1. A little bit of sunshine! ● About my PV system how – “you're putting how many panels up?” ● Designing the system – 3D modelling with sketchup – PV system modelling with python ● Monitoring the system – talking to a SMA webbox – gathering data with python – graphing with dygraphs and javascript – integrating with pvoutput.org ● Future plans – automatic room fan control? – integrate 3D modelling with pv_model – link in a web camera?

2. A little bit of sunshine... ● 29.8kW – 132 Sunpower 225W panels – 6 SMC5000A inverters – 31 breakers – 500M of wiring ● See http://solar.tridgell.net for photos

3. Some terminology ● A few key terms – subpanel: a 24 cell vertical section of a 72 cell panel – MPPT: Maximum power point tracker – string: a series connected set of panels – stringing: choosing the string connections for an array – inverter: a device to convert DC power into AC

4. Designing the system ● Needed quite precise 3D CAD – best I could find for Linux was Google sketchup – tried blender, but couldn't get it to do what I needed ● Shading models – needed good models of shading effects – use sketchup, plus a python numerical model ● pv_model – python model based on diode equations – handles lots of details to allow modelling of complete system – allows for complex shading scenarios to be modeled – allowed me to design the best possible stringing for my system

5. Monitoring the system ● Talking to a SMA webbox – can do ftp, http or JSON RPC (over UDP or http) – chose JSON RPC over UDP for efficiency – well documented protocol – easy to do in python ● Gathering data with python – script runs from cron each minute – appends to CSV files, one per inverter

6. Graphing results ● Easy to graph roughly on pvoutput.org – Just submit data via a http POST every 10 minutes ● More precise graphs – Chose dygraphs and javascript – reads CVS files from monitoring, displays in detail – allows for annotations, zooming etc

7. Future plans ● Control a room fan? – inverters will get hot, and lose power, in summer – maybe control a room fan with X10, based on inverter fan speed and efficiency? ● Integrate pv_model with 3D models? – integrate shading models with numerical model – would allow for much more precise yearly impact calculations ● add a web camera? – maybe use a web camera to measure real shading effects and match to model See http://solar.tridgell.net for more info