Perovskite is considered solar research's biggest hope – above all as a so-called tandem cell, applied on top of a conventional silicon module and able to significantly raise its efficiency. In the lab, the progress is impressive; the road to mass production, however, hinges on long-term stability, this technology's key challenge. For your purchase decision today, that means: buy mature silicon modules, don't wait for perovskite. (As of: July 2026)
Key points in brief
- Today's modules are almost all made of crystalline silicon – a mature, durable and inexpensive technology.
- Perovskite is a crystal material that converts light into electricity very efficiently and can be processed cheaply.
- The biggest lever is the tandem cell: perovskite on silicon uses the solar spectrum better than either layer alone.
- The open question is durability – perovskite is sensitive to moisture, heat and UV, and a roof module has to hold up for 25 years and more.
- For your own roof, it holds: it's not worth waiting. Today's technology is mature, and every year of waiting is a lost year of production.
What are solar modules today – and where's their limit?
Practically every module on Swiss roofs today is made of crystalline silicon – the technology that has carried the solar market for decades. It's mature, durable, and has become inexpensive thanks to enormous production volumes; the differences between monocrystalline and polycrystalline are small against this shared foundation.
Silicon, however, has a physical ceiling: a single silicon layer can only convert a certain share of sunlight into electricity, the rest is lost as heat. Today's modules are already approaching this limit – efficiency only rises in small steps now. Anyone wanting a big leap has to overcome the physics of a single layer. That's exactly where perovskite comes in.
What is perovskite – and what makes it special?
Perovskite refers to a particular crystal structure that's excellent as a solar material: it converts light into electricity very efficiently and can be manufactured as a thin layer with comparatively little effort – unlike silicon, which has to be energy-intensively melted and sawn. That makes perovskite doubly interesting: potentially more efficient and potentially cheaper to produce.
The real trick, though, is the combination. Perovskite and silicon absorb different parts of sunlight particularly well. Put a perovskite layer on top of a silicon cell – the tandem cell – and the module uses a broader part of the solar spectrum than either layer alone. In research labs, this approach has reached efficiencies well above anything pure silicon could ever achieve. That's the reason for all the attention: not a little better, but a new class.
So why isn't perovskite on roofs yet?
Because there's a long road between a lab record and roof-readiness – and perovskite faces a major hurdle on that road: long-term stability. The material that shines so brightly in the lab is sensitive to exactly the conditions a roof module faces for decades – moisture, heat, UV radiation, temperature swings.
| Criterion | Silicon (today) | Perovskite tandem (in development) |
|---|---|---|
| Efficiency potential | maxed out, high values | significantly higher |
| Manufacturing | energy-intensive, established | potentially cheaper, still scaling up |
| Long-term stability | proven over decades | the central open question |
| Market readiness for the single-family home roof | fully | not yet |
Classification, as of: July 2026. Development is fast-moving – the current state of research and available products is what counts.
A solar module isn't a smartphone that gets replaced after three years. It has to hold up for 25 years and more with minimal loss of output – and that's exactly the guarantee perovskite can't yet give in the same way as silicon. Research is making great progress on stability, first commercial tandem products are appearing, but broad, proven mass use on single-family home roofs is not there yet.
Are there other future technologies?
Perovskite is the most prominent, but not the only, route. In research, and partly already on the market, several approaches are moving forward in parallel: tandem concepts with other material combinations too, further-developed silicon cell types that improve the existing technology step by step, and formats such as bifacial modules, which additionally use light from the back. The latter are no longer a future concept but available today – a good example that progress in solar technology usually comes in steps, not as a single big leap.
For the homeowner, the distinction matters: some things that sound "new" have long been available and proven; others, like the pure perovskite mass module, are still under development. A look at the datasheet and the question of real warranties separate the two more reliably than any technology buzzword.
Should I wait for perovskite before buying solar?
Clear answer: no. And for a simple economic reason. Every year you wait for the "better" technology is a year your roof produces no electricity – and today's silicon modules are mature, durable and deliver reliably. The yield you miss while waiting is not made up for by any later leap in efficiency.
There's also this: "waiting for something better" is a bottomless pit with technology – there's always a next generation on the horizon. Anyone who acts on that principle never builds. And finally, for a single-family home, the available roof area usually matters more than the last percentage point of efficiency: whether a slightly more efficient module arrives changes little about the cost-effectiveness per square metre of your roof, as long as the area is sufficient. Buy the proven technology today – and be pleased if, in twenty years, when the inverter is replaced or the system extended, perovskite tandems really are on the shelf.
"Should I still wait for the new cells to arrive?" is one of the more common questions from technically minded clients – and our answer has stayed the same for years, because it's correct: no. We follow developments in perovskite with genuine interest and will offer the technology once it holds up on the roof with proven warranties. Until then, the best module is the one that reliably delivers for 25 years today – and it produces from the first sunny day, while those waiting just watch.
Frequently asked questions
Can I already buy perovskite modules?
First commercial tandem products are appearing, but broad, proven mass use on single-family home roofs isn't there yet. For a typical project today, mature silicon modules are the right choice.
How much more efficient is a perovskite tandem than silicon?
In the lab, significantly higher efficiencies have been reached than pure silicon can physically achieve. How much of that arrives stably in a mass-produced product over decades is the decisive – and still open – question.
What's the biggest hurdle for perovskite?
Long-term stability. The material is sensitive to moisture, heat and UV – but a roof module has to withstand these conditions for 25 years and more. That's exactly what research is working on.
Will today's modules soon become worthless because of this?
No. Mature silicon modules produce reliably over their entire service life, regardless of what's new on the market. A new technology doesn't devalue existing, well-functioning systems.
Is it worth planning a smaller roof coverage for perovskite?
No – a sparse coverage "for later" gives away yield and area today. If the roof can take more, full coverage with today's technology is almost always more sensible than holding back area for an uncertain future.
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Sources: Swiss Federal Office of Energy (SFOE), EnergieSchweiz, research institutions (including EPFL/Empa in the field of perovskite photovoltaics), manufacturer documentation.
Last updated: 9 July 2026 · Author: ecoEn editorial team
