Silicon still dominates solar power, but it is no longer the only serious option. Over the past two decades, a family of thin-film solar technologies has matured quietly — offering lighter, more flexible and, in some cases, more sustainable alternatives.
Among these, three stand out:
- tin sulphide (SnS)
- cadmium telluride (CdTe)
- copper indium gallium selenide (CIGS).
With different advantages, each material could play a distinct role in the clean-energy transition, particularly in northern climates.
Tin sulphide (SnS): the sustainability-first contender
Tin sulphide can be described as a solar material that ‘ought to succeed’.
It is made from abundant, non-toxic elements, absorbs sunlight extremely well, and can be deposited as a thin layer using relatively simple manufacturing methods. In theory, SnS should enable low-cost, low-impact solar panels.
So why isn’t it everywhere?
The challenge has never been light absorption. It has been electrical losses inside the device, especially where the SnS layer meets its electrical contact. These losses allow electrical charges to recombine before they can be harvested, reducing efficiency.
Recent research has shown that adding ultra-thin passivation layers like germanium oxide can dramatically reduce these losses. That’s significant for improving the performance of SnS.
While SnS may never beat silicon on absolute efficiency, it could become one of the most environmentally responsible solar options available.
Cadmium telluride (CdTe): the industrial success story
CdTe is the most commercially successful thin-film technology to date. It has been deployed at scale for years and has proven itself in real-world conditions.
Its strengths are clear:
- High light absorption
- Strong performance in hot and low-light conditions
- Low manufacturing cost at scale
- Consistently good energy yield over time
This is why CdTe panels are common in large utility-scale solar farms.
The trade-off is sustainability perception. Cadmium is toxic, and tellurium is relatively rare. While CdTe modules are safe in use and recyclable, their material footprint raises legitimate long-term supply questions.
CdTe shows what thin-film solar can achieve when industrial optimisation meets scale — even if it is not the final word in sustainable materials.
CIGS: the performance-flexible all-rounder
CIGS sits somewhere between SnS and CdTe in philosophy.
It offers:
- High efficiencies for a thin-film technology
- Excellent performance in diffuse light
- Flexible form factors suitable for buildings and infrastructure
- Strong potential for integration into complex surfaces
CIGS works by carefully tuning its elemental composition, allowing engineers to optimise how it absorbs sunlight. This tunability gives it remarkable versatility — but also makes manufacturing more complex.
As a result, CIGS has seen slower large-scale deployment, despite its strong technical credentials.
For applications where weight, flexibility or aesthetics matter — such as building-integrated solar — CIGS remains one of the most compelling options available.
Comparing the three shows they all matter
Having shone a light on these technologies, we see there is no single “best” solar technology — only the right one for the right job.
- SnS prioritises material sustainability and future potential
- CdTe delivers proven, bankable performance at scale
- CIGS offers flexibility and strong real-world efficiency
For northern regions with varied climates, seasonal light and diverse infrastructure needs, this diversity is a strength — not a weakness.
Thin-film solar is not trying to replace silicon overnight. Instead, it is filling the gaps silicon cannot, expanding where and how clean electricity can be generated.
A more plural solar future
The solar transition will not be powered by one material alone. It will be built from a portfolio of technologies, each refined for a specific role.
As interface engineering improves, manufacturing matures, and sustainability becomes a central design, various thin-film technologies like SnS, CdTe and CIGS are likely to become quiet but deeply effective enablers of a cleaner energy system.
While tin sulphide (SnS) is attracting renewed attention for its sustainability credentials, it is not emerging in isolation. The other thin-film solar technologies — cadmium telluride (CdTe) and copper indium gallium selenide (CIGS) — have already demonstrated how non-silicon approaches can succeed in the real world.
CdTe is the most commercially mature thin-film technology. It has been deployed at scale for years, delivering strong performance in hot, low-light and utility-scale settings. Its success shows that thin-film solar can compete economically with silicon when manufacturing and deployment are optimised.
CIGS, by contrast, has carved out a more flexible role. With high efficiencies for a thin-film material and excellent performance under diffuse light, CIGS has proven especially well suited to building-integrated and lightweight applications where conventional panels struggle.
Together, CdTe and CIGS provide important context for recent advances in SnS: they demonstrate that interface engineering, material tuning and manufacturing discipline — rather than a single “perfect” material — are what ultimately turn laboratory promise into clean electricity on the ground.
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