The degradation of photovoltaic modules is a topic that often goes unnoticed by investors and even industry professionals, but which has a direct impact on the performance and economic viability of solar projects.
Although photovoltaic panels are designed to operate for decades, their yield gradually declines over time, and this loss of efficiency can compromise financial projections and payback periods.
In Brazil, where the hot and humid climate has a strong impact on systems, degradation mechanisms can manifest more rapidly. Issues such as corrosion, weld failures, and damaged bypass diodes are among the critical points that require continuous attention, both during installation and operation.
More than just a technical detail, degradation analysis is a strategic part of ensuring the longevity and profitability of projects. Ignoring this aspect can result in significant revenue losses over the years of operation, especially for large plants operating with generation projections lasting 25 to 30 years.
To better understand the risks, the technologies that help mitigate the effects and how the Brazilian market has dealt with this challenge, the Canal Solar spoke with Laís Andrade, an engineer at CS Consultoria.
In the interview below, the professional details the main degradation mechanisms, monitoring tools, and the need for greater awareness in the sector beyond the pursuit of lower prices.
To begin with, Laís, why should the degradation of photovoltaic modules be a central concern for those investing in solar power plants?
Because degradation impacts the power a module can deliver, affecting its performance. When simulating a photovoltaic plant, investors believed they would obtain a certain amount of energy, but if the module degrades more than the manufacturer's specifications, it could compromise the return on investment.
What does the loss of performance of a module over time mean in practice?
This means that the chemical interaction of the materials that make up the module cells, usually silicon, with air and humidity, leads to degradation and loss of efficiency in the process of converting light into electrical energy.
What are the main degradation mechanisms you observe in centralized and distributed generation projects?
Because we live in a country with a typically hot and humid climate, temperature and humidity are important factors. Humidity impacts the corrosion of cells and their electrical contacts. What prevents moisture from coming into contact with the cells is primarily the encapsulant.
As for the temperature, throughout the day the temperature varies from cold during the early morning to hot in the afternoon and then cools down again at night.
This causes expansion and contraction in the metals that make up the junction box solders. With repeated expansion and contraction, the solder loosens, leaving the bypass diode open and unable to generate power.
Are there technologies or manufacturers that currently offer a lower degradation rate? How has the market evolved in this regard?
Yes, currently HJT technology offers one of the lowest degradations among commercial technologies today.
To what extent can external factors, such as weather and improper installation, accelerate this process?
Improper installation, such as forming a large loop with the string cables, can increase the current induced by lightning and burn out several of the module's bypass diodes.
How does degradation influence the payback and economic viability of a photovoltaic project?
To assess economic viability, large-scale plants usually evaluate energy generation year by year, considering degradation over the 30 years of performance guaranteed by the manufacturer.
Are there any “points of attention” that investors and integrators should monitor to avoid surprises?
It's a good idea to periodically inspect the system using measurements such as the IV curve, thermography, and insulation. The IV curve helps identify problems such as PID (Potential-Induced Degradation), shunt resistance, significant voltage and current differences, and so on.
Thermography can identify damaged diodes and hot spots. Insulation is also important for checking the condition of the glass and encapsulant.
What O&M (Operation and Maintenance) tools can help monitor and mitigate the effects of degradation?
Visual inspection and predictive tests (thermography, IV curve and insulation).
Can field testing and periodic inspections really prevent performance loss problems?
Prevention is difficult because identifying the defect requires that it manifest itself and give some sign of abnormality. However, in some cases, such as PID, it is possible to detect the problem and use anti-PID devices to slow the degradation.
How do you assess the Brazilian industry's maturity in analyzing module degradation? Is there already sufficient awareness of this issue?
There's no awareness. The market is solely driven by price. The problem is that by lowering the price, the quality of the inputs used in module manufacturing can also be reduced.
For example, a poor-quality backsheet may crumble completely after several years of use. And this is just one example of the problems that can occur when a material doesn't meet strict quality requirements.
And looking ahead: what advances can help increase the lifespan and reliability of modules?
Although there are regulations and tests to predict the useful life and reliability of modules, the laboratory is still unable to accurately reproduce the conditions that the modules will face in the field.
For example, even though the modules underwent static and dynamic mechanical load tests, it was not possible to predict the glass cracking problem. This shows that some of the conditions that occur in the field cannot be simulated in the laboratory.
all the content of Canal Solar is protected by copyright law, and partial or total reproduction of this site in any medium is expressly prohibited. If you are interested in collaborating or reusing part of our material, please contact us by email: redacao@canalsolar.com.br.
