Solar power in India

With about 300 clear and sunny days in a year, the calculated solar energy incidence on India's land area is about 5000 trillion kilowatt-hours (kWh) per year (or 5 EWh/yr).[12][13] The solar energy available in a single year exceeds the possible energy output of all of the fossil fuel energy reserves in India. The daily average solar-power-plant generation capacity in India is 0.20 kWh per m² of used land area, equivalent to 1400–1800 peak (rated) capacity operating hours in a year with available, commercially-proven technology.[14][15][16]

Solar electricity generation was 3.93 TWh [53] out of total utility generation of 98.76 TWh,[54] or 3.98% in December 2019.

As of July 2019 by far the largest segment of solar PV installed in India was ground mounted at 27,930 MW installed capacity. This sector comprises mostly larger scale solar projects and even larger utility solar projects that generate power centrally and disperse it over the grid. The next largest segment was rooftop solar at 2,141 MW which can be divided into residential solar, commercial and industrial solar roofs as well as a range of installations including agricultural buildings, community and cultural centres. 70 percent of rooftop solar in 2018 was in the industrial and commercial sectors, with just 20 percent as residential rooftop solar.[8] Rooftop solar as a proportion of total solar installations is much less than is typical in other leading solar countries but was forecast to grow to 40 GW by 2022 under national targets.[6] A rough calculation would imply that India had around just 430 MW of residential rooftop solar, whilst the UK with around half the overall solar capacity of India had over 2,500 MW of residential solar in 2018. The smallest segment was off-grid solar at 919 MW which could help play a role in reaching villages and dwellings without access to the national grid.

Below is a list of solar power generation facilities with a capacity of at least 10 MW.[57]

In August 2016, the forecast for solar photovoltaic installations was about 4.8 GW for the calendar year. About 2.8 GW was installed in the first eight months of 2016, more than all 2015 solar installations. India's solar projects stood at about 21 GW, with about 14 GW under construction and about 7 GW to be auctioned.[95] The country's solar capacity reached 19.7 GW by the end of 2017, making it the third-largest global solar market.[96]

In mid-2018 the Indian power minister RK Singh flagged a tender for a 100GW solar plant at an event in Delhi, while discussing a 10GW tender due to be issued in July that year (at the time, a world record). He also increased the government target for installed renewable energy by 2022 to 227GW.[97]

The installed capacity of commercial solar thermal power plants (non storage type) in India is 227.5 MW with 50 MW in Andhra Pradesh and 177.5 MW in Rajasthan.[98] The existing solar thermal power plants (non-storage type) in India, which are generating costly intermittent power on daily basis, can be converted into storage type solar thermal plants to generate 3 to 4 times more base load power at cheaper cost and not depend on government subsidies.[99] In March 2020, SECI called for 5000 MW tenders which can be combination of solar PV with battery storage, solar thermal with thermal energy storage (including biomass firing as supplementary fuel) and coal based power (minimum 51% from renewable sources) to supply round the clock power at minimum 80% yearly availability.[100]

Solar power, generated mainly during the daytime in the non-monsoon period, complements wind which generate power during the monsoon months in India.[101][102] Solar panels can be located in the space between the towers of wind-power plants.[103] It also complements hydroelectricity, generated primarily during India's monsoon months. Solar-power plants can be installed near existing hydropower and pumped-storage hydroelectricity, utilizing the existing power transmission infrastructure and storing the surplus secondary power generated by the solar PV plants.[104][105] Floating solar plants on the reservoirs of pumped-storage hydroelectric plants are complementary to each other.[106] Solar PV plants clubbed with pumped-storage hydroelectric plants are also under construction to supply peaking power.[107]

During the daytime, the additional auxiliary power consumption of a solar thermal storage power plant is nearly 10% of its rated capacity for the process of extracting solar energy in the form of thermal energy.[108] This auxiliary power requirement can be made available from cheaper solar PV plant by envisaging hybrid solar plant with a mix of solar thermal and solar PV plants at a site. Also to optimise the cost of power, generation can be from the cheaper solar PV plant (33% generation) during the daylight whereas the rest of the time in a day is from the solar thermal storage plant (67% generation from Solar power tower and parabolic trough types) for meeting 24 hours baseload power.[109] When solar thermal storage plant is forced to idle due to lack of sunlight locally during cloudy days in monsoon season, it is also possible to consume (similar to a lesser efficient, huge capacity and low cost battery storage system) the cheap excess grid power when the grid frequency is above 50 hz for heating the hot molten salt to higher temperature for converting stored thermal energy in to electricity during the peak demand hours when the electricity sale price is profitable.[110][111][112]

Array of parabolic troughs.

