Friday, May 14, 2010

Pyranometer for datalogging Sunboxes

14 May : Blaise has offered to install additional Datalogger instruments and channels. It's very important to have a comparison of the Sunboxes' energy output and the daily solar radiation, therefore he is planning to bring a Pyranometer on Saturday, so we could also record solar radiation. This will also help to compare results when the sunboxes are on and off for the same conditions (solar radiations and ambient air temperature). The sunboxes do not only work on direct sun light, they work in cloudy bright sky conditions. The air temperature in the sunboxes is influenced by the solar radiations.
Later, after sunset, the air in the sunboxes has residual heat released by the brick wall, solar heat that was absorbed earlier in the day - assisted by the absence of wind chill.

We already have a pyranometer on the roof, next to the PV panels, but their reading of air temperature is influenced by being attached to roof tiles (which stay hot after sunset for a while). The readings are broadcast live to the internet, via the SMA website. We now need on on the South wall.
The pyranometer was bought with part of his PhD fund for his experiments on Solar collectors. He will need it for his next experiment, which may be due in the next two or three weeks. So I better not drill permanent holes in the wall for this unless the holes can be re-used later.

20 May : PS We decided not to fit the Pyranometer because the one we have on the east roof is good enough for recording weather data. It is very expensive and could only be out for a short while and would require another hole in the wall.

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