A Power Purchase Agreement (PPA) is a legally binding contract between a power producer and a power purchaser that outlines the terms under which the power producer will provide electricity to the power purchaser. Pas are used to purchase electricity from renewable energy sources such as solar, wind, and hydroelectric. They are typically long-term contracts, often lasting 20 years or more. The main purpose of a Power Purchase Agreement is to provide a stable, predictable supply of electricity at a predictable cost for the purchaser. This allows the purchaser to budget and plan for their electricity needs in the long term, as well as hedge against future price increases. The agreement also allows the power producer to secure financing to develop and construct the necessary energy generation facilities. There are two main types of Power Purchase Agreements: bilateral and utility-scale. Bilateral Pas are agreements between two parties, usually a power producer and a power purchaser, for the sale and purchase of electricity. Utility-scale Pas involve a single power purchaser and multiple power producers, and often involve a utility-scale power plant or renewable energy facility. In either case, the agreement outlines the price and quantity of electricity to be purchased, as well as the terms of the agreement such as duration, penalties, termination conditions, and other details.