Grid connected PV systems continue to attract investors and electricity customers all over the world. Due to interconnection with the utility grid, the system can glean some benefits such as selling PV electricity surplus to the utility grid or purchasing electricity from grid for battery storage charging at off peak hours for either self consumption or selling back to the grid during peak hours. This paper present an optimal energy flow dispatch for a small scale grid tied PV system in order to reduce the owner’s system electricity Bills. The simulations take into account the available PV Energy, the battery stored energy and the grid energy. On peak and Off peak Electricity charges dictated by the utility grid and a residential load from Market analysis and information System (MAISY) database are taken into account for energy flow scheduling. A case study of a garage with an installed 5kWp system at Strathmore University in Nairobi, Kenya was considered. The results analysis demonstrated that an appropriate battery size determination for a grid tied PV system is highly governed by electricity tariffs and battery degradation cost.