You may want to do site surveys and measure solar panel output over a few days for various potential locations. Depending on the solar panel, you do not need full light to get full capacity. My main recommendation would be to increase the battery capacities or add spare batteries and just use the solar panels to supplement the battery life. 

Hi Tom,

I'm with Akiba, you have to test.  A collaborator has deployed solar-augmented kit in secondary jungle and some of them got enough light, and others didn't, so it can work.  The open circuit voltage of solar panels doesn't change a whole lot in dim light, but the current drops drastically.  So you would choose an oversize panel of the same voltage (or a bit higher).

Thanks

I've been intrigued by this topic. Thinking about ways you could use drones or some kind of launcher to deploy panels above the canopy. Sadly I live in the great white north so I have no way of testing any concepts. Maybe even some kind of solar balloon that could float above the canopy. Interesting design problem.

Hey Tom,
Since the output is dependent on a couple of factors such as the solar irradiance of the place, shading from the canopy, the type of solar panels (mono, poly or amorphous) and orientation of the panels, etc, I'd suggest you use a software to simulate the different parameters to get an almost accurate estimation of the output. You can try PVsyst- it has a free month trial (I haven't used it before but I hear it's great) or any other PV software :)