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 think about 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 varied “tangible” indicators, together with bifaciality coefficient, effectivity, temperature coefficients, and annual degradation. Consequently, monetary fashions based mostly 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 principle driver of know-how choice at TOPCon.
Nonetheless, Ukar defined the significance of not solely counting on knowledge from datasheets but in addition conducting an intensive and clear evaluation of the long-term conduct of the know-how, particularly in relation to degradation mechanisms. Based on Ukar, you will need to determine and deal with potential dangers related to TOPCon know-how early on.
A specific danger recognized by PI Berlin is said to the presence of aluminum within the cell-to-cell contacts, positioned in entrance of the cell the place moisture accumulates. Damp-heat testing and subsequent electroluminescence testing can detect this concern. TOPCon cells are extra delicate to water vapor, so it’s endorsed to make use of polyolefin elastomer (POE) on the entrance aspect for glass-glass modules, whereas POE on either side is most popular for glass-backsheet modules.
One other danger arises from the strain to cut back the quantity of silver within the busbars of TOPCon cells, which results in thinner busbars and fewer steady cell holding. This can lead to mechanical harm to the print and chipping or chipping of the finger, resulting in decreased efficiency because of elevated efficient sequence resistance. Electroluminescence exams can detect these points.
TOPCon know-how additionally faces degradation challenges just like PERC know-how, corresponding to polarization-induced degradation (PID-p). The entrance a part of TOPCon cells, which has a construction just 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 liable to UV degradation. Whereas PERC know-how is much less affected because of the aluminum on the again aspect, TOPCon is extra prone as a result of the aluminum oxide passivation layers are positioned on the light-exposed entrance aspect.
Ukar says high quality management modifications are wanted throughout TOPCon manufacturing, together with pattern measurement and particular laboratory exams, to handle the dangers inherent in TOPCon know-how. Lengthy-term exams, corresponding to Damp Warmth, Thermal Biking, or Humidity Freeze, are necessary 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 vital part. 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 vital variations in prolonged sturdiness outcomes amongst completely different BOMs, even throughout the similar producer.
Ukar famous that some producers have relaxed acceptance and rejection standards for TOPCon in comparison with PERC to attenuate yield loss and keep productiveness. Nonetheless, you will need to determine and deal with 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.