Southern California Edison has signed a 20-year deal to buy energy from a solar farm in Kern County.

The deal is for output of 20 megawatts that will come from the Redcrest Solar Farm project, which is slated to begin construction on 160 acres of low-productivity farmland next year with the goal of becoming operational by mid-2015.

The farm is being developed by 8minutenergy Renweables LLC of Palo Alto, alongside German solar power firm Saferay Inc. Terms of the deal, announced Monday by 8minutenergy, were not disclosed.

The contract would help SCE, a unit of Rosemead-based Edison International, meet a state rule that the utility gets 33 percent of its power from renewable resources by 2020.

SCE said in a statement to the Business Journal that it has recently awarded 13 such renewable energy contracts for 201.5 megawatts.