How can Building-Integrated Photovoltaics (BIPV) be successfully implemented in industrial plants?

I. Building-Integrated Photovoltaics: A New Favorite for Industrial Plants?

Today, the global community strongly advocates for green environmental protection and sustainable development, and the construction industry is no exception. Among numerous green building technologies, Building-Integrated Photovoltaics (BIPV) technology stands out and has attracted significant attention. Simply put, BIPV technology integrates solar power generation products with buildings, allowing buildings to not only provide shelter but also generate their own electricity, achieving a perfect fusion of "photovoltaics + green buildings." This perfectly aligns with current development trends.

 

In recent years, China has proposed the concept of "ultra-low energy consumption and near-zero energy consumption buildings," bringing new development opportunities to the BIPV industry. Industrial plants using BIPV technology enjoy numerous benefits, including additional electricity revenue, energy saving and emission reduction, improved insulation and cooling for the plant, and savings on traditional color-coated steel roof investments. Therefore, it is likely to become a new trend in building energy development. Below, we will delve deeper into the application of BIPV in industrial plants.

 

II. Building-Integrated Photovoltaic Roof Systems: From Inception to Development

The construction industry has consistently been a major energy consumer in China, and changing this high-energy-consumption status quo is urgent. With the advancement of national strategies such as energy production and consumption revolution, supply-side structural reform, and green development, the integration of photovoltaics and buildings has become an inevitable trend. Statistics show that the total area of roofs and facades suitable for photovoltaic installation in industrial and commercial buildings (including public buildings) across the country is nearly 8 billion square meters, indicating enormous potential for photovoltaic roof development.

As early as the beginning of the 2000s, photovoltaic buildings emerged, with early projects primarily focusing on photovoltaic curtain walls. However, the early integration of photovoltaic materials and buildings was not high, and these projects were mostly led by photovoltaic material manufacturers. Moreover, there were no specific standards for photovoltaic buildings at the time; relevant standards for ground power stations were referenced instead. Although some projects achieved certain application effects and demonstration effects, due to the high cost of photovoltaic power generation and the lack of unified national technical standards and certifications, most projects failed to achieve their expected results. By the end of 2018, the cumulative installed capacity of the domestic BIPV market was only 1.1 GW, a significant gap compared to the development speed of distributed photovoltaics, with a market size of less than 5 billion yuan, and the entire industry was still in its infancy.

 

Previously, most building-integrated photovoltaics applied in industrial plants used the "Building-Added Photovoltaics" (BAPV) model. This model typically involves phased construction; after the building's civil engineering and color-coated steel roof are completed, component brackets and other equipment are installed on the roof later. This not only increases unnecessary investment but also restricts photovoltaic design and installation due to roof structure limitations, and is also less aesthetically pleasing.

With the continuous advancement of photovoltaic technology, many industrial buildings are now adopting the "Building-Integrated Photovoltaics" (BIPV) model. This model uses specially designed integrated BIPV photovoltaic components to directly replace the original roof, making the photovoltaic components part of the building and achieving true integration.

III. Significant Advantages of BIPV Applications in Industrial Plants

(I) Additional Electricity Revenue: A Real "Money-Making Tool"

For industrial plants, installing a BIPV system is like creating a "small treasury." For example, a 10,000-square-meter industrial plant using BIPV design, with 1.2 MW of components and supporting power generation systems installed, has a total investment of less than 5 million yuan. In areas with average resources, it can generate 1.44 million kilowatt-hours of electricity annually. If all this electricity can be used by the plant during the day, based on an average daytime industrial and commercial electricity price of 0.8 yuan/kWh, it can save 1.15 million yuan in electricity costs annually, achieving payback in less than 5 years. This is a considerable return on investment.

(II) Savings on Plant Roof Costs: A "Money-Saving Trick" That Benefits Both Sides

When constructing new industrial plants, using BIPV technology eliminates the need for traditional color-coated steel roofs, allowing for direct installation of the photovoltaic BIPV roof power generation system. This saves on the purchase and installation costs of color-coated steel. For industrial plant roofs where the color-coated steel has reached the end of its lifespan and needs replacement, there is no need for extensive changes to the plant's original structural design or additional roof load; direct replacement with a photovoltaic BIPV roof is sufficient. Generally, the cost of color-coated steel is around 100 yuan per square meter, and BIPV perfectly replaces the traditional roof, saving companies a significant amount of money.

(III) Longer Service Life: A "Hassle-Free Choice" for Long-Term Use

Traditional steel structures typically require major repairs or roof material replacement after 10-15 years. This process involves significant investment and time consumption. However, the lifespan of BIPV photovoltaic roofs can reach 25 years. Compared to traditional color-coated steel roofs, BIPV is practically maintenance-free, significantly reducing the hassle and cost of later maintenance and replacement.

(IV) Contributing to Zero-Carbon, Zero-Energy Building Development: Keeping Up with the Green Development Trend

Currently, the country is vigorously promoting the development of green buildings, issuing numerous plans, implementation opinions, and standards related to green building development. Some provinces have also provided subsidies and incentives for green building projects to reduce building energy consumption and achieve ultra-low energy consumption and near-zero energy consumption building goals. "Made in China 2025" also puts forward new requirements for future high-end manufacturing, with intelligence and greenness becoming the development direction of future manufacturing plants. The energy generated by BIPV buildings can not only meet the energy consumption of the buildings but may even have surplus, fully complying with the green, environmentally friendly, and energy-saving concepts of green buildings, and is an important direction for the future development of industrial plants.

