JUDY WOODRUFF: Now: As the Trump administration is considering whether to put tariffs on solar

panels made outside the U.S., the rapidly plummeting price of solar panels has led to

a boom in rooftop installations and jobs.

The solar industry now employs almost three times as many people as the coal industry.

This growth is also raising questions about how utility companies should respond.

William Brangham is back with this report from Vermont.

It is part of our occasional series of reports Peril and Promise: The Challenge of Climate

Change.

It's also our weekly look at the Leading Edge of science and technology.

WILLIAM BRANGHAM: Andrea McMahon and her son Caulder (ph) run a dog kennel and grooming

business just outside Waterbury, Vermont.

During the recent windstorm that knocked power out for hundreds of thousands of people in

the Northeast, the lights and blow dryers stayed on at their business.

That's because McMahon had just installed these: two brand-new Tesla batteries connected

to the solar panels on her roof.

All your neighbors were out of power, but you weren't?

ANDREA MCMAHON, Solar Customer: No.

No.

We -- it worked.

WILLIAM BRANGHAM: McMahon installed the panels five years ago.

In the summer, with its ample sun, they generate more electricity than she can use, so the

extra energy is sent to the local utility, Green Mountain Power.

ANDREA MCMAHON: And they credit our bill for the winter, which we use up in the winter,

because there's not quite as much solar working in the winter.

WILLIAM BRANGHAM: Right.

ANDREA MCMAHON: But we basically have no electric bill.

And it's usually pretty big.

WILLIAM BRANGHAM: No electric bill?

ANDREA MCMAHON: No electric bill.

WILLIAM BRANGHAM: You went from paying about $200, $250 a month to now paying nothing?

ANDREA MCMAHON: Right.

Yes.

Nice, huh?

WILLIAM BRANGHAM: The new batteries, which she leases from Green Mountain Power for $30

a month, will allow McMahon to, in effect, become her own personal power plant.

She can operate independently from the grid when power outages occur, and she can sell

electricity back to the utility during peak usage, even when the sun isn't shining.

ANDREA MCMAHON: What we're not using here is going over here to the grid.

Kind of a win-win-win situation.

WILLIAM BRANGHAM: Green Mountain Power CEO Mary Powell also thinks it's a win-win.

In fact, she's the driving force behind her company's expanded push into solar and batteries

and new energy technology.

On the day we met her, she was checking in with line

men who were still at work restoring power to customers.

Powell likes to describe her company as an un-utility.

MARY POWELL, CEO, Green Mountain Power: One of the things we really feel like we're in

the business of doing here in Vermont is accelerating what we believe is a consumer-led revolution

to distributed resources and a completely different model.

WILLIAM BRANGHAM: Powell calls existing utility models grandpa's electric grid, powered in

large part by coal, as well as natural gas, hydro and nuclear power.

Indeed, the bulk of Green Mountain's power comes from such sources.

But she says it's an inefficient system.

MARY POWELL: On a good day, the system is built for about 40 to like 43 percent economic

efficiency.

You have massive power-generating stations, and you move energy over miles and miles and

miles.

You have substations that convert it down to distribution level.

You then have miles and miles of distribution lines, and eventually you get to homes, businesses

and communities.

WILLIAM BRANGHAM: Powell's vision is to begin to move away from that, to using a series

of commercial and residential micro-grids all over the state that can store and share

power with each other.

A micro-grid is any small self-contained network, like this housing community, where, if they

get cut off from the main electrical supply, they can generate enough electricity to meet

all of their needs right here.

This 14-unit development in Waltham, Vermont, was built by industry and nonprofit groups

in a first-of-its-kind experiment for low-income housing.

Each home has a six-kilowatt solar panel system connected to a battery, so in the case of

an outage, residents can power their homes independently.

And residents like Alexis LaBerge pay nothing for electricity.

ALEXIS LABERGE, Solar Customer: I wasn't quite sure what to expect when they were like, oh,

we're building some solar-powered housing, and it's going to be energy-efficient.

And it's really reasonable.

And, as a single parent, that's obviously really important.

(LAUGHTER)

WILLIAM BRANGHAM: CEO Powell concedes that it's easier to re-imagine a power system in

a rural state like hers, with just 600,000 residents.

