No, we can't run the country on solar or wind

I happened to pick up a South African magazine with this glaring headline: “One solar plant powers 30 000 homes.” I then read the story.

So, let us look at this. Firstly, let me say that I am not antisolar or antiwind. Contrary to claims made by others, I am not against these renewable options and have never said so at any time. What I oppose is telling people that you can run the country on solar or wind, or at least run part of the country on solar or wind. You cannot.

Both solar and wind can only work when there is a backup system hidden in the background, to come on line at very short notice – when the wind does not blow or a cloud moves in front of the sun. The cost of this backup system is never taken into account by the prorenewables lobby.

This is something like building yourself a solar-powered motorcar, which you drive around to impress your friends, but you keep a conventional petrol-driven car in the garage for a rainy day, or a cloudy day, or for use during the evening. Then you brag about the low cost of your solar transport and leave out the monthly payments on the petrol car.

But back to the solar article. Solar will not “power 30 000 homes”. I have more than once visited houses that are 100% solar powered, a handful. In each case, the owners have been scientists who have done it as a hobby or out of necessity because they have bought some remote place that is not actually connected to grid electricity. The most recent visit was a few weeks ago. In each case, the owner has explained how expensive solar is.

The article, which I read extensively, quotes an executive in a solar company. He points out that South Africa’s energy plan envisages setting the goal of more than 8 GW of photovoltaic power to be installed in the next 20 years. By current logic, that would be 8 GW of power at lunchtime (on a sunny day) and zero at night. So, you would also have to have another 8 GW of some other power to operate at night to fill the gap.

In fact, you only get full solar at lunchtime. As soon as the sun moves off the vertical, the solar drops, and it drops a great deal. Before morning tea and after afternoon tea times, it varies from zero at dawn and dusk to about half. So, you need half the backup before and after the tea breaks.

What power should we use for this backup? Where should we put it?

Our executive in the solar article, quite correctly, points out more than once what a really good investment the solar is. It is a good investment if you are a foreign solar supplier and you provide the system to South Africa, and sign a deal for 20 years, guaranteeing a good income above Eskom’s existing electricity selling price.

To complete the good investment, you are not responsible for delivering any amount continuously. You just say that Eskom backup will handle it, and that is Eskom’s responsibility.

This is like getting a 20-year contract to supply milk to a hotel at a guaranteed high price. But you can deliver when you like. For example, 100 ℓ on Monday, none on Tuesday, 5 ℓ on Wednesday, 40 ℓ on Thursday, and so on. When the hotel phones to say, “We are short of milk”, you say: “Toughies, go to the dairy.” That is one terrific business contract.

I mention ‘system’. The solar exec says that a solar plant that opened in 2013 is equipped with 84 inverters, 42 transformer stations and 840 monitors. That does not include the solar panels themselves.

There is this weird public belief that you just stick a small solar panel on your roof and plug it into the fridge. Noooo. From the solar panel, you get dc voltage, about the same as your car battery. For the fridge, you need 220 V of ac power. So, the solar needs to be converted from dc to ac, and its voltage has to be changed. This all requires a whole load of extra gear, including the inverters, etcetera. Solar is not just a simple case of ‘stick it in the veld’, and you get free electricity.

I am in favour of using solar where it makes sense, such as on farms or in remote areas; I am not in favour of misleading the public.