In my most humble opinion, I'd like to suggest the symptoms your plant is exhibiting might be moisture related rather than from too much sun. Although the leaf margins tend to be tender, damage like your pictures show has always been because of lack of sufficient moisture in my garden. Any "scorching" I've experienced is more akin to sunburn, appearing on the surface of the leaves, when I haven't hardened the plants off sufficiently. Bananas are very sensitive to moisture loss........my two-bits worth!