But she's convinced that even more populous cities and states need to change the way they

think about energy delivery.

MARY POWELL: I drive around different parts of Brooklyn or Queens, and there are, you

know, neighborhood after neighborhood where you could be delivering absolute energy transformation

services, lowering the energy costs of the people that you serve, because you're looking

at it from a total energy perspective.

WILLIAM BRANGHAM: Fifteen miles south lies another vision for changing energy delivery.

Florida Power and Light, the largest utility in Florida, is in the midst of a large-scale

solar construction boom.

This site was one of the first, built nine years ago.

The company now has six other sites, enough to power about 60,000 homes.

WILLIAM BRANGHAM: Kelly Fagan oversees the solar construction.

KELLY FAGAN, Florida Power and Light: We have three plants we just commissioned at the end

of last year.

We have got four more behind that, and we have four more the next year behind that.

WILLIAM BRANGHAM: Those utility scale arrays will use more than 2.5 million solar panels

to generate electricity for the grid, making Florida 10th in the nation for solar generation.

Even so, it will be a small fraction compared to their nuclear and gas resources.

Fagan says it's all about doing what's best for its customers.

KELLY FAGAN: If we go too far in solar, we lose the reliability of our system.

That's why we still need our gas plants and our nuclear plants.

They are the backbone of the system.

They keep us running.

They keep us going when the clouds are out, when the rain is falling and when it's nighttime.

SUSAN GLICKMAN, Southern Alliance For Clean Energy: Historically, despite our nickname

of the Sunshine State, Florida has really lagged behind in adopting solar.

WILLIAM BRANGHAM: Susan Glickman is a lobbyist with Southern Alliance For Clean Energy, and

she has been a loud critic of Florida's private utilities.

She applauds their recent solar building spree, but thinks they game the system by continuing

to build expensive conventional power plants.

SUSAN GLICKMAN: Big monopoly utilities get a guaranteed range of a rate of return on

their capital expenditures.

WILLIAM BRANGHAM: Meaning, if they build a power plant, they're by law allowed to charge

all you customers here in Florida to pay back the cost of that?

SUSAN GLICKMAN: That's right.

Florida regulators will put that in the rate base, and we will all pay for it.

So, like a waiter in a restaurant where there's a guaranteed tip, the more that is spent,

if you buy dessert or you get a bottle of wine, the more money they're going to make.

WILLIAM BRANGHAM: Glickman also says utility companies have tried to put up roadblocks

so that homeowners won't install their own solar panels.

She points out that the utility here spent tens of millions of dollars backing a failed,

and widely criticized, 2016 ballot measure that would've curtailed individual solar projects.

SUSAN GLICKMAN: They want to build power plants, and too often they see rooftop solar as a

threat to that business model.

WILLIAM BRANGHAM: Florida Power and Light says it doesn't discourage residential solar,

but says it isn't very practical.

KELLY FAGAN: FPL is providing solar power through our transmission grid at such a low

cost, it's very difficult to put rooftop solar, even on my own house.

I have looked at it on my own house.

The payback is not very good in Florida because our bills are so low.

WILLIAM BRANGHAM: So, you're arguing that because you guys have provided a lower utility

bill overall, that, on balance, it doesn't make sense for people to do solar individually.

KELLY FAGAN: Yes, that's correct.

Financially, it just doesn't make sense.

WILLIAM BRANGHAM: But that may be changing.

Solar panels have dropped dramatically in price, some 70 percent over the last seven

years.

When we visited Glickman, she was having panels installed on her house, and she says she knows

more and more people who are doing the same.

SUSAN GLICKMAN: I do think there are some people that want to go solar for environmental

reasons.

But more and more people want to go solar for economic reasons, because they see the

payoff.

Solar panels are improving.

They are more efficient.

They can operate even with less solar radiance, so the demand is really there.

WILLIAM BRANGHAM: If that demand continues to grow, Florida utilities may move more into

rooftop solar, joining Vermont and other states where residential solar micro-grids are becoming

almost commonplace.

For the "PBS NewsHour," I'm William Brangham in Arcadia, Florida.

JUDY WOODRUFF: Fascinating.