Even Greenpeace underestimated the rise of solar.
When one of the world's largest environmental advocacy groups released an
optimistic industry analysis called the Energy Revolution in 2010, it was
far more ambitious than any government predictions.
And it still got it wrong.
Greenpeace estimated that by 2020, the world would have 335 thousand
megawatts of installed solar photovoltaic capacity.
That's enough to power almost 64 million U.S.
homes and an increase of over 700 percent from 2010.
But by the end of 2018, there were already over 480 thousand megawatts
installed globally, enough to power about 91 million homes.
Elon Musk promised the world Tesla solar roof tiles in 2016, something the
company has yet to fully deliver on.
But it turns out the solar industry may not need the upgrade.
While the aesthetic of solar tiles that look indistinguishable from normal
roofing material is alluring, the industry has been growing exponentially
thanks to plain old solar panels.
You can see the evidence both on people's rooftops and in the desert,
where utility scale solar plants are increasingly popping up.
Here in the U.S., of all new power capacity added to the grid in 2018,
about 30 percent of that was from solar.
Solar in America has gone from this sort of fringe and very expensive
technology to what is effectively now mainstream when it comes to new
generation. And states like California are leading the way with bold solar
targets, incentives and regulations.
Every new home built in California after the New Year must generate as
much energy as it consumes.
So presumably by making the homes very efficient and installing solar.
But the picture is not all rosy.
Solar power is intermittent.
The sun isn't always shining, and the price of storage solutions like
lithium-ion batteries are still relatively high.
Installing solar can be a large upfront cost and permitting can slow the
whole process down.
These are real problems that the industry needs to tackle if solar is
going to reach its potential.
But if the recent past is any indication, solar power is going to help
lead the transition to a carbon-free future.
And it might do it faster than we all expected.
In 2018, solar power made up around 2.3
percent of electricity generation here in the U.S.
That number may seem small, but it's an impressive leap from 2008, when
solar comprised a mere 0.1
percent of our electricity.
Across the country and utility after utility, what's become fringe is the
idea that you might build another coal plant.
Right. No one is really doing that today.
The surge in solar installations has been driven by a steep decrease in
the price of photovoltaics, the technology that powers solar panels for
both residential and utility-scale use.
Since the 1970s, costs have dropped tremendously.
Back then, solar on the ground was about five dollars a watt.
So 50 cents or more per kilowatt hour.
And solar is down now today, in the best large commercial applications, at
one to two cents.
So a factor of 50 reduction.
And on rooftop systems, if you finance it right and you're in a good
location, your effective cost can be under 10 cents.
It does still cost a lot to get solar.
According to EnergySage, an online solar financing marketplace, the
average rooftop panel system in the U.S.
cost about $12,500 after tax credits in 2019.
But after about seven to eight years of lower electricity bills, customers
typically break even and start seeing significant savings.
And to defray the upfront cost, customers can often get a solar loan or
choose to lease the panels instead.
Overall, the massive price drop for photovoltaics is largely thanks to
China's massively subsidized solar power manufacturing program, which
created a worldwide glut in solar panels in the late 2000s.
Prices plummeted and solar companies around the world had to find ways to
slash costs to stay afloat.
Lots of companies went under, but enough innovated and survived such that
in many parts of the country today, solar can now compete on economics
alone. So solar went from essentially the most expensive form to one of
the cheapest. It may be affordable, but it's not perfect.
Solar panels don't generate any power during the nighttime and they're
much less effective in cloudy or shady environments.
And while the price of photovoltaic panels has dropped, the cost of energy
storage options like lithium-ion batteries is still pretty high.
For example, the newest Tesla Powerwall, one of the few small-scale
batteries meant for residential energy storage, is priced at $7,600, not
including thousands of dollars in installation costs.
So while panels often generate excess power during the day, there's not
always an efficient way to save that energy for later, and so customers
often end up relying on non-renewable energy sources at night.
Energy storage is sort of the last puzzle piece to come together to make
solar and wind, any intermittent source, a reality for 100 percent of our
power needs. Furthermore, permitting for rooftop solar takes time and
money. And depending on where you live, installing solar on either a
residential or commercial scale can still involve a large upfront cost,
especially if your state or bank doesn't provide solar-friendly financing
options. Solar installations require that they have to be permitted.
Whether you can do it all remotely or whether you need a building
inspector to come out to your home, all of those add costs, add time, add
delays, which all make the effective price, if the policy environment
isn't favoring solar, often a real challenge to get large amounts of it
deployed on the residential side.
You'll also almost never see solar on apartments or office buildings,
because landlords just don't have a monetary incentive to install them for
renters who pay their own electricity bills.
As for single-family detached homes, about 2 percent have solar.
And while this actually represents a marked improvement, it still means
residential solar is a relatively rare sight.
But experts say it won't stay this way for long.
In California, we have a mandate to have a million solar rooftops by the
end of 2020. We've already met that goal, we're over a million rooftops
now and still growing.
Even if you haven't noticed the rise in solar roofs, visit the deserts or
plains of California, North Carolina or Arizona, and you'll see that a
large percentage of new solar capacity comes from utility-scale plants
producing hundreds of megawatts of electricity that feed into the grid.
One such plant is the California Flats Solar Project, a 280 megawatt solar
farm developed by First Solar and located in Monterey County, California.
The California Flats project is about 2,900 acres.
That's the carbon equivalent of taking about 22,000 cars off the road and
can power about 116,000 California homes.
In 2018, utility scale projects like this generated a total of 66.6
million megawatt hours of energy in the U.S.
That's enough to power about 6.4
million homes for a year and represents 69 percent of the country's total
solar energy production.
