I have been exploring the NREL's free System Advisor Model for renewable energy systems.
This software provides a modeling tool for a variety of renewable energy systems to estimate system and financial performance.
I have run several scenarios: a small commercial solar PV/Thermal system and a larger utility scale 750kW system and found the software to be intuitive and easily adapteble to many different scenarios.
Weather and solar data is included as well a a variety of funding, incentive, and tax credit options.
This is a great tool to go along with Home Energy Saver, TREAT, or other modeling tools that do not support renewable energy modeling when you are looking to provide renewable energy proposal data for your clients.
Get the download here: https://www.nrel.gov/analysis/sam/download.html
Also, the PV Market Mapper is pretty cool, but I'm not entirely certain what has to offer other than a visual overview of the recent PV Market.