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Projects are underway in India to install captive solar photovoltaic (PV) power systems at the country’s airports, exploiting innovative funding models and long-term power purchase agreements. However, the country’s grid power operators are refusing to purchase any excess power, finds Raghavendra Verma

The Airports Authority of India (AAI), which is owned by the Indian government, plans to generate 50 MW of electric power from solar plants at 30 airports by the end of 2015. A communiqué issued in May 2014 noted that the plan was designed to reduce the sector’s dependence on India’s unreliable grid power and eschew supplementary diesel generators.

At least eight of India’s 130 airports, including those owned by private companies such as the Indira Gandhi International Airport in the capital, New Delhi, already had functional solar power systems, operating smoothly before the announcement of the solar expansion plan. Other Indian airports already fitted with solar power systems or currently obtaining such power sources include Indore city’s Devi Ahilyabai Holkar Airport, Raipur’s Swami Vivekananda Airport, Bhubaneswar’s Biju Patnaik International Airport, Bhopal’s Raja Bhoj Airport, Amritsar’s Sri Guru Ram Dass Jee International Airport, Chandigarh Airport, Ahmedabad’s Sardar Vallabhbhai Patel International Airport, Guwahati’s Lokpriya Gopinath Bordoloi International Airport, Hyderabad’s Rajiv Gandhi International Airport and Jaisalmer Airport.

Of course, India’s move towards airport solar power is far from unprecedented, with other airport industries worldwide assessing its benefit. In November 2010, for instance, the US Federal Aviation Administration (FAA) said that ‘airport interest in solar energy is growing rapidly as a way to reduce airport operating costs and to demonstrate a commitment to sustainable development’, and issued a technical guidance paper promoting the idea.

Generating on-site solar power is a particularly an attractive proposition in India, which receives significant sunshine during most of the year and suffers from chronic power shortages, leading to unreliable grid supplies.

India’s new Bharatiya Janata Party (BJP)-led government, elected in 2014, has plans for expanding solar energy of all kinds. It has already approved 25 large (non-airport) solar energy projects, with a note from its Ministry of New and Renewable Energy (MNRE) saying it wants to develop 20,000 MW of solar power capacity nationwide by 2019.

Each megawatt of solar power generating capacity requires 1.8 ha of land and costs $1.3 million in investment, Rakesh Kalra, regional executive director of the AAI, told COSPP.

In most of the ongoing solar power projects, the AAI has not invested up front, but is making deals with solar power companies to install and maintain the plants. Kalra said it was possible that airports might invest their own money, rather than under a build-own-operate basis, but with a lifespan of 25 years, either system should be “cost-effective.”

The cost of grid power in India has been rising continuously. For example, according to a note from India’s recently replaced Planning Commission, power tariffs for use in commercial establishments rose by 19% between 2008 and 2012. According to Kalra it is expected to continue to do so, while the cost of electricity from existing solar plants should either remain constant or even fall.

Airports lead the way

Delhi’s Indira Gandhi International Airport – which is owned and operated by Delhi International Airport Private Limited (DIAL) – started operations of its 2.14 MW solar power plant in January 2014. The plant includes 8736 PV modules of 245 W each, which have an anti-reflective coating to avoid distracting landing aircraft crew. They are mounted on galvanised iron structures that can be tilted in three positions to adjust with the seasonal changes in the sun’s position.

Spread over 3.64 ha and running parallel to the 4.43 km runway ’11/29′, the solar modules are connected to 16 combiner boxes, which use 630 kW inverters to convert direct current into alternating current. Installed by the German company Enerparc, the average energy generation of the plant is 10,000 kWh, peaking at 13,050 kWh. After synchronising with the low tension voltage received from the grid, the solar power is fed into two 1600 kVA transformers and stepped up to 11 kV in the airport’s high tension distribution network. It is used for aeronautical ground lighting systems installed at the airport’s three runways, taxiways and parking stands.

The system includes a weather monitoring system to check that the energy produced follows actual solar radiation, thereby assessing performance. It also features SCADA systems, which raise alarms about poor performance and generate reports.

