The Solar Panel That Doesn’t Look Like a Solar Panel
Picture a solar panel and you probably picture a rigid, blue-black grid of silicon cells bolted to a rooftop. That’s crystalline silicon, and it’s what dominates almost every rooftop in Bangladesh today. But there’s an entire other family of solar technology that works differently — thinner, sometimes flexible, made by depositing a light-absorbing layer just a few micrometres thick onto glass, metal, or plastic instead of slicing wafers from a silicon ingot.
That’s thin-film solar. And within it, three technologies do most of the work: CdTe, CIGS, and a-Si. Each one made a different set of trade-offs between cost, efficiency, and where it can physically go — and understanding those trade-offs matters if you’re trying to figure out whether thin-film has any place in your project, or whether you should just stick with the crystalline panels everyone already knows.
Thin-Film Solar at a Glance
| Feature | CdTe | CIGS | a-Si |
| Best use case | Utility-scale, hot climates | BIPV, flexible/curved surfaces | Consumer electronics, small devices |
| Module efficiency | 18–22% | 15–18% (rigid); 12–15% (flexible) | 5–12% |
| Temperature coefficient | −0.172%/°C (best) | −0.36%/°C | −0.234%/°C |
| Flexibility | No | Yes | Yes |
| Toxicity | High (cadmium) | Moderate | Low |
| Market share | ~5% (dominant thin-film) | ~2% | ~1% |
A lower temperature coefficient is a good thing here — it means the panel loses less output as it heats up. That single number turns out to matter more than most buyers realise, especially somewhere as hot as Bangladesh gets between March and June.
CdTe: The One That Actually Made It to Market
Cadmium Telluride is, by a wide margin, the thin-film technology that succeeded commercially. It holds roughly 5% of the overall solar market — small next to crystalline silicon, but by far the largest slice of the thin-film pie — largely because it’s genuinely cheap to manufacture at scale.
Two numbers stand out. First, that temperature coefficient of −0.172%/°C is the best of the three technologies, and better than most crystalline silicon panels too. In practice, that means a CdTe panel sitting on a hot tin roof in Bangladesh’s peak summer will hold onto more of its rated output than a panel that heats up faster. Second, its energy payback time — the time it takes a panel to generate as much energy as was used to manufacture it — is just 0.738 years, the shortest of any thin-film option.
The trade-off is cadmium itself, a toxic heavy metal that needs to be handled and disposed of carefully at end of life. It’s not a reason to panic about a CdTe installation — the cadmium is sealed within the module, not free-floating — but it is a real consideration for large-scale deployment and eventual decommissioning, and reputable manufacturers run take-back and recycling programmes for exactly this reason. CdTe also doesn’t come in flexible formats, so if you need to wrap panels around a curved surface, this isn’t your technology.
Where it fits: Utility-scale solar farms and large flat rooftops in hot climates, where the low-heat-loss advantage and low manufacturing cost outweigh the disposal considerations.
CIGS: The Flexible, High-Efficiency Option
Copper Indium Gallium Selenide is the performance leader of the group. Lab efficiencies have hit 23.4%, and commercial modules typically run 15–18%, dropping slightly to 12–15% in flexible formats. That’s genuinely competitive with mainstream crystalline silicon.
What sets CIGS apart isn’t just efficiency, though — it’s flexibility. CIGS can be deposited on metal foil or polymer substrates, which means it can bend, curve, and mould itself onto surfaces that a rigid glass panel never could. That opens up building-integrated photovoltaics (BIPV), where the solar layer becomes part of a facade or roofing material rather than something bolted on top of it, along with portable and mobile applications.
The cost is higher — around $0.60 per watt — and CIGS relies on indium, a relatively rare and increasingly sought-after metal, which puts some long-term pressure on supply and pricing. It’s also less toxic than CdTe, which softens the disposal conversation considerably.
Where it fits: Space-constrained or architecturally demanding projects — a curved facade, a portable power unit, a building where a rigid rooftop array simply isn’t an option.
a-Si: Still Around, Just Not for Powering Buildings Anymore
Amorphous Silicon was one of the earliest thin-film technologies, and it’s now largely been overtaken by CdTe and CIGS for serious power generation. At 5–12% module efficiency, it simply can’t compete on raw output.
That doesn’t mean it’s obsolete — it’s just found a narrower lane. a-Si remains genuinely useful in small, low-power consumer electronics: solar calculators, watches, and similar devices where a tiny amount of power is all that’s needed and the technology’s low material toxicity and high flexibility matter more than efficiency. It also shows up in some niche BIPV applications for the same reasons.
