In my last post, Use It or Lose It, I talked about monitoring the new solar array’s output and performance. On August 12th, we entered a new phase of this evaluation. Up until that date, we matched or exceeded the amount of daylight we received on the first full day of operation. After the 12th, we started seeing how the array performs in steadily lessening daylight as we approach the Winter Solstice. We’ve entered new territory, monitoring, and trying to predict the new limits of our electrical harvest.
A cloudy September day that brought in all the power we needed (Photo: Mark A. Zeiger).
We will lose 5 or so minutes of daylight each day through the next few months. Eventually, this will make a big difference in the electricity we bring in. I notice that on many days, we don’t get any charge at all after the ridge shadow deepens, whereas we used to charge late into the evening. I can’t really match that to what I see, but it reinforces that there’s something more to solar collection than simply visible sunlight. I can’t predict what will happen, whether we’ll steadily lose charge throughout each day, or if snow on the mountains will give us a “bounce” of reflected sunlight. I have to assume so—if the old array benefited from bounce, surely the new array will as well. At any rate, I assume we’ll need to use the wind generator at least a couple of days each week. My weekly generator run to keep the rotor free will eventually provide needed power as well.
We find the implications encouraging, though. It’s no small pleasure to watch our intake soar to 31 amps in weak sunshine. We see incoming power levels that would require a good 20-25 knots of wind or more to get from the wind generator just because the sun comes up. Not only that, but those charging periods—the amp hours we experience—last longer than most windy periods.
Sometime soon, I’ll pull out the oil lamps, clean them, fill them, and light them some evenings. This may or may not offset increased electricity usage as the days grow darker. Waning daylight creates several different factors that will affect the generation/usage equation.
These complications make me less interested in making an exhaustive study of our situation. I don’t really need to quantify it, as I can’t quantify our electricity usage accurately. An overall idea and observation should suffice. And, we expect to see a definite improvement over what we got with our old panels (see Time of Diminishing Returns From Our Solar Array).