The concept of public-private partnerships for developing large infrastructure projects in the power and water industry has been a success story in the Gulf Region since many years, and it is now also spreading to evolving economies in Africa and Asia. The key benefits of such joint ventures between private developers and the states are derived from the contribution of competitive private know-how in technical and financial matters in exchange for secure revenues from these large infrastructure investments. The latter are established through long-term purchase agreements for power and/or water between the state-owned offtaker and the joint public-private project companies which define the tariff equations to be applied for the monthly invoice based on hourly production data. To ensure that the plants are operated and maintained with all necessary diligence over the entire contract term, the purchase agreements also include performance and availability guarantees. The processing of all monthly data with the above-described functionalities is a very complex and laborious task only achievable through a comprehensive software system, and – since the resulting invoice is the only source of income for the entire month – the settlement system is truly business critical for the plant.