Solar Greenhouses Generate Electricity and Grow Healthy Crops

Loik’s team monitored photosynthesis and fruit production across 20 varieties of tomatoes, cucumbers, lemons, limes, peppers, strawberries, and basil grown in magenta glasshouses at two locations on campus and one in Watsonville, California.

“Eighty percent of the plants weren’t affected, while 20 percent actually grew better under the magenta windows,” said Loik. Tomatoes and cucumbers are among the top greenhouse-produced crops worldwide, he said.

In additional experiments, small water savings were associated with tomato photosynthesis inside the magenta glasshouses. “Plants required 5 percent less water to grow the same amount as in more conventional glasshouses,” he said.

“I thought the plants would grow more slowly, because it’s darker under these pink panels. The color of the light makes it like being on the Red Planet,” said Loik. “Plants are sensitive not just to the intensity of light but also to color. But it turns out the plants grow just as well.”

Reducing the energy consumed by greenhouses has become a priority as the global use of greenhouses for food production has increased six-fold over the past 20 years to more than 9 million acres today–roughly twice the size of New Jersey, according to Loik. “It’s big and getting bigger,” he said. “Canada relies heavily on greenhouses for vegetable production, and their use is growing in China, too.” Plastic greenhouses are becoming popular for small-scale commercial farming, as well as for household food production, he added.

Greenhouses use electricity to control temperature and power fans, lights, and other monitoring systems. “This technology has the potential to take greenhouses offline,” said Loik, who specializes in climate change, plant physiology, water resources, and sustainable technologies. Cost per panel of WSPV technology is 65 cents per watt–about 40 percent less than the per-watt cost of traditional silicon-based photovoltaic cells.

“If greenhouses generate electricity on site, that reduces the need for an outside source, which helps lower greenhouse gas emissions even more,” said Loik. “We’re moving toward self-sustaining greenhouses.”