In the wake of competition on larger wafers that prevailed throughout the first half of this year, debate is reemerging about 182mm and 210mm formats as Longi, Jinko, and JA Solar achieved volume production of modules based on 182mm wafers recently.
As China moves towards grid parity, larger wafer sizes have been considered by solar manufacturers as a route to maximize returns in a subsidy-free era.There are two roadmaps for adopting larger wafers. The first one involves upgrading existing lines in ways that make them compatible with 182mm format, which can help bring the power rating of 72-cell modules to 535 Wp. The other roadmap involves new lines that are compatible with 210mm format so that modules can hit 545 Wp in mass production.
Compared with modules based on 166mm wafers and rated at 445 Wp, 210-mm modules boast 23% higher power output than and outperform 182-mm, 535 Wp modules by 10 W when both modules feature the same surface area. Moreover, by using just 55-cell layout, 210-mm modules can outdo 72-cell, 182-mm modules in power rating and have its open-circuit voltage cut to as low as 38 V. The single module string can connect up to 36 cells, pushing the power output of a single string to 20 kW, thus reducing their cost of balance of system.
In fact, whether a module can help to cut the levelized cost of electricity (LCOE) comes down to the PV system itself. Indeed, it is less than realistic to estimate the cost of a given device, and not only module makers but suppliers of inverters and mounting brackets also need to advance technologically to help PV projects achieve grid parity.
On the system’s side, Hebei Energy Engineering Design has conducted a test on 210-mm, 182-mm, and 166-mm modules (all operating on even ground and using a string inverter) used in PV systems operating in the cities of Daqing, Laizhou, and Xingning—with a 100 MW PV plant as the benchmark against which the three modules’ low-voltage cost is measured. The respective parameters of these modules are derived from relevant specs documents provided by a leading module manufacturer.
Costs of the low-voltage side for the three modules is estimated on the basis of their respective technical parameters and the latitudes of different test locations:
Across the three modules, the cost shrinks along as power rating increases. Notably, it is the lowest for 210-mm, 545 Wp modules in all the test locations. There is a difference of RMB 0.1–0.17/W in the cost between 210-mm, 545 Wp and 166-mm, 445 Wp modules, and of RMB 0.03–7/W between 210-mm, 545 Wp and 182-mm, 535 Wp modules.
Take the PV project in Daqing for example, the project uses a string inverter and vertical mounting bracket. Moreover, increased power output allows the use of fewer numbers of brackets, stakes, cables, and string inverters.
Dong Siaocing, deputy general manager of Hebei Energy Engineering Design, says that “based on our cost estimations in these three locations, high-power output modules with string inverters see their costs decline. While cost savings are different across the locations, on the whole it deserves to see how well the low-voltage cost has been reduced among the high-power output modules. The cost estimation takes into account the geographical features of the test locations, installation difficulty, system configuration, and the actual condition of the PV systems.”
210-mm modules with high power output and string inverters deliver impressive cost reduction on the low voltage side because low voltage pushes up the power output of a single module string by around 20 kW. While modules are getting bigger in order to achieve higher power output and lower LCOE these days, it is intriguing to learn how low-voltage modules bring down system cost.