No matter how many components are used to make up a solar module, for a module producer ensuring overall product reliability is an uphill path and the most critical task. During the Reliable PV Module Design virtual conference organized by TaiyangNews in October 2020, Chinese solar cell and module producer Astronergy Chint whose parent company is The Chint Group, shared how it ensures the same for its own brand which is sometimes also referred to as Chint Solar.
Astronergy's Product Manager Aj Hu listed all the factors that can go wrong in a module overtime bringing down its efficiency. These factors range from glass anti-reflective coating degradation, EVA discoloring, delamination of the backsheet, cracked cell isolation, contact failure of the junction box, glass breakage, loose frame, diode failure, corrosion of cell and interconnect, through its life from being produced in the fab to wearing itself out on the field.
As the PV industry moves from mono facial to bifacial modules, from multicrystalline cell to monocrystalline cells (which is basically achieved), from P-type to N-type and towards 500W+/ 600W+ power output for utility-scale modules, it also continuously calls for higher cell efficiencies, which is also bringing in cost-reduction at economies of scale. It would mean, argued Hu, that companies increasingly incorporate intelligent manufacturing with high-throughput.
Astronergy itself uses several wafer sizes for its modules, from 158.75mm G1 wafer to 166mm M6 wafer and has now reached 182mm M10 wafer size for its Astro series calling it Astro 5. For the Astro 5 modules with up to 545W and 590W it uses double glass, half-cell and multi busbar (MBB) technologies that it sees to have led to optical gains, cost reduction, and electrical resistance reduction. Use of double glass ensures better protection from heat, snow and offers high moisture resistance, she said. It offers 30 years power warranty for the glass-glass Astro 5 twin module, 25 years for Astro 5 Semi, and 12 years of product warranty as it claims around 2% 1st year degradation for this series, monofacial annual degradation of some 0.55%, and bifacial annual degradation of about 0.45%.
A non-destructive cutting (NDC) method is used by Astronergy to cut cells into half which improves bending strength of cells and mechanical properties of modules. At the same time, since the busbars are more concentrated, the failure area in case of cracks is smaller than in conventional modules, thereby ensuring higher reliability, she pointed out.
Like any other leading module manufacturer, Astronergy says it also carries out stringent testing for all its various components, and checks compatibility of the final product with mainstream inverters and trackers to confirm convenient application. To control light elevated temperature induced degradation (LeTID) of PERC cells, Hu said her company has developed a LeTID solution involving high quality wafers, advanced passivation process and excellent annealing technology.
However, what's interesting is that Astronergy said it is using Manufacturing Execution Systems (MES) for process control in the production process and AI for EL measurements of cells, resulting in 50% less manpower, 100% full inspection capability and with an accuracy of 97% and a two times faster inspection speed. Astronergy pointed out that its Astro Twins series was the only Top Performer in all 5 PQP categories of the 2020 PVEL/DNVGL PV Module Reliability Scorecard.
The company, which currently operates an annual solar cell production capacity of 4.5 GW and 5 GW for modules at its Haining and Hangzhou locations in Zhejiang province, is currently constructing its new fab in Dafeng, Jiangsu province to host an additional 5 GW annual capacity. It plans to exit 2020 with a total module production capacity of 7.5 GW, scale it up to 9.2 GW in 2021 and reach a total of 15.5 GW in 2025.
A recording of Aj Hu's presentation at the TaiyangNews Virtual Conference on Reliable Module Design is available on our YouTube channel here.