A limit to the size of photovoltaic modules – pv magazine India

There is a threshold at which big becomes too big when it comes to the size of PV modules, argues Hongbin Fang, director of product marketing at Longi Solar. Fang recently told pv magazine’s Roundtables USA event that despite the size limitations, there is still a lot of efficiency and cost-cutting potential to come.

From pv magazine 12/2021

Large format modules have gained market share but face a number of hurdles including shipping, comparable efficiency rates, and system balance (BOS) considerations. What is the key to Longi’s strategy in the face of the high power trend?

Hongbin Fang, Director of Product Marketing, Longi Solar: The size of the wafer and cell of 182mm is the optimum dimension obtained after a thorough analysis of all the manufacturing processes of the cell and module. We believe this is also true of the module deployment processes including shipping and installation – this is the maximum size of the wafers / cells with conventional six row threading in each module. which still fits 40HC containers using today’s best-known shipping method: double stacking the pallets inside the 40HC and landscaping the modules inside each pallet.

With module voltage maintained the same as previous smaller format modules and slightly higher current, only minor adjustment is required on the downstream BOS equipment to make them compatible. We have worked diligently with various BOS component partners to ensure compatibility. Based on this, Longi believes that the 182-72 cell module is the optimized solution for utility projects. This has helped our customers to reduce BOS costs and achieve significantly lower LCOE.

You mentioned the tension and the logistics, but what about the modules installed in the field. Why do you think the 182-72 cell format is better than the bigger modules, some of which are now over 600W?

Photovoltaic projects are designed to operate reliably for 25 to 30 years. But extreme weather conditions are more and more common and we need to include sufficient margins in the design of our systems and components, so that the whole project can survive extreme weather conditions and perform well throughout its duration. of life. With the same efficiency, higher power modules require a larger footprint, which creates deployment challenges and increases reliability risks. For example, under the same mechanical load, 40% to 60% higher deformation is observed on 600 W and above modules compared to 182-72 cellular modules, increasing the risk of U-shaped cracks and glass breakage. .

Other areas of higher reliability risk include higher shear stress at the mounting position under dynamic load, smaller safety margin at the junction box, higher resistive loss at connector contacts and lower glass strength due to larger dimensions. In order to fit into 40HC, oversized modules (600W +) must adopt vertical loading (portrait orientation) within each pallet, significantly raising the center of gravity and posing challenges during the unloading process under site conditions. not very favorable.

So, do you think we’ve hit the threshold for module sizes?

Using large format modules to improve the output power of each module has been an effective way to lower the cost of BOS and improve LCOE over the past two years. The analysis showed that the cost of BOS reached a plateau with an approach of increasing the size and power of the module without improving efficiency. At the same time, using the same 2mm plus 2mm double glass construction, further increasing the dimensions of the modules will lead to higher reliability risks, as I have already explained.

At Longi, we believe that there are significant reliability risks with oversized modules (more than 2.8 m² in area or more than 1.2 m in width). As such, we will not pursue a modulus dimension larger than the 182-72 cell format. Instead, we will focus on improving the efficiency of cells and modules for future technological advancements and bring better value to our customers with higher efficiency modules.

If you don’t go taller, how do you continue to increase efficiency?

With large investments in the development of advanced technologies, the photovoltaic industry is making good progress in improving efficiency and reducing costs to bring advanced technology into high volume production. Our recent announcements showing TOPCon and HJT cell efficiency world records on commercial size wafers are good testimony to recent progress. The market will see more and more advanced, high efficiency technologies in volume production over the next few years.

There is growing attention to carbon footprints in production. What steps is Longi taking to continue to decarbonize and green its supply chain, while addressing end-of-service module issues?

We are in the green energy business and we are committed to making our manufacturing green. Since 2015, we have intentionally located most of our new ingot and wafer manufacturing capacity in Yunnan Province in China and Sarawak in Malaysia, in order to take advantage of local grids primarily powered by clean hydropower. Longi has also joined the RE100 initiative and is committed to powering 100% of our operations with renewable energy by 2028. To help deep decarbonization, we have also created Longi Hydrogen Company with a focus on the development of ‘green hydrogen equipment.

What are two or three steps Longi can take to further reduce the cost of solar power?

We truly believe that with technological innovations, the cost of solar power will be further reduced. The manufacturing processes of ingots, wafers, cells and modules can be further optimized and material consumption further reduced, combined with continuous improvement in cell and module efficiency, the cost of modules per watt will continue to drop.

With improvements in the efficiency of cells and modules, higher power is obtained with the same module dimension. Energy efficiency will also be further improved with the introduction of advanced technologies. Both will help lower the cost of BOS and achieve a lower LCOE than the system level.

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