Solar radiation - Measurement
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).
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.
Home automation www.tomkii.net/tech/pomiary/
- what I measure, which devices
I use, and how do I use them.
Forum forum.tomkii.net/forum-5.html
Contact e-mail:
Napisz@Tomkii.net
Last Modified: 2011-08-07