Parasol is a green micro-datacenter partially powered by solar energy and partially cooled by "free-cooling". It comprises a small container, a set of solar panels, and batteries. The container lies on a steel structure placed on the roof of our building. The solar panels are mounted on top of the steel structure and shade the container from the sun. The container hosts two racks of energy-efficient servers (up to 160 of them) and networking equipment. The container uses free cooling whenever possible, and direct-exchange air conditioning otherwise.
Besides the solar panels, Parasol can draw energy from its batteries and/or the electrical grid. Three manual switches enable different configurations for the supply of energy. For example, we can configure Parasol to operate completely off the electrical grid. Parasol also includes extensive power monitoring infrastructure to quantify how much energy is drawn from each available source.
We are also building software for maximizing the use of green energy in Parasol. Our two first systems, GreenSlot andGreenHadoop, have been described in the literature. Both systems assume that there are no batteries and that brown energy should only be consumed when green energy is not available.