CrazyNeutrino said:
New world record set for converting sunlight to electricity
An Australian team has set a new record for squeezing as much electricity as possible out of direct, unfocused sunlight via a new solar cell configuration. Engineers at the University of New South Wales (UNSW) achieved 34.5 percent sunlight-to-electricity conversion efficiency, a new mark that also comes closer than ever to the theoretical limits of such a system.
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UNSW’s Dr. Mark Keevers and Professor Martin Green set the record with a 28 centimeter-square (4.3 sq in), four-junction mini-module embedded in a prism. This new configuration allows the sun’s rays to be split into four bands so that a higher amount of energy can be extracted from each beam.
Yes, that’s the only way forward. Last I heard a foreign team had the record by splitting the Sun’s rays into two bands to maximise the energy gain. The problem with a single band is that photons in the spectrum have different energies, so you either have to gain a small amount of energy each from a lot of photons, or a large amount of energy each from a few photons. Either way, a single band solar cell (which is what all solar cells on the market are) loses a lot of energy.
UNSW has a record of setting records for sunlight-to-energy conversion efficiencies. I took particular interest in a previous record they set by modifying the surface geometry into cube-corner reflectors, so every incident photon hit three surfaces of the solar cell instead of just one. IIRC, they also set a record for amorphous solar cells, which are cheaper than single-crystal.