Sonoma County Water Agency Installs over 1.5 Megawatts of Solar Power

Our goal is to use 100% renewable energy and the SunPower project is taking us closer to that goal.

– Cordel Stillman, Capital Projects Manager, Sonoma County Water Agency

Sonoma County Water Agency (SCWA) provides water supply, flood protection and sanitation services for portions of Sonoma and Marin counties. As part of their Sustainability Initiative, they are committed to reducing their greenhouse gas emissions to 25% below their 1990 levels by 2015. In addition to the Agency’s solar power systems, by adding a new 1.04-megawatt solar tracking system at the Sonoma Valley County Sanitation District facility, the District will cover at least one third of its power needs there and help achieve SCWA’s overall goals under its Sustainability Initiative.

Following the Sun

The Agency is committed to adopting sustainability measures: they are conducting energy audits of their buildings, upgrading their fleet to hybrid and hybrid plugin vehicles, purchasing 6 MW of landfill gas generated power, and upgrading to higher efficiency motors on their pumps. When SCWA looked to expand their solar investments, they sent out a request for proposal. “SunPower came in with the best and most competitive package,” said Cordel Stillman Capital Projects Managers for SCWA. For long-term capital investments, the Agency looks for solid financial performance and their SunPower solar installation is on-track to deliver this return-on investment at the benefit of its constituents.


The California energy crisis of the 1990’s resulted in significant increase in the cost electricity, so government agencies sought means of helping reduce energy use through energy efficiency measures, distributed generation and conservation. The Sonoma County Water Agency implemented an Energy Policy and Strategy to reduce energy use and stabilize their utility bills.

Optimizing Energy Output

In April 2007, SunPower completed a 1.04-megawatt solar power system, the third installation for the Agency at the Sonoma Valley County Sanitation District facility.With 5,208 ground-mounted solar panels covering nearly five acres, the system will meet at least one-third of the treatment plant’s power needs which is equivalent to powering over 1,000 homes during the day, offsetting the Agency’s expensive utility-supplied electricity. SunPower® Tracker solar technology, which enables the solar panels to automatically follow the path of the sun throughout the day, increasing energy capture by up to 25 percent over fixed-tilt systems. Based on SunPower’s unique system design, SCWA was also able to preserve a good portion of the surrounding wetland area.

Project Overview

Location:    Sonoma Valley Water Agency Headquarters, Santa Rosa,CA
Completed:    May 2006
Installation Type:    Commercial Roof
System Size:    422 kW
Products:    SunPower® PowerGuard®

Location:    Sonoma Valley Water
Completed:    May 2006
Installation Type:    Solar Carport
System Size:    100 kW
Products:    SunPower Parking System

Location:    Sonoma Valley County Sanitation District, Sonoma, CA
Completed:    April 2007
Installation Type:    Ground System
System Size:    1,044 kW
Products:    SunPower® Tracker


Over the next 30 years of the system lifetime, the solar installation will help SCWAto reduce their carbon dioxide emissions by 17,000 tons, which is equivalent to planting 5,000 acres of trees or removing 3,000 cars from California roadways.SCWA has been pleased with their solar investment. Going forward, SCWA looks further expand their solar investments with additional large-scale projects.