Yes, my banana pit is in full sun. They make shade for the terrace and they screen the view so my small yard looks more mysterious - at least that is what I think
I used to throw a lot of garden waste in the pit and it would decay in a short time because of our heat. However, I started thinking that the pockets around it collected water and that mosquitoes might be breeding there, not something I want next to the terrace where we spend most of our time. So, I had it cleaned out and now when I add things like compost, coffee or more soil, I tamp it down to keep an even density. I don't throw cuttings in there much anymore either, it makes it easier to clean the area out and unfortunately my cats often go in there so we clean it out fairly frequently.
I wonder if you could put a soaker hose around your bananas and let it run at night? They really do need a lot of water.
It's true Tarev that people here have bananas growing in bare dirt around their yard. Usually they are near the back fence and they do throw the garden and kitchen debris on them as well as wash water. Lots of houses here have an outside laundry room, open on the sides. If they have a washing machine it is generally not hooked up to the septic but a hose from it just goes out to the ground. That's where they put the banana plants so they get constant water and they add shade to the laundry area. In many rural areas water is free and, unfortunately, people often leave the tap running all the time. Here in the city there is a charge for water as it is potable but even so, it is not much and there is no response if you don't pay the bill. They are not allowed to turn off the water to a home.