Designing for Maximum Energy Production with Solar Trackers: Why Density is King

Across the United States, solar project developers are executing Power Purchase Agreement (PPA) contracts at increasingly lower rates, making it challenging to maintain a viable return on investment. This has driven the need for developers and owners to maximize energy production from photovoltaic (PV) panels to meet these competitive PPA targets. Solar tracking systems have capably fulfilled that need by boosting energy production and providing owners with a more optimized power delivery curve. While it’s clearly established that solar trackers allow for 15-25% higher energy production over fixed-tilt solutions, there is still room to further optimize performance. Designing tracker sites and layouts for maximum energy production, while maintaining the lowest cost of ownership, is the next frontier.

Performance Optimization Strategies
Energy production from a PV project is maximized when the project’s solar modules are positioned exactly perpendicular to the sun, a position commonly referred to as “direct incidence.” A tracker’s main purpose is to maintain as close to direct incidence as possible between modules and the sun throughout the solar day to maximize onsite energy production.

The challenge for solar tracker designers is to balance limiting factors such as cost and land usage with optimized energy production to provide asset owners with the lowest possible levelized cost of energy (LCOE). For any tracker project, energy production can be increased by employing one or more of three basic performance optimization strategies:

Increasing Row/Area Power Density – Increasing the number of modules per land unit in a single tracker row or site.

Optimizing Ground Coverage Ratio (GCR) – Increasing the east to west distance between module rows within a specified plot of land.

Increasing Range of Motion (ROM) – Extending the degree modules can be rotated to track the sun.

Density is King
Of these performance optimization strategies, increasing power density has been found to have the largest standalone effect, with an energy production boost of 5 – 6%. Optimizing power density is up to three times more effective at increasing energy production than adjusting a tracker’s ROM and is twice as effective as adjusting GCR.

Adjusting, or relaxing a tracker’s GCR is the second most effective strategy when implemented in singularity. Relaxing a tracker’s GCR from 33% to 25% can lead to an energy production boost of 1.5 – 2.2%, depending on site location.

Because energy production benefits are limited by geographic circumstances, increasing a tracked solar project’s ROM is the least effective performance optimization strategy. While increasing ROM from +/- 45 degrees to +/- 52 degrees will result in in an energy production boost of 1%, increasing ROM beyond +/- 52 degrees only marginally increases onsite production, roughly .25%. This is in most standard layout cases with a 33% GCR. Even if the GCR is relaxed to 25%, increasing ROM from +/- 52 degrees to +/- 60 degrees will only result in a .33% boost in energy production.

Key Considerations
It is well established that the most effective means for increasing energy production at utility-scale sites is the utilization of solar trackers, primarily for their ability to allow solar arrays to maintain as close to direct incidence as possible with the sun throughout the day. For this reason, system owners rely on solar trackers to provide an energy boost that helps them maintain a viable ROI while delivering energy to their clients at increasingly lower and competitive PPA rates. As PPA rates continue to decrease, it has become increasingly vital that each tracked solar system is optimized for maximum energy production.

Knowing how to manipulate the design of solar projects and employ energy-boosting strategies is particularly beneficial for solar asset owners in this increasingly competitive global market. In most cases, by increasing power density and relaxing GCR at a solar site, project designers can optimize onsite energy production and maximize benefits for financial stakeholders. Additionally, trackers with optimized power density can result in a smaller system footprint which enables efficient construction of solar facilities for area or topographically constrained sites. Understanding design strategies like power density, GCR and ROM, and how they impact energy production is imperative to maximizing the performance of utility-scale solar sites while maintaining the lowest cost of ownership.

Source: arraytechinc