| Work Detail |
Spanish researchers have used a composite material reinforced with glass fiber and an epoxy matrix with cleavable ether groups as an encapsulating material for photovoltaic panels. They discovered that the new material still has performance stability problems, but they also found that it guarantees lower electrical losses.
Scientists at the Spanish research center Tecnalia have encapsulated solar panels with a composite material that they claim has improved chemical recyclability.
The novel encapsulant material is based on a glass fiber reinforced composite material with an epoxy matrix containing cleavable ether groups. “The objective was to improve the chemical recyclability of the encapsulating material and the photovoltaic modules, while maintaining their photovoltaic performance and durability,” explains the research group. "In future work, the improvement of the moisture barrier properties of the compound and the adjustment of the recycling conditions will be studied to allow a recovery of components valid for new modules."
The researchers fabricated twelve solar module samples with monocrystalline silicon cells and encapsulated them with the new material using a linear vacuum resin infusion process. “A fiberglass fabric with an areal weight of 300 g/m2 (0/90?) was used as reinforcement.” The reinforcement arrangement consisted of 3 layers placed at the front and rear of the cell. An epoxy resin system with an amino-based hardener and cleavable chemical groups in its composition was used as a composite matrix,” they noted.
The group tested the panels performance and compared it to reference modules encapsulated with a standard resin system based on a clear bisphenol-A epoxy and an amine-based cross-linker. In the test set, the recyclable encapsulants were contrasted with the reference encapsulant, as well as with bare solar cells without any encapsulation.
“The data of the monomodules with the composite encapsulant based on the recyclable epoxy resin showed an electrical loss in short circuit current of 6.3% when comparing the electrical performance before and after encapsulation,” the researchers point out. “This value was slightly lower than that obtained for the monomodules with standard epoxy compound, which presented a decrease of 7.2%.”
The group observed a similar trend when analyzing peak power losses (Pmp) and external quantum efficiency (EQE) spectra, a metric of the efficiency and spectral response of photovoltaic devices. The researchers also conducted a test of humid heat for 500 hours of exposure on the panel encapsulated with the new material, and found that it had an electrical loss in short circuit current of 3.4%, compared to only 1.5% for the reference panel.
“After 1,000 hours of exposure, the observed decrease in short-circuit current was even more pronounced, being significantly greater in the case of the cleavable epoxy matrix,” the academics noted. “A final loss of 4.9% was measured for the recyclable resin, while the standard epoxy showed a lower value of 2.8%. Regarding the Pmp values, the loss reached 4.7% and 3.4% for the recyclable compound and the standard, respectively.”
In addition, the researchers carried out stability and aging tests by exposure to UV rays and thermal cycles. As for the latter, it presented a loss of around 1% in short-circuit current and Pmp, which is not considered significant, since it is below the measurement precision of the technique. Regarding exposure to UV rays, electrical losses were also close to 1%.
The novel material is described in the article “ Composite material with enhanced recyclability as encapsulant for photovoltaic modules ,” published in Heliyon.
Looking ahead, the researchers pointed out the need to work on analyzing and improving surface homogeneity, as well as studying the aging of modules made with the recovered fibers and, possibly, using a different resin-fiber interface. . Furthermore, researchers see the opportunity to improve the proposed technology. “Future work will also focus on improving the humidity-heat stability of the composite, in a commitment to satisfactory recyclability,” they stated. |