Meanwhile, Devi Ahilyabai Holkar Airport, Indore, installed two smaller, 50 kW systems in October 2013 under the build-own-operate model, with a power purchase agreement for 25 years with Mumbai-based Chemtrols Solar Pvt Ltd. It owns and maintains the plant, charging $0.18/kWh, falling to $0.11 by the end of the agreement.

Such tariffs are fixed through a tender bidding process as per AAI guidance and vary according to location. According to India’s Central Electricity Regulatory Commission, the desert state of Rajasthan and the southern state of Tamil Nadu have very high potentials for solar energy and hence quoted tariffs are low, while New Delhi, for instance, has more cloud and less space and hence bids per kWh are higher.

In Indore, in the central Indian state of Madhya Pradesh, peak power generation occurs during summer afternoons, when systems work at 85% capacity, whereas this reaches only 10%–15% on a cloudy summer morning, a senior Indore airport manager told COSPP.

Despite this useful power contribution, the Indore airport plant contributes only a small fraction of the airport’s average power requirement of 1500 kWh and its electricity is mainly used within the terminal building. The plant draws power from 414 solar panels of 240 W installed over 1200 square metres, 800 metres from the main runway. Made by Mumbai-based PV Power Tech, the solar modules are placed at an 18o incline facing south to catch the maximum amount of sunlight. They can withstand wind speeds of up to 160 km per hour and are resistant to lightning. The system uses two 50 kW inverters from German company KACO.

The plant is equipped with sensors for solar radiation, ambient temperature, module temperature and wind speed. It can be monitored remotely through a KACO web portal that shows various parameters in real time as well as archived data.

According to Kalra, AAI solar power systems are designed to constantly compare the energy generated by the plants with airport power requirements, drawing only the required additional power from the grid.

These solar plants also can be protected by the comprehensive security already in place at airports. And there is little maintenance required except for cleaning the panels. Delhi airport has a pressurised water washing system for cleaning and maintaining the entire plant area. Delhi airport authorities have also planted slow-growing grass to ensure minimum grounds-keeping maintenance and to reduce exposure and damage caused by birds and reptiles.

The design requirement of the Delhi project included a guaranteed life of 25 years, module efficiency exceeding 15% and plant load factor of more than 20%.

A spokesperson for DIAL told COSPP that the project also received customs and excise duty exemptions on buying materials used in the plant. The company also plans to expand the airport’s solar power plant capacity.

Restricted subsidies

Indian government policy provides for a potential 30% subsidy for any solar power project to encourage the generation of renewable energy. However, subsidies have not been given to every solar power project and the government is trying to restrict them to only those projects that would otherwise be unviable, said Rakesh Kumar, director of the Solar Energy Corporation of India (SECI).

Furthermore, according to Kumar, airports now commissioning new solar plants face a key disadvantage as the government has decided not to grant the subsidy to projects (including those at airports) which do not install panels on rooftops. ‘The Ministry says that rooftop is rooftop and not the ground,’ he said. And while that might sound like fuzzy logic, there is a reason: solar panels on roofs are more visible than those on the ground, and this helps the government popularise solar energy, said Kumar.

Explaining why AAI prefers ground-based over rooftop solar projects, Kalra said: ‘The [airport] rooftops are not big enough or are curved at many places, and climbing for the maintenance on the top of these glass buildings is not user-friendly.’ On the other hand, many Indian airports have a vast amount of unused land; for example, Hyderabad Rajiv Gandhi International Airport is spread over 2200 ha, while Chennai International Airport has around 1500 ha.

Kumar believes the government should continue to pay subsidies to land-based projects. ‘This kind of an issue should better not [be] micro-managed,’ he said. There are several pending proposals with ground-based solar panels, but now, without the subsidy, many will remain unviable or may not be optimised, he argued.

Raju VR Palanisamy, president of India’s Solar Energy Association, said companies bidding for ground-based solar power plants have even started to quote prices without factoring in the subsidy. But they are applying for subsidies nonetheless. ‘If the government grants that, it would be their windfall,’ he told COSPP.

Subsidies are distributed by SECI, which is a state-owned not-for-profit company responsible for implementing and facilitating solar development. Since its launch in April 2013, all new Indian airport projects have been routed through it. ‘We ensure quality and remain engaged for two years in the operation of the system,’ said Kumar.

