From lightbulbs to load shedding, why it pays to own your power
By Joshua Mark Holdt, Sector Head: Renewable Energy at Merchant West
On 22 October 1879, in Menlo Park, New Jersey, Thomas Edison placed a carbonised cotton thread inside a hand-blown glass bulb, between two platinum wires, and connected it to a dynamo.
After thousands of failed attempts, the filament glowed for more than 13 hours, a breakthrough that led to the world’s first commercially practical incandescent lightbulb.
The decades that followed filled homes with appliances built on Edison’s work.
The electric stove, kettle and geyser arrived in the 1920s, followed by the refrigerator and washing machine in the 1930s, when a typical household used an estimated 54 kWh of electricity a month.
Fast-forward to 2007, when South Africans learnt about loadshedding and the realities of life without electricity.
Loadshedding peaked in 2023, with 6,907 hours of outages compared with 3,776 in 2022.
The country climbed as high as stage 6, leaving some areas without power for up to 12 hours a day, and trust in Eskom fell with every stage.
South Africans didn’t sit in the dark for long. They queued for candles, then LEDs, gas and generators, and those who could afford it installed solar.
Imports of solar panels, lithium batteries and inverters reached a record R70 billion in 2023, while rooftop solar capacity rose by 349%, from 983MW in March 2022 to 4,412MW in June 2023.
The picture has since changed. South Africa has now gone more than 500 consecutive days without load shedding, a recovery few would have predicted during the dark days of 2023.
Keeping the lights on has come at a price, though.
Since 2007, Eskom’s tariffs have risen by roughly 937% while consumer prices rose about 155%, which makes electricity around four times more expensive in real terms.
Joburg households now pay between R3.34 and R4.37 per kWh.
That shifts the case for solar. In 2023, South Africans installed it to keep the lights on. In 2026, they install it to keep their bills down.
Those bills matter more than ever, since a modern home uses roughly 17 times more electricity than a 1930s one.
There are three main ways to power it today, namely the grid, a diesel generator or the sun, and the table below shows how they compare for a typical three-bedroom home in Johannesburg.
| Grid (city power) | Diesel generator | Hybrid system Panels, inverter + battery |
|
|---|---|---|---|
| Monthly usage | 900 kWh | 900 kWh | 900 kWh |
| Equipment | Meter + grid connection | 10–12 kVA standby diesel | 15 × 550W panels, 8 kW inverter, 10–15 kWh battery |
| Upfront cost | – | ~R60k–R100k | R120k–R180k installed |
| Fuel | Mostly coal (Eskom) | ~360 L diesel/month | Sunlight (free) |
| Monthly cost | ~R3,730 | ~R10,900 (fuel only) | R0 running cost |
| Cost per kWh | ~R4.15 effective | ~R12.15 (fuel only) | ~R1.39 over 10 yrs; under R1 over 20 yrs |
| Calculation | – | 900 kWh × 0.4 L/kWh = 360 L; 360 L × R30.37/L = R10,933; R10,933 ÷ 900 kWh = R12.15/kWh | 900 kWh × 12 months × 10 yrs = 108,000 kWh; R150,000 (midpoint) ÷ 108,000 kWh = R1.39/kWh |
Per unit, diesel costs roughly three times as much as the grid, while solar costs about a third of it, making the sun the cheapest source of power for a modern South African home.
The grid and diesel charge you every month for as long as you use them, whereas solar is paid for once and its fuel is free from then on.
The stakes grow with scale. A farm running irrigation pumps and cold rooms, a manufacturer running machinery or a large corporate office can use tens of thousands of kWh a month, the equivalent of dozens or even hundreds of homes.
At that level, the gap between diesel at about R12 per kWh, the grid at about R4 and solar at under R1.50 runs to hundreds of thousands of rand a year, enough to make energy one of the biggest controllable costs on the balance sheet.
This is where the conversation about financing solar needs to change. Solar finance is too often seen as debt, one more monthly repayment added to the budget, which overlooks what is being bought.
A diesel generator costs money every time it runs, since its fuel must be bought again and again. A solar system draws on fuel that costs nothing and generates power every day the sun rises.
Financing one replaces an expense you already carry, with the monthly repayment taking the place of the electricity bill, and once the term ends the energy keeps flowing at no fuel cost.
Merchants by name, explorers at heart, we see a solar system for what it is, energy you own and draw on for decades.
It pays its way every day the sun rises, shields your business from the next tariff hike and keeps generating long after the final repayment has been made.
South Africa’s energy story has come full circle. A century ago, the lightbulb brought families out of the dark and tied them to the grid.
Load shedding taught a nation that the grid couldn’t always be relied on, and rising tariffs have shown that even when it works, it comes at a growing cost.
The answer now shines down on every rooftop in the country, and the next chapter belongs to those who own their power.
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