It is common knowledge that if your solar panels can track the sun, their energy output can increase by as much as 30–40%. In spite of this, only a small number of solar PV installations use trackers.
Mostly, the problem is that sun trackers are bulky and can also be costly when it comes to residential rooftop installations. Moreover, they work by tilting the whole panel – which is difficult to do on pitched roofs.
According to an NREL report (Estimating Rooftop Suitability for PV), pitched roofs are in a majority when it comes to residential solar rooftops. And would require significant reinforcing to support the weight of conventional sun-tracking systems.
Researchers from the University of Michigan have shown a new way to help solar cells track the sun by fusing art with science. They have demonstrated that kirigami structures combined with thin-film active materials can be used as a simple, low-cost, lightweight, and low-profile method to track the sun’s position, thereby maximizing the generated energy.
The work was published in the journal Nature Communications.
To the uninitiated, Kirigami is a variation of origami that includes cutting of the paper (from Japanese “kiru” = to cut, “kami” = paper), rather than solely folding the paper as is the case with origami.
Researchers have shown that by cutting solar cells into specific designs (inspired from kirigami), they can allow the cells to track the sun’s angle without having to tilt the whole panel.
Applying a specific kirigami cut (like rows of dashes) creates strips in a solar cell. Pulling the two ends in opposite directions causes the cell to be pulled apart into a basic mesh, and the strips tilt to assume the desired angle to an accuracy of about one degree.
When the cell with cut strips is stretched, the surface can twist over an angle of 120 degrees so that it can face towards the sun. According to the research team’s simulations of solar power generation during the summer solstice in Arizona, the kirigami cell is “as good as a conventional single-axis tracker,” offering a 36% improvement over a stationary panel.
The research team tried several complex designs, and the simplest pattern was reported to perform the best.