[By Tim Cohen]

The salesman at the solar power shop told me: “You have no idea how stupid batteries are.” That comment made me wonder about his intelligence, so it took me some time to realise the canny wisdom of this apparently dim statement.

The intelligence of batteries has been one of the surprising, not to mention irritating, things about living without Eskom for the past year.

My wife and I have been living in a fairly isolated spot in the Karoo where it is not economically viable to bring in an Eskom electricity line.

Consequently, we jumped into the organic power lifestyle with the kind of naïveté reserved for those who believe problems will sort themselves out, until they don’t. The important point is that we did not consciously decide to live the sustainable lifestyle on principle. We are not tree-huggers. This was summed up by my wife, Jennifer, who said repeatedly — and pointedly — “I’m fine about living in the desert but I’m not doing without my food processor.”

With that non-negotiable ringing in my ears, I set about designing an electrical system that would not require any compromises, especially on the food processor front. In other words, I cast about frantically on Google.

Little practical advice
It’s odd, in our world of ecology and global warming, how little practical advice there is out there about sustainable electrical solutions. I suspect, slightly darkly, that the people who have such a lot to say about sustainable living are not actually living it themselves.

The people that do actually do the sustainable living, on the other hand, don’t seem to want to talk to other people. Many are isolationists. Nowhere was their simple website titled “Sustainable living for people who want to carry on using their food processors”. Strange.

Interestingly, however, some small outlets are popping up in out-of-the-way places and we discovered one in a small house in the George industrial area, which is where I discovered our battery critic.

When you meet solar power sales people, they tend to want to spend time “designing a system”. In other words, they ask you questions about things you don’t really know. I always thought this was just part of the sales pitch but one of the problems with a solar system, it turns out, is that it requires a careful balance between what you use and what you generate, because — and this was a big surprise — you can generate too much electricity. And then, believe it or not, the electricity turns off!

What helps maintain this balance is the aforesaid battery pack, but the problem lies with the aforesaid stupidity of batteries. This is all a steep learning curve, but it gets better because you suddenly acquire a whole new vocabulary; watts, amps, kilowatts, volts and, very excitingly, kilowatt hours.

No rocket science
Yet, in the end, it’s not actually rocket science, although we made some blunders along the way. Our first correct decision was to keep the house we were building running on 220 volts. We did consider a 12-volt system, but it’s not realistic, and it’s easier to step up the voltage once and use commercially available consumer goods and light fittings.

The second correct decision was to cut out the big electricity consumers. Hence, we use gas geysers to heat water, a gas oven and stove, but not, importantly, a gas fridge.

Gas fridges don’t work and they’re impossible to find in any case. Well-made electric fridges, however, use less power than you might expect.

Gas geysers, on the other hand, are getting much better and are now nothing like those horrible ones you used to find at Parks Board resorts that leaked gas and required something called a pilot light, which never actually lit no matter how many lit matches you stuffed into it.

The key innovation has been to include a monitor so that the water emerges at a constant temperature. The ones we installed are called Rinnai.

Wind versus solar
Another correct decision was to focus on solar panels rather than wind. This is slightly counterintuitive because most people think wind is more powerful.

Actually, it’s not. Power generation, it turns out, is a function of the cost efficiency of generation. Getting the power is actually the simple part; doing so cheaply, efficiently and storing it are much bigger problems. Wind generators are noisy. They have hundreds of mechanical bits that can and do go wrong and the power comes at you in great gushes, or not at all. This is all bad.

With solar, the power arrives at a more constant, reliable and steady pace. Solar panels are now being produced by the zillion and are declining in price at a staggering rate.

I bought 12 120W, 12V panels for about R7 000 each at the start of this year. Six months later I added two more, which also cost about R7 000, except they generated twice as much electricity. A rigid-frame, poly crystalline 24V, 240W photovoltaic solar panel (ie. top of the range) now costs R6 000. It’s an extraordinary example of the unit-cost decline associated with mass production.

My 12-panel array produces, here in the Karoo, about 7kWh/day. Your electricity bill will normally tell you how much electricity you use, but I know from living in Jo’burg in a two-person household in Parkhurst that we typically used three times that.

So how do we live? Actually pretty well. Without heating requirements, without geysers and stoves, this is all a small family really needs. We run a fridge and a freezer, use an electric washing machine, I basically use my computer all day, we have a television, an underground water pump and, yes, the food processor.

Stupid batteries
But we are careful about electricity and monitoring is constant, all our lights are fluorescent, we use the microwave sparingly and we tend to go to bed early. This isn’t a complete and total solution. The first problem is those stupid batteries.

I have 20 deep-cell 12V batteries, which are a little larger than car batteries, attached to the system. They cost around R1 500 each.

This system is sufficient to store enough electricity for perhaps one day — that’s all. Two overcast days in a row equals no electricity. Sometimes, if you use a lot of electricity the previous day, it will not even last overnight. Irritatingly, batteries just don’t store very well, because they accept only a certain amount of power and then they just stop taking more power in.

Because the system is unreliable, you need a backup system, and this was one of my mistakes. I bought a huge three-phase 55kW diesel generator for about R45 000.

I bought it because the price compared well with that of the very complicated systems that kick in automatically when the power goes out and cost R35 000 but generate only 25kW. My one just looked so big and beautiful.

The upside is that the local farmers positively drool when they see it; it’s like a top-of-the-range bakkie — only better. The downside is that it’s far too big. I use only one phase because you need complicated wiring to manage the three phases, which I didn’t do.

For our household and for many others, a 25kW, single-phase backup system is sufficient.

Something else I didn’t realise is the huge difference between winter and summer. You lose about 50% of your power in winter because the sun is less intense and travels in a lower trajectory across the sky.

Big users
It was in winter that we really needed the generator and we tended to run it for an hour or so a day, switching on all the big users, such as the washing machine, at the same time. We used gas heaters and big fires for warmth.

One of the other things you need is a converter to step up the electricity to 220V. You also need a critical mechanism called a maximum power point tracking charge controller. The most well-known brand is Australian-made Outback. This device converts amps to volts, depending on how much power is coming in, and it makes an enormous difference.

Overall, with all these gizmos and wiring and the installation, a system like mine would probably cost a total of R150 000 today. That’s not cheap. At that rate, the system would be paid off only in about four years of Eskom bills, five if you count what we have to pay for gas and diesel.

But this is assuming Eskom bills don’t increase and we know they will. Solar panels also don’t wear out, although batteries do, so the chances are that my system will actually last the five years.

So is it worth it? I think so. The real moral of our story is that no-compromise, food processor-compatible sustainable living is not financially realistic or truly utilitarian at the moment. But it’s very close.

Tim Cohen is contributing editor to Business Day; this article was first published in the Mail & Guardian
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Image credit: Axel Bührmann