As the global population continues to grow with no real sign of slowing down — the
question of resources becomes a greater concern.
Will we have enough food and energy for everyone on Earth both now and in the future?
Turns out, the way to maximize our resources might actually involve killing two birds with
one stone… or… saving two birds with one…
tree…
I don’t know.
The point is that the answer to both food and energy strain might come in the form of
agrivoltaic solar systems.
The idea is to create holistic ecosystems that use agriculture and solar power to maximize
the potential of both!
How do these systems work?
And can they really be the solution for sustaining a growing global population?
Stick around as we explore these questions and more today on Two Bit Da Vinci.
If you’ve ever driven past a solar farm, one thing you may have noticed is that they
require quite a bit of space.
Of course, they need all that space to generate enough electricity to make them viable — and
in general, that’s a good thing.
One drawback of their size, some say, is that it renders the ground beneath them completely
useless.
This poses a problem for farmers who may want to use their land for both solar and more
traditional farming.
The main issue is that the spaces between the rows of panels are too small for modern
farming equipment to pass through.
There’s also the issue of the panels themselves blocking the sun from reaching plants — we’ll
dive more into that in a bit.
One final issue with today’s solar panels, ironically, has to do with heat.
Traditional ground-mounted photovoltaic panels usually have gravel underneath them.
Studies have actually shown that this can create what’s known as a “heat island”
effect — basically, the gravel absorbs heat from the sun and radiates it back, creating
little pockets, or islands, of heat with temperatures above the surrounding area.
The problem here is that, believe it or not, solar panels don’t actually like particularly
hot temperatures.
If solar cells get too hot, they actually lose some of their efficiency.
Panels tend to do best when they stay somewhere between 59 F or 15 C and 95 F or 35 C
However, one solution might actually solve both of these issues simultaneously — and
that’s where Agrivoltaics come in.
The word itself, as you might have guessed, is a combination of agriculture and photovoltaics.
And the concept is essentially to create “novel ecosystems” in which crops and solar panels
work together to maximize the potential of both!
Sounds great — but how would this work exactly?
As we mentioned above — when soil or gravel absorbs heat, it gets trapped under the panels.
So, with agrivoltaic panels, of APVs for short, instead of soil, farmers would plant veggies
under the panels.
As plants take up carbon for photosynthesis by opening up their pores, or stomata, they
also allow water to transpire through their leaves, creating a cooler microclimate, reducing
the heat island effect, and boosting the solar panels’ efficiency.
One challenge for agrivoltaics is engineering the optimal design that fulfills all the requirements
for livestock or crop farming while also keeping the cost of solar panels low enough to remain
profitable.
This can be done in a number of ways.
With livestock farming, solar plant design doesn’t change much from a solar-only project.
Animals are beneficial to solar farms because they can actually reduce the cost of maintaining
vegetation growth without introducing any risks to the panels themselves.
Some farms have even integrated solar parks into the design of the living areas for smaller
livestock like chickens, geese, sheep, and even beekeeping.
In 2016, the Enel Group in Greece began using sheep to basically mow the lawn around their
solar panels which led to both reduced cost of maintaining growth while also reduced fuel
consumption to power larger machinery.
In these instances, however, the land underneath the panels still isn’t useable.
And things get even more complicated with larger livestock like pigs, goats, and cattle.
So what’s the solution?
Well, just like Tony Hawk, the answer is going vertical! [ https://youtu.be/rQ7OqNf19Lc 00:35—
00:38] Vertically mounted bifacial panels collect solar energy from both sides — hence
bifacial.
This allows for more energy per square meter than traditional single-faced panels.
Not only that, but these panels have interesting features that make them particularly beneficial
for farming.
The way these panels are mounted creates more space between and below the panels which allows
more space for farming equipment, while also keeping them out of harm’s way from larger
animals.
In fact, by design these panels need to maintain a certain level of clearance to protect the
stilts from machinery, preserving more of the arable land surface.
These panels can also create a slight wind shielding effect which can protect land and
crops in areas with higher wind speeds.
Some panels can even be outfitted with actuators that allow them to tilt in different directions.
This can allow farmers to optimize solar efficiency as well as plant growth.
Even with these modifications to the panels, not all crops benefit from APVs equally.
In fact, research has shown that there are particular types of plants in particular regions
that may fair quite well when paired with solar panels.
As we know — plants need sunlight to produce energy — we’ve done a whole video on artificial
photosynthesis which you should definitely check out.
So wouldn’t the shading from solar panels hurt the plants?
Well, not always.
