There is a proven need to switch to renewable energy sources, such as solar, but costs are a major hindrance. New research has now shown how solar panels can be made more efficient and less costly.
Rising CO2 emissions have made global temperatures to be on a disturbing upward trajectory. There is an increasing risk of adverse weather events as a result. Urgent action is required to combat these emissions, which are linked to energy use.
There is a pressing need for a shift from traditional energy sources to renewable alternatives. Solar energy and wind energy have been found to offer safer, cost-friendly alternatives despite what many people might think.
Solar power has even been described as the “cheapest electricity.” CSIRO, Australia’s national science agency, confirms that solar photovoltaics (PV) offer the most low-cost source of renewable energy. This remains true even when transmission and storage costs are factored in.
However, there is still an apparent need for cheaper, yet efficient, solar panels. This new research shows how that can be achieved to further help to cut global CO2 emissions.
Efficiency of solar panels
Researchers say humanity has now hit an installed solar capacity of 1 terawatt (TW), with Australia leading in terms of PV installations. However, predictions suggest that 70 TW may be required by 2050.
There is a need for solar panels that boast high efficiency to promote desired fast uptake of solar photovoltaics. These panels should also be low-cost. However, there is a somewhat inverse relationship between efficiency and cost.
Silicon is used in a vast majority (more than 95 percent) of solar panels. Manufacturers carry out “doping,” a process that involves adding impurity materials or atoms into silicon wafers, to make solar cells work.
There are two main types of silicon: p-type and n-type. P-type silicon is made by doping with atoms such as boron, which feature one electron less than silicon. N-type silicon, on the other hand, is doped with phosphorus, which has one more electron than silicon.
P-type silicon is the most common material used in commercial solar panel manufacturing. Solar panels that use the material feature on the roof of most homes in that they are about 10 percent cheaper.
Continuous efforts are being made to make solar panels more efficient to improve power generation for consumers. The highest efficiency to date for a solar cell (26.7 percent) was seen in 2017. Solar panel maker LONGi Solar recently also announced that a solar cell in manufacturing came close to that record at 26.5% efficiency.
These highly-efficient solar cells are known as “silicon heterojunction.” They feature a very thin amorphous silicon layer on their surfaces to smooth them and cut energy losses. These cells tend to cost more money, however.
How to reduce cost and emissions
Researchers wanted to find out whether silicon heterojunction solar cells featuring p-type silicon wafers could be used to reduce costs, as revealed in a The Conversation article published by CSIRO’s Bruno Vicari Stefani, UNSW Sydney’s Brett Hallam, and University of Oxford’s Matthew Wright. To date, such solar cells have used n-type wafers.
The team found that p-type silicon heterojunction solar cells performed poorly in their testing. It was baffled as to why this could be until it had a “literal light-bulb moment.”
The researchers observed that exposing p-type cells to room lighting by mistake for as low as 10 seconds prior to testing cut their voltage by up to 30mV. This is capable of causing a percentage point reduction in efficiency – say, from 22 to 21 percent.
This work provides the missing knowledge as to why p-type cells are less suitable for high-efficiency solar panels. P-type silicon wafers tend to degrade or reduce in performance because of the bonding of boron and oxygen in them.
The problem can be remedied with high-intensity laser treatments, researchers said. These can help to rapidly make cells stable. They can aid the mobility of hydrogen and the control of problematic boron-oxygen defects.
Using this new knowledge, researchers say highly-efficient solar power technologies may be developed at lower costs. This will help to lower electricity costs for consumers and to deal with the problems of climate change.
LONGi Solar announced in March its achievement of a 25.47% efficiency with a silicon heterojunction solar cell that used p-type wafers.