Dutch scientists reported a better danger of degradation of n-type TOPCon cells with EVA encapsulant as a result of potential moisture degradation. Entrance-side metallization makes n-type cells weaker than p-type cells, based on damp warmth exams.
Researchers on the Netherlands Group for Utilized Scientific Analysis (TNO) carried out a collection of damp warmth exams to research the impact, when it comes to moisture degradation, of various encapsulation supplies on the efficiency lack of bifacial PV modules.
“The aim of this analysis is to search out a proof for the degradation phenomena noticed in small samples of the bifacial module within the laboratory after the excessive damp warmth take a look at,” the lead writer of the analysis, Paul Sommeling, talking. pv journal.
To check “Results of corrosion on bifacial crystalline silicon PV modules; interplay between metallization and encapsulation,” printed in Photo voltaic Vitality Supplies and Photo voltaic Cellsthe scientists made a comparability between three encapsulant supplies utilized in PV module manufacturing: ethylene vinyl acetate (EVA), polyolefin elastomers (POE) and thermoplastic polyolefins (TPO).
The analysis group says that it has noticed in earlier research that POE and TPO, in contrast to EVA, don’t launch any acidic substances, which signifies that they could be higher than EVA in relation to acid-induced corrosion. Nevertheless, there’s nonetheless no confirmed proof that these supplies can lead to elevated stability of the sector module, because it takes a very long time earlier than important discipline degradation is noticed. .
By damp warmth testing with a period of as much as 2,500 h, the lecturers in contrast the efficiency of three supplies in glass-encapsulant-cell-encapsulant-glass-based laminates with out the usage of edge sealant.
“Commercially obtainable n- or p-type bifacial cells (TOPCON and PERC respectively) had been used to make these laminates, which had been subsequently examined in a local weather chamber underneath humid warmth circumstances (85 C / 85% relative humidity),” they defined. “Present voltage (IV) and electroluminescence (EL) measurements had been made at 500 hour intervals to observe the change in laminate traits over time.”
They used a method often known as “coring” to carry out autopsy evaluation on all samples examined. For this, they used scanning electron microscopy (SEM) and Vitality-dispersive X-ray spectroscopy (EDX) to research the results of photo voltaic cell floor exams. All encapsulants are examined based on IEC 61215 PV normal and past, with a protracted take a look at time.
Based on the analysis staff, the take a look at confirmed that hydrophobic and chemically inert TPO encapsulants present the best stage of safety in opposition to moisture-induced degradation in comparison with EVA and POE. It additionally reveals that the front-side metallization of the n-type TOPCon cells examined is extra vulnerable to acid- or moisture-induced degradation than their p-type counterparts.
“This front-side metallization of TOPCon cells deteriorates sooner than the again aspect metallization and in addition sooner than the metallization of PERC cells in EVA-based laminates,” the scientists emphasised. “We attribute the variations within the completely different compositions to the cell metallization used.”
They concluded that the principle reason behind the delamination of the metallic grid might be the degradation of the lead glass, which they mentioned is a part of the cell metallization grid and comprises lead oxide (PbO).
“These outcomes are partly shocking,” Sommeling mentioned. “Corrosion results on PV are recognized and reported within the literature learning the results after discipline publicity and after accelerated laboratory testing.”
He additionally defined that probably the most critical corrosion issues are to a big extent associated to the discharge of acetic acid from EVA, probably the most broadly used encapsulating materials in PV panels. Acid causes corrosion of cell metallization and/or tabbing materials or solder joints. Presently, EVA is being changed by alternate options that don’t launch any acidic compounds and this helps to stop many issues associated to corrosion.
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The subsequent difficulty of pv journal, due Wednesday, celebrates China’s journey from photo voltaic new entrant to putting in greater than 100 GW(AC) of panels this yr – Vincent Shaw and Frank Haugwitz contemplate a exceptional 20 yr journey. We take a look at what Indonesia wants to realize its net-zero ambitions and in addition discover the sparks of a photo voltaic renaissance in Europe, by way of commerce reveals and gigafatory planning.
“The unusual or ‘new’ elements described in our paper take into consideration the very exceptional variations noticed between various kinds of metallization and completely different photo voltaic cells in relation to corrosion conduct, which could be correlated with completely different cell metallization compositions,” added Sommeling. “Additionally with out acids, corrosion can nonetheless happen solely by way of the affect of moisture and in addition it varies broadly between the various kinds of metallization used.”
“It may be concluded that the precise mixture of n-type TOPCon photo voltaic cells studied in our paper together with EVA could also be larger danger, in comparison with different mixtures of cell varieties and encapsulants,” confirmed Sommeling’s. “Using EVA together with comparatively excessive corrosion vulnerable metallization ought to and could be prevented. However, if the extra corrosion-resistant metallization sort recognized can be utilized in TOPCon photo voltaic cells, it should additionally assist to construct extra corrosion-resistant n-type PV panels.
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