Preserving Life and Performance with Solar Panel

Having to do a solar panel recall several years ago was painful both for customers and financially for me. But we completed it. It took some time to figure out the root cause of the problem. In designing a new solar panel system, the goal, of course if to completely address this root cause without compromise to the benefits of lightweight solar.

Root Cause of the Flexible Solar Panel Failures

Firstly, they didn’t fail because of the quality of the solar cells. Neither did they fail because of the design of the panels. They failed because of instalation. There were two major problems with the instalation:

1. The panels were fixed directly to the roof of the off-road caravan with an abundance of Sika. So much Sika, carefully snaked over the back of the panel, that when the off-road caravan roof expanded with heat, the panel stretched and tore the fine inter-cell connections apart. This was the major problem.
2. The panels had remote connectors/diodes with the connecting cable passing through the roof of the off-road caravan. Heat and cooling of the interconnecting cable from the hot underside of the panel caused a pumping action of moisture to travel through the connecting cable sheath from inside the caravan up to the panel and short the circuit. This occurred less frequently.

 Some people insisted on replacing with traditional glass panels. The problem with glass panels is:

• Heavy weight on top of the van just where you dont want weight: impacts towing stability.
• Glass holds and does not dissipate heat well, causing a drop in peak performance.
• The heat from the glass panels radiates back onto the roof of the caravan INCREASING the temperature inside. (Top of glass panel will reach 65 deg C, underside with reach 58 deg c)
• Front edge of panels is a vertical raise, impacting higher drag when towing.

After a year of research, we found a solution in similar environment in Arizona, USA, that solved all of these problems and had additional benefits.

1. INSULATION OF SOLAR FROM CARAVAN ROOF

Using a Triple Insulated UV rated Polycarbonate sucessfully separates expansion and contraction of the caravan roof from the solar panel.

Plus it has these benefits: The triple insulation promotes air-flow between the layers cooling the solar panel AND the caravan roof. The inside temperature of the caravan will reduce as the Polycarbonate has an “R” factor of 3. This means it transmits one third of the heat energy through to the caravans inside space. 

The polycarbonate is attached to the solar panel with two simple runs of Sika 252 and additional placement to secure the end caps. The solar panel can expand and flex comfortably.

2. SOLAR PANEL CONNECTOR/OPTIMIZER CONCEALED UNDER PANEL

Having the optimizer installed under the panel and concealed has the major benefit of reducing damage from overhead tree braches running accross the top.

It also allows for the inter-panel cabling to pass through the cavity containing the optimizer so adjacent panels can have their cabling concealed on the roof.

3. EXTRUDED ALLOY PROTECTION CAPS

We designed and developed this extrusion specifically to:

• Cap the front and rear leading edges for general protection.
• Have a 3mm recess so that the new panel can be placed ontop of a failed panel without disturbing the roof.  This is carefulled designed to exactly cover the 55W panels in a Kimberley Kruiser of Kimberley Karavan.

In the photo above, you can also see the Sika penetrating one layer of the “triple insulation” and bonding to the underside of the panel.

RESULTS:

• Excellent performance with less temperature rise than glass panels
• Excellent bonding yet with flexibility 
• No exposure to damage from overhead tree branches.
• Cooler inside the caravan

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