An OPEX PPA (Operating Expenditure Power Purchase Agreement) is a pay-per-use renewable energy financing model where a solar power developer invests in, installs, owns, operates, and maintains a solar power system at the consumer’s premises (rooftop or ground-mounted) or at an off-site solar plant. Under this model, the consumer does not need to make any upfront capital investment (CAPEX) for purchasing or setting up the solar plant. Instead, the consumer agrees to buy the electricity generated at a pre-agreed tariff (price per unit/kWh) for a fixed contract period—typically 5 to 10 years. This allows organizations, businesses, and industries to adopt solar energy with zero upfront cost, predictable energy pricing, and immediate savings on their monthly electricity bills. The process begins with a Power Purchase Agreement (PPA) between the consumer and the solar developer. The developer is responsible for the complete project execution, which includes design, engineering, procurement, installation, operation, and ongoing maintenance of the solar system. Once operational, the developer ensures continuous and optimal performance of the system, while the consumer simply pays for the electricity consumed at a tariff that is usually lower than the local grid electricity rate. This tariff is fixed or may have a pre-decided escalation clause to account for inflation and operational costs. Because the consumer pays only for the energy used and not for the asset itself, this model is often referred to as a pay-as-you-use or energy-as-a-service model. OPEX PPA is particularly attractive for businesses, industries, and institutions that want to switch to renewable energy but wish to avoid the high capital expenditure, technical complexities, and operational risks of owning a solar power plant. Since the solar developer retains ownership, all risks related to system performance, equipment failures, and maintenance are borne by the developer. The consumer enjoys clean, green electricity without worrying about the technical aspects of running the plant.