Shouldn't be a problem to run your GPS from it if it's made to run from a car DC voltage of 12-16 volts and the solar charger has enough current output at that voltage to supply what the GPS requires. So you need to answer those questions first from the specs or measure them. A solar charger won't have voltage spikes so don't worry about that. And any GPS worth it's salt made to work in a car will have protection built in. I'd have no worries hooking it up to a GPS. The hardest problem is likely to be getting a suitable connector but the mfg's usually have them available at a premium. Maybe you could get a GPS with a cig lighter socket on it. My new GPS uses a USB cable for power and data transfer to PC so that's convienent. enine has a good point that you will likely need a battery along with the solar panel to keep the GPS live when not enough output from the solar to run GPS.