Same same but different module


Sample case study

Size of project: 102 MW

Size of panels: 340 Wp

Number of panels: 300,000

Testing sample rate: General Inspection Level I (ISO 2859)

Number of panels to test: 315

Acceptance Quality Level: Up to 0.04% is possible (ie., can detect a failure rate of 0.04% nonconforming items in a fleet of 300,000)

QA Cost (basic): AUD 56,000

Savings if power is 1% under nameplate: AUD 510,000 (assumes $0.50/Wp module price)

Return on investment in testing: 900%

All parties along the supply chain need to ensure that good quality stock is produced and installed without damage to avoid solar panel underperformance. One way to check this is with best practice testing and quality assurance.

When everything goes well, it’s common for the output of utility-scale farms, and smaller systems, to be boosted by an impressive 3%. Better still, this 3% higher output is available from the first day of plant operations, and makes a hard-to-ignore difference to a solar project’s revenue.

Testing lab

Last year alone, 1.42 GW of large-scale solar farms were built in Australia. Increasing their collective output by 3% is equivalent to adding 43 MW of additional clean energy to the grid. If that’s not impressive enough, consider that the cost of implementing an effective quality assurance regime for all these projects would only be a tiny fraction of the cost of building one new 43 MW plant. These statistics speak for themselves.

When I tell people I work in testing and quality control/assessment of solar panels, I’m usually asked: “Which panels should I buy?”

As a solar energy enthusiast, I’m heartened by growing evidence that more solar panels are being installed on rooftops across this sunny country of ours. It helps the domestic market in Australia better understand why testing is a foundation philosophy of PV Lab Australia, which was founded in 2013.

But is the consumer asking the right question when they ask which panels they should buy? I say it’s the wrong question. A better question would be: “How should I buy my panels?”

Testing is an important part of the quality assurance process. Our testing programs are more accurate and cheaper when completed on large volumes of panels. This is great for large-scale commercial purchasers. Small consumers can take heart in reading the Blue Reports we have written, with the support of an Australian Capital Territory government grant. These are targeted to help the market buy in a smarter way.

Case studies

To demonstrate the importance of asking the right question, consider these two case studies (see the charts to the right), which show tests of nameplate power for many solar panels from four solar farms. In both cases, the x-axis shows performance relative to nameplate with 0 (dotted red line) being the nameplate. In both cases, the y axis shows the percentage of panels in the batch that fall into a particular “bin” of performance relative to the nameplate power rating.

So, in case study one, many panels (dark blue bars) were 1% above nameplate and many (light blue bars) were 2.5% below the nameplate. Similarly, in case study two, most of the group indicated by the light blue bars were slightly underperforming and most of the other group were ~5% above nameplate.

In both case studies, if consumers buy panels that fall to the right of the red dotted line, they’re doing well. If consumers buy panels that fall to the left of the red dotted line, then something is wrong with the quality assurance of the purchase. What’s interesting is that the two groups in case study 1 are the same tier 1 brand. The only difference is they were shipped to different Australian solar farms. The two groups in case study 2 are a different tier 1 brand, again shipped to different Australian solar farms.

These results prove that a brand name isn’t a meaningful judge of quality. Even reputable brands vary between batches, and up to a disturbing 6%.

So what do consumers have to do to buy well? It’s essential to build an understanding of various considerations, including:

· What the manufacturer can control, such as the power rating on panels, type of EVA and storage conditions.

· How to check quality, with options including independent third-party testing at the farm gate, combined with factory inspections.

· The repercussions of the quality process, including whether panels are under power and whether the contract price will be reduced accordingly.

Having an independent expert who has an eye for detail on your side is a massive advantage. Quality assurance, testing and risk management on any solar project – but especially large-scale ones – is about gathering the correct information in the right way, starting with asking the right questions.

The views and opinions expressed in this article are the author’s own, and do not necessarily reflect those held by pv magazine.

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