maverick

Since the issue of Maverick containing my Solar Photovoltaics vs. Diesel Generators article is off the newsstands, I can now publish the article in full on Greenerhouse. Enjoy:

Bringing Back the Light:

Diesel vs. Photovoltaic

It began with an email. My brother-in-law asked me, the family’s resident green guru, to weigh up the relative merits of diesel generators vs. solar power.

Load shedding is clearly driving him to distraction. Computers are crashing in his home office, and he has scrambled to reschedule meetings of 30 and 40 people to stay out of the dark. He wants to know that the power will be there where he needs it, when he needs it. “I’m looking for a complete solution, and I don’t want hassles,” he told me, admitting that he was close to choosing the diesel route.

But he also knows that his green credentials need some buffing since he traded in his Honda Jazz for a Land Rover Discovery last year. Is solar electricity an affordable alternative?

Until the beginning of this year, the answer to his question would have been simple: In South Africa, solar cells may be virtuous, but they don’t pay for themselves. (Solar hot-water panels do pay for themselves, but you can’t run your PC on hot water.) Even the national sales manager for Sanyo photovoltaic panels in South Africa, Win Kurzyca, says, “it doesn’t pay me to put 10 of these on my roof—even at staff price—instead of paying 32 cents a kilowatt hour for electricity.”

But suddenly everything has changed. In fact, the question has changed. My swaer is not asking whether photovoltaic panels pay for themselves; he wants to know whether solar electricity is competitive with diesel-generated electricity.

Diesel gensets have become the latest accessory for the manor homes of South Africa’s best suburbs. On one block in Houghton, Johannesburg, three homes in a row glow brightly during each load-shedding event, automatically powered by Cummins engines installed for a cool R200 000 each. Forget the jet set; in 2008 we ogle the genset.

Such outlandish figures are as thrilling for solar cell manufacturers as they are for the diesel makers. The price of a solar roof no longer seems quite so ridiculous, especially once a generator begins slurping fuel. When Sanyo ran a full-page advertisement promoting its panels in The Star and Sunday Times, just before the latest round of load-shedding began, the response jammed the company’s switchboard. “What has changed the picture is the diesel generator,” says Kurzyca, “the longer the running period for a diesel generator, the quicker the payback for solar.”

My task was to determine exactly how long that payback period would be. I started by inviting Deutz, the respected German engine manufacturer, to send a representative, Craig Potts of CDDG Electrical Contractors, to my brother-in-law’s house to size up his needs. The following day, J.P. de Villiers, director of Eco Zone, performed the same exercise on behalf of the sun.

The difference between the mentality of a generator installer and a solar-cell contractor quickly becomes obvious. The genset man’s motto is: “Go big or go home.” Tumble driers, underfloor heating, pool pumps, ovens—put them all on the system. Bulking up from a 15 kVA generator to a 21 kVA model bumps the price up by less than 5 percent. Says Potts: “Rather go larger than smaller, that’s what I say.”

The meaning of life for a solar man, however, can be summed up as: “Every watt is sacred.” These panels are made from the same precious silicon crystals used for computer chips. Double the watts and you’ll have to double the price. De Villiers wanted to replace 59 halogen bulbs with 9-watt mini fluorescents. Such a conversion would cost nearly R10 000. He instantly ruled out using solar to power the pool pump, the oven, and the entire suite of appliances in the scullery. “The tumble drier takes 3 kilowatts, the dishwasher another 3 kilowatts, and the washing machine will use 500 watts on cold up to 3 kilowatts on hot,” he notes, “if you ran more than one of those at the same time, the system would come crashing down.”

Electric geysers, heaters and stoves are also beyond the might of photovoltaic panels. In most homes, de Villiers would like to see electric heat replaced by gas or wood, solar hot water panels mounted on the roof (R20 000 to R40 000 after Eskom’s rebate), and a gas stove installed in the kitchen (R5 000 and up), before adding sun power.

Since my brother-in-law powers his geysers, heaters and hob with town gas, he would be spared those up-front expenses. Still, he was becoming skeptical about the solar hassle factor. “I don’t want to have to know what is working and what is not working,” he moaned.

One conversation with the Deutz workshop convinced me that the diesel hassle factor is just as onerous, however. In addition to checking oil and coolant levels once a month, the engine would need a R2 000 service every 250 hours, more than once a year at current load-shedding levels. “And you must supply the oil; we don’t ride around with oil in our bakkies,” the foreman told me. Fuel deliveries would have to be organized several times a year.

