Intentional Islanding in solar

Intentional Islanding in solar occurs when a solar rooftop system continues to supply to a load even when the grid is down; this can be very dangerous. Therefore, when the grid is down, the inverter, used in the rooftop system solar power plant for generating solar energy for home/industrial/commercial roof top, stops supplying power.

Intentional Islanding in solar is a technical requirement for inverters strictly mandated by CEA and MNRE. However, in view of frequent grid outages in most States, particularly in industry, commercial and institutional establishments, the rooftop system should be able to disconnect from the grid. Thus system should supply continuously solar power to the loads of such establishments using a battery storage system or in synergy with the backup diesel generator. Otherwise, the solar power will be wasted.

Intentional Islanding in Solar Option 1

Intentional Islanding in solar is possible through additional advanced features to be provided in inverters. The hybrid inverter which could work in the off-grid mode and continue to charge batteries with generated power. The inverter can continue to function in grid-tied mode in synergy with the larger backup diesel generator.

Intentional Islanding in Solar Option 2

Generally, for most industrial, commercial and institutional establishments, the second option is more feasible as they have large existing backup diesel generators for their loads. Such backup facilities already have the required safety features which prevent reverse flow to the grid.

Rooftop solar with the right type of inverter is, therefore, technically feasible even when the grid is down, and can also be more cost-effective compared to costlier diesel generation.

For harnessing the full potential of rooftop solar as envisioned by Government, CEA and MNRE should consider allowing such ‘intentional islanding in solar’ rooftop projects. They should formulate technical specifications of inverters with such additional advanced features for automatic and safe operation.

Ref: Grid Integration of Distributed Solar Photovoltaics (PV) in India, Prayas Energy Group, 2014