The large-scale solar projects can be anything from a 200 kilowatt system
that you might see on the edge of a trailer park or a 400 megawatt project
in the desert. However, plants on the scale of Cal Flats are increasingly
proving to be the most cost-effective size for utility-scale operation.
When you get to 200 megawatts in size, you're able to take advantage of
scale economies so you can deliver a really cost-effective price of solar
power. But when you start getting to larger sizes, sometimes it's
difficult to find suitable land, to find suitable transmission capacity.
So I think you'll see probably a larger number of midsize utility-scale
installations that are more strategically located closer to the load where
the power is being used.
The rise of midsize installations is also being driven by a growing
corporate commitment to renewable energy.
In 2018, corporations overall more than doubled the amount of clean energy
they bought in 2017.
In 2018, Facebook alone signed contracts for around 2.4
gigawatts of renewable energy, which is more solar energy than the entire
residential solar market in the U.S.
combined. This kind of corporate buy-in is ultimately necessary for a
carbon-free future.
About two thirds of power is consumed by businesses.
So even if everybody went renewable, if all houses went renewable, you'd
still only get one third of the way there.
Cal Flats has a corporate partnership with Apple, which buys 130 megawatts
of energy from the facility to power its California operations.
The other 150 megawatts are sold to PG&E, which then combines this solar
power with its other energy sources.
Customers received this blended power by default, but can opt into a
program that allows them to receive more of their power from solar or
other renewable energy sources.
Many people live in cities or may not have access to a rooftop where they
could install a solar system.
So it's important that we have utility scale projects to help really
create lots of opportunity for lots of different types of customers to be
able to get solar power.
However, these utility-scale plants cannot achieve their full potential
without energy storage.
To compete with the reliability of fossil fuels, solar farms need to be
able to generate energy on demand, not just when the sun is shining.
When I've got systems out in the desert and a cloud goes overhead, we want
enough of a shock absorber in the system in the form of batteries to help
cover that power that's missing momentarily.
It could be for a minute. It could be for four hours.
Traditionally, storage has come in the form of lithium-ion batteries.
And luckily, the price for this tech is plummeting alongside the cost of
solar panels. According to Bloomberg New Energy Finance, the average cost
for lithium-ion batteries fell 85 percent from 2010 to 2018.
Now, the average lithium-ion battery costs $176 per kilowatt hour.
So you can draw lines very easily in every part of the country, part of
the world, to say okay, is a solar plus storage system today cost
competitive with this natural gas alternative?
You can draw a line pretty quickly and see where those two are going to
cross for every geography.
In some places, Beebe says solar plus storage has already won out.
Today in places like Hawaii and in California, solar plus storage in most
cases is more cost effective than a natural gas contract.
In other words, those developers are winning bids, solar plus storage
versus natural gas.
Solar power with storage is now often more economical than a type of power
plant known as a peaker, which operates infrequently, only firing when
demand is high. In April 2019, the utility companies Southern California
Edison opted for a solar plant with an 100 megawatt battery over a natural
gas peaker plant in the coastal city of Oxnard.
If regulators approve the plans, it would be tied with Tesla for the
largest lithium-ion battery in the world when it goes online in 2020.
But unfortunately, lithium-ion may not be able to get that much cheaper.
Many experts predict that costs will bottom out at around $70 to $100 per
kilowatt hour. At this price, batteries will continue to be an economical
option for replacing peak er plants and smoothing out hours-long gaps in
solar production. But they won't be a good option for storing energy for
weeks or months on end, as this would massively increase electricity costs
for consumers. Some people think lithium-ion is the ultimate, and the path
forward is to research heavily for improvements to lithium-ion.
Then there are others, and I count myself in the others camp, where I say
lithium-ion has done remarkable things for technology.
But let's go to something far better.
So researchers like Sadoway are exploring new horizons.
Now we're seeing flow batteries, which are liquid batteries.
We're seeing high temperature, nickel metal hydride batteries.
And we're seeing other forms of storage that are not chemical or
battery-based storage ramping up their use as well.
For example, Bill Gates' investors fund Breakthrough Energy Ventures is
backing the development of longer duration liquid batteries that would
ideally be one fifth the price of lithium-ion.
And researchers at Sandia National Labs are experimenting with molten salt
thermal energy storage.
This non battery-based system uses concentrated sunlight to heat up molten
salt, which is then stored in tanks for up to several days and later
converted into steam to power a turbine.
So that power production is the exact same as a coal-fired power plant.
Except instead of burning coal, we're using concentrated sunlight as our
heat source. As for residential solar, the grid itself often acts as a
battery. This is because most states have net metering policies that allow
customers to sell their excess energy back to the grid in exchange for
energy credits, which they can then use to power their home when the sun
isn't shining. But whether storage comes in the form of cheaper
lithium-ion or newer experimental technologies, Kammen says that
government policies and incentives will need to drive adoption, just like
they did for solar panels themselves.
Right now, the California utilities are operating under what's called the
storage mandate. They are required by 2020 to have enough storage onboard
so they can meet 2 percent of their peak demand.
And we're negotiating right now with the state's Public Utilities
Commission to increase that number.
When we get to roughly 20 percent of our peak demand available in storage,
we will be able to run a renewable-only system because the mix of solar
and wind, geothermal, biomass all backed up with storage will be enough to
carry us through even some of these potentially long lulls.
In the meantime, expect to see solar installations continue to rise as
prices fall and incentives and regulations spur development.
What we know is that utility after utility is now sourcing wind and solar
instead of sourcing coal and natural gas.
Five years from now, it will be a little bit odd to see new homes that
don't have solar on the roof.
It'll just become part of the landscape.
At the end of the day, this is an inexorable march toward a transition to
a zero-carbon economy.