Since solar panels do not have much burst capability, I would opt for a lot more capacitance. Something like 3 (or more) of these:
http://www.allelectronics.com/make-a...PERCAP-/1.html, or maybe even a couple of these:
http://www.allelectronics.com/make-a...-CAP-/-/1.html
And any time you have that large of a capacitor, you're gonna have to give it time for the cells to charge those bad boys up before you run. Ideally, I would opt for a higher voltage setup (like 10v) with caps around that size, and then regulate them using a CCBEC or something. This will provide a more consistent supply which is less prone to voltage dips.