BUFFALO, WV—Toyota’s engine and transmission assembly plant here will soon be the site of the largest solar panel array in the state.

LANCASTER, CA—Construction has begun on a solar energy project at BYD’s Coach & Bus assembly plant here. When fully operational, the project is expected to save the factory more than $100,000 per year in electricity costs.

When it comes to jewelry, copper is definitely less valuable than gold or silver. In the world of assembly, however, copper is much more in demand. Its uses range from electrical conductors in wire, to solar-cell foundations, to sheet metal products for commercial and residential applications.

SUNDERLAND, UK—Nissan has installed a 4.75-megawatt solar farm at its assembly plant here. Together with other renewable energy sources, the farm will generate enough power to build more than 31,000 cars every year.

PLANO, TX—Toyota will use solar panels at its Texas headquarters, which is currently under construction, to get 25 percent of its power from the sun.

HAGERSTOWN, MD—Volvo Group has installed a 5,000-panel solar canopy in the parking lot of its power train assembly plant here. The canopy will produce 1.3 megawatts of electricity for the facility.

WARREN, MI—General Motors is collaborating with DTE Energy to build a new 800-kilowatt solar array at its Warren Transmission plant here. The 2,800 solar panels will generate clean electricity that will go back to the grid.

HAGERSTOWN, MD—Volvo Group North America has installed 5,000 solar panels at its power train assembly plant here. The company erected a canopy of solar panels above its parking lot to generate approximately 1.3 megawatts of electricity, enough power for 200 homes.

DEARBORN, MI—Ford Motor Co. and DTE Energy Co. plan to build a large solar array at the automaker’s headquarters here.