I do not really understand your third requirement.
But give it a try to http://www.kerkythea.net
It is a stand-alone render engine, that has actually different rendering methods, for photorealistic images, but depending on how skillful is the author.
But it meets your initial requirements. You can make simple shapes. If you need more elaborate shapes you can use also Sketchup to model stuff and then export it to Kerkythea.
You can also assign a sun position by location, date, and daytime.
I did not understand this:
an array of the light values the different pixels
That is probably a "render". In this case, you have a render method that gives the "luminosity" values, called Clay Render.
The problem would be to make an animation.
You can also use any 3D application like https://www.blender.org and you can animate the sun path if you know the values.
There are some tools to create specific types of an exterior, or landscapes, like Terragen, Vue, Bryce. Some of them have a free version, but some have different render quality. Google landscape
I found this application but is more suitable to analyze interior's sunlight http://www.velux.com/article/2016/daylight-visualizer
P.S. There is another forum for this kind of question: https://softwarerecs.stackexchange.com/