Tracker Bankability Reports: Improving Dependability
As a principal engineer for the global quality assurance company DNV GL, Colleen O’Brien’s job is to provide a comprehensive and independent review of the potential risks of proposed solar photovoltaic (PV) projects. Her clients are usually solar developers and investors, who understandably want an objective analysis of how everything from a project’s electrical and structural design to the proposed modules, inverters and tracking system could potentially impact a solar power plant’s generation and revenues.
“We’re here to check as an independent verifier that key risk areas have been addressed,” said O’Brien. In order to do her job in a way that is efficient both financially and time-wise, O’Brien has to rely on technology reviews that are better known as bankability reports. Written by independent engineers, bankability reports are designed to provide a thorough analysis of each technology and design that’s proposed for a project.
But here’s the problem: Something is dramatically amiss with today’s variety of bankability reports. O’Brien knows this from painful personal experience. “Sometimes the challenge I find in the report is simply a lack of clarity on what was reviewed. If a report reviewed the mechanical design and said that everything seems good, you don’t really know what exactly was checked,” she said. “It’s possible that they did a thorough job, but it’s possible they did a very light review and didn’t dig into some key risk areas. And other times I really do find gaps in the work.”
Inadequate bankability reports equal unexposed risk
This inconsistency has real-world implications. While some bankability reports provide genuinely rigorous and illuminating assessments of risk, others are little more than cursory rubber stamps that all will be OK. Put another way, the uncertainty and inconsistency of the very tools that are meant to reduce project risk can actually elevate it.
Not surprisingly, this puts O’Brien and other independent evaluators of solar projects in a tough position. Not having enough detailed information about the proposed technologies and design means she either has to propose an expanded scope of work to do extra investigation or simply be upfront with a client that she can’t complete her review with the available information. “That doesn’t really make anybody happy,” she said. “It can ultimately delay the financing and the project, so it makes it very hard for us to have a happy client and also feel like we’re able to do our job completely.”
To be clear, inconsistent and inadequate bankability reports aren’t just a problem for independent engineers trying to do their job. They also have the potential to put the brakes on the solar industry’s overall growth and credibility. Indeed, if projects that have received a green light from independent engineers ultimately have problems, confidence in the solar industry as a whole could suffer. “A structural failure could cause significant damage to a lot of expensive equipment out in the field. It could have catastrophic consequences,” said O’Brien.
Beyond worst-case scenario failures, solar plants that get built with equipment that was not properly vetted could produce dramatically less energy than expected or have much higher operations and maintenance costs. This could make it harder and more expensive to access the financing needed to develop new solar power plants. “It all affects the bottom line,” said O’Brien. “If lenders start to become risk averse because their investments haven’t panned out the way they expected to, then they won’t be seeking out projects to invest in. That can have a big impact.”
A template for tracker bankability reports
But here’s the good news: There is a better way. And that better way is laid out in detail in DNV GL’s recently released Tracker Bankability Reviews: Guidelines for Stakeholders white paper. The report, authored by O’Brien, outlines all of the elements DNV GL believes should be included in dependable tracker bankability reports. O’Brien’s intent was also to spark industry dialogue and, ultimately, consensus around what should be included in all tracker bankability reports. “The failure of a project is not good for any of us. That’s why we created this white paper. It’s my hope that it’s used as a guideline for these reviews and to open a dialogue as well,” she said. “It’s better for the industry if we work towards standardizing these reviews.”
In the paper O’Brien proposes 16 different factors that should be included in any tracker bankability report. This list is a result of both O’Brien’s pre-DNV GL experience in tracker product development as well as a checklist of factors that her DNV GL colleagues have assembled over the course of many years writing their own tracker bankability reports. “The checklist has evolved over many years as we learn new things in the industry,” she said. “I would say each time we do a technology review, the list gets a few additional items added to it.”
Tracker bankability report must-haves
Past is often prologue. Which is why one of the elements O’Brien highlights as essential to include is a history of the tracker manufacturer as well as a description of the services it offers, including project engineering and on-site assistance during installation and commissioning. It’s also important for bankability reports to specify exactly which product is being reviewed. “Tracker designs evolve over time. The manufacturer may change one of the key components or the way something is assembled,” she said. “So, it’s important to really clearly define which model was reviewed.”
Even the most skillfully designed and hypothetically effective tracker is of little use if nobody can make it work in the field. Because of that, O’Brien says tracker bankability reports should include is a critical review of the installation manual provided by the manufacturer. This is to ensure that the manual has enough detail to allow typical installers to construct the tracking system. Because trackers and modules work in tandem to produce energy, bankability reports should also confirm that a tracking system is compatible with the modules proposed for a project. This means that the tracking system can’t subject modules to inordinate levels of vibration, twisting or unbalanced loading.
Tracker systems must handle weather events found in their locations, which is why bankability reports should include an assessment of a tracker’s structural integrity under very specific conditions. This includes wind, snow loads and soil type. In particular, tracker reports should include a detailed review of wind tunnel testing conducted on the equipment.
The potential for weather events is also why bankability reports should include a review of the product’s tracking algorithm and stow mechanism. In the case of high winds or snow, many trackers are designed to move into a position that reduces vulnerability to damage. Assessing the reliability of these approaches to avoid equipment damage – some of which rely on a so-called “active mechanism” that includes a drive system and controls – is critical. “If you’re relying on batteries, grid power or the control system and motors and drives all to work to protect the system from damaging winds or a snow event, it’s important that its reliability has all been validated through testing,” said O’Brien.
Factors ranging from field history to regulatory requirements related to trackers are also included in the white paper. If all of these elements are considered standard in future tracker bankability reports, O’Brien believes the industry will benefit significantly. “When you’re an independent engineer, you’re being tasked with giving a risk assessment on a technology and it’s important to give an independent conclusion and opinion,” she said. “Having this information in all bankability reports would make that possible.”