With less than two weeks until Joe Biden takes office — and with Democrats taking control of the Senate — the growth of clean energy is poised to accelerate. Even if Congress doesn’t fully embrace the president-elect’s $2-trillion climate plan, there will be plenty of actions his administration can take to support renewable power and put pressure on fossil fuels.
So here’s some food for thought: If Biden’s appointees want to help consumers save money, they might consider devoting a big chunk of their efforts to solar panels and batteries that can be installed at homes across the country.
Critics have long dismissed rooftop solar as a niche product for wealthy homeowners who want to feel good about going green or are looking for security against blackouts. And it’s conventional wisdom among utilities and regulators that large solar farms have an inherent cost advantage over the rooftop alternative because they benefit from economies of scale.
Chris Clack sees things differently.
Clack is a leading energy systems researcher, and to say his latest work caught my attention is an understatement. In a fascinating report released last month, Clack and his coauthors estimated that eliminating nearly all planet-warming pollution from electricity generation would be $473 billion cheaper with dramatic growth in rooftop solar and batteries.
That calculation is based on Clack’s exhaustively detailed model of the U.S. electric grid, which he says includes 10,000 times more data points than traditional models and allows for a better accounting of rooftop solar’s costs and benefits to the grid. The model is such a complex beast that Clack built his own computers to help run the simulations, which can take five days to complete.
But the results come down to simple dollars and cents.
Researchers from Vibrant Clean Energy, the consulting firm Clack founded, looked out to 2050 and projected how electricity costs would change under a national policy requiring emissions to fall by 95%. When they mimicked traditional models that favor large solar and wind farms, they found that consumers would collectively pay $385 billion more for power over the next 30 years. Not an unreasonable price tag for taking a huge bite out of climate change, but still not the preferred direction if we can help it.
But when they optimized for smaller-scale solutions — the thing Clack says his model is uniquely good at — they found the cheapest way to reduce emissions actually involves building 247 gigawatts of rooftop and local solar power (equal to about one-fifth of the country’s entire generating capacity today). In this scenario, consumers would save $473 billion, relative to what electricity would otherwise cost.
Even without strong national climate policy, they found, Americans would spend $301 billion less on energy compared to business as usual, if only utilities and regulators could be prodded or compelled to help people put solar panels on their roofs and batteries in their garages wherever it made economic sense.
I should note that Clack’s research was funded by several pro-solar advocacy groups. That doesn’t mean it’s wrong or biased, just that it’s coming from a different perspective than, say, research supported by a utility company or a gas generator.
“We’re saying something that’s a bit heretical,” Clack told me. “I think we’re getting a different set of answers from the utilities and others because of the way the modeling has been done.”
For some outside perspective, I called Jesse Jenkins, a Princeton University energy engineer whose PhD research focused on the exact types of questions Clack is trying to answer. Jenkins was a lead author on Princeton’s Net-Zero America study released last month, which reached the encouraging conclusion that achieving net-zero emissions by 2050 — the long-term target urged by climate scientists and endorsed by Biden — can be done without increasing energy costs beyond historical levels.
Jenkins told me he’s not quite as optimistic about rooftop solar as Clack is, in part because he’s found that large solar farms are a cheaper way to generate power and that more rooftop solar results in fewer large solar farms. He raised several questions about the precision of Clack’s model, saying it’s incredibly difficult to fully simulate local electrical networks, which vary wildly from city to city, suburb to suburb and rural town to rural town.
Still, the two researchers are mostly on the same page.
While Jenkins and his colleagues didn’t attempt to calculate the optimal amount of rooftop solar on the grid, the amount they assumed would ultimately get built — 185 gigawatts — wasn’t far off from Clack’s 247 gigawatts.
And they both agree we’ll need enormous investments in big solar and wind farms — about 1,500 gigawatts by Clack’s reckoning, and 2,000 to 3,000 gigawatts in the Princeton group’s estimation, supported by massive new transmission lines to carry the clean electrons where they’re needed. To make that happen, America needs to start picking up the pace of development immediately, building much more renewable energy every year than it is today.
“I know there are a lot of folks who don’t study this for a living who have in mind that everybody will have solar on their roof and batteries in their garage, and we won’t need to do all this ugly transmission expansion. And that’s unfortunately not the case,” Jenkins said.
Rooftop solar’s role may depend on how cheap the technology gets. And there’s plenty of room for costs to fall.
Alex Laskey, who founded the energy software company Opower and more recently helped launch the advocacy group Rewiring America, points out that rooftop solar costs much less in Australia than it does here. That’s because U.S. solar installers must spend a bunch of extra money on arduous permitting requirements and other bureaucratic hurdles — and subsequently also on marketing, which is more expensive when you’re selling a costlier product.
“As soon as you make rooftop solar more affordable than grid electricity, the product starts to sell itself,” Laskey said.
Rewiring America released a report in October finding that a national transition to solar-powered, fully electrified homes — with electric appliances replacing gas heating and cooking, and electric vehicles replacing oil-fueled cars — could save the average household more than $2,500 per year. The group sent me California-specific data showing similar results here.
Those savings depend on rooftop solar costs coming down substantially, which is far from guaranteed.
But government policies can help, and here we circle back to Biden. Rewiring America co-founder Saul Griffith, a MacArthur “genius” grantee, said the federal government could support low-cost loans to households that might not otherwise be able to cover the upfront costs of going solar and switching to electric appliances. The Biden administration could also work with local governments to rewrite building regulations and make installation a faster, cheaper process.
Only time will tell what the next four years hold. Clean energy is on the rise, but what that looks like — and whether it happens fast enough to forestall the worst consequences of climate change — is yet to be determined.