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Can nanotechnology make solar PV 80% efficient?

Posted by Alex Barrett on 28 February 2017 at 10:05 am

Solar Photovoltaic (PV) systems are a great way to produce renewable power by converting the energy in sunlight into electricity. However sunlight comes in a wide range of wavelengths, both visible and invisible. The current generation of solar panels are only able to harness a fraction of the potential wavelengths emitted by the Sun. Now developments in nanotechnology are paving the way to increase the range of wavelengths that we can harness, and boost the amount of energy we can generate using solar panels.

Conventional solar panels consist of a semiconductor that reacts to the impact of photons by generating an electrical charge. The new system builds upon this by adding a layer of carbon nanotubes. These can absorb incoming radiation, particularly in the near infrared range of the spectrum, which is invisible to a conventional solar panel [1].

These nanotubes don’t produce electricity themselves. Instead they are heated up, potentially to more than 900 oC. In this way the panel stores the incoming energy as heat. Another layer is then warmed up by the nanotubes and radiates light, in the region of the spectrum that conventional solar cells can harness. In this way the low energy IR photons are converted into higher energy, visible light. A much wider range of wavelengths can be converted into electricity [2,3,4].

In a traditional solar PV system any energy that goes to heating up the panel rather than being converted into electrical energy is wasted, and can make it work less efficiently. This new system captures that heat before it can reach the solar PV cell, transforming it into light instead.

It is only recently that this system has become efficient enough to be viable, so they may not become available any time soon. However once they can be produced in a cost effective manner they are likely to outperform the current generation of solar cells. Conventional solar panels have a top efficiency of 33.7%. The new system should convert energy with an efficiency of 80% or more [5, 6]. Consequently it has the potential to dramatically increase the amount of energy we can produce from solar PV.

This system also presents some intriguing possibilities. The main limitation of solar panels is that they only generate energy while the sun is shining on them. Absorbing radiation in the infrared range could change this, as infrared radiation is emitted by the Earth, even after the Sun has set. Furthermore if enough energy can be stored as heat during the day the panel can form a thermal battery that will continue to emit light during the night, allowing the underlying solar PV cell to continue to convert it to electricity long after the sun has set [7].

References

  1. Physics World
  2. American Society of Mechanical Engineers
  3. Kurzweil, Accelerating Intelligence
  4. Solid State Solar Thermal Energy Conversion Centre
  5. Tech Times
  6. Institute of Electrical and Electronics Engineers
  7. Extreme Tech

Carbon Nanotube Image credit Geoff Hutchison via Flickr

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