Rotating Solar Panels Can Increase Efficiency by 32 Percent, Study Shows

Using existing solar tech, some water and some rocks, rural African communities could soon have reliable electricity.

Beth Parks 

While on a Fulbright fellowship in Uganda, Colgate University professor Beth Parks noticed a serious flaw in the solar panels that communities across sub-Saharan Africa rely on for electricity. The sun moves. The solar panels did not.

Given that the maximum theoretical efficiency for the most commonly used photovoltaic cell is only about 29 percent, every little drop of extra sunlight counts. By remaining stationary, she reasoned, solar panels were letting valuable energy go to waste.

So, using just a bucket of water and some rocks, Beth Parks built a new kind of slowly rotating solar panel designed to track the sun’s daily arc. After a 20-day testing period, Parks found that her slowly shifting panels collected 32 percent more energy than fixed position models, a difference of hundreds of watts, according to the American Physics Society. She presented her findings at the 2019 American Physical Society March Meeting.

A bucket of water and some rocks help steer this solar panel towards the sun.

Beth Parks 

Why Roaming Solar Panels Could Be a Game-Changer

Those few extra hundred watts aren’t enough to make a huge difference in American homes, where the average electricity consumption is about 29 kWh each day, according to U.S. Department of Energy figures.

But in Uganda, where nearly one in four people don’t have access to electricity, the average household’s daily electricity use is just 0.04 kWh/day, meaning that Parks’ design alone — if widely implemented — could transform entire communities. It means access to cell phones. To lights after dark.

As an associate professor of Physics, Parks had seen other solar panel models that used weight systems to slowly shift over the course of a day. But these dynamic frames had never been tested, says Parks, nor had they been designed with economic efficiency in mind.

While the latest innovations like dual layer solar cells have the promise to greatly increase solar panel efficiency, Parks's invention is elegantly simple and incredibly inexpensive. 

Joel Jean/Anna Osherov/MIT News

How to DIY a Pivoting Solar Panel

In collaboration with students at Mbarara University of Science and Technology, Parks created a solar panel frame using metal tubing that local welders could easily obtain. The panel is then attached to a pivot. On the west side, a bucket of rocks; on the east, a bucket of water. As the weight of the water bucket slowly drops, thanks to a controlled leak, the panel slowly, consistently shifts, following the sun. 

Currently, says Parks, even the more inexpensive solar panels still prove too costly for most families, and the majority of panels are welded to the roofs of homes to deter theft. But increased efficiency means panels can be smaller, and thus also more affordable. Easily transportable frames and smaller panels allow residents to bring their systems inside each night, negating the need to bolt them down. The total cost of Parks’ system — which includes a solar cell, a battery, charger and frame — runs about ten percent less than a traditional, mounted solar panel, and her Master’s students recently collaborated with a local welder to produce a $6 frame design.

Parks’ new shifting solar panel — both through its design and its cost — illustrates the importance of immersive research, of building within a community, specifically for that community. How else would she have known to make the design light enough and small enough to bring inside each day? How else would she have understood the effect that just a handful more kilowatts can have on a household’s daily routine?

For now, Parks is back in the United States. But she sees widespread adoption of her design as an opportunity for small industry growth throughout Uganda.

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