 

IV. BIPV Application Cases in Industrial Plants

(I) BIPV Photovoltaic Roof Replacing Color-Coated Steel: "Gorgeous Transformation" of Old Roofs

An old warehouse in Fengcheng City, Jiangxi Province, originally had an asbestos tile roof with a slope of 18 degrees. Later, using BIPV design, construction personnel first removed the original asbestos tiles and purlins, reinforced the new purlin structure, and then, through reasonable design, installed a 40.9 MW BIPV system. This project not only utilizes idle roofs for efficient power generation but also saves funds and time on roof maintenance. Moreover, the renovated roof is expected to have a lifespan of 25 years, giving the old plant a new look.

(II) New Industrial Plant Roofs: "Green Choice" from the Design Stage

A plant in Zhixi Industrial Park, Jintan, Changzhou, Jiangsu Province, incorporated the BIPV concept during the project design phase. During construction, following the principles of energy saving and efficiency improvement and building integration, a BIPV roof power generation system was directly installed, laying 2.05 MW of photovoltaic components. This saves on traditional roof investment while generating electricity revenue, laying the foundation for the plant's green development from the outset.

 

V. Design Considerations for BIPV Applications in Industrial Plants

(1) Fire Hazards: An Unignorable Safety Issue

In BIPV systems, high-voltage DC arcs are the main cause of fires, accounting for approximately 45% of rooftop distributed photovoltaic power generation fire incidents. Therefore, special attention must be paid when designing BIPV DC systems. References can be made to the requirements in "Technical Application Regulations for Photovoltaic Buildings" (T/CBDA 39-2020), such as minimizing the use of DC lines, keeping the DC system voltage below 80V, ensuring the photovoltaic system has the ability to detect arc faults, and equipping each photovoltaic building component with a system disconnection device. In addition, fire-resistant and flame-retardant materials should be used on the inner and outer sides of the components, non-combustible materials should be selected for the component brackets and support bases, and lightning protection design should be implemented comprehensively to ensure safety.

(2) Heat Dissipation: The Key to Balancing Energy Efficiency and Power Generation

Solar panels generate heat during operation. If ventilation is inadequate, this heat will enter the building, leading to a conflict between energy consumption and energy saving, and reducing photovoltaic power generation efficiency as the temperature rises. To address this, based on different building structures, heat dissipation channels should be rationally designed through the installation of air vents, passive wind turbines, etc., using air convection to dissipate heat and ensure the normal operation of the BIPV system.

 

(3) Waterproofing: A Crucial Aspect of Plant Safety

Waterproofing is a critical consideration for Building Integrated Photovoltaics. Previous projects have experienced leakage due to improper waterproofing design. The domestic BIPV market now offers various waterproofing technologies, such as gutter BIPV, photovoltaic color-coated steel sheet BIPV, and component-type BIPV. For example, some projects use a rationally designed gutter system, employing U-shaped waterproof gutters and W-shaped gutters for horizontal and vertical waterproofing. The gutters are connected using a snap-on, hole-free method, and the bottom is secured and sealed with rubber strips. The entire roof surface has no perforated connections, effectively preventing leakage.

(4) Aesthetics: Design Considerations for Enhancing Building Appearance

As building materials, BIPV products should also prioritize aesthetics. During design, the array and maintenance access should be rationally planned, minimizing the gap between the cells and the color-coated steel sheets for a more uniform appearance. Simultaneously, concealing the DC cables beneath the components and color-coated steel sheets achieves a pleasing architectural aesthetic, making the plant both practical and attractive.

(5) Maintenance: Ensuring Long-Term Stable System Operation

The maintenance of BIPV products differs from traditional BAPV distributed photovoltaic components. Because BIPV is closely integrated with the building, removal and replacement are inconvenient. Therefore, during design, it is necessary to rationally plan maintenance access to ensure convenient maintenance without affecting the roof's function and structure. Reliable and high-quality components should also be selected. For example, some components use half-cell technology to reduce heat generated by hot spots and lower system risks; they have stronger front mechanical loads to reduce the occurrence of component micro-cracks during maintenance; and they use aluminized zinc-coated steel plate frames and double-glass encapsulation to reduce the occurrence of potential-induced attenuation.

 

VI. Conclusion: The Future of BIPV in Industrial Plants

Overall, the application prospects of photovoltaic building-integrated rooftop systems in industrial plants are very broad. It can bring additional electricity price revenue to enterprises, save investment, and has an aesthetically pleasing appearance, long service life, and good waterproof performance. However, when applying BIPV technology, special attention should be paid to the requirements of weather resistance, safety, waterproofing, ventilation, sealing, and firmness of the photovoltaic roof to maximize the role of the BIPV system in industrial plants. In the future, with continuous technological advancements and improvements, the application of BIPV in industrial plants will become increasingly widespread, making greater contributions to achieving green buildings and sustainable development.