I have replaced my  12 years old Velux solar module with two SM6150 solar panels (6 V 150 mAh 120x60mm) which I have soldered in series. 

I was inspired by the designs of Joseph Müller and Chris vK.

I sealed the solar modules with silicone. I took the right side panel from Chris vK and shortened it with a saw.

I am happy with the result, the roller shutter is working again. We'll see how long it lasts.