Solar Photovotaic Power
- displaying data on a web page
This unit by Current Cost is designed to display the power used by a house.
A clip is placed round the main power cable entering a house and a radio transmitter sends the data to this meter.
They are supplied by some power companies for free. I got one badged "Sky" at a table top sale and I placed the probe round the cable feeding AC power to the house from the PV inverter connected to a 3.8 KW solar panels array on my roof. The receiver can accept data from several transmitter probes so a second probe clip and transmitter from eBay was used to feed data on the power used by the loads in the house - some of that power comes from the grid when I use more than the PV can generate.
The meter has a data output port (RS232) and spits out strings of data received from the probe transmitters at regular intervals. A cable was purchased from Current Cost that converted the RS232 to USB and this was fed to a Joggler for data processing.
Python is used to get the data from the incoming strings from the Current Cost meter
(Python uses tabs that html will not reproduce - replace each ___ (three underlines) with a tab)
# always ttyUSB0 on first boot - but perhaps not if serial link plugged in later
my $ob = Device::SerialPort->new($PORT);
_________# save channel 0 data
_________# save channel 2 data
_________# save data receiver temperature (comes in both channel 0 and 2 strings)
The end result is three files, updating every 6 seconds, with contents like -
|/var/www/ramdisk/CC_power_channel_0.txt||00014 (panels dark)|
|/var/www/ramdisk/CC_power_channel_2.txt||01628 (house load)|
|/var/www/ramdisk/CC_temperature.txt||26.3 (CC receiver temperature)|
MORE TO COME