It is not a question of if keeping the battery from overheating is important. It is important.
The heatsink won't do you any good if the battery is placed between the panel and and the pannier. And the very fact they have had to incorporate a heatsink should tell you something very important: They are trying to solve the problem of overheating with the battery placed where it is.
In any case, do a bit of research on overheating of li-ion batteries and why it is important to keep it cool. If you are not willing to do that, go ahead and buy an integrated battery. It may be user-servicable, but it still doesn't leave you much, now does it? You will have to buy the same battery again, and because it will get heat since you will have to place the (black) panel and battery in direct sunlight, you will have to change it earlier, rather than later.
I am not talking about expedition grade setups. Voltaic has non-folding panels as you requested, and they have smaller panels too.
I can't help but once again mention that your fears of having a separate battery pack because it involves a connection seem rather ill-founded. People on motorcycles have GPS's, heated clothing, mp3 players, headsets and whatnot connected to their motorcycle and it works fine for them. You are on a bike. It's like you see a potential problem, and instead of solving that, you choose something entirely different which has other, more important problems. It's like choosing to walk 30 miles in spd shoes because there is a risk the bike will have a flat.
In any case, I'm out.
Last edited by SmallFront; 12-07-13 at 10:06 AM.