When does it make financial sense to install a Solar Water Pump?

When you do not have a grid connection (or an unreliable one), it normally makes financial sense to install a solar water pump. The average payback period of such a system is 1-3 years in Tanzania. In case you have a reliable grid connection, it normally still makes sense to pump water using solar power, however, the payback period will be slightly longer (2-6 years).