What Leads to the Degradation of Solar Panels (2023 Guide)?

· About Solar Panels

Introduction:

While solar panel performance has soared to new heights, a slow decline in their electricity production is still unavoidable. Top-quality solar panels see a decline in efficiency at roughly 0.4% each year, leading to a reduction of around 12-15% in energy output over their 25-30 year life.

But what causes solar panels to deteriorate? What determines the rate of their degradation, and can we implement methods to extend their useful life and avoid early disposal? The subsequent sections will delve into these queries comprehensively.

Content:

1.LID and recommendations to minimise the impact of LID

2.PID and recommendations to minimise the impact of PID

3.Natural ageing of solar panels and suggestions

4.Micro-cracks and hot spots of solar panels and suggestions

The degradation of solar panel includes LID, PID, natural degradation, microcracks and hot spot effect. As the solar panels themselves are used over time, the components naturally age and become less efficient. The primary cause of solar panel degradation is the natural wear and tear that occurs over time due to exposure to UV rays and adverse weather conditions. The rate of degradation is typically covered by a panel’s performance warranty. In addition to this, the initial exposure of solar panels to sunlight can cause LID, the high pressure, high temperature and increased humidity can cause PID, improper handling and mounting of solar panels can lead to the appearance of microcracks, and shadowing of the mounting location can cause the hot spot effect. We’ll go into more detail below.

LID (Light-induced Degradation)

LID (Light-Induced Degradation) has various forms of mechanical and chemical degradation stem from the panel’s exposure to light, which includes: BO-LID, LeTID and UVID. It serves as a key reliability parameter in the realm of photovoltaic modules and it encompasses primarily three distinct categories: Boron-Oxygen compound light degradation (BO-LID), light and elevated temperature-induced degradation (LeTID), and surface passivation degradation induced by ultraviolet exposure (UVID).

BO-LID (Boron-Oxygen Compound Light Degradation)

BO-LID, or Boron-Oxygen compound light degradation, is a crucial aspect of solar panel performance. In the realm of LID (Light-Induced Degradation), BO-LID stands out as the primary contributor to the light-induced degradation observed in crystalline silicon cells. When photovoltaic modules are first exposed to sunlight, BO-LID swiftly takes effect, causing a rapid reduction in the rated wattage (Wp) output of the panels. This initial decrease, typically ranging from 2% to 3%, occurs within a mere few hundred hours of operation, with the most significant impact usually noticeable during the initial year of use.

The noteworthy aspect of BO-LID is that it often reaches a saturation point relatively quickly, typically within days or weeks. The encouraging news is that mitigating or even eliminating the effects of BO-LID is possible. This can be achieved through strategies such as modifying dopants, such as the introduction of Gallium, or enhancing passivation techniques. These measures play a pivotal role in preserving the long-term performance and efficiency of solar panels.

Following this initial stabilization phase, the rate of LID undergoes a substantial decrease, reaching levels as low as 0.3% to 0.5% per year for the subsequent 25+ years. Notably, high-performance modules from Maysun Solar, such as IBC, can exhibit LID rates as low as 0.4% per year. This excellent performance is due to proven production techniques and high quality materials.

Fortunately, most manufacturers tend to slightly over-specify the panel’s power rating by up to 5%. This allowance accounts for minor cell imbalances and offsets some of the initial degradation, thereby ensuring the accuracy of the rated panel power (Wp). To illustrate, a 350 Watt panel may initially produce up to 5% more power, potentially reaching up to 368 Watts for a brief period. Nevertheless, this slight overproduction is typically of short duration and might remain imperceptible unless the panels operate under ideal (STC) conditions. The manufacturer’s performance warranty comprehensively outlines the rate of LID and the expected performance decline over the 25-year warranty period.

UVID (UV Light-induced Degradation)

UVID concerns the potential deterioration in the performance of solar modules after extended exposure to ultraviolet radiation. The initial exposure to sunlight causes the crystalline silicon oxide on the panel’s surface to develop a layer of boron dioxide, which reduces its efficiency. This degradation is primarily associated with the materials employed in solar cells, particularly those related to photoelectric conversion. Prolonged exposure to UV radiation can induce chemical reactions or material breakdown within the cells, resulting in performance degradation. This often manifests as reduced efficiency and power output. To address the effects of UVID, manufacturers typically opt for materials with high UV stability, enhance the module’s encapsulation materials to provide improved protection, and subject the modules to UV exposure tests to assess their resilience.

LeTID (Light and Elevated Temperature Induced Degradation)

LeTID (Light and Elevated Temperature Induced Degradation): LeTID represents a decline in performance induced by elevated temperatures, primarily linked to materials and imperfections within solar cells. When subjected to high temperatures and radiation, defects within the cell can multiply, causing charge recombination and heightened resistance, resulting in a decrease in the cell’s performance. LeTID resembles LID in some respects; however, the losses attributed to LeTID have been documented to reach levels as high as 6% within the first year. If not adequately addressed by the manufacturer, this could result in subpar performance and potentially lead to warranty claims.

LeTID effects are typically discernible during real-world module operation, rather than laboratory conditions. To counteract LeTID effects, manufacturers frequently enhance material selection, refine production procedures, perform thermal stability assessments, and assess cell performance at elevated temperatures to ensure consistent module performance.

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