Spring, summer and fall, I take pride in keeping the electricity to my geysers off. The water is heated purely by the sun. With a little bit of luck I can even make it through one overcast, rainy day with the hot water stored in my tanks.
But when we were hit this weekend by three successive gloomy, soggy days, I threw in the towel. With the electricity flowing, I sensed an opportunity, however. I had always wondered how much I was saving with my solar hot-water panels. When I installed them, I was making a hundred other changes to my house. Simply comparing my electricity consumption before and after the solar panels won’t answer that question.
So yesterday morning, I decided to experiment. Assured of no sun, I switched off the pump to the panels and recorded my municipal electricity meter reading. [Switching off the pump was essential because even in cloudy weather, solar panels will warm up enough to heat water to a small degree. Waiting for a cloudy day was essential to avoid overheating the fluid in the panels that was not circulating.]
This morning, I ended my experiment and checked the meter again. My household had used 45 kilowatt hours of electricity in 24 hours, compared to 26 kilowatt hours on a normal weekday in recent months. (I monitor the meter rather obsessively.) This means the solar panels are cutting my electricity consumption by approximately 42 percent.
If we have 300 days a year of decent sun, the panels are saving about 5,700 kWh a year. That translates into sparing the atmosphere 5.7 tons of carbon dioxide annually. My financial savings are not quite as dramatic—and not as important in my mind—but still worth noting. At the current Johannesburg charge of 31.18 cents per kilowatt hour, I am saving R1 777 per year. At this rate it will take me at least 20 years to pay back my large and complicated solar hot water system. Simpler systems cost less than half as much and will pay for themselves much more quickly.
Is my 42% saving typical? Dylan Tudor Jones of Solar Heat Exchangers, the company that installed my system, tells customers that they may save up to 50 percent on their electricity bill. Given that my house used to have two electric geysers, I may have cut back that much. I doubt, however, that most people can slice their electricity consumption in half with solar panels. I have a larger-than-average system—3 panels and 600 litres of storage—and my vigilance against wasting power throughout the house means that geysers were using a disproportionate share of the total. But whether a solar hot-water system saves 20, 30 or 40 percent, it is the smartest step a South African can take toward creating a greener house.
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May 28th, 2008 at 1:48 pm
I’m trying to do as much as I can for the environment in my personal capacity; including recycling, power and water saving, altering my lifestyle and driving style to be more eco-friendly, trying to get the message out to friends and family through various methods and have even started my own “green” blog… But like you mention in various posts in this blog, it’s very difficult to get the facts, and even more difficult to oppose “big media” (the huge advertising campaign for diesel engines for eg.)!
I’m still young and not in the position to purchase or build my own home, but have developed a great interest in energy efficient homes and building styles…
With solar power as one of the examples I’m going to use; is there any research as to the amount of carbon etc produced in the manufacturing of solar panels? Logic tells me that it must be considerably more efficient than electricity, but I’d like the actual figures.
Another thing that could really benefit from more in-depth research are building methods and materials. I’ve read up lightly about different methods; including straw bales, sand compacting, containers, steel framework without the use of concrete, tyre stacking, sand bags within a steel mesh and others…what would be the most energy effcient way to build a home, obviously taking into account the time and money involved?
Ideally, what I’d love to see being researched and formally compiled is a complete “from the ground up” guide on building and furnishing a home for maximum energy efficiency and minimum extra cost.
Naturally I don’t expect you to be able to answer my questions right off the bat, but if you do have more infomartion on the subjet in general I’d appreciate it.
May 28th, 2008 at 4:30 pm
Minyon,
I admire your energy and enthusiasm.
You are right, I should write a book that covers all of these issues, and I am determined to do so. In the meantime, I’ll give you a few thoughts.
On the footprint of solar photovoltaic panels, the manufacturers are surprisingly quiet about this issue. But one study determined that panels save more energy than was required to make them in less than two years of use. You can read about it here: http://www.alphagalileo.org/index.cfm?fuseaction=readrelease&releaseid=519886&ez_search=1
Like you, I am familiar with alternative building techniques, but not an expert. Any building material that avoids the use of cement, which is a major contributor to greenhouse gas emissions, is a big leap forward. Beyond that, you would probably be splitting hairs to worry about whether rammed earth is greener than straw bales. The more important issues would be which is more practical to create a durable house that is energy efficient. Which will allow reasonably large, north-facing windows? Which insulates best? Which has the best track record for durability? Which doesn’t require regular applications of paint?
I’m quite confident that those are some of the important questions. I’m less certain of the answers. Just wait for my book.
May 28th, 2008 at 4:47 pm
Thank you. You have left me pondering those points and eagerly awaiting your book.
It’ll be such a relief to get some genuine information relative to the South African market, climate, costs etc.