Solar power has something that has been proven to be an universial law for all manufacturing: The manufacturing cost decreases is a power function of cumulative production, also known as wright's law.
Moore's law is special because it relies on physical scaling (See Dennard Scaling) of the product. The transistors get smaller with each technology iteration, resulting in a physical correspondence to the economical law. Something like this does not exist for solar cells and most other products.
I've been very interested in finding out what lies behind Swanson's law. I suspect that chip fabrication technologies and methods have much to do with this, and to that extend there would be some carry-over from IC silicon fabs.
This is a very interesting paper about this concept: http://arxiv.org/abs/1207.1463
Moore's law is special because it relies on physical scaling (See Dennard Scaling) of the product. The transistors get smaller with each technology iteration, resulting in a physical correspondence to the economical law. Something like this does not exist for solar cells and most other products.