Exploring the Types of Solar Technologies Utilized in BIPV Panels

Building Integrated Photovoltaics (BIPV) represents an innovative approach to facilitate the development of zero-emissions buildings (ZEBs) by integrating solar photovoltaic materials directly into building components.

BIPV panels have become one high-end panel product on the market. But from a professional standpoint, what types of solar technologies are utilized in these revolutionary panels?

The answers await, keep reading.

What to Consider When Determining the Type of Solar Technology for BIPV?

As BIPV systems serve multiple purposes, the factors to be considered when selecting the right type of solar technology are multifaceted, which can be grouped as follows.

Technological Specs

Installing BIPV solar panels is an important means to equip modern, urban buildings with on-site renewable energy generation capability, which is at the core of either the Zero-Emissions Building (ZEB) or the Nearly Zero Energy Building (nZEB) initiative. 

Hence, the efficiency and energy yields of the BIPV panels are critical technological factors to consider. Higher-efficiency BIPV panels can generate more clean electricity per unit area, which is essential for urban buildings with limited available areas for solar installations.

Architectural Integration & Aesthetics

Aesthetics play a significant role in BIPV adoption. 

Photovoltaic technologies hold varying customization levels in terms of shape, size and color. They also have different weights, thicknesses, and degrees of bendability and transparency.

Taking into account the integration and aesthetic demands of the BIPV project, manufacturers or developers should carefully choose a technology that offers the ideal physical properties to manufacture BIPV panels that meet the desired requirements. Make sure the end BIPV products blend seamlessly with the building's design.

Performance & Durability

The reliability of solar technology to be utilized in BIPV panels is a key factor as well.

Except for BIPV solar roofs, the BIPV modules installed in the facade as well as for the awnings and canopies of a building could be difficult to access for maintenance in contrast to those conventional modules in standard rooftop and ground-mounted projects. In addition, both the installation and maintenance often require specialized knowledge. 

Therefore, it is essential to select a reliable solar photovoltaic technology that is constructed with durable, high-quality materials, ensuring robust performance and longevity under local weather conditions. 

Besides, temperature coefficient and low-light performance are important panel criteria to assess for optimal energy production, particularly in the less-than-ideal installation conditions that diverge from ideal conventional solar project settings.

Economic Factors

Moreover, BIPV panel systems are generally more expensive than traditional panels due to their dual functionality. Therein, the cost of the solar photovoltaic technology to be applied should also be carefully weighed up; and frequently, this is evaluated in conjunction with the expected or simulated efficiency and output of the BIPV product for an ideal input-output ratio.

The Solar Technologies Utilized in BIPV Panel Manufacturing

Solar technologies are diverse and they are selected as per specific needs to suit different BIPV applications. Here are the primary and emerging solar technologies utilized in BIPV panel manufacturing.

Crystalline Silicon Cell Technologies (c-Si)

Crystalline silicon solar cells are the most established and common type of cell technology used in both conventional and BIPV panel manufacturing. 

These cells are made from silicon wafers and known for their high efficiency compared to other types of cells. Notably, the monocrystalline variety (mono-Si) is most frequently used as it offers exceptional photoelectric properties that surpass those of the polycrystalline variety (poly-Si).

However, c-Si has relatively weak absorption of sunlight compared to some other materials, demanding a thicker layer as well as highly transparent front layers to capture a sufficient amount of light. This may, in turn, confine the customization levels and flexibility in the design and manufacture of BIPV products though it provides excellent mechanical strength.

Thin-Film Panel Technologies

Thin-film panels are another popular photovoltaic choice for BIPV. 

Unlike crystalline silicon panels, which require interconnections between individual cells to form a complete panel unit, thin-film panels are made by depositing one or more layers of photovoltaic material directly onto a substrate. This forms a continuous appearance of thin-film panels, making them particularly suited for some BIPV panels that highlight visual continuity.

In addition, the direct bandgap nature, combined with other advanced photoelectric features and optimized processes collectively enable thin-film technologies to be effective in converting sunlight with thinner layers, contributing to superb flexibility. 

They are also renowned for their better-than-average performance in low-light conditions. This feature is especially beneficial for BIPV applications where photovoltaic materials must conform to the building structure and cannot always be oriented in the most optimal directions. 

Their excellent performance in low-light conditions, on the other hand, offers more options for integrating a variety of front materials for BIPV panels. This allows the front layer to go beyond high-transparency options like glass, and it enables the use of colored, textured or patterned materials for a more appealing and adaptive look.

Amorphous silicon (a-Si), cadmium telluride (CdTe) and copper indium gallium selenide (CIGS) thin-film technologies can all be observed in the manufacturing of BIPV panel products.

However, the major downside of these thin-film technologies is their less-than-optimal efficiencies.

Emerging Technologies

The concept of BIPV can be traced back to several decades ago. Scientists have researched and developed BIPV panel products along two parallel paths: by adapting and enhancing existing technologies and by inventing new ones.

One of the best-known emerging techs is MIT’s transparent cell invented around the 2010s. The cell features a novel design incorporating specialized light ‘reflectors’ and photovoltaic materials that are formulated to capture the absorption of infrared and ultraviolet light. Due to the intricacies of this technology, it hasn’t been formally commercialized yet and has chiefly been implemented in demonstration BIPV projects.

Luminescent solar concentrators (LSCs) represent another promising technology for BIPV systems. Like MIT’s transparent cell, this technology regulates incoming light before initiating the actual conversion process, but it involves a more intricate method. To be a bit more detailed, it uses a semi-transparent glass or plastic slab functionalized with fluorophores to absorb and re-emit a portion of light as fluorescence which is then absorbed by photovoltaic cells attached to the edges of the glass or slab.

Another innovative technology is the use of dye-sensitized solar cells (DSSCs) which convert sunlight into electricity through a ‘photoelectrochemical’ process. Like principal thin-film cells, this technology offers great flexibility and performs well in low-light conditions. However, its stability issues hinder its broader adoption in BIPV products.

Which Technology Is Better For BIPV Applications?

Each solar technology has its own advantages and disadvantages for the utilization in BIPV panel applications. The better choice depends on several factors, and there isn't a one-size-fits-all solution.

For example, flexible BIPV applications such as curved surfaces might benefit more from thin-film technologies, whereas applications prioritizing efficiency might lean toward c-Si technologies.

For seamless integration into building designs, mature thin-film such as CdTe transparent panels and CIGS roof tiles offer greater feasibility plus better options and flexibility in terms of transparency, color and more, as compared to the emerging techs with limited availability.

Thin-film and emerging techs like DSSCs may offer cost advantages due to simpler manufacturing processes and lower material costs. However, they may require more surface area to achieve the same energy output as c-Si panels.

When it comes to durability, c-Si is known for it, making it a reliable choice for long-term applications. But advancements in thin-film technologies have already significantly improved their longevity, narrowing such gaps between other photovoltaic options.

It’s worth noting that for semi-transparent to transparent BIPV applications, thin-film and some emerging techs may be the principal choices since it is not common to sacrifice efficiency for high transparency for c-Si technologies.

Wrapping Up

Here we only delve into the photovoltaic part of BIPV panels. When their building materials are entailed, the circumstances may be more complicated, resulting in coupling issues and more.

In any case, the mature c-Si and thin-film solar technologies offer commercially viable and reliable photovoltaic solutions for BIPV applications. On the flip side, emerging technologies geared toward dual missions of high efficiency and exquisite aesthetics represent the future photovoltaic solutions for BIPV.