Green Roofs - Living Architecture Monitor Winter 2020 - 34

" WE'VE FOUND THAT BOTH PLANTS AND SOLAR PANELS
BENEFIT GREATLY FROM BEING CO-LOCATED ON
ROOFTOPS. DURING OUR RESEARCH, WE NOTICED
THAT THE PLANTS UNDER AND AROUND THE SOLAR
PANELS THRIVED IN COMPARISON TO THOSE PLANTS
THAT WERE IN THE FULLY EXPOSED AREAS. "
- JENNIFER BOUSSELOT
Rooftop agrivoltaics are one of the main research areas I
focus on at Colorado State University. Rooftop agrivoltaics
involve the co-location of food and energy production. Putting
both of these systems on rooftops is capital intensive. No doubt
about it. However, with increasing attention to food security and
the vulnerability of food distribution chains during disturbances
such as pandemics, natural disasters, or political unrest, the price
of adding resilience to urban space is less intimidating - especially when you have two systems (food and energy) producing
valuable and renewable products in the same, often previously
wasted, roofspace.
We've found that both plants and solar panels benefit greatly
from being co-located on rooftops. During our research, we
noticed that the plants under and around the solar panels
thrived in comparison to those plants that were in the fully
exposed areas. So, we decided to find out why. It turns out that
temperature variability is lower near the solar panels in both
summer and winter. Plant stress factors such as wind and intense
sunlight are also reduced. In a water limited environment like
a green roof, reducing these stress factors helps conserve water.
Solar panel performance also increases as the plants from green
roofs provide evaporative cooling and improve the efficiency of
panel energy production, even in the high heat environment of
a rooftop.
Making a profit in farming is always a struggle - as a child
of small family farmers in Iowa, I have lived that reality. There
is no doubt that rooftop farming can be even more financially
precarious. I am certain that it is also the case in the photovoltaics industry. History has given us examples of how policy
LIVING ARCHITECTURE MONITOR / WINTER 2020 / 34

can greatly support industries
that had previously been costprohibitive. Think about the
beginnings of the auto industry
and even more recently the
solar energy industry. Rooftop
agrivoltaics could benefit
from a similar scenario. Food
and energy are necessities
that humans will always need
- particularly as our world
population continues to grow
and become more urbanized.
Where do we go from here?
We need research to develop
and test new approaches to
agrivoltaics. As I write this, I
have about $2M in government agency and foundation
grant proposals under review.
They may not be funded,
just like other proposals, also
totaling about $2M, that have
already been declined this year.
Green roofs, and especially
rooftop agrivoltaics, are
tangential to the majority of
currently available funding opportunities. Plus, my genera-

tion of researchers are facing
extraordinarily low funding
ratios and unprecedented cuts
from public sources.
But there is hope. What we
really need are more examples
of projects that incorporate
rooftop agrivoltaics to use as
success stories. That would
help to move rooftop agrivoltaics from theoretical to practical and would transform how
these technologies are viewed
by the public and funding
agencies. This could lay the
groundwork to unleash their
extraordinary potential.
Jennifer Bousselot, Ph.D.,
Assistant Professor at Colorado
University, serves on the
board of GRHC as Chair of
the Research Committee, and
has recently contributed to two
chapters of the upcoming book
Ecoregional Green Roofs by Dr.
Bruce Dvorak. Catch Jennifer's
recent TEDx talk on the topic of
Rooftop Agrivoltaics.
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