California says all new homes must have solar panels

California just became the first state to require that all new homes be installed with solar panels, a continuation of its ambitious plans to completely wean itself off fossil fuels within two decades. 

All five members of the California Energy Commission voted for the mandate Wednesday morning, which will go into effect on January 1, 2020 for single family or “multi-family” buildings three stories or less. Other, less visible standards were also put in place, like improved window insulation to contain costly, climate-controlled air.

The state — which is itself the world’s fifth largest economy — is already well on its way to meeting aggressive renewable energy goals. State law requires California to generate half its power from renewables like wind and solar by 2030. Utilities say they’ll likely meet this goal 10 years ahead of schedule, in 2020. 

Solar panels on new homes can certainly be a boon, powering your fridge and air conditioning during the day while sending any excess power back into the grid. But they won’t be as significant as other, less flashy mandates. 

“They speak to the future,” Michael Picker, president of the California Public Utilities Commission, an agency separate from the state’s energy commission, said in an interview. 

“But a much more brilliant solution were energy efficiency standards,” said Picker, referring to the 1970s-era rules mandating that antiquated, power-hungry appliances become far more efficient. While energy demand has doubled across the U.S. since the 1970s, California’s has remained flat, even with its active economy and burgeoning population, said Picker.

“It’s hard for people to love [the 1970s’ mandate], because people don’t see it,” he said. “Solar is not bad, but it’s expensive and it does produce new challenges.”  

The U.S. is importing more solar panels, mostly from Asia.

There are some grievances about added costs from installing solar, which the state estimates could tack on over $10,000 to building a new home. But the energy commission said new homes with solar panels will cut energy use by over half, saving homeowners around $80 a month. 

“That is something that is paying across over the lifetime of the building,” Hope Corsair, program director and associate professor in electrical engineering and renewable energy at the Oregon Institute of Technology, said in an interview.

Overall, the price of producing solar energy has dropped significantly, mostly because the price of photovoltaic solar panels — the type mandated on Californian homes — has dropped, the U.S. Department of Energy said last year.

Corsair said that in concept, this solar mandate “is great,” especially in places that have a lot of power demand, but not enough supply. Solar installations can pick up the slack here, without emitting heat-trapping greenhouse gases. 

In March 2017, both wind and solar energy combined to produce 10 percent of the nation’s power.

But, Corsair cautions that “the problem starts when you install solar in a location that already has enough power.” 

During the day, especially at high noon when the sun is directly overhead, the panels will typically produce too much energy. 

“This energy has to go somewhere,” she said, and that means that it will be sent back into the greater electric grid. (Most homeowners don’t have expensive battery storage units like like Telsa’s Powerwall). This can certainly be a good thing — providing clean power for the area to use. But much of today’s power grid isn’t capable of accepting flows of energy back into the grid, when it’s already pouring loads of energy out into the community. Corsiar related this to trying to pour water back into an active sprinkler — it’s just can’t be done.

“The power grid is far more complex than water piping,” said Corsair, and if there’s too much energy being pumped back into the grid, equipment can be damaged, or certain power plants may have to be turn on and off, causing overall increases in carbon pollution. This has actually happened in Germany, she said.

“You can only move so much power over a transmission line,” said Corsair. “You’ll find parts of the electrical grid that are 75 or 100 years old.”

Solar panels on homes won’t be California’s renewable savior in and of itself, but they will be part of the greater renewable solution. “It’s not any one thing that works,” said Picker, citing that tightly-sealed insulation in homes and efficient appliances continue to contribute to the carbon-mitigation effort. 

California already has sprawling solar farms in its Mohave Desert.

Even when California homes are powered almost entirely by renewables like solar, they may still need to rely on some natural gas-burning for some time, even if these carbon-emitting plants are only used for around 200 hours a year, said Picker. When the sun starts setting, especially when it’s hot, solar power alone won’t be able to power many homes, requiring energy producing “peekers” to rapidly fire up and meet demand. 

“You need something you can spin up real fast,” said Picker. “It’s a counter-effect, and we can deal with it.”

Exactly how much electricity California will produce on new rooftops in the Golden State’s neighborhoods isn’t know. But it relies on one major factor. 

“It depends on how much new building construction there is,” said Picker.