Whether you should choose to buy or to lease a solar power system depends on your personal situation.
Buying a solar power system will be cheaper in the long run, however, requires you to have the total amount upfront.
Leasing your solar power system will be more expensive in the long run. As you are paying per kWh / per month, however, the company which is leasing you the system has a clear incentive to make sure that the system is performing. Additionally, leasing a system could provide you with the financial space to make investments in areas which yield a higher return. Leasing a system does require you to be creditworthy though.