A number of estimates already say that solar energy will be cheaper than fossil fuels within 15-20 years or so, but a breakthrough has just come through that may bring that forward to just a few years from now, if not sooner.
Most photovoltaic cells, such as those used in rooftop solar panels, use the semiconducting material silicon to convert the energy from photons of light to electricity. But the cells can only use a portion of the light spectrum, with the rest just generating heat.
This heat from unused sunlight and inefficiencies in the cells themselves account for a loss of more than 50 percent of the initial solar energy reaching the cell.
If this wasted heat energy could somehow be harvested, solar cells could be much more efficient. The problem has been that high temperatures are necessary to power heat-based conversion systems, yet solar cell efficiency rapidly decreases at higher temperatures.
This new technology couples parts of the two major solar technologies out there, directly generating electricity from solar voltaics, as well as using the heat that builds up in the panels to generate electricity, which also happens to increase the efficiency of the voltaics, since the heat gets sapped away and voltaics don’t work as well at high temperatures.
“What we’ve demonstrated is a new physical process that is not based on standard photovoltaic mechanisms, but can give you a photovoltaic-like response at very high temperatures,” Melosh said. “In fact, it works better at higher temperatures. The higher the better.”
Melosh calculates the PETE process can get to 50 percent efficiency or more under solar concentration, but if combined with a thermal conversion cycle, could reach 55 or even 60 percent – almost triple the efficiency of existing systems.
“The PETE process could really give the feasibility of solar power a big boost,” Melosh said. “Even if we don’t achieve perfect efficiency, let’s say we give a 10 percent boost to the efficiency of solar conversion, going from 20 percent efficiency to 30 percent, that is still a 50 percent increase overall.”
And that is still a big enough increase that it could make solar energy competitive with oil.
This is seriously exciting news. Solar cannot replace all of generation, at least not without several ground shaking breakthroughs in energy storage, but it could replace 10-20 percent or more. There is no silver bullet, but this could be one big nail in the coffin of the fossil fuel economy.
(Side note… if you want to track the real razor’s edge of developing technology, Kurzweil AI is by far the best source I’ve ever found)