(Photo by Will Stone - KJZZ News)

The new Sandstone Solar facility will provide enough power for more than 8,000 homes.

FLORENCE -- More than 180,000 solar panels soak up the midday sun. Alfalfa once grew here not far from the Gila River. Now the Florence solar facility represents the Salt River Project's largest investment in this abundant form of renewable energy-- the 45 megawatt Sandstone Solar facility.

“And that’s enough to power 8,000 to 10,000 homes,” said Jim Snyder with sPower, which built and now operates the plant for SRP. “Solar power has come down so quickly in cost, that probably within another ten years or so it may very well be equal to, if not less than, most other power sources.”

Currently, about 14 percent of the energy sold to SRP customers comes from renewables. This plant will bring the utility closer to its goal of 20 percent by 2020.

“But even beyond that [date] we want to continue to reduce our carbon intensity," said Tom Cooper with SRP. "Given where we see the cost on that relative to other renewables, [solar] will absolutely play a significant role in getting their over time.”

Under its agreement with sPower, the utility will buy power for the next two decades at the price of about 5.3 cents per kilowatt-hour. 

While it can be difficult to make a direct comparison, Cooper said this plant is producing power at a price that is competitive with other renewable and fossil fuels.

SRP has a diverse portfolio of renewable energy, said Cooper, of which solar accounts for less than half. 

“Just because it’s only producing power for maybe 30 percent of the day, whereas some of the other renewables, like our geothermal and biomass, will produce power around the clock," he said. "So it takes a lot more solar to produce an equivalent amount of power.”

Another challenge is that solar churns out the most energy during midday and that goes right into the grid. Meanwhile, peak demand occurs in the early evening. SRP has seen a rapid decline in rooftop solar installations since it raised rates significantly for customers last year.  

Corporation Commissioner Andy Tobin said large scale projects like this can be another effective way to get more solar online.  

“They’re under some heavy duty requirements to get their renewables under control in a very short period of time, and I think they’ve found this is kind of a bright spot in the show,” Tobin said.

The state’s other major utility, Arizona Public Service, plans to have 15 percent of the energy sold to customer coming from renewables by 2025.