Datacenters range from small numbers of servers in machine rooms to thousands of servers housed in warehouse-size installations. Estimates for 2010 indicate that collectively datacenters consume around 1.5% of the total electricity used world-wide. This translates into high carbon emissions as most of this electricity comes from fossil fuels. On-site renewable energy has the potential to reduce datacenters carbon footprint and power/energy costs. The authors built Parasol and GreenSwitch to explore this potential in a controlled, research setting.