Off-grid Rooftop Solar System with Solar-first and Virtual Grid Features

Abstract

Solar rooftops, particularly for urban area where availability of land can be an issue, have been aggressively pursued by introducing specific incentives like net metering or feed in tariff or for diesel abatement. In case of a grid interactive Solar Photo-Voltaic (SPV) generator, use of diesel generator may be needed under grid outages. This paper proposes a rooftop solar system topology which ensures continued solar power evacuation to the load even in load shedding scenarios. This arrangement has the potential for replacement/ reduction of Diesel generators (DGs) used for backup power. In this system photovoltaic energy serves as the primary source of electricity and utility grid serves as the secondary source. ‘Solar First’ operation ensures that the solar power generated is always evacuated first and any excess requirement of power is supplied by the grid/battery via a Bi -directional inverter. This concept finds high relevance in solar city program in India as well as other countries, as such a topology doesn’t require any change in the existing power infrastructure and will decrease the load on the utility grid and increases the overall energy efficiency.