Create a solar panel layout program in 2D

We are selling solar panels and we need to create a simple and user firendly online tool where our employees can drag and drop our different solar panels (different sizes) to a fictive roof 2D that also will have different sizes of course.

There are plenty of these program already available for free but they all come from some solar panel companies and are to complex. We want to create a really simple tool instead of using PAINT or other graphic design programs every time.

Lets say a client calls us and he say that he have a roof of 20meter long and 10 meter high. Then we want to drag our panels which are 2mx1m in to the design and see how many we can fit in that particular roof. We have about 4 different sizes of slar panels

We do not need login. It is just for internal use