What are the three main types of solar panel?
The familiar three-way comparison is monocrystalline silicon, polycrystalline silicon and thin-film. It is useful for understanding materials, but it is not a complete shopping shortlist. Perovskite is itself a thin-film material under the US Department of Energy's definition, and tandem devices stack it on silicon, so it overlaps these families rather than adding a fourth. [1][2]
| Material family | What it means | What to compare |
|---|---|---|
| Monocrystalline silicon | Wafers with a single crystal structure | Exact module efficiency, dimensions and installed price |
| Polycrystalline silicon | Wafers containing multiple crystals | The actual datasheet, particularly for an existing array |
| Thin-film | Thin semiconductor layers deposited onto a support | Material, complete panel construction and intended application |
Silicon wafers made up about 98 per cent of the world's solar panel production in 2025, and monocrystalline n-type TOPCon has become the dominant technology, according to Fraunhofer ISE's Photovoltaics Report, which draws on the ITRPV industry roadmap. That is global factory output, not a count of UK installations. [12]
A solar cell is the generating component; a module, usually called a panel, contains connected cells. [1] Cell efficiency is not the same as panel efficiency: JA Solar's datasheet quotes up to 26 per cent for its cells and 21.5 to 22.8 per cent for the finished modules. [4]
Monocrystalline or polycrystalline: which matters on your roof?
Both turn sunlight into electricity. The practical comparison is how much rated output fits into the available area and what the complete installation costs. A material label cannot tell you the roof layout, shade losses or annual savings. [1]
If you already have polycrystalline panels, the name alone is no reason to replace them. Ask for the existing system's measured generation, its condition and a replacement forecast before spending money. This is our decision rule, not a claim that every older system is performing well.
What do TOPCon, HJT and back contact mean?
These are cell-design labels. They should not sit alongside mono and bifacial as though you must choose only one.
- TOPCon stands for tunnel oxide passivated contact: an ultra-thin oxide layer and a thin silicon layer form the contact on the back of a silicon cell, according to Fraunhofer ISE, which developed it. [11]
- HJT, or heterojunction, combines crystalline silicon with amorphous silicon layers. [6]
- Back contact moves electrical contacts to the rear. AIKO calls its version All Back Contact, or ABC. [7]
A quote may also say PERC or n-type. Ask for the exact module code and datasheet rather than treating an acronym as proof of better household savings. Our panel comparison looks at documented models, dimensions and warranty terms.
Are all-black solar panels a different type?
Black describes appearance, so ask what the label covers: the frame, cells and backing can differ between models. It does not give you a separate efficiency rating or an annual generation forecast. AIKO's example datasheet lists module construction and electrical performance separately. [3]
Compare the exact all-black option with the proposed alternative on the same roof layout and installed price. For a bifacial model, also check how its rear construction allows light to reach the cells. Do not pay a performance premium based on the colour alone.
Are bifacial solar panels better for a UK roof?
Not automatically. Bifacial panels collect light from the front and rear, and the rear only adds output when light reaches it, often reflected from the ground or roof underneath. [1] That makes mounting height, gaps and the surface below relevant: a 2024 study of bifacial panels on industrial-type rooftops by researchers at Politecnico di Milano found the ideal height above the roof was not feasible there for structural reasons, and that the mounting structure can reduce the gain. [13]
For a panel close to an opaque pitched roof, do not accept a fixed extra-output percentage simply because the datasheet says bifacial. Ask how the forecast models rear light and whether it is already included. Compare front-side ratings first, then any separately justified rear contribution.
Dual glass describes glass on both sides; bifacial describes generation on both sides. Check the exact model for both features. Bifacial is not limited to crystalline silicon: First Solar also documents a bifacial CdTe thin-film product. [5]
How efficient are the different panels?
Commercial monocrystalline silicon modules rose from about 17 per cent to just under 25 per cent efficiency over the past decade, and CdTe thin-film modules from 15.6 per cent to almost 20 per cent, according to Fraunhofer ISE's Photovoltaics Report of 14 July 2026. [12] Compare the complete module at Standard Test Conditions (STC). The two silicon examples below are the same size, 1762 x 1134 mm, yet differ by 1.5 percentage points. [3][4]
| Documented example | Module efficiency | Scope |
|---|---|---|
| AIKO Neostar 3S+ AIKO-A480-MCE54Db | 24.0% [3] | 480 W N-type ABC, dual-glass bifacial model |
| JA Solar JAM54D41-450/LB | 22.5% [4] | 450 W monocrystalline bifacial model |
| First Solar Series 6 Plus family | Up to 19.0% [5] | CdTe thin-film family; large framed module |
Efficiency is useful when roof space is tight. It does not, on its own, establish the lowest installed cost per annual kWh or the best warranty. Request the complete roof design and generation estimate with the price.
Are thin-film panels flexible?
