Setting a new standard for solar efficiency testing

A new study from Simon Fraser University’s School of Sustainable Energy Engineering (SEE) has proposed an innovative standardisation framework to overcome longstanding inconsistencies in testing indoor solar technology, enabling reliable efficiency measurements and accelerating progress towards practical, sustainable indoor energy harvesting.

The study was led by SEE professor Vincenzo Pecunia and his team from SFU’s Sustainable Optoelectronics Research Group, including SEE master’s student Javith Mohammed Jailani and SEE undergraduate students Amanda Luu and Elizabeth Salvosa. The team’s findings were published in Joule.

As smart devices become increasingly integrated into our daily lives, finding reliable ways to power them is becoming ever more important. Currently, these devices rely on conventional disposable batteries, which are known to contribute to pollution due to toxic chemicals and waste generation. Indoor photovoltaics (IPVs) have emerged as a key solution to this rapidly growing issue — while also enabling the wider deployment of smart devices to make our homes and cities more comfortable, intelligent and sustainable. Similar to solar panels that convert sunlight into electricity, IPVs sustainably generate energy by harvesting ambient indoor light to power smart devices.

However, assessing the performance of IPVs presents challenges due to the complexity of indoor lighting conditions. Unlike outdoor solar panels, which are tested under consistent sunlight, indoor lighting varies widely depending on the shape, size, spectra, positioning and brightness of the light sources used. As a result, measurements of IPV performance are often inconsistent and can be misleading. Without reliable measurement standards, consumers cannot trust performance claims, and device designers are left with little guidance.

“IPV development requires accurate, benchmarkable performance data, which is currently hindered by inconsistencies in characterisation and benchmarking methods. The field currently faces a reliability crisis, with reported advances often obscured by measurement inaccuracies,” Pecunia said.

To address this issue, Pecunia and his team investigated how different testing configurations and protocols can skew IPV efficiency results. They found that IPV performance measurements become unreliable under scattered or diffuse light — the kind commonly found indoors. To tackle this, the team developed strategies to reliably quantify IPV efficiency under everyday lighting, while allowing fair performance comparisons across laboratories.

Another challenge the team addressed was the standardisation of IPV measurements amid the vast diversity of indoor light spectra. They found that simply labelling a bulb “warm white” or “cool white”, or referring to its “colour temperature”, is insufficient because there are hundreds of versions of each. Their solutions include a universal ‘reference cell’, which acts as a translator to standardise indoor lighting conditions for consistent IPV performance comparisons across labs.

By providing innovative insights, guidelines and protocols for reliable IPV testing, the team hopes to accelerate progress in efficient indoor energy harvesting. They have set their sights on a future where these devices quietly power the technologies that make our homes, workplaces and cities, smarter and more sustainable.

This is a modified version of a news item published by Simon Fraser University. The original version of the news item can be accessed here.

Image credit: iStock.com/Liudmila Chernetska