How to make the most of the bifacial solar module opportunity

By Leonardo Botti, FIMER

Without doubt, the solar PV industry is one of the most exciting sectors to be working in at the moment. With the International Energy Agency (IEA) reporting a huge 18-fold increase in the amount of installed solar PV capacity between 2010 and 2020, and IEA executive director Fatih Birol, stating that “I see solar becoming the new king of the world’s electricity markets”, the growth of solar looks set to continue.

During this time, we have also witnessed a huge increase in innovative applications – solar is no longer ‘just’ a pure power conversion but it has been the foundation of the DG (Distributed Generation). It can be installed in the most extreme locations to harness the power of the sun and generate renewable power.  At FIMER, we have had the pleasure of working on projects based in locations as diverse as deserts and mountains and even in the sub-zero temperatures of the Antarctic.

One of the major trends we have seen in recent years has been the growth in bifacial module installations.  Although the technology itself is not ‘new’ — bifacial modules have been around for many years — it is only relatively recently that the use of these modules has become more common in the solar PV sector, having previously been regarded as a fairly novel technology.

It’s easy to see why it has become more popular.  As well as achieving maximum energy performance by utilizing both sides of the panel, the technology itself has seen a significant reduction in cost compared to standard modules, making it a more realistic solution for a greater number of projects.  Growth has been also fuelled by the development of PERC (passivated emitter rear cell) technology and favourable tariffs and subsidies in some markets.

In fact, a report last year from the International Technology Roadmap for Photovoltaic (ITRPV) predicted that the marketshare for bifacial modules will increase from ten percent in 2020 to at least about 35 percent by 2030. This reflects a 2019 report from Wood Mackenzie Power & Renewables that predicted that bifacial module capacity will exceed 21 GW by 2024 with Asia Pacific, North America and the Middle East being cited as the biggest growth markets. 

As mentioned earlier, the primary benefit is that they provide higher energy performance.  According to a SolarPro study of PV module manufacturers, bifacial modules have shown energy yield increases of up to 11 percent for fixed tilt systems and 27 percent for tracker systems, when compared to similarly rated traditional modules.  This trade-off between additional cost and extra performance is increasingly seen as worth the investment.

This has been particularly evident in the increasing adoption of bifacial modules in the utility-scale, industrial and large commercial markets, as they benefit from higher solar generation and lower energy costs, particularly for tracker systems.

However — as with many technologies — there are still challenges.  While the side facing the sun works in the same way as traditional modules, variables on the rear side do impact the level of reflective light it receives, for example, the quality or color of the roof or ground.  This unpredictability means that it is not a suitable technology for all applications.  

Bifacial modules also present a challenge for inverter manufacturers who need to ensure that their technology can respond to the higher level of input current generated compared to traditional modules.  In any installation, the inverter must allow for maximum current from strings — with bifacial modules, the inverters installed need to be able to cope with an even higher current.

Therefore, the requirement for inverter load flexibility is crucial, which means that matching the right inverter to a bifacial module project is a critical action to undertake if the project is to be a success. 

As a result, the newly launched and the next generation of inverters are being designed to cope with the increased incoming current requirements for bifacial module systems.  Inverter improvements also include greater granularity of maximum power point tracking (MPPT) and support to higher incoming currents, so, for bifacial module installations, a multi-MPPT string inverter is the optimal choice. 

We recently launched our new string inverter — the PVS-10/33-TL — that is designed to provide this high level of flexibility.  While designed specifically for the commercial and industrial markets, the higher kW units (20, 30 and 33k W) are particularly suited to bifacial module installations, forecasted to increase in those applications too going forward. 

As a result of reducing costs and an increase in successful projects utilizing bifacial modules, installations are expected to grow in almost all territories.  While they do come with their challenges, the possibilities of a higher energy yield mean they will continue to be a popular choice for utility-scale, industrial and larger commercial installations, particularly tracker systems.  This means that, for installers, choosing the right inverter partner will be crucial to maximizing the bifacial opportunity.

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