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Picture: 123RF/PETKOV
Picture: 123RF/PETKOV

SA society urgently needs to be educated on a fundamental misunderstanding of solar energy, or the government, companies and other investors will keep pouring their money down the drain while load-shedding lurks in the shadows every night.

The National Energy Regulator of SA (Nersa) understands the problem and has even raised the alarm, but it appears the penny just hasn’t dropped.

At the time of writing, the country is on a weeks-long stretch of no load-shedding. Everyone is relieved because the lights turn on when we need them and the economy can sigh with relief. However, a cursory glance at energy availability compared with demand shows that while there is adequate supply during the day, expensive open-cycle gas turbines are running from 6pm to  9pm in the form of “emergency reserves”. 

There may be respite from load-shedding, but the country’s energy supply is far from secure. There appears to be little appreciation that solar will do little to nothing to address energy security in SA without a concomitant investment in battery energy storage systems (Bess). Without a fundamental shift of mindset, the status quo will remain, no matter the size of the solar investment. 

To understand the problem, let’s look at Nersa’s warning. There was a R7.8bn investment in solar power generation facilities, including three commercial solar generation facilities at a value of R1.7bn, in the last quarter of 2023. Yet the regulator says only 1MW, or R4m, was invested in batteries.

When the sun shines, solar panels are wonderful tools, able to convert solar energy into electricity. But this is possible for only half a day at best, and most probably for about six hours (assuming the sun shines), because the rest of the daylight hours will be winding up and down.

The reality is that solar panels are little more than roof tiles at night or when the sun isn’t shining because if there are no batteries, none of the electricity being produced is saved. This is not a problem as long as the grid needs the power, but what happens when it doesn’t? This is where the fundamental misconception needs to be addressed so that investors and the government take Bess seriously.

Nersa said that in the last three months of 2023 it registered three commercial solar generation facilities with a combined capacity of 77MW. Imagine one of them is a 50MW facility. A 50MW solar plant doesn’t simply plough 50MW into the grid when the sun is shining. It produces what is demanded of it, and if the grid is not under pressure — as at present — and demands only 1MW, the solar installation will produce just 1MW. The remaining potential power becomes hypothetical. 

However, if you had a bank of batteries and an inverter configured for a 50MW facility, the situation would be radically different. If the grid demands 25MW, that power would be fed into the grid and the other 25MW would be pumped into the batteries for storage, instead of being wasted.

Then, during the peak times of 6am-9am and 6pm-9pm the stored energy sitting in the batteries could be called on to satisfy the shortfall in Eskom’s generation capacity. The saved power could also be used during the night, rather than SA depending on diesel generators.

Big picture

This is not happening. Instead, everyone and their uncle is talking about developing solar farms, but no-one seems to be thinking about the bigger picture, which is the need to store that energy. The problem can be viewed as the solar panel providers being the tail that is wagging the dog, whereas it is the battery and inverter industries that should be doing the wagging as they hold the key to solving the actual problem.

The engineering behind batteries and inverters in Bess is where the real value lies, and it is a tragedy that too few people realise this. All those billions of rand spent on projects without batteries represents an inordinate waste of money. The country could have spent a third of the solar investment to date for the same impact had it added Bess to these solar projects.

If you install solar panels and are not adding batteries, you are wasting eye-watering amounts of money and energy. Every day. While this happens, daytime capacity may well be addressed, but at peak times we will have to keep relying rely on Eskom’s current coal-fired power plants — until they break down. 

• Dickerson is cofounder and MD of energy storage company Revov. 

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