who has had good luck with solar panels?

[fatleon]

I know there are lots of variables on the topic, like season, region, single track in dense forest vs open dirt road, different models of panels....

I've read about some devices *cough* iPhone *cough* turning on and then draining the battery as the panel goes in and out of light. So I'd be charging a cache battery with the panel. I like this one from Anker, claims to make 2.1 amps, weighs 12 oz  https://www.anker.com/products/variant/powerport-solar-lite-2/A2422011

Has anyone had good luck with a solar panel? Is it a waste of money for bike packing? Would a Dynamo hub be a better investment?

[alpamayo]

I have both, although both are relatively new to me and I’m still working it all out. Charging the iPhone direct with the panel is problematic for the reason you state. For both systems, a battery is key. One problem (1st world problems, I know) is that I only have a dynamo for one bike, and I have multiple. That might not be a consideration for you. Given the choice I’d take the dynamo almost every time. Another factor is that the solar panel can used for non-bike activities.

[chrisx]

Solar panel for me.
For the hub to recharge things, you have to ride your bike all day long.  What if you like to sit under a shade tree for a few hours?

An out of camera, or out of phone battery charger could be a good idea.  If your camera is made to charge at 1 amp, erratic charging could harm it.  Why not charge the battery separate from the device?  Better to replace a $40 battery than a $900 camera.   
I can plug this little charger directly into my solar panel without risking damage to my Camera.

[jay werner]

I have both, although both are relatively new to me and I’m still working it all out. Charging the iPhone direct with the panel is problematic for the reason you state. For both systems, a battery is key. One problem (1st world problems, I know) is that I only have a dynamo for one bike, and I have multiple. That might not be a consideration for you. Given the choice I’d take the dynamo almost every time. Another factor is that the solar panel can used for non-bike activities.

Totally worth it!

[askepott]

I have Arc 20W with V72 battery from Voltaic Systems. Works great, even in the shade (I decided to get it when watching a video on youtube where the owner said it works in shade). It's a great gadget. You will be hard pressed to find a power bank which will charge with 1.1A it outputs, be their batteries are great and compatible. I don't have the new V88 but I bet it's even better.

Like chrisx said, you will likely need to charge it for the whole day but the panel is foldable and you can easily attach it to a curved bike pack, your backpack or whatever. They even have backpacks with mounted panels but cycling for long periods of time with a backpack is no good.