
### Solar Energy
To maintain outputs closer to the summer solstice, three solutions have been presented:  
* Fixed frame installation facing 23\({}^{\circ}\) north
* Single axis tracking from east to west daily
* Dual-axis tracking, which tracks east to west and north to south, based on data provided previously  
Each of these solutions has its drawbacks, and decisions regarding which solution will be used usually come down to cost and ROI (return on investment)  
Another issue facing solar PV installations is that of overcast weather. The plant's output is significantly decreased if the plant experiences cloud coverage (even if only partial). Concentrated solar PV plants provide more energy output by using magnification to intensify the irradiance of a single solar PV cell. This technology, primarily due to the cost of exaggeration and the cost of increased spatial requirements, has fallen out of favor worldwide. Concentrated solar power, while being relatively costly compared to solar PV, is the technology most capable of consistently providing power and avoiding the pickup and drop-off in energy experienced by solar PV. This is entirely due to the operating mechanism behind concentrated solar power. Concentrated solar power installations are primarily like the standard layout of a coal-fired power station. The exception is that the coal-fired boiler is replaced with a heat exchanger that operates on heat energy stored in molten salt. The heat in the molten salt comes from a secondary heat exchanger phase,  
Figure 6: Sun altitude vs. azimuth in South Africa over a given year [70], Reproduced with permission from [PERSON], Optimum tilt and azimuth angles for fixed solar collectors in South Africa using measured data; published by Elsevier, 2016.  
wherein a heat transfer fluid (usually non-flammable oil) is heated directly by the sun using either a central tower collector or tubes in parabolic trough mirrors. In the case of the central tower, the facility is surrounded by concave mirrors connected to motors, allowing motion in three dimensions to track the sun's position, called a heliostat field. This heliostat field uses incident sunlight reflection to a collector at the top of the central tower. Heat transfer occurs in the fluid, pumped to the heat exchanger with the molten salt solution. The molten salt solution can then be stored and used to operate the power station at any given time and rate, with plants generally built with a specific amount of working time in mind, which affects the salt storage capacity and the heliostat field size. Parabolic trough installations work similarly, except that, instead of having a central collector tower, the heat transfer fluid is pumped through piping systems at the focal point of the parabolic trough mirror. The critical drawback of concentrated solar power is the plant's overall energy density. A significant field of mirrors, often on hectare footprint orders, must produce between 100 MW and 300 MW, which can be achieved and exceeded by non-renewable energy power plants across a much smaller footprint. Another drawback is that concentrated solar power installations must be in hot places with minimal rainfall to ensure the Thermal Energy Storage (TES) remains at adequate levels. Without consideration of other technologies for energy storage, concentrated solar power is the most capable of solar technologies to provide something close to baseload energy or the energy currently supplied by non-renewable technology. The continent of Africa has the potential to harness and benefit greatly from solar energy. The energy is clean, available to all, and capable of generating more than needed. However, there are a few impediments to the full implementation of the technology [70]. The initial cost of solar energy is not affordable to the average African populace. This is further compounded by the cost associated with importing solar equipment, as there is a limited manufacturing outlet in Africa.