How to quantify the backside power generation efficiency of a double-sided double-glass n-type monocrystalline solar photovoltaic module?
Publish Time: 2025-09-08
Amidst the wave of photovoltaic technology iteration, double-sided double-glass n-type monocrystalline solar photovoltaic modules, with their unique bifacial properties, are becoming a core component for reducing costs and increasing efficiency in photovoltaic power plants. Quantifying their backside power generation efficiency not only supports accurate understanding of module performance but also directly impacts the overall profitability of the photovoltaic system. This process requires a systematic analysis encompassing four dimensions: technical principles, environmental adaptability, testing methods, and system optimization.1. The Technical Essence of Bifacial Power Generation: From Structural Innovation to Light Energy CaptureThe core breakthrough of bifacial double-glass modules lies in the collaborative innovation of the cell and packaging structure. Traditional P-type cells utilize an aluminum backside field (ASF) design, which prevents light from passing through the backside. N-type monocrystalline cells, however, utilize phosphorus doping to create an n+ backside field (ASF), replacing the aluminum paste printing process and maintaining the same gridline structure on the backside as the frontside. This design allows light to be absorbed from both the front and back surfaces of the cell. Combined with the double-layer transparent glass encapsulation, this ensures unimpeded light transmission from the backside. When sunlight strikes the front of a module, it directly excites electron-hole pairs, generating current. Simultaneously, light reflected from the ground, scattered light, and diffusely reflected light from the sky penetrate the back glass and is absorbed by the cell, generating additional power generation gain. This "dual-channel" light energy capture mechanism is the theoretical basis for quantifying backside efficiency.2. Environmental Adaptability: The Dynamic Interplay Between Reflectivity and Installation ScenarioQuantifying backside efficiency requires careful consideration of environmental variables. Ground reflectivity is a key parameter, dependent on material properties and surface conditions. White waterproofing membranes, highly reflective coatings, or snow can produce strong reflections, while grass and water can produce weaker reflections. Furthermore, module height from the ground, mounting angle, and front-to-back spacing constitute spatial variables. Appropriately elevating the module increases the backside's light-receiving area, but excessively high elevation increases wind loads. Horizontal installation requires optimized spacing to prevent the front row from blocking reflected light from the rear row. For example, in desert power plants, the diffuse reflective properties of sand particles are optimally matched to the suspended installation of modules, making backside power generation a key source of system growth. In distributed rooftop scenarios, the moderate reflectivity of concrete floors and the synergy with module tilt adjustment require precise calculation of gain boundaries through simulation models.3. Standardization of Testing Methods: A Closed-Loop Technology from Laboratory to FieldQuantifying backside efficiency requires a dual-track system of "laboratory benchmark testing + field-based validation." In the laboratory, a high-precision IV tester is used to measure the module's volt-ampere characteristic curve under standard light sources. By separating the front-side and back-side current contributions, bifaciality (the ratio of backside power generation to frontside power generation) is calculated. This process requires strict control of parameters such as temperature and irradiance to ensure data comparability. Field-based validation utilizes technologies such as reflectometers and drone inspections to monitor ambient reflectivity, module temperature, and power generation fluctuations in real time. For example, in plateau regions, low air pressure can alter module heat dissipation efficiency, necessitating long-term data collection to refine theoretical models. In coastal salt spray zones, the degree of glass surface corrosion directly affects light transmittance, necessitating accelerated aging tests to assess efficiency degradation over the lifecycle.4. System Optimization: The Value Transformation from Module Performance to Power Plant ProfitThe ultimate value of rear-side power generation efficiency lies in reducing the power plant's cost per kilowatt-hour. By optimizing the bracket design, a "mirror-frame" structure is adopted to avoid rear-side shading. In the combiner box layout, cable routing is moved to the edge of the module to reduce shadow loss. Integrating an intelligent operation and maintenance system, the module tilt angle is dynamically adjusted according to seasonal changes to maximize reflected light capture year-round. Furthermore, the compatibility of bifacial modules with 1500V systems reduces cable usage, further lowering initial investment. Their anti-PID (Polymerization Inertia) properties and low degradation rate extend the effective profit life of the power plant. For example, in agro-photovoltaic hybrid projects, planting high-reflectivity crops (such as white flowers) beneath the modules not only improves land utilization but also enhances rear-side power generation through bioreflection, creating a "technology + ecology" efficiency-enhancing model.Quantifying the backside power generation efficiency of a double-sided double-glass n-type monocrystalline solar photovoltaic module is essentially a three-dimensional game between technology, environment, and economy. From physical innovations in battery structure to dynamic adaptation to environmental variables and global optimization of system design, every step must be anchored by data and driven by profitability. As photovoltaic power plants transition from a focus on efficiency to a focus on incremental growth, accurate assessment of rear-side power generation efficiency will become a key enabler for technological advancements in the industry, driving the photovoltaic industry towards a higher level of sustainable development.
