The research investigated the grid connection of the existing off-grid PV system at Mavuno Secondary School in Tanzania. The national power grid reached the area during 2015; therefore the grid connection has been studied together with eventual increases of the PV array size. Such research provided a feasibility study in the unexplored topic of connecting stand-alone systems to the national grid once it becomes available.
The first part of the study aimed to define the load consumptions of the school. On this regard, a measurement system has been set up. It also measured the values of battery state of charge and PV production. The second part involved the modelling and simulations of the system by means of the software HOMER. The existing system has been simulated showing a cost of energy of 0.42 $/kWh. The modelled results showed an overall similarity with the measured values, although some limitations of both measurement system and simulation tools were present. After that, the optimisations of the system regarding future scenarios have been performed. The investigation involved both PV stand-alone and grid connection configurations. Increased load cases and different grid scenarios have been considered. Depending on the load scenarios, the stand-alone system presented a cost of energy between 0.34 $/kWh and 0.55 $/kWh. Instead, depending on load and grid configurations, the grid connected system showed a cost of energy ranging from negative values to 170 $/kWh. The negative values were due to the higher incomes of the sellback compared to the system expenses.