Types of PV Panels: Mono, Poly, Thin-Film and Beyond

Solar panels look much alike from the street, but the cells inside them differ in material, structure and behaviour. Understanding the main types of PV panels helps when comparing proposals, because the choice affects how much power a roof can produce, how the modules cope with heat and shade, how heavy they are, and how they look on the building.

This article sets out the principal panel families, the newer cell designs that now dominate the market, the module constructions that sit around the cells, and the practical considerations for buildings in a hot, humid climate. It avoids product comparisons and prices, which change quickly; the principles are what last.

Crystalline silicon: the mainstream family

Most panels installed on buildings today use crystalline silicon cells. They are made from thin wafers sliced from blocks of very pure silicon, then processed to form the junction that separates charge when light strikes them. Within this family there are two traditional variants.

Monocrystalline

Monocrystalline cells are cut from a single continuous crystal. The uniform structure lets electrons move with fewer obstacles, so they convert a higher share of sunlight into electricity than other mainstream options. They are recognisable by their even, dark appearance, and most modules sold today are monocrystalline. Higher efficiency matters most where roof area is limited, which describes nearly every urban building.

Polycrystalline

Polycrystalline cells are cast from many small crystals fused together, giving a speckled, bluish look. They were historically cheaper to make but somewhat less efficient. Over the past decade improvements in monocrystalline manufacturing have largely displaced them, and they are now uncommon in new installations, though many existing arrays use them.

Thin-film panels

Thin-film modules deposit very thin layers of photovoltaic material onto glass, metal or plastic rather than using silicon wafers. The main technologies are amorphous silicon, cadmium telluride and copper indium gallium selenide. They generally convert less sunlight per square metre than crystalline modules, so they need more area for the same output.

They have strengths of their own. Some thin-film products cope comparatively well with high temperatures and diffuse light, and their uniform appearance and potential for flexible or semi-transparent formats make them attractive for façades, canopies and curved surfaces. That is one reason they appear in building-integrated applications, discussed in our article on BIPV, and in glazing products covered in our guide to transparent PV panels. Utility-scale cadmium telluride plants also exist, but on Singapore rooftops crystalline silicon remains the norm.

Newer cell architectures

Within crystalline silicon, the way the cell is built has evolved considerably. When comparing modern types of PV panels, these terms appear often in datasheets:

PERC (passivated emitter and rear cell) — adds a layer at the back of the cell that reflects unused light back through the silicon and reduces energy losses. It was the dominant design for several years.
TOPCon (tunnel oxide passivated contact) — a refinement that further reduces losses at the contacts, now widely adopted as an evolution of PERC production lines.
Heterojunction (HJT) — combines crystalline silicon with thin amorphous silicon layers, giving good efficiency and a favourable response to heat.
Back-contact (IBC and related) — moves all electrical contacts to the rear, leaving the front face free of metal lines to capture more light and giving a clean, all-black look.

Beyond silicon, perovskite materials and perovskite-silicon tandem cells are the subject of intense research, including at institutions in Singapore. They promise higher efficiency, but long-term durability in heat and humidity is still being proven, and they should be regarded as emerging rather than established for building use.

Module construction matters as much as the cell

Cells are only part of the panel. The way they are cut, connected and encapsulated affects durability and performance.

Half-cut and multi-busbar cells — cutting cells in half and using more, thinner conductors reduces resistive losses and limits the effect of partial shading.
Bifacial modules — capture light on both faces. They gain the most where the surface below is bright and the panels are raised, such as light-coloured flat roofs, carparks and canopies. On a flush-mounted pitched roof the rear face sees little light.
Glass-backsheet versus glass-glass — conventional modules use a polymer backsheet; glass-glass modules sandwich the cells between two panes, which improves resistance to moisture and mechanical stress but adds weight.
Frames — aluminium frames add stiffness and provide clamping points; frameless modules suit some architectural applications but need suitable clamps.

Weight is a structural consideration. Glass-glass and larger-format modules impose more dead load, and the mounting system must suit the panel dimensions and the wind exposure of the roof. The overall system logic is explained in our guide to the solar PV system.

Choosing among the types of PV panels in Singapore

Singapore’s climate shapes the choice. Modules run hot under strong tropical sun, and every crystalline cell loses output as its temperature rises; the temperature coefficient on the datasheet shows how strongly. Panels with a lower coefficient hold their output better on hot afternoons. High humidity and heavy rain put a premium on robust encapsulation and on certification to recognised international standards for durability and safety.

For most homes and commercial roofs the practical choice is a modern monocrystalline module, with the specific cell design selected for efficiency and heat tolerance. Roof area is usually the binding constraint, so efficiency translates directly into generation. Where appearance matters, all-black modules sit more quietly on a roof. Where the roof is pale and the panels can be raised, bifacial modules may add yield. Thin-film and semi-transparent products earn their place where the panel is part of the architecture rather than an addition to it.

Durability and end of life

All panels degrade slowly. Manufacturers state a warranted output after a given number of years, and the gap between products is worth reading. Look also at the product warranty, which covers defects, as distinct from the performance warranty.

Eventually every module has to be removed and processed. In Singapore, solar panels fall within the national e-waste extended producer responsibility framework, so suppliers carry obligations for take-back. Our guide to recycled solar panels explains what happens to modules at the end of their life.

Frequently asked questions

What are the main types of PV panels?

The main types are monocrystalline silicon, polycrystalline silicon and thin-film. Monocrystalline panels dominate new installations because of their higher efficiency, polycrystalline panels are now less common, and thin-film panels are used mainly where flexibility, appearance or semi-transparency matter more than output per square metre.

Which type of solar panel is best for a Singapore home?

For most homes a modern monocrystalline module is the sensible choice, because roof space is limited and efficiency matters. In the tropics it is also worth comparing temperature coefficients, since panels that lose less output in the heat perform better through the year. Certification to recognised standards and a credible warranty are as important as headline efficiency.

Are bifacial panels worth it on a roof?

They can be, where the panels are raised above a bright surface so that reflected light reaches the rear face, such as a pale flat roof, carpark shelter or canopy. On panels mounted close to a pitched or dark roof the rear face receives little light, so the additional benefit is small.

Do heavier glass-glass panels need structural checks?

Any PV installation on an existing roof should have its loads checked, and glass-glass modules add more dead load than glass-backsheet modules. The mounting system, fixings and the roof itself must be confirmed to carry the weight and resist wind uplift. A structural engineer can assess this before installation.

Are perovskite panels available for buildings yet?

Perovskite and perovskite-silicon tandem cells are progressing quickly in research and early commercial products, with very promising efficiencies. Their long-term durability under heat, humidity and ultraviolet exposure is still being established, so for a building intended to last decades they should be treated as an emerging option.

Specifying panels for a roof or façade and want the structure and fixings checked? Talk to our consultancy or get in touch.