null

Cooling Solar Panels to Increase Efficiency

Just like your car, the solar panels on top of your roof can overheat! Most people think that with the more direct sunlight the more energy the panels will produce, but then don’t worry about the accompanying high temperature. Cooling solar cells can often be a pretty expensive and time consuming process with previous solutions including the use of chemicals or gallons of water. The idea now is that solar panels could actually be more efficient if they did not “overheat” as often.

The problem is how to do this in a gentle and inexpensive way. Researchers at Stanford University have recently unveiled new coating made out of silica glass that will allow the solar cells to cool themselves, but still receive the same amount of sunlight and produce the same amount of energy.

Professor Linxiao Zhu, a physicist, and professor Shanhui Fan of the electrical engineering department at Stanford worked together and published a paper on a passive cooling technology in the journal Optica, by the Optical Society. The Green Optimistic explains that the technology is still in the testing stage, but has now moved on to larger scale systems. There is hope that this will be the alternative to wasting money, energy and water on coolants or high-tech ventilation systems in attempts to cool the panels. “A recognised disadvantage of regular solar cells is the fact that no matter how efficient they are, their maximum capacity is never reached.”

The Daily Fusion agrees saying that some energy is naturally lost from converting sun energy into electricity due to physical limits. But more is also lost when the solar cells overheat. According to the Stanford research team, “for every one-degree Celsius (1.8 °F) increase in temperature, the efficiency of a solar cell declines by about half a percent.” “In addition, solar cells ‘age’ more rapidly when their temperatures increase, with the rate of aging doubling for every increase of 18 °F.” While according to Solar Love the optimum, efficient operating temperature for solar cells is 25°C. Any degree above this results in inefficiencies for the whole system and decreases in the resulting energy production.

At Stanford “the researchers compared two different silica covering designs: one a flat surface approximately 5 millimeters thick and the other a thinner layer covered with pyramids and micro-cones just a few microns (one-thousandth of a millimeter) thick in any dimension.” Ultimately they chose the pattern with pyramids and cones because “they could be tuned to refract and redirect only the unwanted infrared wavelengths away from the solar cell and back out into space.” Silica was used because it is transparent to visible light which is most useful for generating energy.

Gizmag plainly explains that this “is a system where ordinary solar cells are given an extremely thin layer of specially patterned silica glass that is designed to draw heat away from the cells in a manner that requires no energy and exploits the atmosphere’s infrared window to shed the heat.” There is no telling yet what this excess heat will do to the atmosphere, but until then this may be a quick fix. “Only a small amount of the energy from sunlight that falls on solar cells is converted to electricity, peaking at below 20 percent for most cells on the market today.” “Overheating is a constant problem because the sunlight used to generate electricity routinely heats up the panels to 130⁰ F (55⁰ C) or higher.” This waste heat decreases the solar cell’s performance so the research team’s overall goal is to lower the operating system temperature in order to increase efficiency, operating life and solar absorption.

When there is more sunlight coming in then there should be more energy produced from the cells, but this is not the case if the cells get to hot. This is why a process such as passive cooling may be a breakthrough solution. Keep on the lookout for this technology on the market soon!