The many different types of mounts for solar arrays, be it fixed-, single-, or dual-axis trackers, can lead to considerable confusion when trying to decide how to mount your solar panels. However, there are several advantages and disadvantages to each type of mounting system depending on a variety of variables including climate, latitude, landscape, budget, and size of the solar array that you are hoping to build.
Fixed-axis systems are the most mechanically simple, and least expensive mounts for solar panels. They can be used on the roof or on the ground, and because of their mechanical simplicity, tend to have a longer lifespan than trackers. These mounts are also beneficial in less sunny climates, where extra expense of a solar tracker may not be worth the small increase in electrical output.
If you decide that you want a solar tracker, there are many options that you can choose from. Firstly, there are thermal (passive) and electrical (active) trackers. Thermal trackers use the heat from the sun, which heats a liquid inside of the solar panel, to rotate. These are beneficial because they have fewer mechanical parts, and are therefore less prone to failure. They are also less expensive. However they can be slow to react to solar motion. In addition, they can be imprecise in the winter because they rely on heat to rotate. Finally, there are electrical trackers, which are the most popular. They are very precise even in the winter, and can increase electrical output from 20-40% from fixed-axis mounts. However, they require a fair amount of maintenance and are more expensive than fixed-mount and thermal trackers.
Solar trackers are also divided into single-axis and dual-axis trackers. These trackers are very precise and are excellent at collecting sunlight as long as the sun is in the sky so, in order to best utilize your money, it is best to ensure that the solar panels and tracker(s) are in an area that gets sunlight all day long and experiences little to no shading. Single-axis trackers move only on one axis, usually aligned along a true North meridian. These trackers are more reliable because they are less mechanically complicated. Because of this they are also easier to maintain and consume less energy than dual-axis trackers. In addition, these trackers create less shadowing, allowing a closer positioning of panels. Single-axis trackers are more cost-effective for large installations of solar panels.
Dual-axis trackers track the sun along two axes, allowing for a more constant and accurate angle of incidence and a higher yield. These trackers are especially efficient in cloudier climates, at northern latitudes, and in sloped locations. Because these trackers are structurally complex, they tend to have higher installation and maintenance costs. They are also larger and create a lot of shade, requiring greater space between units. These trackers have great collection efficiency, but are very expensive and are most cost-effective for smaller installations.
While all of the different options make choosing a ground-mount a daunting task, it is very important to carefully consider which best suits your project. With the proper ground mount, you can get the most out of your money and be truly satisfied with your solar array.
Helge Biernath is the President & CEO of Sunstall, an installation company in California with the main focus on large solar projects. His company consults clients to find optimized racking and foundation solutions.