Parallel 'Gang' Wiring Several Solar Panels
You could directly connect all three panels in parallel to the MPPT, but I would probably fuse the input unless it has significant input protection of its own. I would isolate each hot line with its own fuse using a 15A fuse. Typically the rule is to use input protection 20% higher than your max expected current because heat at the protection can make it trip sooner (though this applies much more to breakers than fuses). If you get a short anywhere from positive to negative all 3 panels will be shorted at the output. I don't know if the panels have any general output protection or short circuit protection but I would rather be safe than sorry. It's much cheaper to add some fuses than to replace damaged panels.