- Get a Linux box. I run Ubuntu
Server on a crappy Dell box in my basement.
- Get mysql running.
- Add a "solar" user to mysql, create a "solar" database, and give
the "solar" user permissions to do ALL on the "solar" database.
mysql> create user 'solar' indentified by '<password>';
mysql> create database solar;
mysql> grant all on solar.* to 'solar';
- Plug a serial cable (straight through, not a crossover) from your
computer into the Xantrex inverter.
DON'T ELECTROCUTE YOURSELF! Without proper precautions, almost every wire inside the inverter could kill you.
I have 3 inverters, so I spliced the three serial cables I used into
one CAT-5 cable (sharing the ground pin) and ran the CAT-5 from the
inverters through some conduit into the crawlspace under my house,
then to the basement, where I broke it back into 3 separate serial
- Get a few packages that my programs require: python-serial,
python-mysqldb, and python-gnuplot.
bash> sudo apt-get install python-serial
bash> sudo apt-get install python-mysqldb
bash> sudo apt-get install python-gnuplot
You might need to enable universe and/or multiverse to get these.
- Grab my getsolardata.py and run it
as a cronjob. In other words, add something like this in your crontab:
# get data from solar array every 5 minutes
*/5 * * * * /home/keith/solar/getsolardata.py localhost:solar:<password>:solar /dev/ttyS0 /dev/ttyUSB0 /dev/ttyUSB1 >> /home/keith/solar/getsolardata.log 2>&1
getsolardata.py takes a database specification
(host:user:password:database), then a list of serial ports which are
connected to Xantrex inverters. I have a 3 inverter system, with one
built-in serial port (/dev/ttyS0) and two USB-serial adapters
(/dev/ttyUSB0 and /dev/ttyUSB1). Don't worry about the order,
getsolardata.py identifies inverters by their internal serial number
and not by which port they are connected to.
- Grab my plotsolar.py and run it. I run
it once an hour as a cronjob.
# plot the data every hour
1 * * * * /home/keith/solar/plotsolar.py localhost:solar:<password>:solar /home/keith/solar >> /home/keith/solar/plotsolar.log 2>&1
It will read data from the given database specification and produce
some *.png graphs into the directory identified by the second
argument. Do with them what you will. I copy them to my website, also with a cronjob:
# copy generated graphs to keithandkatie.com
2 * * * * scp /home/keith/solar/*.png firstname.lastname@example.org:keithandkatie.com/solar/ >> /home/keith/solar/plotsolar.log 2>&1