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Solar irradiation data of India, , solar irradiation data for gujarat, solar irradiation data for rajasthan, , solar dni india, pyranameter, , Reflected solar irradiance, site prospecting,



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Solar Radiation and Assesment Training programme

by Prathyusha Institute


  • The Tamil Nadu Open University recently held its Convocation. Chancellor Chandrakantha Jeyabalan and P Palaniappan, Minister of Higher Education, Government of Tamil Nadu, hand over an Award to Student S Arul Priyanka The Tamil Nadu Open University recently held its Convocation. Chancellor Chandrakantha Jeyabalan and P Palaniappan, Minister of Higher Education, Government of Tamil Nadu, hand over an Award to Student S Arul Priyanka

Prathyusha Institute of Technology and Management, Tiruvallur, TN, recently established Solar Radiation Resource Assessment (SRRA) and Advanced Measurement Stations (AMS) Stations by the Centre for Wind Energy Technology, Union Ministry of New and Renewable Energy. These centres house sensitive and expensive solar and meteorological sensors where safety and security of the instruments is ensured. The institute also conducted a two-day training programme on ‘Functioning and Maintenance of SRRA stations’ where S Gomathinayagam, Executive Director, Centre for Wind Energy Technology, Chennai, inaugurated the programme. G Giridhar, director, MNRE and Unit Chief, Solar Radiation Resource Assessment, organised this programme. PM Beulah Devamalar, Principal, welcomed the gathering and the speakers who participated were B Amudha, Scientist-D, RMC, IMD; Devanathan, Project Engineer, SRRA, CWET; KN Sheeba, Assistant Professor, Chemical Engineering, The National Institute of Technology, Tiruchy; Indradip Mitra, Senior Technical Advisor, GIZ, New Delhi and Sri Vidhya, Director, Periyar R&D Centre for Solar and Bioenergies, Periyar Maniammai University, Thanjavur.




 It is the amount of solar radiation energy recieved on a surface area per square centimeter per minute. It can be even' hourly irradiance' measured every hour or can be 'daily irradiance' measured every day. 






 The Potenial For Solar Energy In India Is Huge :IEA

According to Mathias Aarre Maehlum, Energy Informative, one year’s worth of solar energy (radiant light and heat from the sun) reaching the surface of the earth would be twice the amount of all non-renewable resources, including fossil fuels and nuclear uranium. The solar energy that hits the earth every second is equivalent to 4 trillion 100-watt light bulbs. Furthermore, the solar energy that hits one square mile in a year is equivalent to 4 million barrels of oil. Thus, the potential of solar energy is immense.

Solar technologies could be characterised as either passive solar or active solar depending on the way they capture, convert, and distribute solar energy. An active solar technique includes using photovoltaic panels and solar thermal collectors to harness the energy. A passive solar technique includes orienting a building to the sun, selecting materials with positive thermal mass or light dispersing properties, and designing buildings that naturally circulate air.

The 2011 report of International Energy Agency (IEA), stressed on the development of affordable, inexhaustible, and clean solar energy technologies (both active and passive) with large longer-term and global benefits. The IEA believed that the reliance on solar energy will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource. The solar energy use will also enhance sustainability, reduce pollution, lower the costs of mitigating climate change, and keep fossil fuel prices lower than otherwise. Thus, the additional costs of the incentives for early deployment should be considered learning investments and that they must be wisely spent and need to be widely shared. In view of the IEA suggestions, the potential for solar energy in India is huge.

India has extensive energy needs and increasing difficulty in meeting those needs through traditional means of power generation. In 2012, for example, the world’s largest blackout — the great Indian uutage, stretching from New Delhi to Kolkata, occurred. This blackout was due to failure of the northern power grid and caused nearly 700 million people, twice the population of the US, to be without electricity. In such a situation, India needs to shift to non-polluting renewable sources of energy to meet future demand for electricity. Solar is the prime inexhaustible energy available to all. And India is one of the sun’s most favoured nations, blessed with about 5,000 twh of solar insolation every year with most parts receiving 4-7 kwh per square per metre per day. Thus, investment in solar energy is a natural choice for India.

