Single-axis vs. dual-axis - Single-axis offers cost-effective yield gains; dual-axis maximizes output in constrained sites.

When choosing a solar tracking system, the fundamental decision often comes down to a single-axis versus a dual-axis system. While both are designed to increase a solar panel's energy output compared to a fixed-tilt system, they do so with different levels of complexity, cost, and efficiency.

Single-Axis Solar Trackers
A single-axis solar tracker has one degree of freedom, allowing the solar panels to move on a single axis. The most common type is a horizontal single-axis tracker (HSAT), which orients the panels to follow the sun's east-to-west movement throughout the day. The panels' tilt, or height, is set at a fixed angle.

Pros:

Cost-Effective: Single-axis trackers are significantly less expensive than dual-axis trackers. Their simpler mechanical design requires fewer components, less maintenance, and is easier to install.

High Reliability: With fewer moving parts, single-axis systems are less prone to mechanical failure and have a longer lifespan. This leads to higher uptime and a lower risk of costly repairs.

Significant Energy Gain: A single-axis tracker can increase a solar array's energy output by 15-35% or more compared to a fixed-tilt system. This provides a strong return on investment (ROI) for a relatively small increase in initial cost.

Dominant Market Share: The simplicity and cost-effectiveness of single-axis trackers have made them the preferred choice for most large-scale, utility-level solar projects, giving them a dominant share of the global solar tracker market.

Cons:

Lower Peak Efficiency: While they significantly boost energy production, they are not as precise as dual-axis trackers. They do not account for the sun's seasonal changes in height, which means they do not capture the maximum possible amount of sunlight at all times.

Dual-Axis Solar Trackers
A dual-axis solar tracker has two degrees of freedom, allowing the panels to move on both a horizontal and a vertical axis. This enables the panels to track the sun with near-perfect accuracy, following its east-to-west movement throughout the day and its seasonal changes in elevation.

Pros:

Maximum Energy Yield: A dual-axis tracker can increase a solar array's energy output by up to 45% over a fixed system and up to 10% over a single-axis tracker. This makes them the most efficient option for energy production.

Higher Power Output: By constantly being perpendicular to the sun's rays, dual-axis trackers provide a more consistent and higher power output throughout the day, particularly during peak hours and in seasons where the sun's position changes dramatically.

Optimal for Limited Space: Because they generate more energy per square meter, dual-axis trackers are ideal for projects where land is expensive or limited.

Cons:

Higher Cost: The increased mechanical complexity, including two motors and a more advanced control system, makes dual-axis trackers significantly more expensive than single-axis systems.

Higher Maintenance and Lower Reliability: With more moving parts and a complex design, dual-axis trackers are more prone to mechanical issues and require more frequent maintenance, which can lead to higher operational costs and a shorter lifespan.

Less Common: Due to their higher cost and complexity, dual-axis trackers are not as widely used as single-axis systems, particularly in large-scale utility projects where the cost-benefit analysis favors the simpler solution. They are more commonly found in smaller, specialized applications, such as for residential use or concentrated solar power (CSP) systems.

Conclusion
The choice between a single-axis and a dual-axis tracker depends on the specific project's needs and constraints. For most utility-scale projects, the single-axis tracker provides the best balance of cost, reliability, and energy gain, which is why it holds the dominant market share. For applications where maximizing energy output from a limited space is the top priority and the budget allows for it, a dual-axis tracker may be the better choice.