| Work Detail |
New research conducted in Malaysia has revealed the limitations and potential of all graphene-based solar module cooling techniques. Scientists affirm that the high costs and treatments of graphene are the main challenges to overcome.
Scientists at Monash University Malaysia have studied how graphene and its derivatives could be used as materials to reduce the operating temperature of solar panels.
In an in-depth review published in Renewable and Sustainable Energy Reviews , the researchers explained that graphene has attracted interest from the scientific community as a means of improving heat transfers in cooling systems since 2004.
When used for photovoltaic cooling applications, graphene can be used in different ways. For example, it can be used as a selective absorbent coating or embedded in a working fluid as a nanofluid. Graphene nanoparticles can also be added to thermal interface materials (TIM) or phase change materials (PCM) used for cooling solar modules.
The group divided all graphene technologies applied to photovoltaics into two categories: passive and active cooling.
The first category was divided into pre-illumination and post-illumination techniques. The second encompasses all methods that use a heat sink to dissipate the heat generated by the solar cells, while the first includes all approaches that decompose the solar spectrum before it reaches the photovoltaic cells.
The pre-illumination category is represented by all types of graphene coated neutral density (GCND) filters used as selective absorbent coating.
“The application of the GCND filter as a passive cooling technique prior to lighting is very advantageous, especially in the cooling of CPV systems,” the academics say. “This pre-light cooling technique attenuates solar radiation before it reaches the photovoltaic panel, thus reducing the amount of heat generated in the photovoltaic panel.”
They also recommended using GCND filters only for small-scale domestic applications, due to their high cost.
“Instead of coating the entire substrate with graphene, focusing the graphene coating specifically on the focal point area could help reduce coating costs,” they added.
As for the post-illumination category, the list includes the use of graphene as a thermally conductive filler in TIM and PCM.
“Although both TIM and PCM have their own advantages and disadvantages, there is no universal answer to whether TIM or PCM is better for passive cooling of photovoltaic panels,” the group noted.
The active cooling category includes all techniques based on graphene nanofluids configured as working fluids. These techniques, like all active cooling methods, require the construction of pumps and pipes to circulate the nanofluid through the modules, which, according to scientists, significantly increases production costs.
“The challenge of using graphene nanofluids is the expensive and complex manufacturing process, which prevents graphene nanofluids from being adopted into routine industry practice,” the researchers say.
The group acknowledged that further research will be needed to reduce costs and improve cooling efficiency. The researchers also noted that the main technical challenges to be overcome are the synthesis of graphene nanofluid and the hybridization of graphene nanofluid and graphene-enhanced PCMs. |
