What Are Solar Panels Made Of?

Author: Steve Fairless
Originally Published: 2nd January 2024 · Updated: 2nd September 2026

Most modern crystalline-silicon solar modules are made mainly from glass, aluminium, polymer encapsulants and silicon cells, with smaller quantities of copper, silver and other materials used for electrical interconnection, coatings, junction boxes and soldering. The exact stack varies: some panels use a polymer backsheet behind the cells, while many newer products use a second sheet of glass.

At Sustainable Energy Engineering, module construction matters because materials affect weight, dimensions, electrical characteristics, mechanical loading, moisture resistance, fire behaviour, degradation and how a panel should be handled on site.

An Illustrative Material Breakdown

Fraunhofer ISE’s July 2026 Photovoltaics Report includes a reference module material breakdown based on an 11.6 kg/m² module dataset dated 2021. It is useful for understanding the scale of different materials, but it is not a universal recipe for every 2026 module.

The same Fraunhofer reference also includes smaller fractions for junction-box materials, solder/metals and cell metallisation. Modern glass-glass, frameless and alternative-back-layer products will have a different mass balance.

1. Solar Glass

The front of a conventional module uses high-transmission, toughened solar glass. It protects the cell circuit against impact and weather while allowing light to reach the cells. Surface texturing and anti-reflective treatments can improve optical performance.

Glass is also why a module can be mechanically robust yet still require careful handling: edge damage, severe impact or incorrect clamping can compromise a product designed to carry distributed environmental loads.

2. Silicon Solar Cells

Silicon is the active semiconductor in the dominant PV technology. Fraunhofer’s current report says silicon wafer-based technology accounted for about 98% of total PV production in 2025 and that monocrystalline n-type TOPCon had become dominant in the market data it cites.

The older distinction between “monocrystalline premium” and “polycrystalline budget” is therefore no longer a good description of the current residential module market. Modern products use advanced monocrystalline cell architectures including TOPCon and back-contact designs, with continued work on reducing silicon thickness and metal consumption.

3. Encapsulant

The cells and interconnections sit inside polymer encapsulant layers. EVA is a familiar example, although alternative encapsulant chemistries are used. The encapsulant contributes to adhesion, electrical insulation and environmental protection while remaining optically suitable on the light-facing side.

Long-term problems such as delamination or moisture pathways can therefore be material-system issues, not simply “bad silicon”.

4. Backsheet or Rear Glass

A glass-backsheet module uses a multilayer polymer rear sheet. A glass-glass module replaces that conventional backsheet with another glass layer. Neither architecture should be judged by one word alone; the full product design, sealing, mechanical loading, warranty and reliability evidence matter.

The distinction is relevant to bifacial products, moisture behaviour, weight, handling and mounting. We always use the exact module datasheet when designing a system.

5. Aluminium Frame

Many modules use an anodised aluminium frame around the laminate. The frame gives a defined mechanical edge for handling and mounting and helps the module resist specified loads when clamped in approved zones.

Frameless products also exist, especially in some glass-glass formats. The mounting system must therefore match the exact module’s approved installation method rather than assuming every panel has the same frame geometry.

6. Copper, Silver and Cell Interconnections

Electrical current has to move from individual cells into a module circuit and then to external cables. Copper is widely used in interconnection, while silver remains important in cell metallisation. Manufacturers continue reducing silver use and exploring copper or aluminium alternatives because material efficiency affects both cost and resource demand.

7. Junction Box, Diodes, Cables and Connectors

The rear junction box contains electrical connections and bypass diodes, with DC leads and connectors carrying power into the string. These parts are small by mass but critical to safety and reliability. A connector mismatch or damaged cable can disable an otherwise perfectly good module.

How a Solar Cell Becomes a Module

The US Department of Energy’s PV manufacturing overview describes the broad manufacturing chain from silicon material and wafers through cells and module assembly. In a finished module, cells are electrically interconnected, encapsulated between protective layers, combined with the rear layer and glass, and then completed with frame/junction-box/cabling components as the design requires.

What About Bifacial Panels?

Bifacial cells can generate from light reaching both sides, but the module construction must allow rear-side light to reach the active cells. That commonly goes with transparent rear layers such as glass, although product architectures vary. Whether rear-side gain is meaningful depends on mounting height, rear shading, surface reflectance and layout.

Are Modern Solar Panels Recyclable?

Yes, but “recyclable” and “economically recovered at high purity today” are not the same statement. The large glass and aluminium fractions are relatively obvious recovery targets; recovering smaller quantities of silicon, silver, copper and polymer layers can require more specialised processes.

IEA PVPS published an updated module-recycling life-cycle inventory in 2026 describing advances in mechanical, thermal and chemical processing routes. Its life-cycle inventory work also reflects the changing material inputs of newer PV technologies.

Why Materials Matter When We Choose a Panel

When we specify domestic solar PV, material construction is therefore one part of the system design rather than a trivia question about what is inside the panel.

Our View: The “Silicon Panel” Is Mostly a Protective Engineering Structure

Silicon is the part that performs the photovoltaic conversion, but by mass a module is dominated by the materials that keep that thin electrical device protected, connected and mechanically usable outdoors. That distinction helps explain why two panels with similar efficiency can have very different weight, construction, warranties and installation requirements.

For examples of how current modules are used on real systems, see our AIKO panel case studies and our broader project case studies.

Cell Technology Has Changed Faster Than the Basic Module Stack

The familiar glass–encapsulant–cell–rear-layer construction remains recognisable, but the cells inside have evolved rapidly. N-type TOPCon has taken a large share of current production, while back-contact designs move front-side conductors away from the illuminated surface. These changes can improve optical/electrical performance without making the outside of a panel look dramatically different.

That is why “monocrystalline” is now too broad to describe the meaningful technology choice. Two monocrystalline modules can use very different cell architecture, interconnection and rear-layer design.

Glass-Glass Changes the Mass and Mechanical Design

The Fraunhofer material example is a glass-backsheet construction. Replace the polymer backsheet with rear glass and the material percentages change substantially. A double-glass module may be heavier and can have different approved mounting zones or clamp requirements.

For a roof design, those differences feed into handling, mounting-system selection and structural loads. They are not simply manufacturing details.

Why Manufacturers Keep Reducing Silver and Silicon per Watt

Silver is valuable and silicon production consumes material and energy, so using less of both for each watt can reduce cost and resource intensity. Fraunhofer’s current report shows silicon use per watt has fallen sharply over the long term as wafers have become thinner and efficiency has improved.

Modern multi-busbar and busbar-less approaches also change how current is collected from the cell. The engineering challenge is to reduce material without sacrificing resistance, mechanical durability or long-term reliability.

Polymers Are Small by Mass but Important to Lifetime

Encapsulants and backsheets form a much smaller share of mass than glass, yet they perform critical insulation, adhesion and moisture-barrier functions. Degradation such as delamination, cracking or embrittlement can therefore matter out of proportion to the kilograms involved.

Recycling Is Moving From Bulk Recovery Toward Higher-Value Recovery

Traditional module recycling can recover the bulk glass and aluminium relatively readily. The harder task is separating laminated layers and recovering silicon, silver, copper and other materials at a purity and cost that supports reuse. IEA PVPS’s 2026 recycling update documents the continuing development of mechanical, thermal and chemical approaches.

For customers, this means solar panels are not an unrecyclable block of “silicon waste”, but neither should we pretend every valuable atom is already recovered economically in every recycling route.