What Are Solar Panels Made Of?

A solar panel is a precisely engineered stack of six or seven layers: tempered low-iron front glass, a clear EVA encapsulant, the silicon cells that generate current, a polymer backsheet (or a second sheet of glass), an aluminium frame, and a rear junction box with bypass diodes. Each layer does a specific job — generating current, protecting it, insulating it, and holding the whole thing rigid on your roof for 25-plus years of Australian weather.

<div class="tldr" style="border:1px solid #cbd5e1;background:#f8fafc;padding:16px 20px;border-radius:8px;margin:24px 0;"> <strong>Quick answer</strong> <ul> <li>The power comes from crystalline silicon cells (typically 108, 120 or 144 per panel).</li> <li>Monocrystalline (20–23% efficient) now dominates residential; polycrystalline (15–17%) is fading out.</li> <li>Layers: low-iron tempered glass → EVA → cells → backsheet or rear glass → aluminium frame → junction box.</li> <li>Construction details — cell type, busbars, glass-glass vs backsheet — drive long-term durability more than the headline wattage.</li> </ul> </div>

Where does the power come from — the silicon cell

At the centre of every panel are individual solar cells — typically 108, 120 or 144 wired together — each a thin wafer of crystalline silicon doped to create a p-n junction (the mechanism covered on How Does Solar Power Work?). How that wafer is manufactured determines which of two main cell types you're looking at.

How do monocrystalline and polycrystalline cells differ?

Monocrystalline cells are cut from a single, continuous crystal of silicon grown using the Czochralski process — a seed crystal is dipped into molten silicon and slowly withdrawn while rotating, pulling up a cylindrical ingot with a uniform crystal lattice, then sliced into wafers. Because the structure is uniform, electrons move with less resistance and fewer recombination losses, giving higher efficiency — generally 20–23% for current commercial panels, sometimes higher with advanced architectures like TOPCon or heterojunction (HJT). Monocrystalline now dominates the residential market.

Polycrystalline cells are made by melting fragments of silicon together and casting them into a block. This is cheaper but leaves grain boundaries — microscopic seams where electrons recombine before reaching the busbars. That gives the distinctive speckled blue look and lower efficiency, typically 15–17%. Polycrystalline has become increasingly rare in new residential installs.

<div style="overflow-x:auto;"> <table style="border-collapse:collapse;width:100%;min-width:520px;"> <thead><tr style="background:#eef2f7;"> <th style="border:1px solid #cbd5e1;padding:8px;text-align:left;">Cell type</th> <th style="border:1px solid #cbd5e1;padding:8px;text-align:left;">Typical efficiency</th> <th style="border:1px solid #cbd5e1;padding:8px;text-align:left;">Appearance</th> <th style="border:1px solid #cbd5e1;padding:8px;text-align:left;">Residential status</th> </tr></thead> <tbody> <tr><td style="border:1px solid #cbd5e1;padding:8px;">Monocrystalline</td><td style="border:1px solid #cbd5e1;padding:8px;">20–23% (higher with TOPCon/HJT)</td><td style="border:1px solid #cbd5e1;padding:8px;">Uniform black</td><td style="border:1px solid #cbd5e1;padding:8px;">Dominant</td></tr> <tr><td style="border:1px solid #cbd5e1;padding:8px;">Polycrystalline</td><td style="border:1px solid #cbd5e1;padding:8px;">15–17%</td><td style="border:1px solid #cbd5e1;padding:8px;">Speckled blue</td><td style="border:1px solid #cbd5e1;padding:8px;">Increasingly rare</td></tr> </tbody> </table> </div>

What do busbars do?

Each cell has a fine grid of metal conductors printed on its surface — thin "fingers" collecting current, feeding into thicker busbars. Older panels used three to five busbars; most current panels use multi-busbar (MBB) designs with nine, ten or more thinner wires, or ribbon-style connections, which reduce resistive losses and make the panel more tolerant of partial shading or a hairline cell crack, since current has more available paths.

