Constellation Wines will build solar energy systems at its Clos du Bois and Ravenswood wineries in Sonoma County as part of a companywide green energy program, it said Monday.

The system at Clos du Bois in Geyserville will generate about 1.7 million kilowatts per year, or about 75 percent of the winery's energy needs.

At Ravenswood in Sonoma, solar panels will produce about 885,000 kilowatts per year, 100 percent of the winery's energy demand.

The New York-based wine company also is doing solar projects at two of its Monterey County locations, Gonzales Winery in Gonzales and Estancia Winery in Soledad.

About 17,000 solar panels will be installed at the four wineries by the end of this year, the largest solar footprint in the wine industry, the company said. The cost of the 3.95 megawatt project was not disclosed.