by Prof Mandla Msimanga
Contemporary research suggests a strong causal link between increasing levels of greenhouse gases in the atmosphere and extreme weather events around the globe. Greenhouse gases like carbon dioxide (CO2) and methane trap heat that is reflected off the Earth’s surface from the sun. Whilst the bulk of CO2 emissions are from natural sources like plant and animal respiration, and the oceans, man-made sources like the burning of fossil fuels like coal and oil now have an increasingly disruptive effect on the natural CO2 ecosystem. Changes in weather patterns, quite extreme at times – are a direct result of global warming. The fact that there is an urgent need to shift from traditional fossil fuel energy sources to cleaner sources of energy is clearly undeniable.
The conundrum that we face in Africa, when it comes to renewable energy, is the almost tangible disconnect between the amount of energy that we need to drive factories and heavy industry (which need is currently met by fossil fuels, coal in particular) and that which cleaner sources can reliably supply. It is an unfortunate reality that while we need to rid ourselves of fossil fuels, renewable energy alternatives are currently just not good enough.
What is the extent of emissions from fossil fuels by domestic users though? Some ball park calculations may help shed light on the severity of atmospheric pollution caused by coal in particular. I will base my argument on the energy requirements of a typical three bedroomed home in South African suburbia and use internet sources for my ‘numbers’ (and avoid physics calculations like heat of combustion, efficiency, etc). Extrapolations to bigger and smaller households should become apparent. Let us assume that on average, energy consumption in a three bedroomed home with five inhabitants is 1000 kWh per month (I base this assumption on estimations provided by a number of solar panel vendors’ estimations). A cursory google search suggests that the average amount of coal needed to give 1 kWh (or 1 unit of energy) is 7.0 kg. An average household thus burns about seven tonnes (one truckload) of coal to keep the lights on every month. This spews over twenty tonnes of CO2 into the atmosphere over the same period. For comparison, roughly 0.00002 kg, or a thousandth of a teaspoon, is needed in the case of nuclear fuel to produce the same amount of energy – with no direct CO2 emissions.
Prof Mandla Msimanga
If we consider photovoltaic energy, just how much of solar installations do we need to really have a meaningful reduction in fossil fuel emissions? Let us use the same 1000 kWh energy estimate that is required in a three bedroomed home per month for estimate figures. Commercial vendors of solar PV installations cite, on average power output of 400W per panel for residential panels. Total energy generation would be about 2 kWh per panel (assuming not less than 6 hrs of peak sunlight i.e. say 10 am to 4 pm). So, in one month one panel generates roughly 60 kWh. This means a single rooftop would need about 16 or so 400 W panels, to generate about 1000 kWh to be off-grid. In practice though, most of the domestic installations are hybrid - ooba Solar, a platform that provides consumers with solar installation quotes estimates that over 50 % of domestic installations are in the 3 kWp range (i.e. 8 panels).
Now the typical size of a 400W solar panel is about 2.2 m2, weighing roughly 20 kg. For a typical average home installation (500 kWh) this means a coverage of 18 m2 or 160 kg of material. According to the 2024 SA Housing Report by CAHF Citymark, there are about 1.4 million residential properties in Gauteng (flats and high rise buildings excluded). Reports from solar PV installation companies are that the residential adoption rate in 2023 was as high as 3.5% and growing. A conservative 3.0% annual installation rate in Gauteng means 42 000 homes get rooftop installations every year, which would translate to about 7 000 tonnes of new solar panel material installed every year. Vendors tell us the lifetime of a solar panel can be as much as 25 years. This may be true for top of the range premium panels – a more realistic estimate is 15 years.
If all of my heuristic assessment is anything to go by, starting around 2040 there will be upwards of 7 000 tonnes of solar waste every year that will need to be disposed of from home installations. For perspective this is roughly three 7-ton trucks of waste every day, from Gauteng alone. Looking at the South African solar PV industry as a whole, the amount of waste from solar panels can very easily be ten times what I have estimated here, if we factor in commercial and industrial installations, which are generally much bigger and more stringent in terms of performance requirements when compared to domestic installations. Granted, my arguments may be replete with averages and suppositions, but it would be folly of anyone to think that waste from solar PV installations will be anything less than a hundred thousand tonnes annually in the next fifteen to twenty years.
The solar waste recycling industry in South Arica is at the very least at its infancy if not non-existent. Existing recycling companies do not regard solar panel recycling as profitable business. In the United States, according to a recent Harvard Business Review magazine article, The Dark Side of Solar, recycling one panel costs an estimated $20–$30. Sending that same panel to a landfill would cost a mere $1–$2. Our landfills in South Africa are in dire straits – they are filling up fast. And no new ones are being built. There is thus an urgent need for role players within the energy and environmental health sectors to seriously consider how the pending tsunami of solar panel waste will be handled. If it means establishing a government subsidised PV recycling industry this has to be done on a massive scale, and soon. This conundrum should be a sobering thought to many who believe that solar energy is the one silver bullet to our energy crisis. While vouching for solar energy, I believe our approach to the energy problem should be measured, and other clean sources of energy like nuclear power deserve well informed consideration.
Further reading:
- https://hbr.org/2021/06/the-dark-side-of-solar-power
- https://www.energy.gov/eere/solar/end-life-management-solar-photovoltaics
- https://www.instituteforenergyresearch.org/renewable/solar/the-mounting-solar-panel-waste-problem/
- https://www.wired.com/story/solar-panels-are-starting-to-die-leaving-behind-toxic-trash/
- https://green-cape.co.za/assets/Solar-Panel-Waste-Workshop-Report-5Mar2020.pdf
Mandla Msimanga is an Applied Nuclear Physicist and Associate Professor of Physics at the Tshwane University of Technology and Senior Research Scientist at iThemba LABS. His current research focus is on application of nuclear techniques and methods in the study and development of new, environmentally friendly photovoltaic materials.