The Colfax Wastewater Treatment Plant faced electric rate increases averaging 8% per year from Pacific Gas & Electric.Leaders of Colfax, just north of Sacramento, California, saw potential for savings by building on-site power generation. In 2023, the city commissioned a 481 kW DC photovoltaic array developed with solar energy supplier Holt Renewables. It is expected to save the city $5.1 million over the next 30 years.Optimum efficiencyColfax, a community of 2,000, built its new activated sludge wastewater treatment plant in 2008 with a design capacity of 0.5 mgd. The city and Holt Renewables determined that on-site solar power would cost