Generating hot water or air or steam using concentrated solar reflectors, is increasing rapidly. Presently concentrated solar thermal installation base for heating applications is about 20 MW_th in India and expected to grow rapidly.[113][114] Cogeneration of steam and power round the clock is also feasible with solar thermal CHP plants with thermal storage capacity.

Bengaluru has the largest deployment of roof-top solar water heaters in India, generating an energy equivalent of 200 MW.[115] It is India's first city to provide a rebate of ₹50 (70¢ US) on monthly electricity bills for residents using roof-top thermal systems,[116] which are now mandatory in all new structures. Pune has also made solar water heaters mandatory in new buildings.[117] Photovoltaic thermal (PVT) panels produce simultaneously the required warm water/air along with electricity under sunlight.[118]

The lack of an electricity infrastructure is a hurdle to rural India's development. India's power grid is under-developed, with large groups of people still living off the grid.[119] In 2004, about 80,000 of the nation's villages still did not have electricity, 18,000 out of them could not be electrified by extending the conventional grid due to inconvenience. A target of electrifying 5,000 such villages was set for the 2002–2007 Five-Year Plan. By 2004 more than 2,700 villages and hamlets were electrified, primarily with solar photovoltaic systems.[12] The development of inexpensive solar technology is considered a potential alternative, providing an electricity infrastructure consisting of a network of local-grid clusters with distributed electricity generation.[120] It could bypass (or relieve) expensive, long-distance, centralized power-delivery systems, bringing inexpensive electricity to large groups of people. In Rajasthan during Financial Year 2016–17, 91 villages have been electrified with a solar standalone system and over 6,200 households have received a 100W solar home-lighting system.

India has sold or distributed about 1.2 million solar home-lighting systems and 3.2 million solar lanterns, and has been ranked the top Asian market for solar off-grid products.[121][122][123][124]

4 MW horizontal single-axis tracker in Vellakoil, Tamil Nadu

Thin-film solar cell panels offer better performance than crystalline silica solar panels in tropical hot and dusty places like India; there is less deterioration in conversion efficiency with increased ambient temperature, and no partial shading effect. These factors enhance the performance and reliability (fire safety) of thin-film panels.[137][138][139] Maximum solar-electricity generation during the hot hours of the day can be used for meeting residential air-conditioning requirements regardless of other load requirements, such as refrigeration, lighting, cooking and water pumping. Power generation of photovoltaic modules can be increased by 17 to 20 percent by equipping them with a tracking system.[140][141]

Residential electricity consumers who are paying higher slab rates more than ₹5 (7.0¢ US) per unit, can form in to local groups to install collectively rooftop off-grid solar power units (without much battery storage) and replace the costly power used from the grid with the solar power as and when produced. Hence power draw from the grid which is an assured power supply without much power cuts nowadays, serves as cheaper back up source when grid power consumption is limited to lower slab rate by using solar power during the day time. The maximum power generation of solar panels during the sunny daytime is complementary with the enhanced residential electricity consumption during the hot/summer days due to higher use of cooling appliances such as fans, refrigerators, air conditioners, desert coolers, etc. It would discourage the Discoms to extract higher electricity charges selectively from its consumers.[142] There is no need of any permission from Discoms similar to DG power sets installation. Cheaper discarded batteries of electric vehicle can also be used economically to store the excess solar power generated in the daylight.[143][144]

Solar-power plants equipped with battery storage systems where net energy metering is used can feed stored electricity into the power grid when its frequency is below the rated parameter (50 Hz) and draw excess power from the grid when its frequency is above the rated parameter.[145] Excursions above and below the rated grid frequency occur about 100 times daily.[146][147] The solar-plant owner would receive nearly double the price for electricity sent into the grid compared to that consumed from the grid if a frequency-based tariff is offered to rooftop solar plants or plants dedicated to a distribution substation.[148][149] A power-purchase agreement (PPA) is not needed for solar plants with a battery storage systems to serve ancillary-service operations and transmit generated electricity for captive consumption using an open-access facility.[150][151] Battery storage is popular in India, with more than 10 million households using battery backup during load shedding.[152] Battery storage systems are also used to improve the power factor.[153] Solar PV or wind paired with four-hour battery storage systems is already cost competitive, without subsidy and power purchase agreement by selling peak power in Indian Energy Exchange, as a source of dispatchable generation compared with new coal and new gas plants in India”.[154][155]

