A new farm is going up along Interstate 19 near Rio Rico, but it's not raising cotton or even pecans.

Workers are building a 37-acre, 5-megawatt photovoltaic array that will supply power to customers of UniSource Energy Services, a subsidiary of Tucson-based UNS Energy Corp. that serves about 91,000 customers in Mohave and Santa Cruz counties.

The system, expected to provide enough power to supply about 1,500 homes, is being installed in two phases and is expected to be turned on sometime in the first quarter of 2014, UniSource spokesman Joe Barrios said.

The $15 million solar farm is being built for UES by the U.S. arm of German solar energy developer Gehrlicher Solar AG.

The land, on the east side of I-19 near Exit 22, is being leased from the Santa Cruz Valley Unified School District.

The installation is being handled by Southwest Energy Solutions, another subsidiary of UNS Energy Corp., Barrios said.

Like other state-regulated utilities, UniSource Energy is required to generate electricity equal to 15 percent of its retail power sales from solar or other renewable sources by 2025.

Other utility-scale renewable-energy plants that supply UniSource Energy include a 10.5-megawatt combined wind and solar energy farm near Kingman and the 10-megawatt Black Mountain photovoltaic project, also near Kingman.