Technical difficulties in concentrating photovoltaic power generation system - News - Global IC Trade Starts Here 工业

Photocoupler

I. Introduction

The cost of solar power systems has remained high, and the primary reason is the low energy density of sunlight. On average, the sun's intensity at ground level is about 1 kW per square meter. While single-crystal silicon can achieve a conversion rate of up to 23%, polycrystalline silicon reaches around 16%, and thin-film panels only about 8%. Gallium arsenide cells, though highly efficient with over 35% conversion, when used in full-scale solar systems, only deliver about 25% efficiency due to system losses.

To reduce the overall cost of solar power systems, increasing light intensity is a viable solution. This can be achieved using convex lenses, fluorescent lenses, or reflectors to concentrate sunlight. By doing so, the amount of silicon and gallium required is significantly reduced, making solar power more affordable. This concept led to the development of Concentrated Photovoltaic (CPV) systems.

II. Technical Challenges of CPV Systems

Although the principle of CPV systems seems straightforward, several technical hurdles prevent them from being widely adopted. In theory, higher concentration ratios should lower costs, but they also bring significant challenges.

1. Handling High Light Intensity

While gallium arsenide can handle up to 1000 times the normal light intensity, it is expensive and contains toxic arsenic, which makes large-scale use environmentally problematic. As a result, most systems still rely on monocrystalline silicon, which can only withstand 3–5 times the light intensity. For substantial cost reduction, concentrations need to reach around 10 times, requiring specialized silicon that is more expensive and harder to produce.

2. Heat Dissipation Issues

Ordinary solar panels can reach temperatures above 75°C in summer. At twice the sunlight intensity, they begin to blister; at five times, they may foam within 10 minutes, leading to oxidation and rapid efficiency loss. At ten times intensity, the panel could be completely damaged in just five minutes. Traditional cooling methods like aluminum heat sinks are costly and less reliable than the silicon itself. Forced air cooling uses too much energy, and water cooling, while more efficient, is complex and prone to leaks and maintenance issues.

3. Reflector Reliability

Most reflectors made from plastic or glass-based materials suffer from thermal expansion issues, causing the reflective surface to degrade within 2–4 years. In extreme environments like deserts, their performance drops rapidly. Even high-quality aluminum reflectors have limited lifespans—around 8 years—and their reflectivity decreases significantly over time, falling below acceptable levels for long-term solar systems.

4. Tracker System Limitations

CPV systems require precise tracking to keep the photovoltaic cells aligned with the concentrated light. Without an accurate tracker, the system cannot function. Trackers are mechanical and prone to wear, failure, and reduced accuracy over time. A single malfunction can lead to complete system downtime, making reliability a major concern.

III. The Solution

To overcome these challenges and master the core technology of CPV systems, Beijing Anxin Hi-Tech’s General Manager Chen Pingjian led a research team starting in March 2008. After two years of extensive R&D and numerous trials, the team successfully developed a monocrystalline silicon cell capable of withstanding 15 times the light intensity. This breakthrough not only increased output by 15% but also surpassed global competitors. The company has since filed or obtained over eight patents related to this innovation.