Repairing flexible solar panels using UV gel

My panels, 150W Semi Flexible Monocrystaline Solar Panels – Sunpower E20 Cells, have started to develop small bubbles in the laminate between the active panel and the upper substrate.
I bought these panels in 2020 from Bimble solar. The panels are now 6 years old. I started to notice smaller bubbles forming over the summer, (2026), which saw average temperatures in the mid 30’s across the UK.

Ventilation

My panels have no air ventilation between them and the steel roof of the boat.

They’re sealed with CT1 adhesive and Soudal Fix All Sealant. CT1 to secure them to the boat, and Soudal Fix All Sealant around the edges to keep moisture out.

This has worked well, but is has had the effect of not being able to keep the panels cool in hot weather.

If left untreated, these bubble join and grow and as the laminate comes away from the panel in it’s entirety.

Below are panels I bought in 2018. I tore the laminated top layer off completely as the bubbling had greyed out, making parts opaque.

They’re now discoloured and the surface is textured with small cracks.

Efficiency reduction

Disconnecting the panel arrays and monitoring the Victron SmartSolar MPPT150-35, it’s possible to measure and calculate exactly how much each array was generating, (2×2 150/140w flexible panels).

When I bought them, these two panel arrays were like-for-like, apart from a 10w difference in the output wattage.

On a peak solar, summer day:

Old flexibles: 84w
New flexibles:204w

That’s 40% the rate of the new panels, a 60% loss in efficiency.

Substantial.

Repair

To try and prevent a repeat of exactly the same problem.

It is possible to repair panel solar panels with bubbles like this. This fix I’m using is called a ‘UV Resin repair‘.

You can buy a clear, viscous fluid resin that sets under UV light which you smear into the bubbles and stick them back to the photovoltaic substrate of the main panel body.

Here’s what I used:

5 Items to repair a flexible solar panel

1. UV Resin: This is the main item. UV will set in direct sunlight. Most good kits come with a UV pen. £12 – Amazon
2. Plastic spatula: To smooth the applied resin under the bubble and ensure even coverage. £2.55. – Ebay
3. Syringes: 1ml with blunt tip needles. £3 – Ebay
4. Nitrile gloves: Screwfix
5. Microfibre cloth: Aldi
6. Felt-board tack.

Repair Environment

Due to the nature of the UV resin, the repair needs to be carried out in a dry environment without any sunshine, wind or rain.

8 Steps to repair

1. Clean the solar panel: Clean off dust and residue with a mild detergent and water.
2. Dry: Completely dry the panel in the area where you are working.
3. Pierce: Pierce the bubble with the felt-board tack, making a hole large enough for the syringe needle to enter.
4. Fill the syringe: With UV resin. Fill first, then place the needle on the syringe, ready to go.
5. Inject: The bubble with UV resin. First in one direction, then re-angle, and repeat making sure the bubble is completely full of UV resin.
6. Smooth: Using the spatula, smooth the UV resin throughout the bubble, making sure any air is completely expelled and the bubble is pressed flat.
7. Wipe: Wipe off any excess with the microfibre cloth.
8. UV: Shine the UV pen over the repair for around 20 seconds.

Rinse and repeat.

The UV resin is viscous and it sets on exposure to UV light. For this reason, the needles and syringe will become blocked as the gel gloops up. When the sun came up, the resin set in the syringes pretty quickly…

If you’ve a number of bubbles, take this into account and purchase enough needles and syringes that you can do, or split the job over a couple of sessions.

As you can see from the BEFORE and AFTER photos, the bubbles are almost entirely gone, the only trace being the tiny entry point of the tack and syringe.

Summary

A quick and simple repair just what I was looking for. Although it’s not solved the underlying causes, it will stop further damage, loss of efficiency and the spread of bubbles wrecking the panels in the near future.

Related content

UV Resin repair – Youtube