A friend just blogged about his successful attempt to reverse engineer his solar-cells inverter to grab stats out of it. He says:

The inverter (the device that converts DC into AC) is a SolarMax C-series. It has a 2-line LCD display that gives out some basic information: current, voltage, power; produced energy today, this month, this year, … This is very useful information, but is a bit hard to access. The instruction manual reveals that there is a computer interface available to read out its data. Naturally, I wanted to explore this!

The interface is physically an 8P8C (usually called RJ45). Electrically it’s a serial interface. The manual isn’t exactly clear whether it’s an RS-232 or an RS-485 interface. After some mailing and calling, the people at Sputnik Engineering just mailed us the pinout diagram and document (both in German); it appeared to be RS-232. Their website even has a free utility called MaxTalk to read out the data!

Read the full post here. If you'd like to see scripts to generate graphs of the electric production you should ask it in his comments.