Viewing post #885295 by Steve812

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You are viewing a single post made by Steve812 in the thread called Solar Panel Update.
Jun 28, 2012 9:08 AM CST
Name: Steve
Prescott, AZ
We were so happy with our first 4kW system that we installed a second system and now have 8kW peak power generation capacity. During the long days of summer we will typically produce more than 50kWh of power on each clear day. We produce nearly $240 worth of electricity per month at the rates we are paying.

In the cooler months of the year we generate more power than we use. It's credited to our account according to when it is generated. On-peak power gets us $.165/kWh, off-peak power earns $.05/kWh. The credits build up until June, July, and August when we use something like 15kWh more power per day than we generate - thanks to air conditioning loads. In two months of summer we will use up most of the credits we accumulated during earlier months. If we get to the end of the year and have excess credits, then we sell them back to the power company at the wholesale rate of $.05/kWh. It looks like we might end up doing that for some of the power.

What's kind of cool, though, is that the stucco and insulation of our house delays much of the cooling load so that a quarter or a third of our cooling is done after 9:00 pm when outside air is cool (so efficiency of the A/C unit is high) and electricity rates are low. In fact, we notice that the A/C might still be running as late as 1:00 am. During the daylight hours up until about 4:00pm the solar panels produce more power than the A/C system uses. During most of the daylight hours on most sunny days we sell power back to the power company. So it's just that stretch of time between 4:00pm and 9:00pm when our house behaves like an energy hog. If we were forced to economize, we could turn off the A/C for a while and use fans.

We don't anticipate upsizing from here, at least for a while. When we offset our own energy usage we get $.165/kWh, but when we sell power back to APS in excess of our own annual usage we get only $.05/kWh. So the benefit of installing more solar panels is about 1/3 as big as it was for the first two systems. That's enough difference that solar power systems would have to come down in price by more than 60% before it would make sense to consider doing it. But that might happen. The price fell more than 30% in the year between our first installation and our second installation. I note, too, that APS is building a solar farm not far away in Chino Valley. This suggests that they believe it's a good deal right now.

I never thought I would live to see the day when solar electric power actually made good economic sense. I'm glad to see that I was wrong.

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