While sunlight is a crucial element in plant growth — it provides the photo in photosynthesis
— plants can’t actually convert all available sunlight into biomass.
Once plants reach what’s called the “light saturation point” they can’t absorb any
more energy.
[ https://www.youtube.com/watch?v=SiMHTK15Pik 00:09- 00:14]
Once plants reach that threshold, they expel that excess energy by evaporating water.
Some plants have higher thresholds than others.
Sun plants — also known as “shade-intolerant plants” require higher levels of sunlight.
These would be like the “surfer” plants who love to spend all day having fun in the
sun.
On the other hand — some plants do better in partial shade.
These are kind of like writers who spend days on end inside in front of their computer researching
different types of solar technology.
Both groups of plants still have a saturation point, but one group is much higher than the
other.
Still, both groups can benefit from at least partial shade to avoid essentially getting
sunburned — something.
What this means is that pairing solar panels with certain crops could actually create a
cooperative ecosystem in which the plants and the panels are mutually beneficial for
one another.
So how does this pan out in the real world?
GroenLeven, a subsidiary of the BayWa group in Germany, has conducted a number of pilot
projects to see how agrivoltaic panels might actually work in the real world.
Working with local fruit farms, the group focused on crops like wheat, potatoes, celery,
and various types of berries.
Berries happen to be notoriously fragile crops.
For one experiment, the group turned about 3 hectares, that’s about 7 and a half acres
— into a 2 MW agrivoltaic farm while leaving one hectare as a traditional farm for their
control group.
Typically, for growing crops like raspberries, the farm would use a plastic cover to protect
the vulnerable berries from over-exposure to not only sunlight, but wind, rain, and
other elements.Data from these experiments revealed that on hot days, temperatures beneath
the panels were between two and five degrees cooler than traditional growing methods.
This brought a number of benefits, One, it significantly reduced heat stress on the plants,
and two it reduced evaporation from the soil, which meant less water demand.
At night, the heat was better retained under the solar panels than under the plastic coverings.
Eliminating these plastic sheets could be a major win for farmers who often end up having
to replace them throughout the year as they get destroyed by hail storms.
In fact, during summer storms that occurred throughout the duration of the experiment,
the crops under the panels sustained no damage whatsoever, while the harvest from the control
field was completely destroyed.
These results aren’t isolated to one experiment.
The US Department of Energy conducted experiments with chili peppers and tomatoes.
The peppers yielded three times more with agrivoltaic compared to the control.
Water efficiency was 65% greater for the tomatoes and 157% greater for the jalapenos.
Plus, the experimental panels were about 9 degrees C cooler than the control, leading
to efficient electricity production.
So, judging by these experiments, pairing agrivoltaic panels with the right crops, especially
in hotter, more arid regions, could yield positive results for both the panels and the
plants.
So are we going to start seeing more of the agrivoltaic solar plants popping up in farms
across the world?
Well… that will all depend on a number of mitigating factors.
One major concern for farmers is how introducing agrivoltaic panels may impact some of the
subsidies they receive from the government.
Both the EU and the US offer grants for land used primarily for agriculture.
One crucial question will be whether farmers will still be eligible for financial support
if they introduce more of these types of solar systems.
It’s a question that may come down to percentages — how much land is used for agriculture
and how much is dedicated to solar.
There are also issues relating to costs and permits required to build these solar structures
on the farms.
Offsetting the construction and permit costs with better crop yields may e enough to turn
heads.
But, like most things, it will likely come down to the market to decide the fate of this
emerging technology.
Agrivoltaic solar doesn’t yield as much energy as traditional solar.
Not only that, but the cost per kWh can be between 10-20% higher than traditional solar.
Other factors include who will actually profit from the energy produced by the panels.
In the Netherlands, for example, the farmers are neither the investors nor the owners of
the solar installations, therefore participation comes down to the impact on crop production.
Most farmers are only willing to participate in these types of endeavors if their crop
yield doesn’t fall below 80% of the normal numbers, according to the Fraunhofer Institute.
And that’s only if the farmer can make up that 20% reduction from the energy produced.
Right now, there are plenty of better incentives in place to choose either crop production
or solar production, so it may come down to government intervention or price guarantees.
Without those factors, agrivoltaics may never stand a chance at even getting off the ground.
Still, it’s hard not to dream about using this type of eco-conscious engineering to
design better, for cooperative systems to better integrate green energy into other,
currently under-utilized places.
It will be the companies that come up with the right business models that will truly
bring this idea to light.
Sure it might not be all crops, but the benefits of reduced sun stress and water evaporation,
and better solar efficiency is enough to really make a big impact.
But what do
you think?