Developers will break ground in South Jersey on Wednesday on a $90 million solar-energy farm, one of the nation's largest photovoltaic projects and the latest sign of how renewable power is going mainstream.

Con Edison Development and Panda Power Funds, a power generation investment firm based in Dallas, will build the 20-megawatt solar in Pilesgrove Township, Salem County.

The 71,400-panel solar facility, scheduled to take six months to build, will consume about 100 acres of agricultural land. It will feed the regional grid, so its power can be sold to customers throughout the area.

"It is a big deal," said Todd W. Carter, president of Panda Power Funds. "It will be the largest of its kind in the Northeast, and that's a big project."

The market for solar energy is being stimulated by state mandates calling for an increasing volume of renewable power, such as wind, solar and biomass. New Jersey and Pennsylvania are among 29 states that have adopted such standards, which force utilities to buy renewable power and pass the higher cost on to consumers.

"New Jersey has a very progressive stance on renewables," said Mark Noyes, vice president of Con Edison Development, a subsidiary of Consolidated Edison Inc. of New York. "They've really embraced the concept of clean and green energy."

Residents in the agricultural township with a population of 4,000 had some misgivings about the project, though there is little they could do to stop it as long as the developers complied with zoning regulations.

"There's mixed opinions about it," said Edward J. Kille, Pilesgrove's mayor. He said farmers are concerned that the project - as well as several other solar farms envisioned in the region - will remove productive agricultural land from the market, driving up farm costs.

"Is this an efficient use of prime farming land?" said Kille. "Some of the farmers don't think so. I'm kind of in the middle on it."

Kille said the project will be built on a tract at the intersection of Robbins Road and Yorketown Road whose owner had proposed building an 80-unit housing development before the economy crashed. The property is near a retired township landfill.

Indeed, the solar developers said their project is saving the township from the cost of a suburban housing development, rather than taking a farm off the market.

"We're not using farmland for this solar facility," said Carter.

Con Ed and Panda announced a joint venture in April to build at least two utility-scale solar power projects in the U.S. Northeast. Pilesgrove Solar L.L.C. is their first project.

The facility will be built by RMT Inc., a Madison, Wisc., company that specializes in designing and constructing energy projects. About 100 workers will be employed during construction, Noyes said.

Once the facility begins producing power, it will employ two maintenance workers. The project will be able to supply about 5,100 homes.

Noyes said the panels will be supplied by Suntech Power Holdings Co. Ltd., a Chinese company that is one of the world's largest producers of solar panels.

Suntech is also the chief supplier of solar panels to Petra Solar Inc., a New Jersey company that is installing 80 megawatts across New Jersey on behalf of Public Service Electric and Gas Co.

Noyes said the project benefits from the continued decline in the cost of solar panels. The Pilesgrove project will cost $4.5 million per megawatt. By comparison, a 3-megawatt project at Pocono Raceway in Blakeslee, Pa., cost $5.3 million per megawatt. A megawatt, or one million watts, can power about 800 homes.

The demand for solar is chiefly being driven by state mandates for renewables.

New Jersey's Renewable Portfolio Standard requires that renewable power account for 22.5 percent of the state's electricity by 2021, and that solar contribute 5,816 gigawatt hours by 2026.

Contact staff writer Andrew Maykuth at 215-854-2947 or amaykuth@phillynews.com.