Gener8

In 1984, the cost of power to Eskom was 0.69c/kWh. This year, it is about 14c.

Thus, the cost of power has escalated at an average of 13% a year since. Given these figures, is it possible that a solar photo-voltaic installation can pay for itself? If we take a 200-W installation and assume that it operates for eight hours a day, 300 days a year (that is, 2 400 hours), and that the cells cost about R6 000 in total and the inverter about R1 000, then, allowing for all things at a further R500, the installation will cost, say, R7 500.

At today’s rate of 13c/kWh, our first-year revenue will be R52. By 2032, when the unit rate will be R2,44, our yearly income will be R976 and our total lifetime revenue to that date will be R8 092. It would have been better to put our R7 500 in the bank. But this is all based on the assumption that we and Eskom are trying to find out if/when solar power will be good as prime power generation.

What happens from the consumer’s standpoint? Here, the rate paid by consumers for each kilowatt hour currently is 35c. Thus, the first-year revenue will be R140. By 2025, the consumer will get his or her money back and, thereafter, will score about R10 000 a year.

A clever consumer could use the R10 000 a year to set up further solar stations so that, by 2032, he or she would have a reasonable income. Naturally, the income will be for our children since some of us (I, for example) will be nearly 80 and being fed whiskey and milk as I am wheeled out into the sun every morning.

All this means two things: solar power is a long-term investment, which eventually pays off handsomely and, right now, it hardly competes with putting one’s money in the bank. But it does do better, even though just slightly.

Is any aspect of my prediction wrong? The most wrong part is probably the cost esti-mate for solar cells. When I was young, you could make your own solar cell by scraping the paint off an OC44 transistor. From this, you could get about 60 microwatts of power.

The OC44 cost about 11c, so you were paying about R1 800 a watt. Today, it is about R50 a watt. There is no doubt that this will come down further, say, to about R2 a watt.

If this was to happen, then there would be a good market for solar cells, which consist of a solar cell, an invertor and a socket outlet. One just mounts the cell on the roof, plugs in the inverter and watches as the solar cell feeds power into one’s domestic mains. Okay, I know one has to get it synchronised and all, but that’s not all that difficult. In general, one should be able to pick up between 200 W and 500 W for each house, which is a great deal better than solar geysers or geyser blankets.

Will we ever be able to run a whole building on solar cells, as in commercial building? The short answer, if the building has lifts and air conditioning, is ‘No’.

There is just not enough surface area on a building to pick up and supply that sort of power. Will solar cells become much more efficient? Well . . . right now, the most efficient is about 42%. This means that, from a half square metre, one can get about 500 W, which is pretty good. But there is the cost factor that still makes commercial mains more desirable. 

However, there is no doubt that the three things – the falling cost of cells, greater efficiency of cells and higher electricity prices from commercial power utilities – will all come together to produce, in the not-too-distant future, a house which runs nearly totally on power from the sun – during daylight hours, at least. In my lifetime? I think so. But we will see