Transcriber: Kristina Tacoy Reviewer: David DeRuwe
The other day, I got into a fight.
This fight was between one of the largest solar energy companies
in the United States and residents of a small Arizona town.
Now, we were all packed into a county courthouse,
and this is where the solar energy company
explained that if they could do the development project in the small town,
it could bring clean, green energy to most of Arizona.
The farmer whose land they wanted to develop was also in this room,
and he explained how doing this project would be a great benefit
to him and his family.
On the other side of the room, you had local residents and farmers
who were worried that if they put solar panels on this land,
it could never be used for farming again.
Now, I got in the middle of this fight because I wanted to share my experience
as a researcher studying agrivoltaic farming.
Agrivoltaics, that’s agriculture and photovoltaics,
growing food beneath solar panels.
Photovoltaics is a technology that allows solar panels
to convert sunlight into electricity.
The same solar panels you find on the roofs of houses,
covering parking lots,
and built into those little yard lights that will never stand up straight.
Now, when I shared my experience working on agrivoltaic farms,
the planning and zoning commissioner himself told me,
“You can’t grow plants in shade.
It’s impossible to grow crops beneath solar panels.”
So, what is agrivoltaics, and why did I get into this fight?
Let’s go back.
The idea of agrivoltaics originated in Germany in the 1980s,
when Adolf Goetzberger and Armin Zastrow
published a research paper describing, that if you could raise solar panels
high enough and space them far enough apart,
you could share the sunlight between the panels and the crops below,
producing food and electricity on the same piece of land.
But you have to realize
that solar panels were inefficient and expensive at that time.
So the idea laid dormant.
That was until the 1990s when the Japanese
built the very first agrivoltaic farm in the world.
Remember, Japan is a series of mountainous islands with little flat land.
Most of it is already used for cities and infrastructure,
and the rest is for agriculture.
So when the Japanese wanted to adopt solar energy,
the only place they could put it was where their agriculture already existed.
And so in 2013, the Japanese government created a program
to support the adoption of agrivoltaic farming.
And by 2018, there were nearly 2000 agrivoltaic farms throughout the country.
What’s fascinating is that no one in the Western world
knew anything about them until we had a global conference in 2020.
So in Europe, agrivoltaic farming began in the mid 2000s.
The French built an agrivoltaic farm
to study field crops like wheat and corn beneath solar panels.
And the Germans quickly followed suit,
building their own agrivoltaic farm to study field crops below solar panels.
By 2015, the Chinese had built the largest agrivoltaic farm in the world,
growing goji berries on the edge of the Gobi Desert.
Now, it was around the same time that my academic advisor,
Dr. Greg Barron-Gafford, was doing research in southern Arizona.
Him and a team of student workers were looking at mesquite trees
and native grasses, trying to understand how they share sunlight and water
in the extreme desert environment we live in.
They had a solar panel out there to power their equipment at this remote field site,
and near the end of the rainy season,
these students decided to go on a road trip, that is,
without telling Greg.
And when they got back, all of the grass in the area had died.
Now, that was except for the grass growing beneath the solar panel.
Greg might have been upset with the students,
but he was even more intrigued to see green grass growing
beneath the solar panel when the grass all around had turned brown and died.
At the same time, he was studying
the potential heat island effects of solar panels.
That is, when you have big fields of solar panels,
does it raise the air temperature?
And, yes, he found it does raise it by a few degrees.
He also knew that plants have this effect of cooling the air
as they move moisture from the soil into the plant and into the atmosphere,
so he thought, “Could we actually counteract
that effect of warming by the panels, by growing crops below them?”
And what he did was repeat the experiment.
He got more solar panels and rolled out turf grass below them,
and to the side in the full sun.
He found the same results.
The grass growing beneath the solar panels stayed green longer,
while the grass in the sun turned brown and died.
At this point, he was ready to scale things up,
and he built the agrivoltaic research farm at the Biosphere 2 that we work at today.
Now, here we’ve grown every crop you can imagine
from onions, tomatoes, potatoes, herbs, lettuce.
And everything grows really well in the shade of solar panels, we found.
In fact, we’re able to conserve water, and we do address that heat island effect.
So let’s walk through some of this:
When we grow crops beneath solar panels,
we produce the same amount of food as in the full sun,
if not more sometimes, and the food that we grow doesn’t taste any different.
