Hi again,

yes, I am doing strange things again - or is it Ecotect doing strange things?

I did a simple flat-plate, single-glazed solar collector - and then a thermal analysis - mainly to see what would happen. I used no heating/cooling and no internal gains or infiltration.

The temperatures it gives are .... well, have a look at the graph.

For the middle of Summer in Perth, Australia, it gives a night-time temperature of -5 C and about 0 C for the next evening. (I assume the jump from one night to the next is the same as an earlier post where I found that from night to night the temperatures were usually about +/- 5 C different, even with 'fake' data with multiples of the same days data.)

Anyway, you can see that the Outside temp is 15 to 25 C, and even allowing for some nocturnal radiative cooling, the interior temp of the collector will never fall below 1 or 2 C below ambient - but this is saying I can use it at night as a freezer!!! No matter what I do, it always gives temperatures of 15 - 25 C below ambient at night

Also I would expect that under stagnation conditions at day that it would exceed 100 C - probably it should go to 140 C.

So what's going on?

Susan