During the summer of 2010, I had the oppurtunity to work with a small team in the San Jose office of German solar inverter manufacturer REFU Solar Electronics. While REFU is new to the US market, it is well-established in Germany, having made AC motor drives for 30 years before changing its focus to solar inverters. I took on many small project to assist market adoption, including presenting at trade shows, designing trade show displays, and assisting in UL certification. The inverter is now UL certified, and the 12-20KW string inverter line had the highest efficiency of any solar inverter in a recent test by the popular publicationPhoton.
However, the vast majority of my time with REFU was spent on our SunSpec project. Sunspec is a new communication protocol, developed to standardize communication between solar loggers, inverters, and other devices that are involved in photovoltaic power generation. Because our inverters operated on RSS, a communication protocol different from the Modbus protocol on which Sunspec operates, I decided to develop a translator so our inverters could communicate with other Sunspec devices. I chose to use a MOXA Box, an small industrial computer which ran ARM-Linux, a flavor of Linux developed for Reduced Instruction Set Computers (RISC). Although I have experience programming in C and C++, I was not well-versed in communication protocols, so I had to learn RSS, Modbus, and TCP/IP for my solution. I worked with REFU engineers in Germany to develop the best translator solution, and was able to present the prototype device to other Sunspec developers at a conference at Caltech in September 2010.