Thursday, February 2, 2012
Thermal efficiency of a "Jimmy Carter" solar panel
For our Energy and Energy Efficiency class lab today we pulled some of the college's famous "Jimmy Carter" solar panels out of storage for cleaning and testing.
I'd often wondered what the thermal efficiency of these older flat plate collectors would be, if properly measured. There's just such a large weight of materials in them, it seemed likely that there would be large losses due to heating up that mass.
The largest thermal efficiency score among the three groups was 24%.
(That was the group that blocked off all the air holes assiduously.)
This compares to efficiencies of modern solar collectors, both flat plate and evacuated tube, in advance of 60%.
Without a pyranometer there isn't a great amount of accuracy to these calculations, but it's good practice in using conversion factors to do them anyway.