Everybody wants flexible panels. That includes me, however, I would like to take that statement a bit further and say I want flexible panels...to work!
6 years and hundreds of installs later, I still get constant requests for flexible panel installations. In the image above you will see a factory installed solar array on a Leisure Travel Van. What's not to like? The panels are sleek, lightweight, and invisible from the ground. Well, it turns out, there's quite a bit to be wary of.
Now before we dive any deeper, let's mention that there is more than one kind of flexible panel out there. What we are discussing today are monocrystalline, semi-flexible solar panels. We are not talking about CIGS solar cells which are a completely different animal but will still share at least some of the drawbacks and constraints we will mention in the post.
So what's the quick and dirty on this? Simply put, semi-flexible solar panels have no right to be installed directly on your roof. You may ask why, and well, a picture is worth a thousand words.
What you see here is the aftermath of removing flexi panels from a Leisure Travel Van. It may be a bit hard to tell from the image, but that discoloration is heat damage! Those flexi panels were glued directly to the RV's fiberglass roof, and they have gotten so hot that they have discolored and cracked the fiberglass! This poor customer's roof is actually ruined from these panels! The glue holding the fiberglass to the wood beneath has failed and the heat cracks in the fiberglass are deep enough that this could eventually cause leaks. Not good!
Want some more fuel for this anti-flexi-panel conversation, take a look at how these panels are constructed.
If you're thinking, ''that sure looks like plastic!" You are correct! Semi-flexible solar panels are laminated, and we all know, plastic doesn't hold up well in sunlight.
Alright, last nail in the coffin. Let's look at a data sheet for a generic solar panel.
Now this doesn't take a rocket scientist to understand. The higher the solar panel's cell temperature, the lower the voltage. Since we know Wattage is the product of Voltage times Amperage, that means that this lower Voltage is going to translate to lower output. This basically translates to hot panels don't make power!
So the fast summery here is flexi panels leave us with a panel that has a higher cost per watt, made of a material that doesn't hold up well in sunlight (is this an oxymoron?), and they are generally mounted in a way that directly degrades their performance. IE: more money, less lifespan, lower performance. Not much of a sales pitch if you ask me.
Now don't think I'm an absolute enemy of flexi panels. I absolutely won't install them on the rooftop of your RV or camper van, but that doesn't mean that they aren't a useful tool for the right application. For those of you absolutely determined to install them on a rooftop, it is possible to space them off the roof for airflow to minimize temperature degradation. However, by and far our favorite use for them is for ground arrays!
Using your flexi panels as a supplementary ground array is by far a favorite way to produce some extra power when off grid. They're lightweight, easy to store, quick to setup, and since they aren't permanently mounted we aren't worried about sunlight ruining the laminated surface at the quick speeds that rooftop mounting does.
So there you got it folks. Love them or hate them, just keep those flexi panels off your roof! Oh ya, and don't flex them, because monocrystalline is a fancy way of saying there's crystals in those panels, and we all know crystals don't actually flex.