Wiring between buildings is a bad idea.  During periods of uneven static charge such as thunderstorms, the static charges will equalize between the buildings using the path of least resistance.  This is usually your wiring.  I have seen several instances of this happening with computer networks that were stretched between the main building and a small shipping/receiving building.

Our solution as recommended by electricians and telephone techs for this was fiber optics.  I know this won't work to carry power.  But, the better the surge protection on the AC side, the better off you will be.  

keep having fun

A varister is something like a Zener diode except it works on AC current as well. When the voltage goes up to the rated voltage of the varister it becomes almost a dead short and loads down the overvoltage. The normal 120vac line is a sine wave with the peaks at about 170 volts so you will need a varister rated at 175 or 180 volts, very common at RadioShack. While the peaks are 170 volts, the RMS average is 120 volts. If you wanna use one on the phone line you need a varister rated at 90 volts to accommodate the ring voltage which is much higher than the talking voltage.

This sounds tedious, but now days... when I suspect lightning when Im gone, or if it gets near - I simply unhook the inverter.  The most important part to unhook I think is the AC side.

Most inverters that have died up here are killed not by a direct strike - it could be some distance!  But most of the fried inverters had long AC lines plugged into them, like... 2 story houses, or places with outside shops and lines running to those.  The long AC line I think is dangerous... a near strike will induce a voltage in in the line - enough to fry the inveter!  Especially dangerous are lines in the air - the first one that died here was hooked up to an outbuilding via a powerline running through the air on insulators.  Better is to bury the line. - at least, thats my "theory"!