An electrostatic heliostat cleaning robot won first prize in Circuit Cellar's recent Renesas RL78 Green Energy Challenge. Contestants were asked to use a Renesas RL78 microprocessor in a renewable power application. Scott Potter designed a robot that cleans heliostats, the solar tracking mirrors, used in Concentrating Solar Power Plants. The simple rectangular robot is powered by photovoltaic cells and rolls back and forth over a mirror using a high voltage AC field to clean dust and debris from the mirror. For more see the Circuit Cellar announcement. For the technical details, see Scott's contest abstract (PDF format) and his entry archive (ZIP format) which contains drawings, schematic, and source code.