Chinese language producers have made giant investments on this cell know-how, and traders, unbiased energy producers (IPPs), and funds have develop into accustomed to its potential. A key consider TOPCon’s success story is its value, which has decreased by virtually €0.01 ($0.01)/W greater than PERC within the final two years.
TOPCon outperforms PERC in numerous “tangible” indicators, together with bifaciality coefficient, effectivity, temperature coefficients, and annual degradation. Consequently, monetary fashions primarily based on TOPCon present a extra engaging return on funding in comparison with PERC. Asier Ukar, director of the Spanish headquarters of PI Berlin, says that this has at all times served as the primary driver of know-how choice at TOPCon.
Nevertheless, Ukar defined the significance of not solely counting on knowledge from datasheets but additionally conducting an intensive and clear evaluation of the long-term habits of the know-how, particularly in relation to degradation mechanisms. Based on Ukar, you will need to determine and tackle potential dangers related to TOPCon know-how early on.
A specific danger recognized by PI Berlin is expounded to the presence of aluminum within the cell-to-cell contacts, situated in entrance of the cell the place moisture accumulates. Damp-heat testing and subsequent electroluminescence testing can detect this situation. TOPCon cells are extra delicate to water vapor, so it is suggested to make use of polyolefin elastomer (POE) on the entrance facet for glass-glass modules, whereas POE on either side is most popular for glass-backsheet modules.
One other danger arises from the strain to scale back the quantity of silver within the busbars of TOPCon cells, which ends up in thinner busbars and fewer secure cell holding. This can lead to mechanical injury to the print and chipping or chipping of the finger, resulting in decreased efficiency because of elevated efficient collection resistance. Electroluminescence assessments can detect these points.
TOPCon know-how additionally faces degradation challenges much like PERC know-how, similar to polarization-induced degradation (PID-p). The entrance a part of TOPCon cells, which has a construction much like the again a part of PERC, could also be affected by this phenomenon.
As well as, the aluminum oxide passivation layers of TOPCon cells are susceptible to UV degradation. Whereas PERC know-how is much less affected because of the aluminum on the again facet, TOPCon is extra inclined as a result of the aluminum oxide passivation layers are situated on the light-exposed entrance facet.
Ukar says high quality management modifications are wanted throughout TOPCon manufacturing, together with pattern measurement and particular laboratory assessments, to deal with the dangers inherent in TOPCon know-how. Lengthy-term assessments, similar to Damp Warmth, Thermal Biking, or Humidity Freeze, are essential for evaluating the long-term reliability of modules past the usual knowledge specified within the datasheet.
Inside the invoice of supplies (BOM) for TOPCon modules, the encapsulant is a crucial element. Insufficient or low high quality encapsulant will negate the advantages of TOPCon in comparison with PERC. PVEL’s 2023 scorecard, which incorporates the PID192h check, reveals important variations in prolonged sturdiness outcomes amongst completely different BOMs, even inside the similar producer.
Ukar famous that some producers have relaxed acceptance and rejection standards for TOPCon in comparison with PERC to reduce yield loss and keep productiveness. Nevertheless, you will need to determine and tackle these dangers early and with transparency from the trade to completely exploit the advantages of TOPCon.
Regardless of the related dangers, correctly constructed TOPCon modules outperform PERC and present little degradation phenomena.
