Grid-scale solar costs less, provides more environmental benefits than residential rooftop solar


With more than 300 days of sunshine every year, Arizona is a natural for solar power. In fact, the state was recently ranked number two for total solar energy capacity. This clean resource will remain an important piece in powering Arizona’s energy future, and APS continues to evaluate how to get the most solar and most solar benefits for the least cost to customers.

According to recent reports from MIT, Harvard and the Brattle Group, grid-scale solar power generation (large solar farms that typically contain solar panels that track the sun across the sky) has been shown to be more cost-effective and provide more environmental benefits than residential rooftop solar generation. Put another way, both grid-scale solar and rooftop solar could achieve the same environmental benefits, but the cost to do so with grid-scale solar would be much lower. In addition, grid-scale solar means all APS customers are solar customers, not just the ones who can put panels on their roof.

“At APS, we understand how important solar is to our customers and to our state,” said Tammy McLeod, APS Vice President of Resource Management. “We also understand the importance of the environmental benefits solar power brings. Our question is: why pay more for the same sun?”

For an equal hypothetical $20 million investment, grid-scale solar in Arizona could generate 28,500 megawatt-hours (MWh) of energy in a year, compared to residential rooftop at 12,400 MWh. Using the same example, when it comes to environmental impact, grid-scale solar avoids 25.6 million pounds of carbon emissions in a year, while residential rooftop avoids 11.1 million pounds. Water savings from grid-scale solar are 8.9 million gallons per year, while residential rooftop saves 3.9 million gallons.

“We’ve seen purchase agreements for grid-scale solar of five cents per kilowatt-hour, or less,” McLeod said. “We pay nearly three times that to purchase from rooftop solar.”

Grid-scale solar costs less and operates more efficiently due to the economies of scale gained by building a plant with thousands of panels, as opposed to the average residential rooftop. In addition, these large scale solar plants can be optimally situated in areas of peak sunshine, not wherever a home happens to have been built. Finally, the technologies used at grid-scale solar plants incorporate sophisticated tracking mechanisms, so panels move to face the sun throughout the day, including late afternoons when our customers need the most energy.

Since 1954, APS has led the advancement of solar energy. In fact, for the past five years APS has been hard at work overseeing the construction, maintenance and delivery of solar energy from nine grid-scale solar plants around the state that are part of the APS AZ Sun Program. APS understands how important solar is to Arizona, and the company will continue to invest in solar technology to power homes across Arizona.

APS, Arizona’s largest and longest-serving electricity utility, serves nearly 1.2 million customers in 11 of the state’s 15 counties. Stay up to date on the latest APS news and events by visiting or

Media Contact:
Jenna Shaver

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