In contrast, de Villiers said that his solar system could be left untouched for five years, at which time the batteries should be checked. With no moving parts, the Japanese-made panels’ power output is guaranteed for 20 years; the Deutz generator set’s warranty lasts for 24 months.

So neither side scored a technical knockout, and I had no doubt that the match between diesel and solar would ultimately be decided on points, or, more precisely, rands. And when the quotes came in, the opening round left solar slumping in the corner. Deutz was asking a fairly steep R162 000 for a 22 kVA generator set that would power the entire house, including installation and an automatic changeover panel that would start the motor whenever the electricity was cut. Sixteen roof-mounted Sanyo solar panels connected to a bank of batteries and an inverter, however, begged a whopping R322 000. This would provide continuous, clean power for lights, fans, security system, microwave, televisions, hi-fi, computers and peripherals, every day of the year—for free. Well, for R322 000, but for free.

The diesel quote was not entirely complete, however. Even with automatic changeover, the generator would take a minute or so to respond each time Eskom pulled the plug. Without uninterruptible power supply (UPS) battery backup on each computer, television decoder and clock, the house would still need a reboot.

And every home with a generator should have two layers of protection against voltage spikes according to Seamus Finnegan of Northern Technologies SA, which provides surge protection for generators to Vodacom and other telecoms operators. “If you don’t, you will have problems,” he warns. Steven Moss of Deutz says that the voltage regulators on his generators are adequate for most houses, unless they have “really sensitive or expensive equipment.” Playing it safe means adding another R23 000 to the diesel total.

The solar quote had room to move in the other direction. Replacing an aging refrigerator with a new, energy-efficient model could save two kilowatt hours a day. It might cost R10 000, but the payback would be instantaneous—knocking two R10 000-panels off the roof and six batteries out of the storeroom. Diesel still had the edge, R185 000 to R300 000, but solar was starting to find its feet.

The final rounds would be fought on a spreadsheet calculating operating costs and savings over the next 20 years. Of course I had to make some assumptions. Is load shedding going to get better or worse? I opted for slightly worse: 10 hours a week. If summer was unmanageable for Eskom, what happens when the underfloor heating is switched on? For diesel prices, I optimistically assumed 13 percent inflation, half the rate South Africans have endured for the last four years. And I allowed Eskom its 61 and 51 percent rate hikes for the first two years before applying the brakes and marking up annual increases of 15 percent.

The spreadsheet shows the solar panels gaining ground as the genset runs out of gas. By the end of the fifth year, cumulative fuel costs and maintenance bills have just about made up the R115 000 difference in the original price. Meanwhile, the solar panels would have saved my brother-in-law a running total of R34 000 on his municipal bill.

Starting out by opting for diesel and investing the R115 000 difference in an interest-bearing account instead of spending it on, say, plasma televisions, puts off the day of reckoning for the genset by a few years. But its defeat is inevitable.

From there, two scenarios confront his generator. Either load shedding continues to push the diesel engine deeper into deficit, or Eskom pulls out of its crisis and lands my brother-in-law with a rusting white elephant. Either way, the solar panels continue to save, finally paying for themselves about when the warranty expires.

Allow greenhouse gasses on the balance sheet and the generator sinks deep into the red. Over five years, one diesel generator operating just 10 hours a week to power a house will coat the atmosphere with more than 15 tons of carbon dioxide. That’s enough to blanket a one-acre property in a 2-metre-deep layer of the greenhouse gas. Over the same period, the solar panels would have reduced the home’s C02 contribution by double that amount.

Carbon dioxide suffocates the planet, not your children, but diesel particulates are one of the most dangerous air pollutants for human health. A report last year in the South African Medical Journal estimated that particulates in outdoor air pollution lead to 4,637 premature deaths in South Africa each year, largely from cancer, strokes and heart attacks. Measurements of particulate matter in major South African cities are on average more than triple the levels deemed safe to breathe.

While tightening emissions regulations are gradually cleaning up diesel cars in South Africa, the sky’s the limit for stationary engines belching particulates and smog-forming nitrogen oxides. Deutz engines, cleaner than most, do at least meet the European pollution standards of 12 years ago. Still, they can emit up to 5 times the levels of particulates allowed by the EU today. Had any regulator imagined that these engines would be running on a weekly basis in the gardens of family homes—in this case 8 metres away from my nieces’ treehouse—particulate filters would have been mandatory.

For now, winter is approaching and my brother-in-law still has not made his decision. Both quotes came in well above what he had anticipated, and the spreadsheet seems full of uncertainties. Besides, it’s hard to read all those figures in the dark.