Flexible Solar Panels

What are flexible solar panels?

Flexible solar panels are thin, lightweight modules that can be bent or rolled up. Their portability makes them suited for off-grid applications such as camping, caravans, motorhomes or boats.

Due to their lower efficiency, these types of panels are not generally suitable for rooftops as they’d need an inordinate amount of space to generate power for the building - about twice as much space as crystalline panels for the same output. For domestic and commercial roofs, we’d always recommend traditional polycrystalline or monocrystalline panels. Flexible PV does have some interesting niche uses, however, and the potential for future applications in places where regular panels aren’t suitable.

How are flexible solar panels made?

There are two forms of flexible panels - one is a specific type of thin film solar, and the other a lightweight version of monocrystalline cells.

Image: Wikimedia Commons.

Flexible thin film is usually made from Copper-Indium-Gallium-Selenide (CIGS). A thin layer of these materials is placed on plastic backing, then connected to electrodes on the front and back. It absorbs sunlight so well that only a thin layer is needed to generate sufficient electricity. It’s made from layers of silicon over 300 times thinner than those in standard cells - just a few micrometres thick. Super flexible, they can often be bent to fit curved surfaces or rolled up for portability.

You can also buy monocrystalline semi-flexible panels, for example those manufactured by SunPower. These have a metallic backing but no glass front. Only a few mm thick, they’re relatively lightweight and have a limited bending angle (around 30 degrees).

How to install flexible solar panels

If you’re using flexible or semi-flexible panels for solar power on the go, then you’ll likely be unrolling them and propping them to face the sun. If you want to get the best out of them, check out our best angle guide to optimise your positioning.

When it comes to more permanent installation, for example on boat or caravan roofs, the panels are often glued in place with powerful adhesive. Watertight cabling then goes through the roof to charge a battery via a charge controller. It’s best to stick rather than drill through the panels to avoid damage and voiding the warranty. Some flexible PV film even comes with a self-adhesive backing for sticking in place.

This and top image: RV with Tito.

Can you walk on flexible solar panels? This is a particular consideration when it comes to installation on boats, and some panels you can walk on - or at least occasionally step over in soft-soled shoes. Always check the product specifications.

Learn more about all types of building integrated PV in our free guide:

Flexible solar panel efficiency

Thin film panels are generally up to around 13% efficient, while SunPower monocrystalline systems claim efficiencies up to 25%. In terms of the power they generate, panels are generally available between 50-170W output.

Advantages of flexible panels

• Better performance in cloudy weather - thin film can absorb a broader range of light than crystalline cells, including UV and infrared light waves, which are present even on cloudy days. So these flexible panels perform comparatively better than regular ones when it’s cloudy.
• Lower efficiency drops in high temperatures - when panels heat up, their efficiency drops. While crystalline modules can experience drops of up to 25% in high temperatures, thin film’s efficiency is only about 8% lower than normal.
• Portable - you can’t take the mounted panels off your roof when you go for a road trip or down to the campsite, but you can roll up a flexible panel for off-grid solar power on the go.
• Semi-transparency is possible with thin film solar, opening up potential for solar canopies and windows.
• Low cost - flexible PV modules are available to buy online for a few hundred pounds and don’t necessarily require the professional installation that regular panels do. If you were getting thin film installed in place of crystalline panels, however, this price difference would usually be wiped out by the extra installation costs needed to fit so many extra panels to supply the desired power.
• Lightweight - so they can be used for low load-bearing roofs that wouldn’t be able to support the weight of traditional panels and mounts.

Image: Wikimedia Commons.

Disadvantages of flexible panels

• Damage - in order to be flexible, the panels usually have a plastic front coating, which is much more prone to damage than the glass used in regular panels. It may get scratched by overhanging branches or knocked by other sharp objects depending on where it’s installed.
• Efficient angling - if glued in position (on a boat or motorhome roof), they are essentially flat, which isn’t the most efficient angle for PV generation.
• Overheating - This method of installation can also result in a lack of airflow under the panels. If glued in position, they heat up with the roof and become less efficient (though not to the degree that heat affects regular PV).
• Short warranty - flexible panels often only have a warranty of 12-18 months compared to 25 years for regular panels. Due to the strains of being flexed and moved around, plus the plastic fronting clouding with age, the panels simply aren’t expected to last as long.

Speak to an expert

While it’s unlikely flexible panels will be suitable for the systems we install, get in touch today for advice on the best panels for your project. Call us on 0118 951 4490.