New research, developed by scientists at the University of California, argues that solar panels may be able to generate electricity 24 hours a day, even at night. Solar panels are one of the main ways to produce renewable energy from solar power. Unfortunately, nighttime electricity generation is not possible, for obvious reasons.
However, researchers at the University of California claim that it would be possible to design solar panels that work at night by capturing the Earth’s invisible infrared light. These panels could generate about 25% of the electricity produced by a solar panel during the day.
Nighttime solar energy
In fact, a specially designed photovoltaic cell could generate up to 50 watts of power per square meter under ideal conditions at night, about 25% of what a conventional solar panel can produce during the day, according to the paper “Nighttime Photovoltaic Cells: Electrical Power Generation by Optically Coupling with Deep Space” published by researchers at the University of California, Davis, in the journal ACS Photonics.
They have called it the ‘anti-solar’ panel, designed and engineered to work in exactly the opposite way to those that work during the day.
Research director professor Jeremy Munday said the process is similar to how a normal solar cell works, but in reverse. An object that is hot compared to its surroundings will radiate heat as infrared light. A conventional solar cell is cold compared to the sun, so it absorbs light.
Space is very cold, so if you have a warm object and point it at the sky, it will radiate heat towards it. Humans have been using this phenomenon for nighttime cooling for hundreds of years.
Thermo-radioactive cell to produce solar energy
This nocturnal device, according to the researchers, would use a thermo-radioactive cell, which is capable of generating electricity thanks to radioactive cooling (where infrared or heat radiation leaves the cell and produces a small amount of energy in the process). This cell should be made of a material that can capture extremely long wavelength light.
These new devices emit light, then the electrical flow and voltage go in the opposite direction, but power is still produced. These cells are already in use in industries like manufacturing, which use them to convert waste heat generated by engines at high temperatures.
The device would also work during the day if you take steps to block direct sunlight or move it away from the sun. Because this new type of solar cell could operate 24 hours a day, it is an intriguing option for balancing the power grid during the day-night cycle.
Basically, you must use conventional cells to pick up thermal energy coming from the Sun when it hits Earth, so you need two different temperature bodies and a way to convert that energy.
While solar panels are made of silicon and are good at capturing light from the visible spectrum, this device should be made of something that can capture light with extremely long wavelengths. As a result of its alloys, mercury has been proposed for these purposes and for prototype development.
Other options for solar energy production
- Floating photovoltaic panels
The sun and the sea form a perfect energy mix in floating photovoltaic systems. According to a report by the World Bank and the Solar Energy Research Institute of Singapore, at the end of 2018, the global cumulative installed capacity of floating photovoltaic was 1.1 GW, 100 times more than just four years earlier. Floating solar technology has huge advantages for countries where land is scarce or power grids are weak. In addition, its offshore location allows land to be used for the production of other resources and brings these solar power plants closer to urban areas that are densely populated but near coastal areas.
- New tandem solar cell systems
Tandem solar cells work in cascade. As each cell stacks on top of the other, it converts a particular band of sunlight into electrical energy in order to avoid waste since the remaining energy always goes to the next cell.
According to an analysis by several institutes specializing in solar energy, there are different emerging photovoltaic technologies depending on the materials used, or the types of connection. Moreover, this approach helped manufacturing the world’s most efficient solar cells, which can convert up to 48% of sunlight into electricity.
- Agro-photovoltaics
One of the solutions to mitigate the space occupied by solar panel plants is to combine photovoltaic energy production with agriculture. As an article in Nature magazine explains, dual-use agrovoltaic systems represent a great opportunity for the future of energy sustainability. Global energy demand would be offset by solar production even if less than 1% of cropland were converted to an agrovoltaic system, according to the research. The key is to grow crops under solar panels, as researchers have confirmed the benefits of taking advantage of the shade they produce for crop yields and water consumption. An example of this is the Disney Resort theme park we talked about in a previous article.
Solar trees
The operation of solar trees is inspired by natural trees, as they have leaf-shaped solar panels connected through metal branches that use sunlight to generate energy.
These structures, which emulate the natural shape of a tree, are more ergonomic than horizontal solar panels and take up almost 100 times less space to produce the same amount of electricity as a conventional installation.
In addition, the shade they cast helps to mitigate the heat, especially in urban areas where, in addition to producing energy, these structures can be used to light streets, facilitate WIFI connection or charge mobile devices.