Dual-axis solar trackers perform significantly better in regions with high sky clearness compared to static solar panels and single-axis trackers. The sky clearness index, which measures how clear and sunny the atmosphere is (ranging from about 0 for very cloudy to above 0.7-0.8 for very clear skies), strongly influences the effectiveness of dual-axis trackers.
Performance in High Sky Clearness Regions:
- When the sky clearness index is high (above 0.7 or 0.8), indicating mostly direct and bright sunlight with minimal atmospheric pollution or cloud cover, dual-axis trackers can improve solar energy production by approximately 40-45% over fixed-tilt solar arrays optimized for latitude.
- In very clear conditions, dual-axis trackers can achieve efficiency gains ranging roughly from 60% up to over 80% compared to static solar systems, according to some theoretical and experimental studies. For example, studies in locations with high clearness indexes, like Malaysia, showed efficiency improvements of about 82% under clear skies.
- The increased efficiency comes from the dual-axis tracker’s ability to continuously orient PV panels to face the exact position of the sun throughout the day and year, maximizing the capture of direct solar radiation (specular light) which dominates under clear skies.
Relative Gains at Lower Sky Clearness:
- In regions with lower sky clearness (index closer to 0.5 or below), such as temperate climates with more cloud cover or haze, the performance gain of dual-axis trackers over static systems decreases. This is because diffuse light from scattered sunlight becomes a larger proportion of total solar radiation and cannot be as effectively captured by precise solar tracking.
- For example, in Ontario, Canada, with lower clearness indexes around 0.35 to 0.5, dual-axis tracking only slightly outperforms single-axis tracking or fixed-tilt systems in capturing energy, often by less than 4%, and simpler single-axis trackers may be preferred due to higher reliability and lower maintenance.
Trade-offs:
- Dual-axis trackers have higher complexity, cost, and maintenance requirements compared to single-axis or fixed systems. Their high performance is most justified in clear-sky environments where the gains are substantial.
- On cloudy or hazy days, gains reduce significantly, with some reports showing only about 20-25% improvement on overcast days, indicating that the benefit of dual-axis tracking is very weather-dependent.
In summary, dual-axis solar trackers excel in regions with a high sky clearness index (above 0.7–0.8), producing 40-80% more energy than static solar panels by optimizing direct sunlight capture. Their advantage decreases in less sunny, more diffuse-light regions where simpler systems may offer better cost-effectiveness and reliability.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-do-dual-axis-trackers-perform-in-regions-with-high-sky-clearness/
