Solar Advancements in 2020-2021

Record Breaking Tandem Cell Efficiency


Oxford PV a perovskite developer has set out a new world record for perovskite-silicon tandem cell efficiency at 29.52%, edging out the previous record set less than a year ago by Helmholtz Zentrum Berlin. This new record places these tandem cells as the future of PV. Both Oxford PV and HZB have stated that they have clear roadmaps to push this record beyond 30% in the near future. Silicon panels are coated with a thin film layer of perovskites which absorbs light of longer wavelength. This helps in increasing the module efficiency with the same number of cells. Perovskites have been regarded as the third-generation solar cells which could eventually dominate the PV industry. Perovskites have achieved efficiencies similar to Silicon PV with just 10 years while researchers have been working on Silicon PV for more than 60 years.


Silicon Solar Cell in Tandem With a Thin Film Perovskite Layer Structure

Quantum Wells Enable Record-Efficiency Solar Cells


Researchers from NREL and the University of New South Wales has achieved a new world-record efficiency for two-junction solar cells, creating a cell with two light-absorbing layers that convert 32.9% of sunlight into electricity. The design features 150 ultrathin alternating semiconductor layers that create quantum wells in the cell’s bottom absorber, allowing it to capture energy from a key range of the solar spectrum. A quantum well is created when a thin layer of semiconductor material is sandwiched between two layers of material with a wider bandgap, confining charge carriers to the central layer.

This diagram illustrates the many layers found in both the single-junction (left) and two-junction (right) versions of the new solar cell (Source: REL)

The top layer is made of Gallium Indium Phosphide and the bottom layer is made of Gallium Arsenide with 80 stacked layers of quantum wells. The inclusion of so many quantum wells increases the possibility of absorbing light of a longer wavelength. Capturing longer wavelengths increases the efficiency of the solar cells. This is the first multijunction solar cell where the tensile and compressive layers are pseudo morphically strained to a crystalline substrate which is Gallium Arsenide. This design holds great promise for future improvements

A Quantum Leap in Solar Manufacturing

Traditionally solar wafers have been manufactured using a wire saw to cut the ingot into wafers, and the material removed by the cutting blade, known as kerf, is lost as waste. Kerfless wafer manufacturing refers to producing thin slices of silicon wafers from a slab of silicon crystal. A company called 1366 Technologies manufactures kerfelss silicon wafers. Standard thickness wafers have achieved lifetime and efficiency near parity with standard multi wafers and even greater. Direct Wafer™ a proprietary technology of 1366 Technologies is a fast, scalable process that makes high performance, standard size, and thickness multicrystalline silicon wafers directly from the silicon melt. In 2020 1366 Technologies have started manufacturing the next generation furnace to manufacture multiple wafers at a time. They are also planning to open a gigawatt-scale production facility in Malaysia with Hanwha Q Cells. This is a technology that promises to reduce the cost of high-performance silicon wafers by more than a factor of two, by reducing CAPEX, consumables, labor, and silicon consumption

Solar Panel Manufacturing Plant

Floating PV Technology

This technology is considered to be the third pillar of PV technology. More than 35 countries have installed Floating PV structures which till then end of August 2020 had a cumulative capacity of 2.6 GW. It is still a niche field and is expected to grow in the coming years. Asia accounts for roughly two thirds of the installed systems with China being at the top followed by Korea. Geographical considerations are naturally a key factor in building floating PV systems for example countries with high population density, less availability of land and at the same time the availability of waterbodies. When it comes to cost factors, they vary from project to project as they depend on water level variation, depth, quality and salinity. The bathymetry of the water body determines the design layout of the anchoring and mooring system. Depending on the locally prevailing wind area, the FPV plant design requires the ability to withstand stronger wind loads. Today, a number of companies are pushing the boundaries of FPV for example one concept is combing exiting off shore wind turbine with floating PV’s. It may take some years until the proof of concept has been established.

Ariel view of Floating PV Structure on a Lake

Trend in Wafer Size

Manufacturers are calling for a new industrial wafer size. In 2018 the M2 wafers measuring 156 mm were seen as the industrial standard. Since 2019 the trend has been changing. Manufacturers began tweaking with wafer size in 2018 to optimize the cost. M2 wafers measuring 156mm were seen as the standard industrial wafers representing more than 90% of the market. Virtually every major manufacturer is now preparing to offer a module based on one of the larger format wafers incorporating 180 mm to 210 mm in size. Manufacturers of these modules promise that the increase in size will ultimately lead to modules of more than 500 W to be available in the market.


Solar Wafer size from 2012 to 2020

Green Hydrogen using Solar Energy

Green Hydrogen is an alternative energy produced using clean energy and could help bring global carbon emissions to zero in the coming decades. The market for green hydrogen is expected to grow exponentially in the coming decade. Hydrogen is the most abundant element and cleanest fuel in the universe. The only by-product of hydrogen fuel is pure water, unlike hydrocarbon fuels such as oil, coal, and natural gas that release carbon dioxide and other contaminants into the atmosphere when used. A company called Sun Hydrogen has developed a method of producing clean hydrogen using nanoparticles which enables the solar electrolysis reaction to take place. Powered by solar energy they don’t emit any green house gases. The produced hydrogen can be used to

Hydrogen produced using Green Energy

AFSHIN BAKHTIARI

AE Solar Senior Engineer



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