Today agriculture sector has a big contribution to the development of economy for many countries. Irrigation is a method which supplies amount of water required in proper time to the cropped land and contributes to the increases of agriculture productivity. Using diesel pump to deliver water to the place of use causes problems both in terms of profitability and environmental perspectives. Higher price of diesel increases operation costs of diesel water pumping system thereby reducing the incomes. In addition the use of diesel pump emits a huge amount of CO2 emissions which cause global warming. A possible solution to those problems is to use solar energy, a source of energy which is environmental friend and available for free. The main target of this thesis is to design and optimize a cost effective PVWPs considering three alternatives with tank storage, battery storage and a system without storages medium. The two areas in Eastern province of Rwanda were taken as case study to grow coffee and cassava with five hectares each. To run simulations, different tools have been used. Those includes CROPWAT to determine water requirements for two crops; MS Excel to design a PVWPs directly connected to irrigation system, make economic analysis, evaluate CO2 emissions and calculate other parameters. Furthermore in PVsyst software the design and simulation for PVWPs with storages medium has been carried out.  Results showed that using PVWPs directly connected to irrigation system is the most profitable way when compared to the rest two alternatives.  They also showed that systems designed to irrigate coffee becomes the most profitable due to huge amount of electricity surplus and higher price per kilogram of coffee. Finally fully replacement of DWPs results in annual reduction of CO2 emissions by 6.6 tonnes. Keywords: Photovoltaic system, storages medium, pumping system, economic analysis, reduction in CO2 emissions.