The “duck curve” illustrates the demand for energy throughout the day. Solar energy reduces demand during the day when the sun is shining. (Photo: California Independent System Operator/Department of Energy via The Republic)

The California Energy Commission this week required all new homes built in that state to have rooftop solar starting in 2020.

The bold new requirement raises an interesting question for the Golden State’s sun-drenched neighbor: What would happen if Arizona enacted such a policy?

Some new housing developments offer solar as an option, or even a standard feature, but Arizona doesn’t require the panels on new homes.

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