Thin-film describes the semiconductor layer, not whether the finished panel bends. The supporting material can be glass, plastic or metal. CdTe and CIGS are examples of thin-film materials. [2]
First Solar's Series 6 Plus demonstrates that thin-film can be a framed large-format product. Conversely, Renogy sells a flexible monocrystalline panel: flexible does not automatically mean thin-film. Neither example establishes suitability for your tiled roof. [5][10]
For a lightweight or specialist roof, ask for the module's intended mounting method, roof-system approval and installation warranty. Do not substitute a portable or vehicle panel for a designed household array because it is light.
When will perovskite solar panels be available?
Some are already in commercial use. Oxford PV announced its first perovskite-on-silicon tandem shipment to a US utility project on 5 September 2024. It gave 24.5 per cent module efficiency for those commercial panels, separately from a 26.9 per cent prototype figure it called a module efficiency record. [8]
That announcement is not a confirmed retail launch date for an ordinary UK home. It mentioned pilot residential applications, but it gives no UK installed price, local stock or homeowner warranty. We are not giving a UK household availability date from that evidence.
In a later step, Trina Solar announced on 22 June 2026 what it called the first global order for its perovskite and silicon tandem modules, from a high-end distributed energy customer in New Zealand, which it described as a premium residential PV market. Neither announcement gives a UK retail date, price or homeowner warranty. [14]
A tandem stacks materials that absorb different parts of sunlight. For a proposal using one, ask for the actual module specification, certification, warranty and named installer support. Do not compare a laboratory cell record with a roof panel's published module rating. [2]
What is solar glass, and do panels work behind glass?
Photovoltaic glass incorporates electricity-generating material into a building element, such as a facade or skylight. Onyx Solar offers crystalline and amorphous silicon glass, and says its amorphous glass comes in versions from fully opaque to partly transparent. Ordinary window glass and a glass-fronted roof panel are different products. [9]
A panel can generate behind a window if usable light reaches it. The output depends on the glazing, light level, angle, shade and panel. We give no universal loss percentage: the technical sources here do not supply one for household windows. That conclusion follows from the light-dependent operation described by the Department of Energy. [1]
Do not use the rated outdoor output as an indoor forecast. For a building-integrated system, get a design that addresses both electricity generation and the glazing or roofing job it replaces. See our in-roof solar guide for that separate roof-construction decision.
Which type of solar panel is best for your home?
Compare two complete proposals on the same roof assumptions. Check exact model codes, total kWp, annual generation estimate, panel area, shade assumptions, installed price and warranty exclusions. If roof space limits how many panels fit, compare the total kWp each proposal fits on the same layout, because efficiency then decides capacity. If both proposals already fit the system size you need, compare installed price and warranty terms first. Choose the proposal that fits the house and budget; we do not name one technology the universal winner.
If the salesperson promises more generation because a panel is bifacial or uses a newer cell design, ask where that increase appears in the forecast and what assumptions support it. Use our quote checklist to check the numbers rather than buying the acronym.
Sources
- US Department of Energy: PV Cells 101. 3 December 2019; definitions only, not its dated market shares or efficiency ranges; read 14 October 2026. Back to the relevant section.
- US Department of Energy: Solar Photovoltaic Cell Basics. Live technical explainer; read 14 October 2026. Back to the relevant section.
- AIKO, Neostar 3S+54 AIKO-A-MCE54Db datasheet. 202601, V3.1 EN; read 14 October 2026. Back to the relevant section.
- JA Solar, JAM54D41/LB 25-year version datasheet. 25-year product warranty version, Version No. Global-EN-20241129A; read 14 October 2026. Back to the relevant section.
- First Solar: Series 6 family. Live EMEA manufacturer page; read 14 October 2026. Back to the relevant section.
- REC: Mastering HJT. 12 June 2023; structure definition only, no comparative marketing superiority claims; read 14 October 2026. Back to the relevant section.
- AIKO: All Back Contact cell. Manufacturer technology description; read 14 October 2026. Back to the relevant section.
- Oxford PV: 20% more powerful tandem solar panels enter commercial use for the first time in the US. 5 September 2024; read 14 October 2026. Back to the relevant section.
- Onyx Solar: photovoltaic glass for buildings. Live manufacturer description; read 14 October 2026. Back to the relevant section.
- Renogy UK: Flexible monocrystalline panel. 100 W 12 V flexible monocrystalline panel, live supplier listing; no price or availability inference; read 14 October 2026. Back to the relevant section.
- Fraunhofer ISE: TOPCon. Research institute project page; read 14 October 2026. Back to the relevant section.
- Fraunhofer ISE: Photovoltaics Report. Updated 14 July 2026, Executive Summary; read 14 October 2026. Back to the relevant section.
- González-Moreno, Mazzeo, Dolara, Ogliari and Leva: Outdoor performance comparison of bifacial and monofacial photovoltaic modules in temperate climate and industrial-like rooftops. Applied Sciences 14(13) 5714, 29 June 2024; abstract read via OpenAlex; read 14 October 2026. Back to the relevant section.
- Trina Solar: Trina Solar signed the first order in the global premium residential market for perovskite/crystalline silicon tandem module products. GlobeNewswire release, 22 June 2026, as syndicated by AAP; read 14 October 2026. Back to the relevant section.