Rooftops as energy farms

MICRO GENERATION

GPCL has invited bidders to buy the ‘request for proposal’ (RFP) documents for these five solar roof-top projects. The two pilot projects in the state capital have been developed under a public-private-partnership (PPP) model in collaboration with Azure Sun Energy India and Sun Edison.

“The successful implementation of the PPP transactions for the two Gandhinagar pilot projects,prompted the government to replicate the roof-top solar project in five other cities of Gujarat,” government sources say. The International Finance Corporation,an arm of the World Bank is advising the government on the roll-out of these projects.

The Gandhinagar project is the first of its kind in the country,and aims to become a benchmark for green energy generation at the household-level.

Under the scheme,the solar rooftop project developer will build,finance,own,operate and maintain the solar photovoltaic system units,all of which will be connected to the state electricity grid.

The project developers will rent rooftops from housing societies and commercial establishments,put up the solar units and sell the power to the state electricity distribution company,Gujarat Urja Vikas Nigam and its subsidiaries.

The project mandates that distribution companies would purchase this solar power from the developers for 25 years.

There is a huge gain in store for the landlord who rents out his rooftop. Under the scheme,the owners will earn a ‘green incentive’ calculated on a per-unit basis of power generated from the sun,translating into a direct source of income that would be paid on a monthly or bi-monthly basis.

For the pilot project in Gandhinagar,a sum of R3 per unit of solar power generated is paid as ‘green incentive’ and has roped in the terraces of private homes,commercial buildings and government property.

THE MECHANICS

The photovoltaic modules (consisting of an array of solar cells) or solar panels in the system directly convert sunlight into DC power. This is converted into AC power through an inverter. In the Gandhinagar pilot project,a special type of inverter known as ‘grid-interactive’ inverter is being used. Such inverters can feed the AC electricity directly into the electricity grid.

Many such photovoltaic modules are connected in series and parallel combinations to achieve the desired capacity of the system in kilowatts. According to GPCL,a typical 1 kilowatt photovoltaic system generates an average of 3-4 units (i.e. kilowatt-hours) per day in Gandhinagar.

Larger photovoltaic systems would generate proportionally more energy. On the same lines,a 5 kilowatt system will generate around 22.5-25 units per day.

The amount of power generated depends on the the extent of shadow-free space available. The project has different generation capacities that can be deployed and the range is extensive. The lowest starts at 1KW,going up to 5KW,10KW,20KW and larger spaces can accommodate capacities of 50KW,100KW and a maximum of 500KW.

THE FINE PRINT

In the projects floated for the new cities,a 5 MW project will be developed each in Vadodara,Mehsana and Surat. Rajkot will have 6.5 MW projects while Bhavnagar will house 3.5 MW.

The project developer would install an energy meter with the photovoltaic system in the premises through which power will be injected into the state grid. This energy meter,which looks the same as property owner’s conventional electricity meter,will show how many units have been injected into the grid. The green incentive will be calculated on the unit values shown by this meter.

There is,however,no provision as yet,to let some of this power flow into individual homes and the electrical grid simultaneously. The project does nothing towards reducing power drawn from the state grid. The payments received for the power generated could offset a portion of the household electricity bill.

For the Gandhinagar pilot project,GPCL had imposed certain restrictions on the age or size of buildings that will host the solar panels. For instance,buildings applying for the projects should not more than 8-10 years old and the minimum super built up area required is 1,500-2,000 square feet.

The properties would need to be located preferably in a commercial locality of a city,or in close proximity to the business district and also be situated on an arterial road not less than than 40 feet width.

The operation and maintenance of the photovoltaic system would be the responsibility of the project developer. However,the property owners can do their bit to help with maintenance such as ensuring that the panels remain dust free,or clean up bird droppings as that would result in higher generation efficiency,which means higher income.

Energy experts opine that the quantum of energy generated under such rooftop projects could be a tiny speck in the total electricity generation capacity of Gujarat (about 15,000 MW),but goes a long way in setting a precedent in the generation of clean energy.

GREEN POWER

* The project is a public-private partnership between the Gujarat Power Corporation and a solar power developer with a time-frame of 25 years

* The developer would rent rooftops of houses and commercial establishments in order to place the photovoltaic modules

* The power generating equipment would be owned,operated and maintained by the developer and the output would be fed to the state grid

* The property owner would get a ‘green incentive’ proportional to the total power generated. In Gandhinagar it is currently R3 per unit

* A 1 kW photovoltaic system would generate 3-4 units of power a day and a 5 kW system between 22.5-25 units a day

— avinash.n@expressindia.com