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Solar radiation - Measurement

module in electrical box glued LED - rear culvert through the roof (tube) top view Measurement of solar radiation is based on CLD240E diode and DS2438 system. I applied for this purpose module from Hobby-Boards 1-wire solar detector (Photo on the right). Diode installed in it must be exposed directly to sunlight. For this reason I would not recommend buying the version with humidity sensor. However, if you decide on a set with humidity sensor then humidity sensor (along with the entire printed circuit board) should be placed in shade and diode measuring solar radiation should be soldered out from the board and connected by wire. This solution will make it possible to install humidity sensor in shade and diode in sunny place.

Photos shows how did I install the whole set in my home. I used copper pipe (the same as used for water installation) Φ15 mm as culvert. The hole in the roof is secured by some liniment. The LED is glued into plastic cap (the one I just had at home). Due to the conditions in the attic the board and the lower part of the mentioned cap with diode in it were sprayed with protective lacquer ("Plastic" lacquer for PCB).
glued LED - front culvert through the roof (tube) bottom view The data is read with command:
owread 26.no_sensor/vis
Then we make calculations (in addition we secure ourselves against the appearance of negative result):

solar_rad=`echo "x=($in / 390 ) * 1730463 ;y=0 ;if(x>0)y=x ;y" |\
  bc -l |awk '{printf "%.1f\n", $1}'`

1730463 - experimentally determined value - I found it here in - voltage readings from the sensor,
solar_rad - result in W/m2.
390 - value of the resistor connected to the diode. For modules from the Hobby-Boards is 390 Ω
1730463 - experimentally determined value - I found it here

This also shows that the maximum radiation that could be measured is: 1024 (10-bit) * 0,2441 = 0,25V / 390 * 1730463 = 1109 W/m2.

At the end we get graph:

Personal Weather Station.

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Last Modified: 2011-08-07