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American scientists have developed a monocrystalline solar panel based on polysilicon "minicells" on passivating silicon oxide contacts.
A group of scientists led by the US Department of Energys National Renewable Energy Laboratory (NREL) has designed a monocrystalline mini solar panel capable of converting laser light into electricity.
“This technology is cheap, since it is based on silicon and uses the same processes that are used for terrestrial cells, such as TOPCon devices, which rely on passivating silicon oxide contacts,” the lead author of the study told pv magazine . the investigation, Paul Stradins. “The module is made up of mini-cells with passivated poly-Si/SiO2 contacts. These minicells offer remarkably low contact resistance, ideal for operation in high sun.”
In the article “ High-voltage monocrystalline Si photovoltaic minimodules based on poly-Si/SiOx passivating contacts for high-power laser power conversion ”. of high-power laser energy), published in Solar Energy Materials and Solar Cells , the scientists explain that the panel can be used, for example, in applications such as wireless data transmission in special environments or the transmission of energy in medical implants, among others.
The multi-junction mini-panel is designed with silicon oxide (poly-Si/SiOx) passivated contacts using a very thin SiOx layer of approximately 1.5 nm. These passivated contacts are used to build minicells that are reported to offer remarkably low contact resistance, suitable for operation at high solar radiation. The minicells are placed “edge on” and packed into modules.
“These minicells can be made into micromodules simply by mechanically stacking them,” explains Stradins. “We have used 10 cells, but it can be any number. Thus, the voltages of these micromodules can be high, while the currents remain low.
In the solar module, direct metal contact from one cell to the next allows electricity to flow freely between them, as the large contact surface limits series resistance. Light penetrates vertically through the narrow edge of the device and current is collected laterally through the large surface area pyn-type passivator contacts.
According to the researchers, this architecture allows the cell current to be collected in the entire "side" area of ??a minicell, which is considerably larger than the light input area. “These stacks of 10 or more minicells can be assembled into a power beam conversion module of any size,” explains Stradins. "There is no size limitation, it can be meters if necessary, with refrigeration, tabulation and power electronics at the rear."
The research group tested the module under illumination of around 1000 nm and found that its photoconversion efficiency was over 40% and the open-circuit voltage was over 7 V. The fill factor was around 78%. "From the current results of the device, a power transfer of 25 W is expected to be obtained for a 10 cm2 module with a 12 kW laser source at a distance of 1 km," the academics note.
According to Stradins, the minicells are made without the need for expensive lithography. “We use mechanically aligned masks for all deposition steps, which are easily fabricated with a laser scanner,” he explained. “The minicells are also made using the same laser scribing process. They remain attached to the wafer and are processed as a whole wafer in all steps, including final metallization. Only then are they separated and assembled into a micromodule. All of this can be automated on a production line.” |
