As a Solar designer and integrator I have found the following obstacles to reducing the costs of Solar PV installations.
1. Required custom design of each site to meet utility production requirements to obtain available incentives.
2. Every utility having it's own rules.
3. Code and utility required structural and electrical engineering.
4. Delays and costs associated with permitting.
5. Labor costs.
Aggregated State or region wide production should be the focus for Solar PV production goals not each individual site.