It's been over a year since I purchased this kit, and I genuinely couldn't be happier with it. It's around the same weight as carrying an extra 14Ah battery, but essentially it gives my ebike unlimited range.
The fact that it all packs down into a pannier is really what sold me on this, but I'm glad I supported a small business like Off Grid Trek, because the quality of the product (and the personalised customer service) is far beyond what I expected, and much better than what you can get from any of the cheaper brands on places like Amazon or eBay - I'm speaking from experience, having tried various combinations of cheaper folding panels in the past. None of them are anywhere near as good at getting a usable current as this panel and MPPT combination is.
In the central UK, in typical summer weather, I am able to put about 3-4Ah of charge into the battery per hour, even at 5pm. At midday in summer, the battery actually becomes the bottleneck in the system, not the panels, and it's not possible to safely charge the bike any faster than this charging setup allows - at times it's almost twice as fast to charge from sunlight as it is to use the mains charger that came with the battery.
In the evenings in summer, I have found that this setup puts usable charge into the battery *right up until the moment the sun disappears over the horizon* - admittedly, in the last couple of hours of the day, it's generally not worth bothering with solar charging at all, but the fact that you can still 'trickle charge', even when the sun is so low in the sky that you can safely look at it, is quite mind blowing to me.
You do need to do a balance charge with the mains charger every few weeks, just to make sure none of the cells are getting undercharged, and give the BMS a chance to do it's usual battery maintenance jobs under more 'normal'/expected charge conditions, but after more than a year of use, I am not seeing any major battery degradation as a result of using this solar charger setup, despite the faster charge times.
In Winter, as you'd expect, charge times are much slower - but they're still faster than the mains charger that came with the battery when it's sunny outside. If it's cloudy/overcast in winter, this setup will 'trickle charge' the battery (I get maybe 2-5 miles of extra charge per hour), which is better than nothing - and 'nothing' is exactly what I get out of every other panel/controller setup I've tried in these conditions, so again, the Off Grid Trek setup is streets ahead of competitors.
Negatives: If I had to nitpick... I'd love to see some sort of Watt meter, inline on the charge cable between the MPPT controller and the battery, that showed how much power the controller was sending to the battery. It would really help with solar panel alignment when you're first setting up the panels to charge - perhaps this can be an idea for an add-on product?
Other than that, I managed to tear out one of the grommets from the solar panels in high winds one day (but this was absolutely my own fault), so perhaps they could be strengthened a little.
The price of the panels IS high, especially if you're buying from abroad like I did - but really this is just the cost of such high quality, and I can't begrudge a man for wanting to make enough money to put food on his table! If I needed another set of panels like this, I would definitely buy from Off Grid Trek again.