(ORDO NEWS) — Scientists continue to improve the efficiency of solar cells, and here is a new record: a new solar cell has achieved 39.5 percent efficiency under standard global illumination conditions of 1 sun.
That 1 sun mark is just a standardized way of measuring a fixed amount of sunlight, and nearly 40 percent of that radiation can now be converted into electricity. The previous record for this type of solar panel was 39.2 percent efficient.
There are more types of solar panels than you might imagine. The type used here, III-V triple-junction tandem solar arrays, is often used in satellites and spacecraft, although they have great potential on solid ground as well.
“The new cell is more efficient and has a simpler design, which could be useful for a variety of new applications such as space-constrained applications or low-radiation space applications,” says physicist Miles Steiner of the National Renewable Energy Laboratory (NREL) in Colorado. .
The “triple transition” part of the equation is important in terms of solar cell efficiency. Each junction concentrates on a specific portion of the solar spectrum, which means less light is lost and left unused.
A further increase in efficiency has been achieved through the use of so-called “quantum well” technologies.
The physics behind them is quite complex, but the general idea is that materials are carefully selected and optimized, and made as thin as possible. This affects the gap, the minimum amount of energy required to excite electrons and allow current to flow.
In this case, the three junctions consist of gallium indium phosphide (GaInP), gallium arsenide (GaAs) with some additional quantum wells added, and gallium indium arsenide (GaInAs).
“The key element is that although GaAs is an excellent material and is commonly used in multi-junction III-V cells, it does not have the correct bandwidth for a three-junction cell, which means that the balance of photocurrents between the three cells is not optimal,” says physicist Ryan. Frans from NREL.
“Here we have changed the bandwidth while maintaining the excellent quality of the material through the use of quantum wells, which allows the use of this device and potentially other applications.”
Some of the improvements added to this last cell include an increase in the amount of light absorbed without a corresponding loss in voltage. Several other technical improvements have also been made to minimize restrictions.
This is the highest efficiency at 1 sun of any solar cell ever recorded, although we have seen higher performance with more intense solar radiation. While it takes time for technologies to go from the lab to real products, the potential improvements are encouraging.
The cells also showed an impressive space efficiency of 34.2 percent, which they should achieve when used in orbit. Their weight and resistance to high energy particles make them particularly suitable for this task.
“Because these are currently the highest-efficiency 1-sun solar cells, these cells also set a new standard for achievable efficiency for all photovoltaic technologies,” the researchers wrote in the published paper.
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