The U.S. Postal Service (USPS) has been making an effort to add solar power to its offices as part of the Million Solar Roofs Initiative. They have been working with the staff at the National Renewable Energy Laboratory (NREL) to implement energy systems at USPS facilities.
NREL assisted the USPS in rehabilitating an inoperable photovoltaic (PV) power system at the Rancho Mirage Post Office in California. The system was installed in 1987 to directly power DC compressors used for air-conditioning. Then in 1993, the system was modified to provide grid-connected AC power. All the equipment and wiring is in place to provide the power, but there are no connections between the PV panels and the inverters, or between the inverters and the service entrance panel. With a minimal amount of effort, and at relatively little cost, the PV system could be connected to the inverters that are already there to produce 5 kW of AC power. The USPS is working with a local utility and NREL to get the PV system up and running and connect it to the utility grid.