Instead of choosing vendors for each project, SECI chooses them for each city on the basis of the best-priced tenders, taking into account bidders’ technical and financial strengths. Furthermore, to create competition, it selects at least two bidders in each city to encourage a second-placed bidder to match the price of the first, said Kumar. SECI has already selected 25 solar power vendors and installers for 37 cities – mostly state capitals – and it will slowly expand its approvals to smaller towns and cities for airport and other solar energy projects.

The chosen companies themselves search for solar power business in a city. In the case of an airport project, SECI shares the details of chosen vendors in the particular city with AAI and starts the bidding process between the two chosen local competitors, Kumar explained.

After an initial agreement, a solar power beneficiary and project installer/operator bring a detailed project report to SECI, which sanctions it for a fee. Upon satisfactory completion of a project, two-thirds of the subsidy amount is released by SECI directly to the project installing company. The remaining subsidy is paid in two equal instalments after the first and second year of successful and satisfactory performance. ‘So we remain engaged with them from allotment to two years of operations and ensure quality and performance,’ said Kumar.

However, he said subsidies will be harder to secure in future even for rooftop projects, as the government has a limited budget. ‘30% subsidy is going to be reduced to about 15%,’ he added, although it is not yet known when.

Financing models

SECI does not insist on any particular financial model for agreements between a solar power operator and the land or rooftop owner. Kumar said the ‘build-own-operate’ model, which is preferred by AAI, is beneficial because the installing company is encouraged to demand better quality products to avoid future generation losses. But even here he foresees potential problems, which could even generate court action. ‘If, in the future, a rooftop owner doesn’t make payments in time or starts finding fault with the service or decides that he does not need the system and tells the vendor to take it away, it could lead to legal complications,’ he warned.

Kumar said SECI recommends installing grid-connected solar power systems so that surplus power can be sold onto the grid. Indeed, the AAI’s April communiqué noted that solar power plants are being set up on a site ‘to meet not only its own requirements but also to feed the surplus power generated to the local grid.’ Likewise, Kalra stressed that some of the smaller Indian airports have little power consumption and big stretches of empty land to generate excess solar power.

According to Kumar, one possible approach is net metering, where bills are settled at the end of every month or year. ‘But [first] we have to see all this happening as it is a very new concept,’ he said. One potential problem with such a system is pricing disparity, with solar power being costlier than conventional power, leading grid operators to refuse to pay the higher price for excess solar electricity. ‘They do not have any interest in promoting solar energy and want separate government help if forced to purchase solar power,’ he said. This is especially likely to be a problem if solar panel operators become net exporters onto the grid, he suggested.

Kumar argued that India needs new regulation to deal with solar power. ‘Solar is going to replace many things and people will become self-reliant,’ he said. Indeed, solar power will continue to be attractive to users with a poor grid supply, as they have to run costly diesel generators. ‘Even if you are able to reduce the running of generators for a few hours in the week, you are making a good saving,’ said Kumar.

Solar power is also especially attractive to business customers, as Indian power tariffs for commercial units are higher than for the residential sector. For instance, the Indore airport pays $0.13/kWh to the grid supplier, while local residential tariffs are $0.08/kWh.

Pressing ahead

These benefits are encouraging airports to press ahead with their on-site solar power projects despite the recent difficulties over subsidies. Cochin International Airport, in the southwestern state of Kerala, is pushing ahead with a plan to sell excess power from its solar units to the grid. It has negotiated a power banking contract with local power company the Kerala State Electricity Board Limited (KSEB), under which any excess solar power supplied to the grid could only be adjusted against future power bills. ‘We have given in-principle approval’ for the airport’s proposal, a senior official of KSEB told COSPP.

Cochin airport plans to add 12 MW in solar PV capacity on 22 ha of land before the end of this year. It already has a 1 MW system installed at three locations, including a 320 kW plant on a hangar roof.

One potential way out of grid supply deals for Indian airports would be to install power storage systems – but such developments are unlikely in the short term. ‘Storage is a very costly affair and not very environmentally friendly,’ said Kalra. ‘The batteries have a limited life; it takes lot of energy to manufacture them, and bulk power cannot be stored.’

Meanwhile, diesel generators will continue to operate on standby mode at India’s airports whether they have solar power systems or not.

Raghavendra Verma is a New Delhi-based journalist.