Arizona utility Tucson Electric Power has signed an agreement to buy solar energy at a historically low price from a new local system, which includes storage, large enough to power 21,000 homes. Excluding the cost of storage, TEP will buy the system’s output for 20 years for less than 3 cents per kilowatt hour – less than half as much as it agreed to pay under similar contracts in recent years. The new 100-megawatt solar array and accompanying 30 MW energy storage system are expected to be in service by the end of 2019. Together with a planned 100 MW wind project, the new system will give TEP a renewable portfolio that produces enough clean energy each year to serve the annual electric needs of nearly one out of every three Tucson homes. TEP has set a target of delivering at least 30 percent of its power from renewable resources by 2030, doubling the state’s 2025 goal.