Bottom Line: leasing is better if it's allowed in the your state and you do not have money to pay the upfront cost of the solar panels. Ownership is better if you want to realize greater returns on your solar system over its lifetime and don't need immediate returns on your upfront capital.
The value proposition of leasing or owning your solar system really depends upon where you live. Although many states offer solar leasing, you often need a good credit score to qualify. State green banks are helping to expand private-sector solar leasing and loans for customers with lower credit scores, but they currently only exist in five states.
Owning can offer benefits that leasing cannot. These benefits include tax incentives and rebates for installing systems and Solar Renewable Energy Certificates (SRECs) value that are created based off the actual electricity produced by your solar system and can be sold in certain markets.
The Institute for Local Self-Reliance has created a convenient tool that compares leasing and owning, customized to your location.