Wednesday, March 14, 2012

A few more records tumbled today.

We had the glorious weather again, so much so that the water that is heated by the surplus energy from the solar panels, the "dump load", was heated to such an extent that it went off the end of the temperature gauge - ie over 70°C. That's the first time this year.

The water in the solar-heated tank (a black plastic box with a glass lid) reached 26.5°C and that's the highest so far (but still a far cry from the 45°C of midsummer) and if it hadn't have been so windy, I would have put some of the water out of the dump load into the solar-heated tank to bring the temperature up to about 38°C and I would have had the first solar shower of the year. But it was far too windy - I would have died of exposure I reckon, and the fact that showering outside in the all-together is the way that it's done around here, it would have been indecent exposure from which I would have suffered.

Talking of the wind, it's died down now, after the last few days, but once again I had more wind energy created today than the cumulative amount of wind since I installed the power meters 2 weeks or so ago. Mind you, I don't think that we will have that again tomorrow.

But here's an interesting and little-known fact, one that I can now prove. And that is that you can often have more power from a low-powered wind turbine than you can from a high-powered one. Confused? Well, let me explain. Most electric motors, and wind turbines are no exception, have magnets in them and these operate the coils of the motor. Of course, the bigger and more powerful the motor, the bigger and more resistant are the magnets. And so you need more force to overcome the resistance in the magnets. When you have a low-powered wind it will overcome the resistance in the magnets in a low-powered motor, and make the motor turn. However, there will not be enough force in this low-powered wind to overcome the resistance in a big magnet in a high-powered motor so that this motor won't turn.

And there I was today, watching the 90-watt wind turbine quite happily ticking over and giving me 10 - or 15 watts for much of the day while the big 400-watt wind turbine was doing nothing at all. And then, all of a sudden there would be a stronger gust of wind and the big turbine would start to turn, and once it had built up steam it would be there with 50 watts, or 80 watts, or even 113 watts on one occasion, while the smaller wind turbine was giving out 30 or 40 watts. But be that as it may, the smaller wind turbine chucked out in total three times as much energy as the larger one over the 24-hour period under review. And it's done that consistently over the last few years.

There are lessons to be learnt here of course - namely a collection of low-powered turbines will do more good than one big one over a continuous period, especially in a place like this.


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