I'll have to do the Clean Energy Assessment when it's available.
but in terms of obstacles, I'd say that lack of information and up front cost are what come to mind.
That said, I found some great alternative energy inspiration here: http://www.instructables.com/group/alternativeenergy/
And there's no shortage of DIY solar videos out there. But my head is spinning just thinking about watching them. probably better to look into local clubs or other resources that could help me get started.
I'm not sure what it would take to get to 90% but I could easily start with a small solar charging station for devices and then expand from there.