Reaching the ‘ready-to-repower’ stage of solar PV project maintenance

However, as solar PV assets reach the ends of their operational lives, the industry could benefit from an increasing awareness of the ‘ready-to-repower’ milestone, a threshold at which a project owner needs to seriously consider what—whether repowering, revamping or decommissioning—comes next for the project.

The phrase was coined by Joe Miletic, founder and director of UK-based consultancy Solclaris, during a panel discussion earlier this month at Solar Media’s Clean Power 2030 Summit. In conversation with PV Tech Premium, he admits that the phrase came to him during the discussion, reflecting the fact that more attention needs to be paid to this milestone when considering end-of-life work at solar PV projects.

“It came to me during the panel at the event where we were talking about revamping and repowering!” he tells PV Tech Premium, and draws a comparison between the new idea of the ready-to-repower phase, and the much more established ready-to-build phase.

“Ready-to-build is really asking whether the project is ready to be constructed,” he explains. “Ready-to-repower is ‘are we ready to answer the question of what happens next with that operating asset?’”

A shift in mindset

When asked about what answering this question looks like, Miletic says that asset managers will need to create and consider an “evidence pack” of project information, which will illuminate the best course of action for each individual project.

“The practical outcome of ‘we need to repower’ is an evidence pack with a set of options,” he says. “It’s not purely a repowering [process], there can be alternatives: extensions, partial repowering or decommissioning, which could be the most viable option for that particular asset.”

“What I see as this ready-to-repower milestone is initially an assessment of what are the different options, what does it look like, what are the main constraints, and what are the main challenges at that time, and being able to move to the execution stage,” he adds.

Simply being aware of the range of end-of-life options for a solar PV asset, and being able to assess which is most appropriate for a particular project, is crucial, as there is no one-size-fits-all answer to how best to manage an asset at the end of its operating life.

The decision must be made with an understanding of all of the myriad components that go into project operation, including financial, technical and legal questions. As a result, comparing the idea of a ready-to-repower milestone to other project development benchmarks, such as reaching the ready-to-build stage, can be difficult as there are a lot more moving parts associated with an asset already in operation, compared to one where construction has not yet even started.

However, Miletic says that this is a comparison worth making, as the sheer scale of questions facing those at the ready-to-repower stage contrasts to the more specific technical questions a developer must answer at the ready-to-build stage.

“I don’t see [ready-to-repower] as a technical certification or assurance [as] the reality is a bit more nuanced,” he says. “It’s a good concept to compare to what we define as ready-to-build, which is already a concept that sometimes is hard to define. What I see as ready-to-build is, for a new project, typically sufficient development has been done—typically defined developments—and you are ready to proceed into construction.”

“But the idea we need to offer is a bit more complex because it’s an operating asset, as a start, and the owner of the asset needs to understand what’s the status to be able to make a decision.”

Reaching the ready-to-repower stage is therefore more of a mindset shift for an asset owner, than it is simply being aware of new technical requirements for a project. Miletic says that he knows of companies that have had to take “shortcuts” when reaching the repowering stage as they did not plan sufficiently far enough in advance, and so are left scrambling to source new components and products before their existing hardware shuts down completely.

“What I’ve seen sometimes is a bit of a shock for early revamping projects, so they’re not fully repowered but the asset manager may have taken some shortcuts in getting a quote quite quickly from a major place without actually having all that information in place, to make a fully informed decision,” he says.

Addressing technical issues

While technical concerns do not account for the entirety of questions that must be answered at the ready-to-repower stage, Miletic notes that deciding what to do with panels, inverters and electrical infrastructure is a key part of managing an ageing solar asset.

“Some of the critical equipment on a solar farm are known to have a shorter useful life, especially inverters and associated equipment,” he explains, pointing to the rapid pace of innovation in these industries that makes simply replacing a product or component quite challenging. “Typically, the useful life has been defined as 12 years; the reality in the market is that technology has shifted very quickly.”

“Obsolescence and availability of parts have been issues, so a lot of projects have very high opex issues [and] finding like-for-like replacements for inverters has led to early consideration on having to repower inverter stations, sometimes with different technologies or sometimes trying to fix other issues at the same time with the transformers [such as] early issues with panels.”

Miletic also says that he knows of projects with “major issues” with the modules themselves, which tends to lead towards large-scale revamping rather than wholescale repowering.

“The challenge has been that [accommodating] module defects can be very expensive, slow and difficult,” he explains. “You’re looking at the performance of many solar panels put together … so where there’s a major systemic issue, it can take time to put together all the evidence.”

The global solar industry is facing questions about manufacturing quality more broadly. Figures from Intertek CEA, published earlier this year, show that more than two-thirds of solar manufacturing facilities worldwide exhibited “major” or “critical” defects, as manufacturers have sought to produce vast quantities of modules to meet global demand whilst simultaneously cutting manufacturing costs; the result has been a clear decline in module quality.

Indeed, even beyond module failures, module design trends have made their long-term operation more challenging. Modules are, in general, becoming larger and thinner, as manufacturers look to improve module efficiency and cut production costs, which led Theresa Barnes, who manages the Photovoltaic Reliability and System Performance Group at NREL, to point to the current trend of “big floppy modules” that are available in the global solar sector.

Perhaps most pressingly, at least for the O&M companies that are tasked with replacing defective inverters and modules, the rapid pace of new module launches in the sector, and the speed at which some components are declining, means that some of these companies are struggling to keep up.

“It’s hard, its complex, its granular and in a way it challenges sometimes the boundaries of what is expected of an O&M,” says Miletic. “What are the expectations of an O&M contractor where there start to be issues with equipment that now looks very different? It creates engineering complexity that has not necessarily been welcomed by O&M contractors about where they expected to be.”

No demand for specialist revampers and repowerers

Considering these challenges facing O&Ms, which are often made responsible for end-of-life work despite perhaps lacking the specific knowledge to be able to complete this work, is there space for specialist revampers and repowerers, who could acquire projects at the ready-to-repower stage and bring them to the ends of their operational lives?

This would mirror the work of specialise EPCs at the start of a project’s operational life, who are involved in project construction but not asset management, but Miletic says that there is not yet demand for these kinds of highly specialised end-of-life services.

“There have been some projects to change hands, but I don’t think it’s the case of seeing specialist buyers that would just want to buy straight away and repower,” he says. “I think this may come in the next years.”

“It does require a disciplined approach from an engineering perspective, and also from a commercial perspective, because an intersection between different aspects: there’s the operational aspect, there’s the engineering aspect related to revamping, there’s the developer mindset as well,” he continues. “There’s a question about what is the owner’s preference in terms of whether to [work] internally or partner with a company or potentially decommission.”

Ultimately, the complexity and site-specific nature of end-of-life work means that companies that reach the ready-to-repower stage will often have to make a decision based on the specific conditions of that project, and their broader project portfolio plans, rather than relying on a one-size-fits-all approach to end-of-life work. Or, as Miletic puts it, companies will simply have to develop “credible options” that they can assess and act on when it comes time to make a decision.

“It’s developing credible options,” he says. “This is the stage where we understand the different scenarios: extend it, revamp, wait and repower completely, partial revamping followed by full repowering, combine with co-location or prep for sale.”

“The more information you have on your existing asset and the state of your permits, the more informed you are in terms of what you see as your best baseline. Then the best baseline is to have an optimal approach—maybe extend up to five years—and give yourself [time] to prepare a sale.”