Policy Watch With millions of rooftops, solar power is within reach

India has plenty of sunshine. It has many people. Consequently, it has very little land per inhabitant (see table).

Any policy regarding solar power must, therefore, take into account the twin advantages of people and sunlight. And this is where India appears to have forgotten something important – rooftop solar. The Jawaharlal Nehru National Solar Mission was right to harness solar power targeting a capacity of 20 GW by 2022. There have been significant successes as well: During the past five years solar tariffs have fallen from `19/kWh to `6.52/Kwh in the last round of reverse bidding in Andhra Pradesh. At this rate, solar power tariffs should reach grid parity before 2017.

But the Mission does little to harness the power of households. To understand this, consider India’s population of 1.2 billion.

Assume five people to a household. That gives us 250 million households. To be conservative, let’s take just one-fifth this number, 50 million, as households with rooftops.

As Avinash Patkar, advisor, technology, Tata Power, explains, even a conservative figure of 200 square feet per rooftop (village rooftops can be significantly larger), with 100 watts of installed capacity per square metres, gives us a 2 kW system per rooftop. The 50 million households will thus have a combined capacity of 100,000 MW. That should give us an annual output of 1,600 kW/hour of installed capacity.

Critically important, this can be done without using up large tracts of land. Today, there is a growing suspicion that many solar farms have been put up because of the land factor.

Each household thus becomes both producer and consumer. The household consumes freely his own rooftop’s power but also earns when he sells surplus power to the grid. Since the distance between the solar panels and the households isn’t great, there will be huge savings in transmission (capital and recurring) costs. Once installed, maintenance costs are minimal. The savings would be massive for rural household electrification.

Some grumble about the capex involved. At around Rs 100/W, each rooftop would require investments of Rs 2 lakh. Collectively, the country would have to invest around $200 billion, or `10.84 lakh crore, (100/W x 2,000 W per household x 50 million households).

But large land tract solar producing are already spending that much. Moreover, considering the increased gas tariffs that the Rangarajan Committee is willing to pay to private gas producers this is a better way to create energy capacity. Finally, `2 lakh per household isn’t much, especially if it can be done on a public-private-partnership basis. Thus, India could save on energy import bills and have an environmentally friendly solution.

Some policymakers have begun to respect this concept. In November 2012, the Punjab government decided to make rooftop solar compulsory for all buildings, public or private, especially for houses constructed over an area of one kanal and above plots in the urban estate. It began to partly introduce what Germany did ten years ago, and revolutionised the solar power industry. But more on that next week.