The Union government’s target of producing 40 gigawatts of rooftop solar power by 2022 is unrealistic: The country could produce only 4.4 GW rooftop solar energy till March 31, 2021, according to the Union Ministry of New and Renewable Energy.

What is Solar Rooftop?

• A solar photovoltaic (PV) system mounted on a rooftop of a building is a mini-power requirement or feed into the grid.
• The size of the installation varies significantly depending on the availability of space, amount of electricity consumed by the property and the ability or willingness of the owner to invest the capital required.

Why rooftop?

• Rooftop solar with a storage system is a benefit for both, end consumers as well as discoms (power distribution companies).
• A one-kilowatt (kW) rooftop system can produce three to five units of electricity a day.
• The combination increasingly becomes cost-effective for electricity generation compared to the traditional grid supply and diesel generators.
• In 2021, solar and storage will be cheaper than grid supply for most commercial and industrial (C&I) customers.
• The increase in penetration of rooftop solar in the distribution grid will have a significant impact on the stability of the grid.

A viable alternative

• Most housing societies in urban India rely on diesel generators for power backup. However, as power availability improves in the country, diesel generators will become redundant.
• The operational cost of diesel generators is quite high— R16-18 per unit against Rs 5-6 a unit for solar rooftop systems. So rooftop solar power makes financial sense.Solar rooftop is also a perfect solution for commercial and institutional buildings that operate mostly during the day.
• Their rooftops can be utilized to generate electricity, and they can, partially or completely, replace diesel generators. This would also help them reduce their electricity bills.

Question of energy storage

• In order to integrate rooftop solar and electric vehicles, the grid needs to be flexible and smart.
• Energy storage systems will play a key role in providing this flexibility by acting as a load when there is a surplus generation, as well as generating sources when there is a supply shortage.
• There are two major methods of integrating battery storage into the electric grid:

1. Front-of-the-meter (FTM): It is implemented at the utility-scale, wherein the battery system is connected to the transmission or distribution network that ensures grid reliability. This happens on a considerably large scale (~MWh scale).
2. Behind-the-meter (BTM): The other method is implemented at the residential and commercial/industrial level, mainly to provide backup during a power failure or to store excess locally generated energy from solar rooftop photovoltaic (PV) systems.

India’s storage capacity

• About 34 GW / 136 GWh of battery storage is expected to be installed by 2030, according to the Central Electricity Authority of India.
• This capacity would be used for RE integration, demand-side and peak load management services.

Storage challenges

• The solar segment offers a huge market opportunity for advanced battery technologies.
• However, manufacturers have some ground to cover in addressing technical limitations of batteries, such as charging characteristics, thermal performance and requirement of boost current to charge deep cycle batteries.
• Since solar companies may directly procure batteries from manufacturers and require after-sale services and technical support, battery companies should have wider a presence to address these expectations.

Other key challenges

• Rooftop solar source doesn’t match the rise in renewable energy in India.
• While industrial and commercial consumers account for 70% of total installed capacity residential consumers remain a big untapped potential to give the boost
• Solar rooftops also face several challenges such as little consumer awareness, lack of innovative government policies or attention, bureaucratic hassles, and limited support from discoms.

Way forward

• Supportive policies and innovative technological approaches are needed for the sector to achieve its potential.
• Indian policymakers need to plan for rooftop solar plus storage, rather than rooftop solar alone with the grid as storage (net / gross metering).
• The declining cost of storage solutions, along with that of rooftop solar solutions, is likely to change the future of the Indian power sector.
• Several countries such as Australia, the United States, Germany, among others have already endorsed solar power with battery storage.
• Energy storage, therefore, represents a huge economic opportunity for India.
• The creation of a conducive battery manufacturing ecosystem on a fast track could cement India’s opportunity for radical economic and industrial transformation in a critical and fast-growing global market.

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