Solar Warm Air Panel: Initial Results

An Eccentric Anomaly: Ed Davies's Blog

Today (Sunday) started quite bright but by the time I'd sorted myself out it had clouded over.

There was a slight bit of warmth in the sun but it was not bright enough to cast shadows. The ambient air temperature was about 11 °C so I was pleased to feel noticeable warmth coming out of the top of the panel - hardly a blast, though, more of a trickle. The actual temperature was fluctuating quite rapidly in the approximate range 24 °C to 33 °C spending most of its time around 29 °C to 30 °C. The rapid fluctuations are a good sign in two ways: it shows it was not just residual heat from the early sunshine and also that the collector is thermally lightweight, as intended, to make good use of short bursts of sunshine.

Later, at about 13:00 Z (14:00 BST), the Sun did come out but by that time the collector was in the shade of the house:

Ambient temperature had risen about 1 °C but the collector temperature was now only 18 °C. Still, 6 °C rise above ambient from only indirect sunlight is not too depressing.

[[Update 2011-06-07: Yesterday (Monday) morning it was forecast to be dry but luckily I'd taped over the top of the collector as, when I woke, it was bucketing down. When I had to go out about 10:30Z (11:30 BST) it was still cloudy with very light drizzle but brighter than Sunday morning. Removing the tape there was quite a noticable waft of warm air out of the top which continued steadily. Temperatures were mostly in the high forties but when the sun came out for a moment, so you could actually feel some heat and cast a shadow, it went up to 51 °C.

Today (Tuesday) it's hissing down again and very dark. ]]

[[Update 2 2011-06-07: At about 14:00 Z (15:00 BST) with the hypothetical Sun behind the house, thick cloud just about at the top of Ben Tongue (280 m), moderately heavy rain and ambient temperature flickering between 8 and 9 °C on my meter the temperature in the bottom of the panel, in front of the absorber, was a steady 9 °C and at the top, behind the absorber, was flickering between 9 and 10 °C. So roughly 2 °C gain in light conditions about as poor as it gets around the middle of the day. This was just after I'd peeled back the waterproofing duct tape so is hardly indicative of gain available if there was a significant airflow through the collector. ]]