Solar panels are more productive when they face the sun directly, and their output is diminished when sunlight reaches them at an angle. Solar trackers are mechanisms that can adjust the direction of photovoltaic panels to maximise their output during the day. Although the rated power of the solar array stays the same, it can operate near peak output for more hours each day, thus increasing kilowatt-hour production.
The orientation of a solar panel can be described with two angles:
- The tilt angle is measured with respect to the horizontal position.
- The azimuth angle indicates how much the panel is rotated with respect to a north-south orientation.
In Australia, a country in the southern hemisphere, solar panels are more productive when tilted north, also considering than the sun is higher up in the sky during the summer and lower in the winter. The ideal azimuth angle changes throughout the day, since the sun is in the eastern portion of the sky during the morning, and in the western portion during the afternoon.
The Two Main Types of Solar Trackers
Solar trackers can be classified into single-axis and dual-axis systems. A single-axis tracker is designed to adjust either tilt or azimuth, but not both. On the other hand, a dual-axis tracker adjusts both angles dynamically during the day, ensuring that photovoltaic modules always face the sun directly.
In most cases, you can expect around 25% more energy generation from a single-axis solar tracker and around 40% more from a dual-axis system. The price to pay is more dollars per kilowatt, and also the addition of moving elements; keep in mind that simple maintenance is one of the main benefits of a fixed solar array, but the installation becomes more difficult to service if solar trackers are included.
Solar tracking tends to be useful when space for a photovoltaic array is limited, and you want to increase the amount of energy produced without increasing total solar panel area. Keep in mind that solar trackers increase the ownership cost, so they make sense from the financial standpoint when the extra energy produced has a higher value than the extra ownership cost.
Solar trackers achieve the best performance in open fields with few buildings or natural obstacles, where the sun is visible in the sky for many hours each day. Their application in urban settings or when surrounded by hills is very limited: there is no benefit from pointing a photovoltaic array at the sun when it is hidden behind a building or a hill.
Solar trackers can be useful enhancements for a photovoltaic arrays when space is limited and you want to maximise energy output, but also consider that the installation becomes more expensive, both in terms of upfront cost and maintenance.
A professional assessment of your property is the best way to determine which solar power configuration works best. Keep in mind there are many ways to enhance a solar PV system: solar tracking is one option, but make sure you also consider the financial viability of a larger installation or an energy storage system.