June 19, 2024

Harvesting Energy at Night: Solar Cell Keeps Working Long After Sun Sets

The device produces electricity in the evening from the temperature level difference in between the solar cell and its environments. Credit: Sid Assawaworrarit
Harvesting energy from the temperature distinction between solar battery, surrounding air causes a viable, sustainable source of electricity at night.
About 750 million individuals in the world do not have access to electrical energy during the night. Solar cells offer power throughout the day, but conserving energy for later use needs substantial battery storage.
In Applied Physics Letters, by AIP Publishing, scientists from Stanford University constructed a photovoltaic cell that harvests energy from the environment during the day and night, avoiding the requirement for batteries entirely. The gadget uses the heat leaking from Earth back into area– energy that is on the exact same order of magnitude as inbound solar radiation.

In the evening, solar batteries radiate and lose heat to the sky, reaching temperature levels a few degrees below the ambient air. The device under development uses a thermoelectric module to create voltage and existing from the temperature level gradient between the air and the cell. This procedure depends on the thermal design of the system, that includes a cold side and a hot side.
” You want the thermoelectric to have great contact with both the cold side, which is the solar cell, and the hot side, which is the ambient environment,” stated author Sid Assawaworrarit. “If you dont have that, youre not going to get much power out of it.”
The team showed power generation in their device during the day, when it runs in reverse and contributes extra power to the standard solar battery, and during the night.
The setup is affordable and, in concept, might be included within existing solar cells. It is likewise simple, so building and construction in remote locations with limited resources is possible.
” What we managed to do here is develop the entire thing from off-the-shelf components, have an extremely good thermal contact, and the most pricey thing in the entire setup was the thermoelectric itself,” said author Zunaid Omair.
Utilizing electrical power in the evening for lighting needs a few watts of power. The present gadget generates 50 milliwatts per square meter, which indicates lighting would require about 20 square meters of photovoltaic area.
” None of these elements were specifically crafted for this function,” said author Shanhui Fan. “So, I think theres space for enhancement, in the sense that, if one really crafted each of these components for our purpose, I believe the performance might be much better.”
The team intends to optimize the thermal insulation and thermoelectric elements of the device. They are checking out engineering improvements to the solar cell itself to enhance the radiative cooling efficiency without influencing its solar power harvesting capability.
Recommendation: “Nighttime electric power generation at a density of 50mW/m2 by means of radiative cooling of a photovoltaic cell” by Sid Assawaworrarit, Zunaid Omair and Shanhui Fan5 April 2022, Applied Physics Letters.DOI: 10.1063/ 5.0085205.