pv – a Python library to monitor/control PV Inverters

After having the solar electricity system installed, I can monitor the energy output of the inverter using Pro Control. However, because the software runs on Windows, I’d have to have a PC turned on just for that purpose wasting quite a bit of energy. So, my goal is to use a low-power embedded Debian box (which is usually on) to do the monitoring. Instead of just writing an application to do the job, I’ve decided to write a library others can use to write their own custom logging software.

pv can be found at http://pv.codeplex.com/, and should work for you if you have a Carbon Management Solutions CMS-2000 or Schneider Electric SunEzy 600E (judging from a sample protocol exchange).

I’ll have to give full credit to the folks at http://www.solarfreaks.com/cms2000-inverter-rs232-serial-port-hack-cms-2000-rs232-t271.html who did the initial work on reverse engineering the communication protocols. Building on what has already been done on working out the protocol, and doing a bit of reverse engineering myself, the library supports sending arbitrary data frames for further exploring, as well as the known protocols.

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Installing Solar Panels to Generate Grid-fed Electricity

Not long ago, we took advantage of the various NSW government rebates plus the massive 66c/kWh EnergyAustralia feed-in tariff, and had solar panels installed on the roof of our house by Andrew Hanna Electrical. The specs of our system are as follows:

• Carbon Management Solutions CMS-2000 grid interactive inverter
• 10x Solar Enertech SE185-72M 185W Monocrystalline Silicon PV Modules

During the installation, they’ve kindly put a Cat5 cable through the house for the RS-232 serial connection from the PV inverter to the computer. The CMS-2000 is basically a re-badged Solar Energy Australia “Orion” grid feed inverter, which comes with monitoring software “Pro Control” to log data from the inverter. Armed with this software, we can now pull some interesting data to see how much energy we generate at various times throughout the day.

The only problem is, it doesn’t make sense to have a computer switched on 24×7 just to monitor the inverter box – it’d be a massive waste of energy. So the fun begins when I want to monitor the solar inverter from a low-power, embedded computer which is actually a QNAP TS-109 NAS running my favourite Debian linux. More on this in upcoming posts.