Solar energy seems to have had a rough time as of late; government subsidies have been reduced, installations are down and it seems as though every other form of green energy has had some major innovation – leaving solar in the shade. But there have been a few rays of hope for, arguably, the most readily available low-carbon energy source. Earlier in the year German was able to meet 55% of it’s private and commercial electricity needs with solar power, a vast new solar array has been installed in Greece, and we featured a new style of fibre-optic solar panel just last week.
However, a new innovation from Princeton University in the United States could well be the piece of news the solar industry has been waiting for.
Dubbed Plasmonic Cavity with Subwavelength Hole array or ‘PlaCSH’, scientists at the Ivy League university have created a nano-mesh that works with existing solar panels to boost efficiency.
Currently, industry-standard silicon and indium-tin-oxide-based solar cells are approaching the theoretical limit of 33.7% efficiency, however nanomesh reduces reflectivity and boosts efficiency of light capture to create a panel that is more than three-times more effective.
A mere 4% of direct sunlight escapes a panel covered in the golden nanomesh, whilst on a cloudy day with indirect sunlight PlaCSH is still 81% more light-efficient than a conventional solar cell. Over a typical year, Princeton’s research team this would make their creation over 175% more efficient than your average photovoltaic cell.
Broad-band Omni acceptance (near angle and polarization independence) in PlaCSH-SC. Measured incident light angle and polarization dependence of photocurrent under a white light (a)
As well as allowing less light to be reflected, the ingenious design of Princeton’s nanomesh allows light to be ‘captured’ rather than bounced away before it can be processed.
The mesh itself is a mere 30 nanometers thick, but the holes of the mesh are around 175nm in diameter. This makes the mesh smaller than the wavelength of the light that it’s collecting (Go on, take a minute to think about how incredible that is. We’ll wait.) and harnesses the unusual way light behaves in sub-wavelength structures to essential trap the light next to the solar cell.
It’s creators also created a fabrication method that would be suitable for this mesh over a decade prior, meaning it could begin to be mass produced sooner, rather than later. Perhaps most importantly the nanomesh replaces the costly Indium-Tin-Oxide (ITO) layer on the top of most panels, making them cheaper to produce, in theory.
Whilst 2012 was the year in which some seemed to lose faith in solar, the rate at which innovation seems to have happen around it at the end of the year seems to suggest there’s still plenty of room for it in the commercial electricity market, yet.