US utility Ameren and smart grid firm S&C Electric Company have announced the completion of a successful 24-hour islanding test at Ameren’s 50kW microgrid in Illinois – where a microgrid is completely separated from the national grid and its assets. Ameren unveiled the project earlier this year and has now shown that it can be a self-sustaining system. The project will act as model for other future microgrids, potentially on a larger scale. The microgrid cost $5m and serves 190 homes in Champaign, Illinois. It uses a range of distributed energy resources (DER) including a 125 kW solar PV array from Yingli Solar, a 100 kW wind turbine from Northern Power Systems and 1 MW Caterpillar natural gas-fired generator, as…