Researchers at the European Commission’s Joint Research Center have assessed the potential of installing floating solar plants on 146 hydropower reservoirs in Africa. They concluded that, in addition to increasing installed capacity, the plants also reduce water evaporation, allowing for increased annual hydropower production.

Africa has the lowest electricity access percentage (54 percent) in the globe, with Sub-Saharan Africa having a substantially lower rate (47.7% compared to 96.5 percent in North Africa). This data demonstrates the urgent need for additional power infrastructure deployment in Africa to compensate for the lack of electricity availability.

In Africa, particularly in eastern and southern Africa, hydropower is a significant source of electricity. Hydropower, for example, generates 90% of the electricity in Ethiopia, Malawi, Mozambique, Namibia, and Zambia. Africa also has the most untapped technical hydropower potential of any continent.

In 2019, about 1 GW of new hydropower capacity became operational in Africa, bringing the total installed capacity to 37 GW and energy output to 138 TWh. More than 50 hydropower projects are now under development, with a total capacity of 15 GW planned by 2025. Over the decade 2020-2025, the compound annual growth rate is expected to double, reaching 9.7%. Water shortage, on the other hand, is a problem in many parts of the continent, and in recent years, Africa has had lengthy and severe droughts, which have had substantial consequences for hydroelectric output.

In light of Africa’s growing energy requirements and abundant solar resources, this research examines the viability of developing Floating PV systems to create an effective energy symbiosis between solar photovoltaics (PV) and hydropower (FPV). FPV systems are a great alternative for African hydropower reservoirs since they can quickly ramp up installed power capacity thanks to existing infrastructure and local knowledge. Furthermore, FPV might at least partially compensate for the fall in hydropower generation during dry months and decrease evaporation water loss.

FPV systems have evolved as a new way to generate power that avoids the difficulties and constraints associated with land usage. In the recent decade, hybrid systems combining hydropower and land-based PV systems have received a lot of attention. One of the key benefits of these systems is the simple connection to the grid that hydropower plants provide.

Cost considerations of FPV systems

FPV applications have greater prices than ground-mounted applications of equal size and position, but they are less expensive than rooftop PV. Increased deployment rates (industrial learning and economies of scale) are projected to benefit FPV costs, as with any new technological application. FPV systems accounted for about 1% of total worldwide solar PV consumption in 2019, with projected predictions suggesting a 22% annual growth rate through 2024.

The current research examines the possibility of FPV in Africa’s 146 major hydropower reservoirs. According to the study’s key findings, the overall FPV resource potential in terms of power capacity (100 percent coverage) is expected to be 2922 GWp, which is more than 250 times the cumulative installed PV capacity at the end of 2020. This must be weighed against Africa’s 28 GW of pre-installed hydropower. The total electricity created by fully using the FPV technological potential (covering all 146 hydropower reservoirs) is 5293 TWh/year, which is 50 times greater than the existing hydroelectricity produced in these reservoirs.

Findings from the Research Experiment

The results show that a total of 46 TWh/year may be obtained with FPV covering an area of less than 1%, in which the envisioned capacities of FPV equal the current hydropower capacities (108 reservoirs evaluated). When compared to present hydropower generating, this equates to a 58 percent increase in electricity output. Northern Africa and South Africa, in particular, benefit from the installation of FPV, which may equalise or even double the electricity produced by hydropower in some circumstances, even with minimal FPV coverages of 1% to 5%.

This is owing to these countries’ low hydropower production (capacity factors) in comparison to other African countries, along with their high sun irradiation. The advantages of FPV installation in other African locations with larger hydropower capacity factors are similarly considerable, increasing energy generation by over 50% with average coverage of 4%. Two floater types were evaluated in the research in terms of evaporation savings and possible extra hydroelectricity generation created by these water savings: fully covered floaters (floater Type I) and suspended systems (floater Type II).

Due to the minimal evaporation happening on the surface covered by FPV, the water savings for the floater type I in the EQIC instance are maximised, resulting in 743 mcm of water saved and a possible extra hydroelectricity generation of 170 GWh. Scientific studies of the evaporation mechanisms that occur with FPV are currently ongoing.

A more extensive and region-specific research of the evaporation processes, including evaporation models that take into account the local climate and reservoir features, might enhance the findings in this study even further. The African continent has a high sun irradiation, with average sun irradiation of above 2000 kWh/m2 in all reservoirs studied. Despite many African nations’ strong reliance on hydropower, the continent has the world’s largest unmet technical hydropower potential, with just 11% built. While many governments continue to make significant efforts to assist the development of hydropower on the continent, integrating FPV into existing hydropower reservoirs would give multiple benefits and advantages.

FPV can help supplement hydropower generation during Africa’s more regular dry spells, while hydropower offers a more reliable and flexible operation than intermittent PV. Furthermore, the existing grid connection in hydropower reservoirs is one of the most significant benefits that greatly aids the installation of FPV. In terms of cost, the falling prices of PV panels, as contrasted to the rising prices of hydropower developments, provide a significant incentive for FPV installation. FPV can help ease water shortage in Africa by minimising evaporation loss, a key problem that affects many parts of the continent and has a severe influence on hydropower output.

Installation of PV on the face of existing dams, which may be used in conjunction with FPV to boost clean electricity output, is another possibility for the hydropower and solar energy symbiosis. An earlier study by the authors, which focused on South Africa, found that choosing optimal positions for PV systems on dam faces can be highly beneficial and cost-effective. Floating PV is a new, fast-growing technology that has a number of issues that must be addressed and researched further. Unknown environmental difficulties (e.g., algae development, influence on local fish food chains, ecosystem response to temperature fluctuations, etc.) and technological concerns (e.g., bird fouling, electrical insulation, corrosion, mechanical wear, and anchoring)

The diversification of Africa’s energy portfolio is possible thanks to its strong solar potential, and the use of FPV in existing hydropower reservoirs can decrease risk and enhance the supply of dependable power supplies. This improves Africa’s climate resilience and capacity to adapt to major occurrences without having to take drastic actions or restructure current infrastructure.

Read the conclusions of the study Assessment of floating solar photovoltaics potential in existing hydropower reservoirs in Africa written by experts from the Joint Research Center of the Commission European and published in January 2021 in Renewable Energy.