The Victorian Government defines a solar PPA or solar power purchase agreement as an activity where “a business provides, installs and maintains, at no initial cost, a solar panel system to a customer and in exchange, the customer buys the electricity provided by the solar panels for an agreed price and for an agreed period. Any electricity that is not used is sold to a licensed retailer.”
Given that the customer buys the energy generated from that solar system at a rate (c/kWh) generally lower than the rate they would get from the grid, they are able to enjoy the savings of the solar system from the first day it is generating energy, without having to invest their own capital.

https://onestepoffthegrid.com.au/what-is-a-solar-ppa/

Northam Boulevard Shopping Centre PV shaded car park. A distributed generation PPA in Northam, WA