9th PV Module Reliability Scorecard

Of some 250 solar module types listed as the top performing solar modules under PV Evolution Labs’ (PVEL) Product Qualification Program (PQP) in its 2023 PV Module Reliability Scorecard, 37 models represent TOPCon technology along with 9 based on heterojunction (HJT).

The 9^th edition of the annual report has a record 35 manufacturers and almost 250 model types qualifying as top performers. Models tested for the scorecard were manufactured in 12 countries by companies with global sales. At least 11 companies had one or more model types that are top performers in every reliability test.

The report covers modules under 6 main Product Qualification Program (PQP) test categories. Analysts share following main key takeaways for each of these categories:

Thermal cycling (TC)

• 84% of the BOMs tested degraded by less than 2%.
• There was 0.5% median degradation for glass-glass as compared to 1.8% for glass-backsheet modules.
• Analysts found both PERC and TOPCon panels equally reliable, but HJT faces the challenge of low-temperature soldering.
• A total of 6 manufacturers experienced one or more failures during TC testing including catastrophic junction box issues such as failed diodes, melted connectors, exposed wires and no output due to open solder bonds in the junction box.

Damp heat (DH)

• There was 1.3% median degradation and 1.5% average degradation for modules tested. At least 72% of BOM’s exhibited less than 2% degradation compared to only 50% in 2022 scorecard.
• Glass-glass modules had 1.0% median degradation while for glass-backsheet panels with identical cells, it was 1.9%.
• Average degradation of 1.2% to 1.7% was seen across CdTe, HJT, PERC and TOPcon products but no specific technology outliers were seen.
• From 4% BOMs having DH related power loss failure as reported in 2022 scorecard, PVEL says the volume dropped to 0% in 2023.

Mechanical stress sequence (MSS)

• 98% of BOMs tested had less than 2% power loss thanks mainly to multi-busbar (MBB) of 9BB or greater. PVEL says these are the lowest average and median MSS degradation rates in its history.
• No additional cracked cells were seen in glass-glass modules following MSS.
• More issues were seen for tracker mounted MSS, as compared to traditional 2-rail mounting.
• 7% of BOMs testes experienced an MSS-related failure.

Potential-induced degradation (PID)

• 79% of BOMs tested were PID top performers but 5% had more than5% power loss.
• Very strong PID results were seen for CdTe, while HJT, PERC and TOPCon median degradation ranged from 1.1% to 1.6%.
• Modules using EVA for rear-side encapsulant had an average median degradation 4-times higher than those using POE or EPE proving that encapsulant choice affects PERC PID results.
• A total of 4 manufacturers experienced higher than expected PID power loss.

Light-induced degradation (LID) + Light-and-elevated temperature induced degradation (LETID)

• 97% of BOMs tested had less than 2% power loss prompting PVEL to consider raising the top performer threshold for this test in the future.
• 100% of PERC BOMs in the scorecard this year were gallium-doped.
• Average LID+LETID power loss across CdTe, n-type, TOPCon and n-type HJT was 0.0% and the median was 0.2%.
• Pre-stress testing failures continue to be a challenge.

PAN performance

• PVEL increased top performer threshold for this category this year by a relative 0.8% and found only 2 of 16 2022 scorecard top performers met the requirement.
• All PAN-tested bifacial TOPCon and bifacial HJT modules are top performers.
• HJT stands out for better temperature coefficient, followed by TOPCon and then PERC.
• There is no single technology with clear advantage for low light efficiency across HJT, PERC and TOPCon.

Details of the 9^th PVEL scorecard are available on its website.

TaiyangNews covered the subject of module reliability in our Virtual Conference on Reliable PV Module Design in December 2022 with PVEL’s VP Sales and Marketing Tristan Erion-Lorico in attendance. Conference summary and presentations are available for free on our website here.