November 21, 2025
A community in Northern California has flipped the switch to a 5 MWdc solar energy + battery energy storage system that supplies power to a water treatment plant. The City of Vacaville held a “turn the switch” ceremony this week to celebrate the commissioning of the new facility at the Eastern Wastewater Treatment Plant (EWWTP).
The solar energy and storage system is designed to offset the annual electricity demand of the EWWTP facility and will generate almost 8.1 million kWh of renewable electricity annually. The system increases overall energy efficiency while lowering utility bills, providing the city with an expected savings of more than $25 million in electricity costs over its 20-year lifespan.
“Vacaville’s sustainability goals are about better outcomes for people, healthier air, smarter use of resources and reliable public services,” said Vacaville Mayor John Carli. “By combining solar energy with smart battery storage in an industrial facility that treats an average of 7.5 million liters of wastewater every day, this project will help support energy activities that are essential to minimizing risks to human health and our impact on the environment.”
Increasing sustainability
The project, developed in partnership with ForeFront Power, advances Vacaville’s sustainability strategy to reduce greenhouse gas emissions, stabilize energy costs and strengthen reliability at a critical 24/7/365 public utility. Powering essential wastewater treatment operations with solar energy further reduces carbon emissions and supports better air quality in Solano County.
During the day, the solar array provides power to electrical loads – including large motors, equipment, HVAC, security systems and IT – while the battery storage stores excess energy produced during extended sunshine. Stored energy can be dispatched at night, on cloudy days, or when facility demand exceeds solar energy production, ensuring consistent, cost-effective energy for essential services. EWWTP’s energy-intensive operations can now leverage smart battery reserves to avoid paying peak rates, reducing local energy costs and easing pressure on California’s electric grid.
“We applaud the City of Vacaville for its leadership in deploying clean, renewable energy in a mission-critical facility,” said Ruben R. Fontes, CEO of ForeFront Power. “The Easterly WWTP now benefits from solar power generation combined with intelligent storage, producing energy when it is abundant and dispatching it when it matters most, supporting local public health and community resilience for decades to come.”
PPA helps cost savings
The EWWTP solar and storage system was developed through a 20-year Power Purchase Agreement (PPA) between Vacaville and ForeFront Power. Under the terms of the PPA, ForeFront Power owns and maintains the system, while the city purchases the electricity at a fixed, lower rate than the utility, ensuring long-term budget predictability and protection against rate increases. ForeFront Power will continue to operate and maintain the system free of charge for the duration of the PPA.
This project supports the city’s wider sustainability initiatives, including the Energy and Conservation Action Strategy (ECAS), a long-term plan to reduce carbon emissions and conserve resources. ECAS calls for community-wide measures that increase energy independence, limit utility spending and improve air quality through reduced emissions from municipal facilities. The EWWTP solar and storage system furthers these goals and complements the city’s ongoing Sustainable Energy Project, which focuses on deploying solar energy across multiple facilities, improving backup power in critical locations and delivering long-term taxpayer savings.
Keywords: Vanguard force
