New Delhi, Oct. 22 -- Integrating battery storage with residential rooftop solar systems could reduce daytime electricity exports to the grid by 85-90 per cent, but the higher upfront cost could extend the investment payback period to around nine years, according to a report by global energy think tank Ember.

The report said a 3-kW rooftop solar system paired with a 5-kWh battery could shift 1,600-1,800 units of electricity annually from daytime exports to evening consumption.

However, under the current net-metering framework, households have little financial incentive to invest in batteries because surplus electricity exported during the day can be credited against power consumed later, it added.

Ember modelled a household consuming 3...