Here's where I think your problem lies...
Mac computers draw a fair bit of current. If you look at your magsafe puck it's likely 60 or 85W (i think) and 35ish for the macbook air. In order to get 60W from a solar panel, you're looking at something the size of your computer desk (2ftx3ft minimum). The Gorilla charger looks to put out about 10W. So, will your computer register that it's "charging", probably. But this is likely not the case. It only registers that because your magsafe is plugged in and there is SOME current coming from it, but not enough to actually run your computer. I don't know what the actual draw is on a macbook but it's more than 10W (Volts X Amps). So, when you're running off of your solar panel you're actually drawing most of your power from your battery and only a tiny bit from the panel. The net result of this is that you actually kill your battery. Not sure why, it just does. Same goes if you try to charge a macbook pro with a macbook/macbook air charger. The current isn't sufficient, and because of that it draws strangely on your battery and WILL kill it. My friend has gone through 3 macbook pro batteries because he was using a 60W charger rather than a 85W. Took him 3 batteries to figure out why they were dying after only a week.
If you do want to charge your macbook with a solar panel, I'd only do it if your computer is off. I think this should work to slowly recharge your battery.
My theory behind this method. Lithium batteries die when they drop below a certain voltage. Your computer knows this and shuts down before you get into this critical phase of the battery cycle. When you use your solar panel your computer "thinks" it's charging properly and therefore doesn't shut down when the battery gets critically low (because a normal mac charger has enough current to power your computer and charge your battery at the same time). Your makeshift charger cant perform both of these tasks because it doesn't pump enough juice. As a result, you constantly drain your battery (albeit slowly because the solra charger is aiding a little) below it's safe range. Inevitably, your battery drops below the critical voltage (something like 2.8v per lithium cell) and it will never charge again.
Does using a solar charger always kill your computer battery, no, but more than likely it's going to dramatically shorten the life of it.