Considering the solar possibility, in 2009, India unveiled a $19 billion plan to produce 20 gw of solar power by 2020 (Jawaharlal Nehru National Solar Mission, or JNNSM). Under JNNSM, the use of solar-powered equipment and applications would be made compulsory in all government buildings, as well as hospitals and hotels. From August 2011 to July 2012, India has gone from 2.5 mw of grid connected solar photovoltaic to over 1,000 mw of the same power.

In fact, India’s energy under JNNSM is competitively placed among world players. For example, a report by World Bank titled, “Paving the Way for a Transformational Future: Lessons from JNNSM Phase 1,” says that JNNSM has been instrumental in bringing down the cost of solar power to a level that is competitive across the world. As per the report, JNNSM has reduced the costs of solar energy to $0.15 per kwh, making India amongst the lowest cost destinations for grid-connected solar photovoltaic in the world.

According to the World Bank report, solar power has the potential to reduce India’s dependence on imports of diesel and coal for power generation, reduce greenhouse gas emissions, and contribute to energy security. Ashish Khanna, lead energy specialist and one of the authors of the report says that growth in the solar sector will help India increase its share of clean energy and help meet its target of reducing emissions per unit of its GDP by 20-25 per cent by 2020 over 2005 levels. MORE...

Now you can forecast the  Future Solar Energy Output!!

Forecasting the future output of solar energy systems is an essential strategy for integrating high penetration of solar onto the nation's power grid. 

If your company is looking to understand one of the key grid integration strategies for large-scale and distributed solar energy systems in 2014 and beyond, download your copy of this exclusive report from the Solar Electric Power Association (SEPA) titled "Predicting Solar Power Production: Irradiance ForecastingModels, Applications and Future Prospects." 


In the report you will find comprehensive coverage of:


• Methods used in modern solar forecasting systems for each forecast time horizon


• Factors that impact solar forecast accuracies including weather patterns and single solar array predictions versus multiple geographically dispersed arrays


• The unique forecasting challenges for distributed, behind the meter solar relative to utility-scale solar systems


• Current uses of solar forecasting at both the transmission and distribution levels through case studies


• Recommendations to expand the market for and end-user acceptance of solar forecasting as a tool to accommodate expanding deployment of solar energy systems nationwide more..


A New Small Hand Held Machine Determines Solar radiation to Position 

With its internal solar detector and meter, PVM210 helps solar/PV engineers locate most appropriate site to place solar panels. Form factor allows unit to be held in one hand while working on sloping roof or atop ladder. Along with measurement range up to 1,999 W/m² for solar power readings, unit features 3¾-digit LCD, data hold feature, and accuracy within ±10 W/m² or ±5% in sunlight. Unit can also verify stated short circuit current in conjunction with multimeter or clampmeter. 

    Megger, one of the world’s leading manufacturers and suppliers of test equipment and measuring instruments for electrical power applications, now offers the PVM210, a new handheld irradiance meter that aids in locating the most appropriate site to place solar panels.

Designed with both the solar detector and meter inside the unit, the PVM210 provides solar/photovoltaic engineers with a pocket-sized instrument that is easy-to-use and can be held with just one hand while working on a sloping roof or atop a ladder.

The PVM210 includes an easy-to-read 3-3/4 digits LCD with a measurement range up to 1999 W/m², providing fast and accurate solar power readings.  The unit’s data hold feature allows the user to freeze the display to read measurements easily and clearly. more..


New technique to analyse solar irradiation during cloud cover  :research US Dept of Energy

Sandia National Laboratories engineers have been studying the most effective ways to use solar photovoltaic (PV) arrays -- a clean, affordable and renewable way to keep the power on. Systems are relatively easy to install and have relatively small maintenance costs. They begin working immediately and can run unassisted for decades.


