Solar modules used in FPV systems are typically the same as those used in land-based solar PV systems. However, there are a few key considerations that need to be taken into account when selecting solar modules for FPV systems. Since the modules operate in a highly humid environment, glass-glass modules are preferred. To further protect the cell matrix from moisture ingression ,module encapsulation with POE, which has lower water vapor permeability than EVA, is typically recommended. With glass-glass modules, opting for bifacial technology can improve the energy yield. Although water has a very low albedo, any bifacial gain is a bonus. However, glass-glass modules may not be even required in some cases, according to Isigenere's CEO Andrés Franco. He explains that by taking humidity as an example, as panels that are suitable for standard rooftop applications in tropical areas can easily be a good fit for extreme humid conditions of any dams in Europe too. "The module selection depends a lot on the site location," he emphasized.
A close collaboration with module makers is underscored by most of the FPV experts we spoke to in atypical cases such as near-shore with saltwater. All FPV solution providers we talked to prefer the use of common products in order to directly benefit from the latest developments associated with the module segment. Then the goal is also to house the most powerful module, especially with larger projects. It is also a matter of costs, whether to opt for M10, G12 or other sizes. Most of the leading FPV solution providers can accommodate most of the commercially available module sizes including the larger ones. However, an important trend with respect to modules, according to Franco, is that unlike in the past, where larger modules were preferred, developers are now increasingly opting for mid-sized standard modules of 2,382 x 1,134 mm (see FPV On Different Water Bodies)..
Interaction with module manufacturers may be required with regards to mounting solutions of the module onto the floaters. Exercising the same practices used in mainstream onshore applications may not be optimal as FPV is completely different. This is a requisite for Ocean Sun's membrane based floating system, which does require a few modifications at the module level. For the rear of the module to have full contact to the membrane, the junction box is arranged on the front side. Ocean Sun is cooperating with GCL, which can offer such specially designed modules with similar warranty conditions as for mainstream modules. At the same time, the company is developing partnerships with other module makers. On the other hand, FPV is emerging as a strong sub-branch of PV that is attracting the attention of leading module producers. Speaking from the perspective of module makers regarding FPV at the TaiyangNews Advanced Solar Module conference, JASolar's senior technical manager Ignacio Espinosa discussed in his talk Maximizing Sustainability & Efficiency – The Future of Floating Systems and Agri-PV the key characteristics of modules that make them compatible with FPV applications.
One of the major challenges with FPV is the wide variety of installation types, such as reservoirs, lakes, offshore, near-shore and treatment plants. This makes it difficult to have a dedicated product for all scenarios. According to Espinosa, the key characteristics of modules suitable for FPV are the ability to operate in salt mist and corrosive environments with high reliability, high bifaciality, and the modules should be built with non-hazardous materials, especially in relation to water. To ensure that the modules meet these conditions, JA Solar tests its modules in harsh conditions, such as the IEC 61701 salt mist test and a 3x IEC test. The company also cooperates with PVEL for reliability testing. Modules also need to have a REACH certificate, which confirms that they do not contain any hazardous materials. Warranties at par with mainstream products are also important, as are references (see Membrane Based Solution For Floating PV Systems).
However, a special bill of materials (BOM) is the main way to meet all of the above requirements. JASolar uses specially treated glass in a double-glass configuration, optimized encapsulation material, and anti-corrosion treated frames to build modules for FPV. To be able to cater to different types of applications and installation scenarios, JA Solar promotes a range of n-type TOPCon modules for FPV with power outputs ranging from 445 W to 620 W and efficiencies ranging from 22.2% to 22.4%. There is also a PERC module with 565 W and 21.4% efficiency in the list. Huasun, for example, has developed a HJT module series for offshore solar power plants, calling it V-ocean, which it presented at the TaiyangNews Virtual Conference on Global PV System Technology Trends H1/2023 held at the end of June 2023 (see FPV For Offshore).
For offshore applications, Huasun has developed a module with a special BOM that is designed to withstand the harsh conditions of the marine environment. This BOM includes double-layered coating glass, multi-coating frame, PIB sealant, IP68 connector with protect cap and SMBB interconnection with inter cell spacing of 0.8 mm. These upgrades have enabled the modules to pass the IEC salt mist Level 8 test and they are also the first to be certified for module reliability under marine environment from Bureau Veritas. The module has a power rating of 720 W, 23.2% efficiency and comes with a power warranty of 30 years. Huasun claims that its offshore modules can reduce BOS costs by7% and transportation costs by 6% in floating PV applications. Based on a theoretical calculation, when compared to a PERC module of the same size, an offshore project equipped with V-ocean series HJT modules can achieve an annual power gain of 6.9%, according to Huasun (watch Huasun presentation here)
The text is an excerpt from the TaiyangNews Floating PV 2024 Report, which can be downloaded for free here.