Raman’s findings were published in the journal Joule today. His device — made from easy-to-find materials including Styrofoam and off-the-shelf aluminium parts — takes advantage of radiative cooling, the process that allows objects to release heat after the Sun sets.
The top portion of the device cools down more quickly than the bottom, allowing it to turn the temperature swing into electricity with the help of a thermoelectric generator.
So yes it generates very little power now but shows where research is going (and this is way lower cost than solar PVs). We should remember too that the first solar panels themselves generated very little power and it took a decade or more for them to become really commercially viable. It took another decade or more before prices fell for us to afford them at home so any idea like this will take time to see if it works out.
The device is made out of conventional materials including Styrofoam and off-the-shelf aluminum parts.