Sweet Spot: TrueCapture’s New Split Boost Mode Optimizes Half-Cell Module Performance

Since TrueCapture™ was introduced in 2017, the solar tracker yield enhancement and control platform has helped solar asset owners gain gigawatt-hours of additional production and millions of dollars in revenue. Our team is continuously iterating and innovating to enhance the software’s one-two punch of row-to-row and diffuse optimization capabilities. The latest addition to TrueCapture is what we’re calling Split Boost, a patent-pending row-to-row feature of TrueCapture that helps maximize the energy gain on PV plants utilizing split-cell solar modules.

Shade Avoid, the first TrueCapture row-to-row operational mode, allows site operators to harvest more sunlight for traditional full-cell module architectures. But with the advent of innovative half-cell or split-cell designs driving the current trend of large-format modules, we knew there was an opportunity to increase the irradiance on these newer modules in the early and latter parts or “shoulders” of the daily production curve, much like TrueCapture Shade Avoid does with full-cell modules. Split-cell modules are inherently more shade-tolerant due to their electrical architecture, so the trick is to use that shade tolerance to our advantage.

Split-cell Module Architecture: Because of the six-substring design, split-cell modules can be shaded up to half of the module and still produce 50% or more of the power. Traditional modules essentially lose all of their power output even if a small portion of the module is shaded.

Split-cell Module Architecture: Because of the six-substring design, split-cell modules can be shaded up to half of the module and still produce 50% of the power. Traditional modules essentially lose all their power even if a small portion of the bottom of the module is shaded.

The TrueCapture row-to-row methodology has now expanded its capabilities to include module optimized modes to maximize production where rolling terrain and other topographic and construction variances would otherwise cause shading problems. While Shade Avoid mode is optimized for full-cell modules, Split Boost takes advantage of the split-cell module’s unique substring architecture by intelligently adjusting how the independent tracker rows interact with each other. Each tracker row is positioned to increase irradiance on the top half of the modules, while the row behind it is allowed up to 50% shade on the bottom of the modules. The algorithm finds the sweet spot of the maximized angle of incidence (AOI) between standard backtracking and true tracking. This optimization provides a boost in production even if the site terrain is perfectly flat.

Of course, any performance-enhancing tracker algorithm must be properly modeled to be effective—and bankable. We model Split Boost with our internal raytracing-based backtracking software where the shade tolerance of the module, as well as Split Boost operating mode, are baked into our row-to-row energy gain algorithm, so we can accurately estimate gains. By using the algorithms in “simulation mode” before deployment to a solar plant, we can estimate TrueCapture performance at a given site with that site’s specific energy model, tracker geometry, and terrain.

Split Boost in Action: For split-cell modules, the tracking angle of each independent row can track more directly towards the sun, while allowing up to 50% of shading on the row behind it. This results in a power boost to the top half of the modules even on flat sites.

There are limitations to accurately modeling Split Boost in PVsyst, but we are working with independent engineers to help them in their energy performance evaluations. In my role as the technical lead for our TrueCapture business development group, I meet with customer engineering teams and independent engineers regularly to help them understand the benefits of Split Boost and TrueCapture in general. Performance engineers understand that AOI losses can be high, and an enabling software tool like TrueCapture with Split Boost offers a best-fit solution.

We’ve been conducting field testing of Split Boost at a customer site in California for nearly a year, and preliminary data shows up to a 1 % yield improvement compared to conventional backtracking for the specific terrain, weather, and site design. As expected, the electrical benefit of the half-cell tracking algorithm has been observed in the early morning and late afternoon. We are continuing to refine our modeling, field experiments, and data analysis procedures to further validate the findings. However, one thing is clear, traditional backtracking for half-cut modules is now a relic of the past, even on perfectly flat sites.

 

Defne Gun is the Technical Sales Engineer for yield technologies at Nextracker, which includes TrueCapture and NX Navigator. With an extensive background in solar performance engineering and over six years of direct industry experience, she is the subject matter expert, facilitating product validation, development, and market adoption of emerging software solutions.