Climate control....

This summer has been exceptionally hot and dry in Kentucky. To keep the heat down at the house site, we've been opening a few first floor windows at night and placing an exhaust fan in one of the windows on the third floor. If the outside temperature is in the high 90's in the day and mids 60's at night, I can keep the temperature in the house between 72 and 80 degrees with the fan alone.

Even though I've only mounted 6 of 36 solar electric panels on our roof so far (1200 of 7200 watts), we've had a surplus of solar electricity all summer. So I went out and bought a small 8000 btu window air conditioning unit (less than $150) in order to do something with the extra electricity when the batteries were full. (we are not connected to the utility grid, so we don't have the option of selling back the excess energy capacity.) The sticker on the 8,000 btu unit said it would consume about 1000 watts, but in reality I think it consumes 700 or 800 watts (based on our inverter display readings). Somewhere in the 700 to 1000 watt range is just right for using up the average daytime electricity from the 1200 watt array on our roof, without dipping into the batteries too much when a cloud passes over.

Our SIP panel walls are R-24 and our ceilings are R-50, and we have a fairly tight house, so the little 8000 btu unit actually does make a difference. No, it won't change the temperature of the whole house by more than a couple of degrees during the course of a day, but it can drop the relative humidity by at least 10%. When we get the rest of the panels on the roof, there is no doubt in my mind that they will be able to run an air conditioner of sufficient size to cool our house during the hottest months of the year (July and August). I'm also hoping (confirming?) that for 6 months out of the year, all we'll need is a fan and opportunistic window openings/closings in order to keep the house at a comfortable temperature. That's good news!