Battery storage is also used economically to reduce daily/monthly peak power demand for minimising the monthly demand charges from the utility to the commercial and industrial establishments.[156] Construction power tariffs are very high in India.[157] Construction power needs of long gestation mega projects can be economically met by installing solar PV plants for permanent service in the project premises with or without battery storage for minimising use of Standby generator sets or costly grid power.[158]

The land price is costly for acquisition in India. Dedication of land for the installation of solar arrays must compete with other needs. The amount of land required for utility-scale solar power plants is about 1 km² (250 acres) for every 40–60 MW generated. One alternative is to use the water-surface area on canals, lakes, reservoirs, farm ponds and the sea for large solar-power plants.[159][160][161] Due to better cooling of the solar panels and the sun tracking system, the output of solar panels is enhanced substantially.[162] These water bodies can also provide water to clean the solar panels.[163] Floating solar plants installation cost has reduced steeply by 2018.[164] In January 2019, Indian Railways announced the plan to install 4 GW capacity along its tracks.[165] Highways and railways may also avoid the cost of land nearer to load centres, minimising transmission-line costs by having solar plants about 10 meters above the roads or rail tracks.[166] Solar power generated by road areas may also be used for in-motion charging of electric vehicles, reducing fuel costs.[167] Highways would avoid damage from rain and summer heat, increasing comfort for commuters.[168][169][170]

The architecture best suited to most of India would be a set of rooftop power-generation systems connected via a local grid.[171] Such an infrastructure, which does not have the economy of scale of mass, utility-scale solar-panel deployment, needs a lower deployment price to attract individuals and family-sized households. The cost of high efficiency and compact mono PERC modules and battery storage systems have reduced to make roof top solar PV more economical and feasible in a microgrid[172][144]

Greenpeace[12][173][174] recommends that India adopt a policy of developing solar power as a dominant component of its renewable-energy mix, since its identity as a densely-populated country[175] in the tropical belt[176][177] of the subcontinent has an ideal combination of high insolation[176] and a large potential consumer base.[178][179][180] In one scenario[174] India could make renewable resources the backbone of its economy by 2030, curtailing carbon emissions without compromising its economic-growth potential. A study suggested that 100 GW of solar power could be generated through a mix of utility-scale and rooftop solar, with the realizable potential for rooftop solar between 57 and 76 GW by 2024.[181]

During the 2015-16 fiscal year NTPC, with 110 MW solar power installations, generated 160.8 million kWh at a capacity utilisation of 16.64 percent (1,458 kWh per kW)—more than 20 percent below the claimed norms of the solar-power industry.[76] The annual net peak solar power generation is around 20,000 MW only (nearly 60% of name plate DC rating of 34,000 MW) after accounting the applicable derating factors and system losses before feeding in to the high voltage power grid since the name plate capacity of solar PV plants is actually the gross DC capacity of the installed PV modules.[182]

It is considered prudent to encourage solar-plant installations up to a threshold (such as 7,000 MW) by offering incentives.[183] Otherwise, substandard equipment with overrated nameplate capacity may tarnish the industry.[184][185] The purchaser, transmission agency and financial institution should require capacity utilisation and long-term performance guarantees for the equipment backed by insurance coverage in the event that the original equipment manufacturer ceases to exist.[186][187][188] Alarmed by the low quality of equipment, India issued draft quality guide lines in May 2017 to be followed by the solar plant equipment suppliers conforming to Indian standards.[189][190][191]

Solar radiation resource assessment stations in India

Fifty-one solar radiation resource assessment stations have been installed across India by the Ministry of New and Renewable Energy (MNRE) to create a database of solar-energy potential. Data is collected and reported to the Centre for Wind Energy Technology (C-WET) to create a solar atlas. In June 2015, India began a ₹40 crore (US$5.6 million) project to measure solar radiation with a spatial resolution of 3 by 3 kilometres (1.9 mi × 1.9 mi). This solar-radiation measuring network will provide the basis for the Indian solar-radiation atlas. According to National Institute of Wind Energy officials, the Solar Radiation Resource Assessment wing (121 ground stations) would measure solar radiation's three parameters—Global Horizontal Irradiance (GHI), Direct Normal Irradiance (DNI) and Diffuse Horizontal Irradiance (DHI)—to accurately measure a region's solar radiation.[192][193]

