A friend of mine had a photovoltaic system (consisting of 14 solar panels) installed on his rooftop last year. As I was looking for another raspberry pi project I convinced him I would setup a reliable monitoring solution that will lead him to an access to the data in real-time data. The current setup comes with an inverter by the company Kostal.

Kostal Piko 55 converter

The Kostal Piko 5.5 runs an internal web server showing statistics like current power, daily energy, total energy plus specific information for each string. However, the visual layout of the the web page and the bundled software look like they were designed in the late 90s and development has been abandoned:

Kostal Piko converter web interface

The power inverter itself logs data at either a 15 minutes interval for about 100 days or at an hour interval for about 400 days. At the current setting the 15 minutes interval has been selected. Furthermore my friend took notes irregularly from the built-in liquid-crystal display.

The final plan is now set. A Raspberry Pi would fetch data from the inverter, store it in a database and a web application would render the results to a browser:

The SolarPi setup

The project is live at http://solarpi.tafkas.net