We’ve already explored the importance of maximizing power production in small commercial projects: without a clear understanding of how the project will perform (and pay for itself), you’ll never be able to get a project off the ground. Moving beyond the dollar-per-watt to focus on the project’s dollar-per-kilowatt-hour value is a great way to ensure that your project will create a long-term return on investment. The higher the production capacity of your system, the higher your return will be.
Capturing the Most Energy
Maximizing power production comes down to picking the right equipment: while your panels play a large role in production capacity, the racking system you mount them on is even more important. Dual-axis trackers are the single most effective way to increase the energy output of a PV system. By consistently maintaining the optimal PV-array-to-sun angle throughout the day, trackers can improve a system’s output by over 40%. The combination of trackers and high-efficiency PV panels allows for the maximum level of energy harvest at every hour of the day.
The Proof Is in the Power Curve
The superior production capacity of a tracker is especially evident when you compare its output directly to that of a fixed system. The chart below shows two 3kW PV arrays located on the same property in Vermont. The black line represents an AllEarth dual-axis solar tracker; the red line represents a fixed roof-mount system, south-facing at a 30° tilt. While the fixed system only collects maximum power for a few hours in the middle of the day, the tracker maintains full power output throughout the entire day, from dawn to dusk--a significant increase in production over the roof-mount system.
Utilities also prefer tracking systems, because they deliver peak power throughout the day and into the late afternoon, which is typically when the grid reaches its summer and daily peak demand. Peak demand is increasingly shifting later in the afternoon because of the amount of fixed solar penetration that drives down the load during solar noon hours.
This superior production is also important when it comes to return on investment. The more energy per watt a system produces, the more easily the upfront investment can be met and surpassed over time in savings, which is a worthy selling point for customers. As energy value from the utility increases, solar energy value increases with it.
Track or Overbuild?
Some developers believe that the solution to increasing a project’s production capacity is to simply overbuild the PV array. While it’s true that the same energy harvest can be obtained by overbuilding the DC component of a PV system, this method has some negative effects. It will overdrive the inverter, lower its life expectancy, and uses more land than a single tracker of the same energy capacity. Larger arrays also mean more potential for perimeter shading, which would decrease production from affected panels. Trackers provide a higher energy output while using less space, and come with none of the downsides of overbuilding.
Dual-Axis Trackers vs. Fixed Solar
The advantages of a dual-axis tracker become clear when you compare its characteristics directly with those of a fixed roof-mount system.
Tracker: Always positioned at the ideal angle to the sun, from dawn to dusk, which increases capacity factor of PV array.
Roof-Mount Solar: Often positioned at a non-ideal angle, depending on roof pitch/orientation. The optimal angle is also limited to a fraction of the day.
Tracker: Better utilizes high-efficiency PV modules. Panels mounted on a tracker work more efficiently, operating at a cooler temperature when exposed to free air movement behind panels.
Roof-Mount Solar: Wastes potential energy from high-efficiency PV panels. Roof-mounted panels also run hot, derating panel output power.
Return on Investment
Tracker: Because it harvests more energy annually, you’ll see a quicker ROI (depending on the value of energy in your region).
Roof-Mount Solar: Because it has a lower energy output, it will take longer for the project to see a return on the upfront investment.
Tracker: Typically comes with higher upfront costs, as well as slightly higher O&M costs.
Roof-Mount Solar: Typically comes with lower upfront costs, as well as slightly lower O&M costs.
Though upfront and operations and maintenance expenses might be a little higher for a tracker, the return it creates over the life of the system due to superior production capacity--especially when paired with high-efficiency solar panels--makes it the smartest choice for increasing power output and reaping a strong return on investment.
Want to learn more about building high-production projects? Watch a recording of our recent webinar on Maximizing Power Production for Small Commercial Projects.