The Indian government is promoting solar energy. It announced an allocation of ₹1,000 crore (US$140 million) for the National Solar Mission and a clean-energy fund for the 2010-11 fiscal year, an increase of ₹380 crore (US$53 million) from the previous budget. The budget encouraged private solar companies by reducing the import duty on solar panels by five percent. This is expected to reduce the cost of a rooftop solar-panel installation by 15 to 20 percent.

Solar PV tariff

Price of silicon solar cells since 1977. The great thing about solar power is that it is a technology and not a fuel. It is unlimited and the more it is deployed the cheaper it would be.[194] While the more limited fossil fuels are used, the more expensive they become.[195][196]

The average bid in reverse auctions in April 2017 is ₹3.15 (4.4¢ US) per kWh, compared with ₹12.16 (17¢ US) per kWh in 2010, which is around 73% drop over the time window.[197][198][199] The current prices of solar PV electricity is around 18% lower than the average price of electricity generated by coal-fired plants.[200] By the end of 2018, competitive reverse auctions, falling panel and component prices, the introduction of solar parks, lower borrowing costs and large power companies have contributed to the fall in prices.[201] The cost of solar PV power in India, China, Brazil and 55 other emerging markets fell to about one-third of its 2010 price, making solar the cheapest form of renewable energy and cheaper than power generated from fossil fuels such as coal and gas.[202]

The global levelized cost of solar PV electricity fell to 1.35¢ US per kWh (₹1.02 per kWh) in April 2020, much cheaper than the fuel cost of any pit head coal-based power plants in India.[203][204] The intermittent / non-dispatchable solar PV at the prevailing low tariffs clubbed with Pumped-heat electricity storage can offer cheapest dispatchable power round the clock on demand.

The Indian government has reduced the solar PV power purchase price from the maximum allowed ₹4.43 (6.2¢ US) per KWh to ₹4.00 (5.6¢ US) per KWh, reflecting the steep fall in cost of solar power-generation equipment.[205][206][207] The applicable tariff is offered after applying viability gap funding (VGF) or accelerated depreciation (AD) incentives.[208][209] In January 2019, the time period for commissioning the solar power plants is reduced to 18 months for units located outside the solar parks and 15 months for units located inside the solar parks from the date of power purchase agreement.[210]

Solar PV generation cost fell to ₹2.97 (4.2¢ US) per kWh for the 750 MW Rewa Ultra Mega Solar power project, India's lowest electricity-generation cost.[211][212] In first quarter of calendar year 2020, large scale ground mounted solar power installations cost fell to Rs 35 million/MW by 12% in a year.[213] Solar panel prices are lower than those of mirrors by unit area.[127][214]

In an auction of 250 MW capacity of the second phase in Bhadla solar park, South Africa's Phelan Energy Group and Avaada Power were awarded 50 MW and 100 MW of capacity respectively in May 2017 at ₹2.62 (3.7¢ US) per kilowatt hour.[215] The tariff is also lower than NTPC's average coal power tariff of ₹3.20 per kilowatt hour. SBG Cleantech, a consortium of Softbank Group, Airtel and Foxconn, was awarded the remaining 100 MW capacity at a rate of ₹2.63 (3.7¢ US) per kWh.[216][217] Few days later in a second auction for another 500 MW at the same park, solar tariff has further fallen to ₹2.44 (3.4¢ US) per kilowatt hour which are the lowest tariffs for any solar power project in India.[218] These tariffs are lower than traded prices for day time in non-monsoon period in IEX and also for meeting peak loads on daily basis by using cheaper solar PV power in pumped-storage hydroelectricity stations indicating there is no need of any power purchase agreements and any incentives for the solar PV power plants in India.[219][220][221] Solar PV power plant developers are forecasting that solar power tariff would drop to ₹1.5 (2.1¢ US) /unit in near future.[222][194]