The layered sandwich

Individual cells, wired into strings, are encapsulated into the full panel structure:

• Front glass — a sheet of low-iron, tempered glass, typically 3.2mm thick. "Low-iron" matters: standard glass has a faint green tint that absorbs some light; low-iron is far more transparent. Many panels add an anti-reflective coating. Tempering lets it withstand hail impact and thermal stress.
• Encapsulant (EVA) — a layer of ethylene-vinyl acetate above and below the cells, bonding glass, cells and backing into a single unit while insulating and cushioning against vibration and thermal expansion.
• Backsheet (or rear glass) — standard panels use a multi-layer polymer backsheet for weatherproofing, insulation and UV resistance. Increasingly common are glass-glass panels, which replace the polymer with a second sheet of tempered glass for better durability, lower long-term degradation, and often a longer warranty — and enabling bifacial designs that capture reflected light from the rear.
• Aluminium frame — an anodised aluminium frame gives rigidity, a mounting point, and a grounding path. Anodising resists the corrosion Australian coastal and high-UV conditions accelerate.
• Junction box and bypass diodes — on the rear, the junction box connects internal strings to external cabling. Inside are bypass diodes: if part of a panel is shaded, the diode lets current bypass the shaded section rather than letting it bottleneck (and overheat) the whole panel.

How do the panel brands in the market compare?

Construction quality — not just the brand badge — is what matters, but buyers naturally want to know how the common Australian panel brands sit. The table below reflects the confirmed range panels are sourced across.

<div style="overflow-x:auto;"> <table style="border-collapse:collapse;width:100%;min-width:520px;"> <thead><tr style="background:#eef2f7;"> <th style="border:1px solid #cbd5e1;padding:8px;text-align:left;">Panel brand</th> <th style="border:1px solid #cbd5e1;padding:8px;text-align:left;">Cell technology (typical current range)</th> <th style="border:1px solid #cbd5e1;padding:8px;text-align:left;">Typical performance warranty</th> </tr></thead> <tbody> <tr><td style="border:1px solid #cbd5e1;padding:8px;">JA Solar</td><td style="border:1px solid #cbd5e1;padding:8px;">Mono PERC / TOPCon</td><td style="border:1px solid #cbd5e1;padding:8px;">25–30 years</td></tr> <tr><td style="border:1px solid #cbd5e1;padding:8px;">LONGi</td><td style="border:1px solid #cbd5e1;padding:8px;">Mono PERC / TOPCon (HPBC on some ranges)</td><td style="border:1px solid #cbd5e1;padding:8px;">25–30 years</td></tr> <tr><td style="border:1px solid #cbd5e1;padding:8px;">Risen</td><td style="border:1px solid #cbd5e1;padding:8px;">Mono TOPCon / HJT</td><td style="border:1px solid #cbd5e1;padding:8px;">25–30 years</td></tr> <tr><td style="border:1px solid #cbd5e1;padding:8px;">Jinko Solar</td><td style="border:1px solid #cbd5e1;padding:8px;">Mono TOPCon (N-type)</td><td style="border:1px solid #cbd5e1;padding:8px;">25–30 years</td></tr> <tr><td style="border:1px solid #cbd5e1;padding:8px;">Trina Solar</td><td style="border:1px solid #cbd5e1;padding:8px;">Mono TOPCon (N-type)</td><td style="border:1px solid #cbd5e1;padding:8px;">25–30 years</td></tr> </tbody> </table> </div>

<p style="font-size:0.9em;color:#475569;">Warranty terms vary by model and tier — always confirm the exact performance <em>and</em> product warranty on the specific panel's datasheet, as covered in <a href="/solar-panel-warranty-types-explained">Solar Panel Warranty Types Explained</a>.</p>

Why the construction matters for buyers

Panel specification sheets list efficiency and wattage prominently, but the construction details above — cell type, busbar count, glass type, backsheet vs glass-glass — are what actually determine long-term degradation rate, hail and heat tolerance, and real-world performance on an Australian roof over 25 years.

Frequently asked questions

Are monocrystalline panels worth the premium over polycrystalline?

For most new residential installs the choice is largely made for you — monocrystalline now dominates, and the manufacturing cost gap has narrowed sharply while efficiency and durability favour mono.

What is a glass-glass panel?

A panel that replaces the polymer backsheet with a second sheet of tempered glass, giving better durability, lower long-term degradation and often a longer warranty, at a small weight and cost premium.

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