Thermal radiation from the sun is largely lost on most silicon solar cells.
Up-converters transform the infrared radiation into usable light, however. Researchers have now for the first time successfully adapted this effect for use in generating power.
There is more to solar radiation than meets the eye: sun- burn develops from unseen UV radiation, while we sense infrared radiation as heat on our skin, though invisible to us. Solar cells also ‘see’ only a portion of solar radiation: ap- proximately 20 percent of the energy contained in the solar spectrum is unavailable to cells made of silicon – they are unable to utilize a part of the infrared radiation, the short-wavelength IR radiation, for generating power.
Researchers of the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, together with their colleagues at the University of Bern, Switzerland, and the Heriot-Watt University in Edinburgh, Scotland, have now for the first time made a portion of this radiation usable with the assistance of a practical up-converter. The technology that transforms infra- red into usable light has been known about since the 1960s. However, it has only been investigated in connection with solar cells since 1996. “We have been able to adapt both the solar cells and the up-converter so as to obtain the biggest improvement in efficiency so far,” reports Stefan Fischer happily, a scientist at ISE. The potential is big: silicon solar cells theoretically convert about thirty percent of sunlight falling upon them into electrical power. Up-converters could increase this portion to a level of forty percent.
A ladder for light particles
However, how does the up-converter manage to utilize the infrared radiation for the solar cells? As solar radiation falls on the solar cells, they absorb the visible and near-infrared light. The infrared portion is not absorbed, however, it goes right through them. On the back- side, the radiation runs into the up-converter – essentially a microcrystalline powder made of sodium yttrium fluoride embedded in a polymer. Part of the yttrium has been replaced by the scientists with the element erbium, which is active in the optical range and responsible in the end for the up-conversion.
As the light falls on this up-converter, it excites the erbium ions. That means they are raised to a higher energy state. You can imagine this reaction like climbing up a ladder: an electron in the ion uses the energy of the light particle to climb up the first step of the ladder. A sec- ond light particle enables the electron to climb to the second step, and so on. An ion that has been excited in this manner can “jump down” from the highest step or state. In doing so, it emits light with an energy equal to all of the light particles that have helped the elec- tron to climb on up. The up-converter collects, so to speak, the energy of several of these particles and transfers it to a single one. This has so much energy then that the solar cells “see” it and can utilize it.
Researchers had to adapt the solar cells in order to be able to employ an up-converter such as this. Normally, metal is vapour-deposited on the backside, enabling current to flow out of the solar cells – so no light can shine through normally. “We equipped the solar cells with metal lattices on the front and rear sides so that IR light can pass through the solar cells. In addition, the light can be used by both faces of the cell – we call this a bi-facial solar cell,” explains Fischer. Scientists have applied specialized anti-reflection coatings to the front and rear sides of the solar cell. These cancel reflections at the surfaces and assure that the cells absorb as much light as possible. “This is the first time we have adapted the anti- reflection coating to the backside of the solar cell as well. That could increase the efficiency of the modules and raise their energy yields. The first companies are already trying to accomplish this by implementing bi-facial solar cells,” says Fischer, emphasizing the potential of the approach.
Go deeper with Bing News on:
- SunRoof Solar Expedites Solar and Roof Installation, Savingson February 22, 2021 at 8:30 pm
Hence, the importance of hiring a good roof installation company cannot be overemphasized. Complementing a good roofing structure is the solar panel, an eco-friendly, significant investment that is ...
- Floating Solar Panels Market Revenue to Reach $2,301.8 Mn by 2026 Says P&S Intelligenceon February 22, 2021 at 4:39 pm
Though solar energy is one of the best alternatives to creating electricity from fossil fuels, the requirement for large areas for the installation of photovoltaic (PV) panels discourages many ...
- The perfect recipe for efficient perovskite solar cellson February 22, 2021 at 3:59 pm
A long-cherished dream of materials researchers is a solar cell that converts sunlight into electrical energy as efficiently as silicon, but that can be easily and inexpensively fabricated from ...
- Solar Panel: Can Suns’ Booker get to superstar status?on February 22, 2021 at 1:40 pm
About Us. Follow the Suns Solar Panel crew on Twitter @SunsSolarPanel, @Espo, @DaveKingNBA and @Saul_Bookman. Dave has media access to all the Suns games, practices, press confere ...
- US can’t compete with cheap Chinese solar panelson February 22, 2021 at 12:06 pm
FOX Business’ Grady Trimble talks with an executive from one of the few companies that manufactures solar panels in the U.S. about competing with China.
Go deeper with Google Headlines on:
Go deeper with Bing News on:
Solar cells utilize thermal radiation
- Streets could become their own energy companies by sharing solar panels, under plans being looked at by MPson February 22, 2021 at 7:46 am
Streets could set up their own energy companies by sharing solar panels, under plans being looked at by MPs. Currently, those who create their own electricity by using solar or wind power in their ...
- Minnesota homeowners, solar groups back solar panel billon February 19, 2021 at 9:01 pm
Jonathan Edmonson had plans to put a 16-kilowatt solar array on the roof of his suburban Minneapolis home, covering its dark blue roof with sleek ...
- Genie Solar Energy Completes Rooftop Solar Installation Using Panels Made In Americaon February 16, 2021 at 9:13 am
Genie Solar Energy, a developer, designer and installer of commercial solar systems, has completed an innovative rooftop solar installation for Kraft Power, a provider of generator and cogeneration ...
- I Installed Solar Panels On My 89-Year-Old Garage To Make My Electric Car Truly Zero Emissionson February 11, 2021 at 3:01 pm
The blending of new technology and old makes me extremely excited these days. Whether it’s the idea of shoving an electric motor into an old VW van, or powering my near nonagenarian home with modern ...
- How Pioneering Solar Tech Aims To Bring Energy To Gaza’s Refugeeson February 11, 2021 at 1:30 am
Palestinian families in the blackout-stricken Gaza Strip could soon see the benefits of a cutting edge solar energy system being developed by engineers at the University of Birmingham in the U.K.