One of the things anti-solar people like to bring up is that it can take up space. Sure, rooftop solar is popular and doesn’t take up space that could be used by something else, but utility solar installations often entail large “farms” where acres and acres of land are taken up by long rows of solar panels. At the same time, we’re experiencing a decline in pollinators, especially bees. A recent study shows us that the two issues can actually be put together to solve them both.
It’s nothing new for traditional farmers and solar farmers to work together to see if they can share a plot of land. This is known as agrivoltaics. Most crops can’t grow under solar arrays because they just don’t get enough light, but there are crops that do fine and maybe even a little better. This usually involves lower crop yields and fewer panels (and thus less electricity output), but the overall use of the land is greater than either use would yield alone. Panels must be raised above the ground a bit to allow room for agricultural machinery and workers in most cases, but the extra moisture below the panels helps lower their temperature and increase output.
Animal agriculture can also be a type of agrivoltaics when the land used for animals is shared with solar panels. For example, one can raise and graze smaller animals like goats or sheep in the same fields where solar panels generate electricity. By having grass or other animal-edible plants under the panels instead of bare dirt, the panels are more efficient.
When we think of animal agriculture, we don’t often think of insects. In many cases, insects are bad for crops because they’ll destroy the crops, eat them, or end up in the finished product. Bees are a special case, though. By placing beehives near a field, you can increase production by helping move more pollen around, while also ending up with honey that can be sold. It’s a win-win in that case, and it can be a win-win-win if you add solar panels to the mix. Even ground-based panels with little room under them can fit small plants and bees.
But does this work out well, for solar panels, bees, and a crop to all share a space? The limited light under panels, one might naturally think, would reduce the pollen and thus reduce the supply of food for the bee colonies. It turns out that this has been studied, and it’s something that can work out not only OK, but quite well for the bees.
What The Research Shows
The researchers put some plants under panels where they’d always get shade. They put others in between rows, where they’d get partial shade. Finally, they put some plants out in the sun to serve as a fair point of comparison (control).
The places where there was full shade, as one might intuitively guess, didn’t do so hot. There were fewer flowers and less diversity of flowers in the full shade, and thus it was less of a good place for the bees. The surprise came when the researchers compared the partial shade with the full sun groups. It turned out that pollinator abundance, diversity, and richness didn’t take a hit in the partial shade.
In fact, the partially shaded areas ended up having greater diversity and the bloom was delayed. This benefited later-season pollinators (including bees), which would give a pollinator an advantage in dry areas. The “farming” season would be longer for bees when there are areas with partial shade because the late season still has good pollen due to the delayed flowering.
When we aren’t talking about domesticated beehives, this availability of plants and flowers is especially important. When we cut down whole fields and leave them bare under a new solar farm, we deprive wild bees and other pollinators of any pollen to make food with. If we instead grow plants of some kind under the panels (even if the main goal is just to cool them off), the availability of food can actually increase in the solar farm’s area and help save wild bee populations from extinction.
Even if nothing is growing that humans can eat, it’s still beneficial for the health of bees and other pollinators (domesticated or wild) to not leave the ground bare under the panels. That may make management easier (no need to deal with weeds, etc), but it lowers panel efficiency compared to those that have plants beneath them to lower temperatures and increase moisture.
In other words, it’s good for the bees and the panels to have some flowering plants under the panels, especially between the rows where shade will be partial and not full. There’s no reason to not do this.
Why This Matters
The loss of bees worldwide is an extinction-level risk for humans. The plants we rely on to eat and stay alive in turn rely on bees to spread their pollen. If the pollen doesn’t get moved around from flower to flower and plant to plant, the plants can’t produce food. Obviously, that’s a bad thing for humans, because we need food.
Research shows that food production hasn’t been affected yet because the pollinator-plant system can take a pretty good hit before things go wrong. Even with 3/4 of the pollinators gone, things are largely OK at this point, and mathematical models show that this can continue under increasingly harsh conditions–to a point. When things get extreme and the tipping point is reached, human agriculture and the bees collapse completely, and fast.
If that happens, we might not all starve to death that year, many crops use wind for pollination or use vegetative propagation and thus no pollen is needed, but things will get bad. Some vital portions of our nutrition (notably vitamin A) would get wiped out. Billions would die as vital nutrition from fruits and vegetables was lost, and many others would get sick. If this went on long enough, it could end up killing us off in the long run.
Anything we can do to make more space for pollinators and make life better for them is better for us, too. Putting the plants in is good. Putting fields of solar with plants and some rows of honeybees is even better for the agriculture in an area. Bees can travel 5 or more miles from the hive, so it doesn’t take that many of these agrivoltaic fields to help.
Featured image: Beehives in Minnesota by Jonathunder, CC-BY-SA 3.0.