Making choices for the future: UFH research informs thinking about the feasibility of rooftop solar systems

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Images from the hailstorm event in Alice on September 30, 2022: (a) dimension of some hailstones, (b) damaged property and (c) impact of hailstones on solar PV modules

Concern for the environment along with rising costs and loadshedding has resulted in an increased number of people and businesses turning to solar power for their energy needs. 
While there are many benefits to having photovoltaic (PV) panels installed on rooftops, systems can be damaged by extreme weather events such as hailstorms.
An experimental analysis conducted by a University of Fort Hare research team consisting of Dr Oyeniy Alimi, Professor Edson Meyer, doctoral candidate Olufemi I. Olayiwola and Professor Ochuko Overen showed that every 1°C increase in the summer mean temperature would result in a 40% increase in the the severity of hailstorms, which occur when a thunderstoom updraught lifts water droplets above the freezing level in the atmosphere.
In South Africa, the mean annual temperature has increased atleast 1.5 times the observed global average increase of 0.65°C during the last 50 years as a result of global warming. All this gives rise to questions about the feasibility of solar-powered PV systems if the likelihood of costly damage increases.
The Misgund area in the Langkloof Valley as well as the southern slopes of the Winterberg Mountains in the Eastern Cape (north of Somerset East to north of Fort Beaufort) are popular hailstorm ‘hotspots’ in South Africa. 
In the last four months, a record number of five hailstorms has occurred in the Raymond Mhlaba Municipality (RMM) and at least two have caused major damage to infrastructure.
A hailstorm that occurred on September 30, 2022 was categorised as H3 on the Tornado and Storm Research Organisation (TORRO) scale as it caused considerable damage to exposed infrastructure including rooftop solar PV modules.
The TORRO scale ranges from H0 to H10, where H0 corresponds to ‘no damage’ and H10 corresponds to ‘catastrophic damage’.
Concerns about the adverse effect of extreme weather events on solar PV systems led the UFH research team to investigate their impact on the feasibility of the systems themselves in a study that involved monitoring the systems installed at SolarWatt Park on the Alice Campus.
Monitoring of the 6 year old polycrystalline modules installed on the rooftops at SolarWatt Park after the first hailstorm in December 2021 revealed a drop in obtainable power output of about 13%.
After the second severe storm on September 30, 2022, the output further dipped by another 17% for a moderately damaged module and 62% for a module with major cracks (Figure 2). The system at SolarWatt Park was initially designed to generate a minimum of 7.875 kWh per annum.
However, in its current state, it can only generate about 2.520 kWh per annum since more than half of the modules have been badly damaged. One of the reasons for installing solar PV systems is to save on energy costs, with consumers often calculating the time it will take for savings in the cost of buying electricity to cover the cost of installation. The period taken to cover the cost of the system as a result of savings is referred to as the ‘payback time’. 
The cost of replacing PV modules significantly damaged by these hailstorms has been calculated as R 53,500. All this means that consideration needs to be given to whether or not solar PV systems will be sustainable or financially viable if adverse weather events increase as a result of climate change.
Given annual solar radiation levels, Alice has the potential for significant solar PV power generation, with the result that a strong argument can be made for a campus that is completely solar powered on the basis of cost savings. 
However, climate change may mean that this argument has to be revisited as an increase in severe weather events results in damage that reduces generation power. This then leaves arguments about the value of solar PV systems in contributing to sustainability. 
Regardless of the focus of future discussions, the University will be able to count on its own researchers at the Fort Hare Institute of Technology and associated departments to provide sound research-based advice, as the
study reported above shows.