When we’ve tested this with randomized trials,
no one can tell the difference between food grown beneath solar panels
and food grown in the sun.
And we're able to conserve water here, which is so important in our state.
In the middle of summer, we have to water our plants in the sun at least every day.
Under the solar panels,
we might only have to water them once a week.
And that could mean the difference between giving up farming
or continuing to farm,
as farmers here face water cuts and shortages.
Now yes, the solar panels actually are cooled
by the plants growing beneath them.
We counteract that heat island effect, but solar panels don’t like to be hot.
For every degree above 77 Fahrenheit, they start losing efficiency.
And by growing crops below those solar panels, cooling the panels,
we’re actually increasing the efficiency of the solar panels.
That means combining agriculture and solar energy produces more electricity
than solar panels over bare ground.
Now, we don’t like to be hot either,
and we have to spend entire days
in the field doing measurements here in Arizona in the summer.
From before sunrise until after sunset,
we are in the sun and by noon, you’re exhausted and ready to collapse.
But under the shade of solar panels, you can work all day and still feel fine.
This is important because millions of farm workers in our country
face these conditions every single day,
and they are 20 times more likely to die of heatstroke than the average person.
So, if these farm workers could be working beneath the shade of solar panels,
that could mean the difference between life and death.
Now, I’m fascinated by agrivoltaics,
and I wanted to see all the different ways it was used in the world.
So last summer I traveled to Europe and began in Germany,
where farmers are using solar panels to cover their apple orchards.
These solar panels are actually semi-transparent,
mostly glass with little black squares, so they still produce electricity.
But importantly, these solar panels protect trees from damaging hailstorms.
Normally, farmers in this region have to buy expensive plastic netting
every few years to protect their apple orchards,
but by replacing it with solar panels, they’ve now saved money,
reduced their waste, and permanently protected their orchards from hailstorms.
There’s something surprising they found though:
when these apple trees are growing in the sun,
they produce way too many flowers,
and the farmers have to manually pick off hundreds of flowers
in order for the apples to grow to the right size.
Under the shade of these solar panels,
the trees actually produce the desired amount of flowers,
and the farmers don’t have to do any extra work.
That’s huge.
And it’s these kind of surprising findings
that drive us to continue studying agrivoltaics.
So next I went to Italy
and found a completely different type of agrivoltaic system.
Here, we had solar panels raised 20 feet in the air.
They tracked the sun from east to west during the day
and north to south throughout the seasons to maximize the energy they produce.
Beneath, there were rows of corn, soy and flax as far as the eye could see.
And the important thing was that when I was visiting,
they were having a historic drought.
The river that fed agriculture in this region,
the most agriculturally important region of Italy, was at a record low,
and agrivoltaics might just be the solution they need
to face the future that’s going to be hotter and drier.
The situation was very similar in my next location.
I went over the Alps and over to southern France,
where you might imagine what they were growing.
That’s right. Grapes for wine.
Here, the solar panels were in a similar design,
high in the air, tracking the sun throughout the day.
But these panels had the unique ability to change their orientation on demand
to allow more sunlight to hit the grapevines
or to hit the solar panels to produce more electricity.
And this was up to the farmer, depending on their needs.
Now, as our world continues warming and continues drying out,
this innovation is the difference between wine or no wine.
Now, what about back in the United States?
What’s going on here?
Do we have agrivoltaics besides our Biosphere 2 farm?
I’m lucky that I work on the largest agrivoltaic farm in the United States.
This is Jack's Solar Garden, just north of us, outside of Denver, Colorado.
Now, here we have over four acres of solar panels tracking the sun,
and we’re growing a variety of vegetables and herbs
that are sold throughout Denver County.
The electricity produced here goes straight to the communities
surrounding the farm.
And the farm hosts workshops, events, concerts,
all types of ways for the community to come into direct contact
with agrivoltaics and see that, yes, the food is good to eat,
the energy is helping the community,
and this is something that we not only can have, but need.
So, that’s agrivoltaics.
And when we think about why I got in the middle of the fight,
it was because I wanted to show these people
that there’s a middle ground.
There’s an option between just this or just that.
And that planning and zoning commissioner
could actually be the solution and not the problem,
because in the end, it was only a change in zoning
that allowed agriculture and electrical production
on the same piece of land that made Jack’s Solar Garden possible.
So I invite you all to imagine agrivoltaics in your community
and think about how we can make that possible.
Thank you.
(Applause)