The Payback Tool allows for a comparative assessment between income and three different irrigation pumping options. Information required for using this tool includes investment and operational costs for the different pumping systems, anticipated income from agricultural production, and basic economic conditions (e.g. inflation rate). Even when the profitability of the farming enterprise is confirmed, however, this does not automatically imply that an investment into an SPIS is the most sensible choice. This is especially true if other pumping technologies are readily available on the market. A Diesel or Grid-connected eletric pump might be more feasible where water pumping is only required for a limited time per year. The INVEST – Payback Tool considers and compares solar powered irrigation systems with other pumping technologies. Basic data is collected from technology suppliers and the payback period against the farm profit and the different technologies is automatically calculated.