Why Factory-Fitted Lightweight Solar Panels Fail on Caravans (And The Permanent Solution)

The lifespan of factory-fitted lightweight solar panels on many modern caravans has been found to be unacceptably short. While these panels offer weight advantages, owners frequently report premature failure and power loss.

We have received a high volume of enquiries from caravan and camper owners seeking a solution to this recurring issue. Rather than simply replacing like-for-like, our engineering team conducted a deep-dive investigation to understand exactly why these standard flexible panels fail and how to prevent it happening again.

Executive Summary: The Root Cause

The solar panel lifespan on many campers is shortened by excessive thermo-mechanical stress. Put simply, the roof and the panel expand at different rates in the heat. This creates tension that fractures the internal solar cells.

Ultimately, these micro-fractures worsen until they become a complete "open circuit," resulting in zero power output.

Pictured Right: An Electroluminescence (EL) image from our lab. It shows one row of cells is completely dead (dark spots), while bright white spots indicate dangerous "hot spots" where current is focusing due to damage.

Detailed Investigation: Why Standard Lightweight Panels Fail

Category 1: The Physics of Thermal Expansion

ISSUE 1 - Thermal Mismatch Between Roof and Panel

The Problem: Different materials expand at different rates when heated. Caravan roofs (often fibreglass) expand significantly in the Australian sun. Solar cells (silicon) and internal copper wiring expand very little.

The Result: When the roof expands, it stretches the solar panel bonded to it. Since standard plastic panels aren't stiff enough to resist this force, the fragile solar cells and copper interconnects are physically pulled apart.

The Fix:

• Utilize mounting methods that allow for differential expansion.
• Install panels with a structural composite base (like eArc) that resists stretching forces.

Category 2: Manufacturing & Component Quality

ISSUE 2 - Vulnerability of Half-Cut Cells

The Problem: Many factory-fitted 55W panels utilize "half-cut" cells. In older standard panels, these half-cells often rely on a single electrical interconnect. Full cells typically share the load across three interconnects.

The Result: With only one connection point, there is no redundancy. If the roof expansion stretches that single connection to the breaking point, the entire cell—and often the whole string—fails immediately.

ISSUE 3 - Hidden Cell Quality

The Problem: Visually, a low-grade solar cell looks identical to a high-grade one. Without advanced EL testing (like an X-ray for solar panels), it is impossible for consumers to see micro-cracks present from the factory.

The Fix: Ensure your replacement panels are from a Tier-1 manufacturer that performs EL testing on every single unit before shipping.

ISSUE 4 - Weak Backsheets

The Problem: The bottom layer of a solar panel (the backsheet) determines its tensile strength. Cheap backsheets stretch easily, transmitting all the stress from the moving roof directly into the fragile solar cells.

The Fix: Advanced panels use glass-fibre reinforced backsheets. These act like a shield, absorbing the stress from the roof so the solar cells remain unstressed.

Category 3: Installation Environment

ISSUE 5 - The Fibreglass Factor

The Problem: Most caravan roofs use polyester resin fibreglass. While cost-effective, this material has a very high coefficient of thermal expansion. It moves a lot.

The Fix: Direct bonding to fibreglass requires specialized structural silicones or VHB (Very High Bond) acrylic tapes that can absorb this movement without transferring it to the panel.

ISSUE 6 - Heat Build-up on Insulated Roofs

The Problem: Caravan roofs are insulated to keep the heat out. This means heat generated by the solar panel cannot escape through the roof—it gets trapped in the panel itself, causing extreme operating temperatures that accelerate degradation.

The Fix: Creating a vented air gap (using materials like corflute or specialized mounts) between the panel and roof can drop operating temperatures by 15-20°C, significantly extending lifespan.

The Long-Term Solution: Sunman eArc Technology

Replacing a failed generic panel with another generic panel will only lead to another failure in 2–3 years. The permanent solution is to upgrade the technology type.

Sunman eArc panels are the only lightweight solar panels on the market approved by the Clean Energy Council (CEC) of Australia for installation on buildings. This certification confirms they meet the same durability standards as heavy glass residential panels.

Why eArc is different:

• Aerospace Materials: Instead of soft plastic, eArc uses a patented glass-fibre reinforced composite (similar to aircraft windows). This mimics the thermal expansion properties of glass.
• Proven Durability: These are the only lightweight modules trusted for mass installation on government buildings (e.g., the Sydney Maritime Museum features 235kW of eArc modules).
• Easy Retrofit: Sunman has produced a module specifically sized to match the footprint of common factory-fitted panels, making the upgrade simple and cost-effective.

Ready to fix your solar permanently? Contact our technical team to discuss the right replacement for your caravan.