No. It was a tax on wealth. Glass windows were a luxury good only the rich could afford. Poor people got too much sunlight because they were outside all day, and even those inside could just open their windows for more light. The tax was on the glass, not on the sun.  

 It wasn't glass actually, the law was vague as fuck. Many people paid tax on having a hole in the wall. 

 In a coal bunker even, in some cases. 

 The Irish law was exceptional then. 

Most of those old window taxes were exclusively on glass windows.  

 Right, must dive into it a little more, thanks man.