The lowest solar tariff in May 2018 is Rs 2.71/kWh (without incentives) which is less than the tariff of Bhadla solar park (₹2.44 per kWh with VGF incentive) after the clarification that any additional taxes are pass through cost with hike in the tariff.[223][224] In early July 2018 bids, the lowest solar PV tariff has touched ₹2.44 (3.4¢ US) per kWh without viability gap funding incentive.[225][226] In June 2019, The lowest tariff is ₹2.50 (3.5¢ US)/kWh for feeding in to the high voltage interstate transmission system (ISTS).[227][228][229]

The tariff for rooftop installations are also falling with the recent offer of ₹3.64 (5.1¢ US) with 100% locally made components.[230] In February 2019, the lowest solar power tariff is ₹1.24 (1.7¢ US) per kWh for 50 MW contracted capacity at Pavagada Solar Park.[231]

In May 2020, the discovered first year tariff is ₹2.90 (4.1¢ US) per KWh with ₹3.60 (5.0¢ US) per KWh levelized tariff for round the clock hybrid renewable power supply.[232]

Incentives

Grid parity for solar PV systems around the world[233]
  Reached grid-parity before 2014
  Reached grid-parity after 2014
  Reached grid-parity after 2016
  U.S. states poised to reach grid-parity soon

At the end of July 2015, the chief incentives were:

1. Viability Gap Funding: Under the reverse bidding process, bidders who need least viability gap funding at the reference tariff (RS 4.93 per unit in 2016) is selected.[234] Funding was Rs 1 Crore/MW for open projects on average in 2016.
2. Depreciation: For profit-making enterprises installing rooftop solar systems, 40 percent of the total investment could be claimed as depreciation in the first year (decreasing taxes).
3. Liberal external commercial borrowing facility for the solar power plants.[235]
4. To protect the local solar panel manufacturers, 25% safe guard duty is imposed for two years period from August 2018 on the imports from China & Malaysia who are suspected of dumping solar panels in to India.[236]
5. Capital subsidies were applicable to rooftop solar-power plants up to a maximum of 500 kW. The 30-percent subsidy was reduced to 15 percent.
6. Renewable Energy Certificates (RECs): Tradeable certificates providing financial incentives for every unit of green power generated.[237]
7. Net metering incentives depend on whether a net meter is installed and the utility's incentive policy. If so, financial incentives are available for the power generated.[238]
8. Assured Power Purchase Agreement (PPA): The power-distribution and -purchase companies owned by state and central governments guarantee the purchase of solar PV power when produced only during daylight. The PPAs offer fair market determined tariff for the solar power which is a secondary power or negative load and an intermittent energy source on a daily basis.
9. Interstate transmission system (ISTS) charges and losses are not levied during the period of PPA for the projects commissioned before 31 March 2022.[239]
10. Union government offers 70% and 30% subsidy for the hill states and other states respectively for the installation of rooftop solar units.[8] Additional incentives are offered to rooftop solar power plants from various state governments.[240][241]

The 2018 manufacturing capacity of solar cells and solar modules in India was 1,590 MW and 5,620 MW, respectively.[243][244] Except for crystalline silicon wafers or cadmium telluride photovoltaics or Float-zone silicon, nearly 80 percent of solar-panel weight is flat glass.[245] 100-150 tons of flat glass is used to manufacture a MW of solar panels. Low-iron flat or float glass is manufactured from soda ash and iron-free silica. Soda-ash manufacturing from common salt is an energy-intensive process if it is not extracted from soda lakes or glasswort cultivation in alkali soil. To increase installation of photovoltaic solar-power plants, the production of flat glass and its raw materials must expand commensurately to eliminate supply constraints or future imports.[246]

The Ministry of New and Renewable Energy (MNRE), India, has issued a memorandum to ensure the quality of solar cells and solar modules.[247][248] Compliance with the requisite specifications will grant manufacturers and their specific products an entry in the ALMM (Approved List of Models and Manufacturers.) [249][250][251] Indian manufacturers are gradually enhancing the production capacity of monocrystalline silicon PERC cells to supply better performing and enduring solar cells to local market.[172]

For utility scale solar projects, top solar module suppliers in 2016-17 were: Waaree energy ltd, Trina Solar, JA Solar, Canadian Solar, Hanwha and GCL Poly.[252] For rooftop solar projects, international companies with the largest market share in the Indian market were: Waaree energy ltd, Trina Solar, Canadian Solar, Renesola, REC Solar and Jinko Solar.[253]