Where it fits: Small consumer devices and specific low-power BIPV uses — not something to consider for a home or industrial power system.
Thin-Film vs. Crystalline Silicon: What Actually Changes Your Decision
If you’re weighing thin-film against the mono- or poly-crystalline panels that dominate the Bangladeshi market, the honest answer is: for most rooftop installations, crystalline silicon is still the more practical choice. It’s more efficient per square metre than CdTe or a-Si, it’s the technology local installers, suppliers, and after-sales support networks are built around, and spare parts and expertise are far easier to find.
Thin-film earns its place in more specific scenarios — when a surface is curved rather than flat, when a project genuinely needs to save weight, when heat performance is the deciding factor over a huge utility-scale footprint, or when the application is small enough that a-Si’s low output doesn’t matter. If none of those apply to your project, that’s a reasonable signal that crystalline silicon is still the more sensible route.
Where This Leaves Bangladesh
Rooftop and industrial solar in Bangladesh today is overwhelmingly crystalline silicon — that’s simply where the local supply chains, installer expertise, and after-sales support have developed. Thin-film hasn’t established meaningful commercial availability here yet, so anyone hoping to source CdTe or CIGS panels locally should expect to work with specialised importers rather than standard local solar retailers, and should treat any pricing as something to confirm directly with suppliers rather than a fixed market rate.
That said, the climate argument for CdTe is a real one, not a marketing angle. Bangladesh’s hot, humid summers are exactly the conditions where a low temperature coefficient pays off, and as BIPV becomes more relevant in dense urban development — think apartment facades in Dhaka or commercial buildings in Chattogram where rooftop space is limited — CIGS’s flexibility could eventually find a foothold. For now, though, these remain emerging possibilities rather than mainstream options.
Which One Should You Actually Consider?
- Large flat-roof or utility-scale project in a hot climate: CdTe is worth investigating, mainly for its heat tolerance and low cost per watt.
- Curved, portable, or architecturally integrated surface: CIGS is the only one of the three built for this.
- Small electronic device: a-Si is still doing exactly what it was designed for.
- Standard home or factory rooftop in Bangladesh: Crystalline silicon remains the practical default, given local supply chains and installer familiarity.
If you’re not sure which category your project falls into, that’s usually a sign it’s worth getting an assessment before committing to a technology — the right choice depends as much on your roof, climate exposure, and budget as it does on spec sheets. Muspana works with businesses and homeowners across Bangladesh evaluating exactly these kinds of decisions, and can help you weigh whether a mainstream crystalline system or a more specialised technology genuinely fits your situation.
FAQs
What is thin-film solar made of?
Thin-film solar panels are made by depositing a very thin layer of light-absorbing material — typically cadmium telluride (CdTe), copper indium gallium selenide (CIGS), or amorphous silicon (a-Si) — onto a surface like glass, metal, or plastic, rather than using thick silicon wafers like conventional panels.
Is thin-film solar cheaper than crystalline silicon?
CdTe can be cheaper to manufacture at scale, which is why it dominates utility-scale thin-film deployment. CIGS, at around $0.60/W, tends to cost more due to efficiency and flexibility advantages. For a typical rooftop system, crystalline silicon is usually still the more cost-effective and accessible choice, especially given how established its supply chain is in Bangladesh.
Which thin-film solar technology is most efficient?
CIGS leads on efficiency, reaching up to 23.4% in lab conditions and 15–18% commercially. CdTe follows at 18–22% module efficiency, while a-Si trails at 5–12%.
Is thin-film solar good for hot climates?
Yes, particularly CdTe, which has the lowest temperature coefficient of the three (−0.172%/°C), meaning it loses less power as temperatures rise. That makes it comparatively well-suited to hot, humid conditions like Bangladesh experiences for much of the year.
Is thin-film solar available in Bangladesh?
Not as a mainstream local product — the Bangladeshi solar market is dominated by crystalline silicon panels, and thin-film technology has limited commercial presence here. Anyone interested in CdTe or CIGS panels locally would likely need to work with a specialised importer rather than a standard solar retailer.
Can I put flexible solar panels on my roof?
Flexible CIGS or a-Si panels can work on curved or unconventional surfaces where rigid panels don’t fit, but for a standard flat rooftop, rigid crystalline silicon or CdTe panels are generally more efficient and cost-effective per square metre.
