Solar panels, throughout their entire existence, have had the same issue over and over again: once the Sun’s light began to hit them with an angle, they became inefficient, so fixed solar panels were only great at noon. Soon after people realized that, they began constructing all sorts of contraptions that would modify the panels’ position so to face the Sun directly.
The problem with the solar trackers is that they’re expensive (sometimes even more expensive than the solar cells themselves), and their maintenance also costs a lot. A solution to this problem comes from a technology already used in your auto-focus cell phone camera, which uses a liquid and electricity to vary the shape of the lens.
The principle is called “electrowetting” and the technology for using it in solar cells is being researched by University of Maryland scientists. Their “electrowetting-based dynamic liquid prism” focuses the light directly on the solar cells. It consists out of a thin liquid layer on top of the photovoltaic cell that tracks the sun without having any moving parts.
ARPA-E, the Department of Energy’s experimental wing, which invests in cutting-edge green technologies, describes the electrowetting lenses this way: “The electrowetting effect controls the contact angle of a liquid on a hydrophobic surface through the application of an electric field. With two immiscible fluids in a transparent cell, they can actively control the contact angle along the fluid-fluid-solid tri-junction line and hence the orientation of the fluid-fluid interface via electrowetting. The naturally-formed meniscus between the two liquids can function as an optical prism. Without any mechanical moving parts, this dynamic liquid prism allows the device to adaptively track both the daily and seasonal changes of the Sun’s orbit, i.e., dual-axis tracking.”
The energy used by electrowetting devices to focus the sun’s light onto solar cells is dramatically less than that used by sun trackers, not to mention the tiny costs associated with maintenance.
[via ecogeek]
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