Power ships vs home solar installations — the best value for R218 billion

MyBroadband compared the price and effect of installing hybrid solar systems in South African homes instead of spending the money on the Karpowership deal, and solar is a viable alternative.

While solar power has limitations, the fact that South Africans would own the infrastructure rather than leasing it is a significant advantage.

Solar alternatives bought for the same price as the Karpowership deal, currently believed to be worth R218 billion, can also potentially mitigate much higher stages of load-shedding.

To attempt to compare these two very different proposals meaningfully, we must make some assumptions for our calculations. They were:

  • The average person in South Africa uses 70MWh over 20 years, 30MWh during the daytime and 40MWh at night. This is based on total power consumption per capita of 3,487kWh/year.
  • Karpowership would cost R218 billion and output 1,220MW constantly for 20 years.
  • “Daytime” is 6 hours per day. While South African days can be much longer, this accounts for poorer output in the mornings and evenings, and inclement weather.
  • Solar generates 4.75kWh per kW of panels installed during the daytime.
  • Solar power would be stored in batteries first for nighttime use, and the excess will be used during the day.
  • Supply for solar and battery components would be available at current consumer pricing regardless of the total demand.

These assumptions may not be perfect or account for all situations, but they allow us to estimate and compare power availability between different scenarios.

We considered three different scenarios for a national home solar installation project:

  1. Typical home solar install with 8kW hybrid inverter, 10kWh battery capacity, and 4kWp panels at a cost of R300,000, which includes a battery replacement after ten years.
  2. Solar installation with double the panels. 8kW hybrid inverter, 10kWh battery capacity, and 8kWp panels at a cost of R330,000, which includes a battery replacement after ten years.
  3. Solar installation without batteries. 8kW hybrid inverter, 8kWp panels at a cost of R120,000.

Solar prices vary, and bulk installations could be done significantly cheaper, but we used a conservative estimate based on current market pricing for this comparison.

Based on these assumptions, the Karpowership deal should generate 213,744 GWh of electricity over the 20-year timeline.

This should consistently provide power to 1.8 million people during peak daytime hours, and 4 million people at night, which is 3% and 6.7% of the population of South Africa.

It would also reduce a little more than a single stage of load-shedding for the whole of South Africa, for 24 hours per day.

The first solar alternative would provide around 1.6 million people power during the day and 1.3 million at night.
This is clearly not the best alternative but has the advantage of not relying on transmission infrastructure to get the power to homes.

Homes would essentially be off-grid and be able to supply excess power to their neighbours.

This reduces the chances of being without power due to cable theft or lack of maintenance.

Adding more solar panels to each system is an easy way to increase power availability during the daytime without significant cost increases.

The second scenario would be able to provide power for over 4.5 million people during the day but only about 1.2 million overnight.

At peak power, it could cover around five stages of load-shedding for all of South Africa, but it would only do this for about four and a half hours per day.

The third option is to install solar systems without any storage capacity.

This would bring costs down significantly and provide power for 16.8 million people during the day, but it would not help the grid at all during the night.

During the day, it could cover 14 stages of load-shedding for four and a half hours or around 11 stages for all 6 hours of daylight.

Ideally, a system like this would be paired with industrial-scale energy storage solutions on the grid, which may be much less expensive per kWh than consumer-level lithium batteries.

Over 20 years, solar systems with excess panels could generate more power than Karpowership. However, they are limited by the times of day power would be available.

While having power at night feels like more of a necessity for most consumers, having electricity during the day would go a long way to keep businesses and factories running, which is critical for the economy.

The solar solutions also benefit from being cleaner energy compared to the Karpowership, and the infrastructure would remain even after 20 years.

While we allowed for a battery replacement after ten years, many consumer-grade batteries come with a 10-year warranty to still have around 80% of their original capacity left.

These batteries can still be used after this period to increase the storage capacity of the grid further.

Concentrating these solar installations in specific neighbourhoods could allow them to become their own microgrid, which would run independently from the current transmission network and act as a power station for surrounding areas when excess power is available.

The solar alternatives have potential drawbacks, such as longer installation times and possible supply shortages of components.

Disposal of solar panels and batteries after their usable lifetime also poses challenges.

Equal distribution of the power generated by the solar installations will also be tricky, as the neighbourhoods that get solar will benefit a lot more than those without.

However, in terms of value for money, the solar options are probably a much better way to spend R218 billion over 20 years than emergency power ships.

Karpowership vs Home solar installations
Karpowership Solar with Battery Solar with Battery (More Panels) Solar Only
Installations for R218 Billion 1 726,667 660,606 1,816,667
Peak Capacity day 1,220 MW 5,813 MW 5,285 MW 14,533 MW
Peak Capacity night 1,220 MW 5,813 MW 5,285 MW 0
Total Power Generation over 20 years 213,744 GWh 100,789 GWh 183,252 GWh 503,943 GWh
Million people with power during daytime
1.78 1.59 4.50 16.80
Million people with power during nighttime 4.01 1.33 1.21 0

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Power ships vs home solar installations — the best value for R218 billion