What you describe is what I believe is called the "packing problem". There is a good Q&A over on GIS stack exchange here. I personally created a tool many years ago in ArcMap that would create a grid of points and "jig" them around until it settled on the maximum number it could fit into a polygon, these were notionally wind turbines for off-shore wind farms. But I can immediately think of several things that makes your task more complex. For me the Sea was "flat" but for you the ground could be uneven which will no doubt complicate issues. I've driven past solar farms where the panels are individual as well as long sections of connected panels. As for your logic I would suggest that drawing a polygon then generating a solution is probably the wrong way of doing it as drawing will be temporary. I think a better solution is to simply create a shapefile with your intended farm boundary, then you have it for testing other scenarios and the all important map that you want to create? You don't actually state what environment you want to do this in, desktop, if so which, or online? I consider myself a desktop developer, originally for ArcMap but I'm making the move to ArcPro. I've yet to developer in the .Net SDK all my current development is in the Python geoprocessing framework. I'm based in the UK.
