Will solar panels able to produce energy during night time? This question was aroused on day one when I started my career in Solar.
Solar panels are designed to produce current only when sunlight is incident on the panels and their efficiency depends on Peak-Sun hours (i.e.) the location where the panel would receive maximum sunshine for a certain period. So, Solar Panels are constrained to work in daytime only and remain inactive in Cloudy days and night time. During winter season and at nighttime, consumers have preferred alternative solutions like net metering and Battery back-up for their energy demands.
Apart from that, researchers are working on a solar panel which would capable of harvesting solar energy during night time and the Idaho National Laboratory has done research and development on solar cells that can absorb energy from the sun even after sun set. This research evolves the production of Nano antennas - Thin solar film that contains embedding square spirals of conducting metal onto a sheet of plastic. The main function of Nano antennas is to absorb the electromagnetic radiation of specific wavelengths that are proportional to the size of the nano antenna.
The theory behind the operation of Nano antenna:
As the name implies, nano antennas are very small each less than a micron in length and it is made up of small portions of Aluminum and Gold. A team from Tel Aviv University have proposed that when the length of the Nano- antenna varies, the wavelength of radiation that it can absorb also varies and the researchers concluded that the panel with a variety of lengths of antennas could be able to absorb more radiation with a different wavelength from the solar spectrum. This unique feature made the Nano antennas more efficient and the possible way to convert the electromagnetic radiation to electric current even after sun set.
The sun provides infinite amount of energy in the form of a spectrum of electromagnetic waves ranging from infrared (IR) to Ultraviolet rays(UV).While this electromagnetic radiation strikes the earth’s atmosphere, a fraction of the radiation is absorbed and the remaining is sent to earth’s surface as heat. This remaining electromagnetic radiation is absorbed by the antenna at its designed frequency and it gets excited into a resonance mode. Due to this, cyclic plasma movement of free electrons is occurred in the metal antenna and generating alternating current at the same frequency as the resonance.
Thus, the Nano antenna can make energy from the radiation which is already absorbed by the earth surface during the daytime and released after the sun goes down. It is capable of producing more energy because it takes energy from both sunlight during day time and the earth’s heat during the night. However, this innovative product has not developed yet up to the solar market level but it’s just a matter of time.