Which solar modules are the best?
How to avoid performance losses and secure yields with the right choice
Photovoltaic systems are considered a reliable source of sustainable energy – but not every solar module delivers what it promises. Over the years, performance losses caused by degradation, heat, UV radiation or material fatigue can noticeably reduce yields. This is where the difference becomes clear: High-quality PV modules with modern cell technology and a well-designed structure not only offer better initial performance, but also significantly lower losses over long-term operation.
In this article, we show you which solar modules are among the best, what you should look for when choosing – and how the right decision will help you generate more electricity in the long run and reduce maintenance costs. Whether for a private home, a commercial roof or a large-scale project: Investing in quality pays off with maximum efficiency.
Why do photovoltaic modules lose performance over time?
Solar modules are subject to various ageing processes during operation, leading to a continuous decline in power generation. This performance loss can already occur in the first hours of operation (initial degradation) and continue over many years (long-term degradation). The most common causes include:
- Light-induced degradation (LID)
- Voltage-related effects such as potential-induced degradation (PID)
- Microstructural defects such as microcracks
- Thermally induced hotspots
- Weather-related material ageing
These processes are influenced by various factors, e.g. silicon doping, encapsulation quality, external environmental influences and the electrical system configuration.
How can PV degradation be avoided? – Modern solutions and technologies
Choosing modern cell technologies such as TOPCon, HJT or IBC can significantly improve long-term stability. These N-type cells have a much lower degradation rate – often below 0.4% per year – and are more resistant to common ageing effects.
Advantages of N-type modules at a glance:
- No boron–oxygen complexes → no LID
- Higher initial output
- Better stability at high temperatures
- Reduced ageing due to improved materials
Understanding and avoiding LID – light-induced degradation
At first exposure to sunlight, certain cells can experience short-term performance losses. Modules with boron-doped p-type cells are particularly affected. Depending on the type, a distinction is made between:
- BO-LID: Degradation due to boron–oxygen complexes
- UVID: UV-related efficiency losses
- LeTID: Combined effect of light and heat
Practical countermeasures:
- Use gallium instead of boron for doping
- Use low-oxygen wafers
- Use UV-resistant encapsulation materials
- Prefer high-efficiency cell technologies (e.g. HJT, TOPCon)
Understanding and avoiding PID – potential-induced degradation
PID occurs when high system voltage and humidity cause ionic contaminants to migrate into the cell interior. This can lead to massive yield losses within just a few years – in extreme cases up to 50%.
Recommended protective measures:
- PID-certified modules (e.g. according to IEC 62804)
- Inverters with PID protection function
- Optimised string lengths to reduce voltage
Other ageing mechanisms and how to prevent them
- Encapsulation and backsheet foils: Ageing due to UV radiation, moisture and temperature fluctuations can lead to clouding, delamination or cracking. High-quality materials such as POE or glass-glass laminates offer better long-term stability.
- Microcracks in cells: Caused by mechanical stress. They lead to increased resistance and can cause hotspots. Solutions: Use shingled, half-cell or multi-busbar technology.
- Hotspots: Local overheating caused by shaded or defective cells can permanently impair module performance and may even trigger fires. Countermeasures: Use modules with fast bypass switching (e.g. MOS switches), plan for shade-free installation areas, and carry out regular cleaning and inspections.
Why is the degradation rate in photovoltaics so important?
Even small differences in annual degradation add up over decades. Those who invest in durable, high-quality PV modules today benefit in the long term from more stable yields and lower maintenance costs.
Example:
A module with only 0.35% annual performance loss delivers around 8–10% more electricity over 25 years than one with 0.5% – with the same initial output.
Conclusion: Minimise degradation – maximise yields
If you value maximum energy yield and economic efficiency, you should look for low degradation rates and certified quality when choosing your solar modules. Investments in modern cell technologies and robust module designs pay off in the long run.
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