But clouds could dim industry growth: What happens when they cover part of a solar PV array and cause a dip in output, how big is the dip and how can a utility company compensate for it? Sandia researcher Matt Lave has been working to understand that drawback and determine just how much clouds can affect solar power plant output. Typically, sunlight is measured using a single irradiance point sensor, which correlates nicely to a single PV panel. But that doesn't translate to a large PV power plant. "If a cloud passes over, it might cover one panel, but other panels aren't affected," Lave said. "So if you use the single point sensor to represent the variability of the whole power plant, you will significantly overestimate the variability."


To get a more accurate picture of how clouds affect PV power plants, Lave partnered with Sandia engineer Josh Stein and University of California, San Diego professor of environmental engineering Jan Kleissl to develop a Wavelet Variability Model. The model uses data from a point sensor and scales it up to accurately represent the entire power plant. The model uses measurements from an irradiance point sensor, the power plant footprint -- the arrangement and number of PV modules in the plant -- and the daily local cloud speed to estimate the output of a power plant.


In many cases, output measurements from the power plant aren't available, but point sensor data is, so the model is useful for estimating how much energy must be stored to make up for cloud-caused fluctuations.


The variability is a concern for grid operators as unanticipated changes in PV plant output can strain the electric grid. At short timescales, measured in seconds, sharp changes in power output from a PV power plant can cause local voltage to flicker. At longer timescales, measured in minutes, generating less PV power than expected produces balancing and frequency issues, where load can exceed generation. Backup systems such as battery storage to mitigate the variability can substantially add to the cost of a PV power plant.


Lave points to Puerto Rico , where changes in power output are required to be less than 10 percent per minute. "With this tool, you can estimate how often you'll exceed that limit and determine how to mitigate those effects," he said.more info



TERI launches new WEB-GIS tool : Indian solar radiation software


The Energy and Resources Institute (TERI) unveiled the first-ever cloud based open-source Web-GIS Tool for estimating Rooftop Solar Power potential for Indian Solar Cities. The main objective of this initiative is to develop a high performing and flexible Web-GIS tool to estimate the rooftop solar power potential for Indian cities. The first city where the tool will be launched will be Chandigarh, followed by other cities in India. more..


 * Solar Irradiation centers to be expanded 


The nation-wide Solar Radiation Resource Assessment (SRRA) stations network of Centre for Wind Energy Technology (C-WET) will be expanded next month with the addition of 64 stations, said its Executive Director, S. Gomathinayagam on Thursday.SRRAs are established to estimate reliable ground solar radiation and meteorological data that are crucial for planning and implementation of solar power plants and other devices. Data derived from the field stations will be transmitted to the Central Server at C-WET Chennai on daily basis. Courtesy




It’s no secret. PV installations are on the rise all over the world with over 4000MW forecast just in the US for 2013 and nearly half of that capacity is distributed generation from residential and commercial rooftops. All of this growth is, of course, very encouraging, but it is also forcing the energy system and the solar industry itself to adapt very quickly to manage the energy influx.

This map shows how irradiance conditions varied from their long-term average in June, July, and August 2013, with deviations ranging from  /-10%. The analysis is based on  15 years of continuous, hourly irradiance records from 3TIER's global solar dataset, which was used to determine long-term average irradiance and calculate conditions for the summer of 2013.
This map shows how irradiance conditions varied from their long-term average in June, July, and August 2013, with deviations ranging from /-10%. The analysis is based on 15 years of continuous, hourly irradiance records from 3TIER's global solar dataset, which was used to determine long-term average irradiance and calculate conditions for the summer of 2013. 


Finding the cause of underperformance


Due to the rapid growth of distributed solar over the past few years, owner-operators managing large portfolios of rooftop generation now face the issue of performance reconciliation on a daily basis. The new challenge of determining whether underperformance was caused by weather or by equipment now affects both large and mid-sized companies with geographically dispersed fleets.


Satellite accuracy


Due to the expense and scarcity of high-quality ground station data, satellite based methodologies developed by the global scientific community have become a broadly accepted alternative for estimating surface irradiance. In fact, they have proven to be the most accurate estimate of solar resources beyond 25 km of a well-maintained ground station. This technology uses visible satellite imagery to determine cloudiness, which is then combined with additional data sources such as elevation, snow cover, and atmospheric turbidity from water vapor and aerosols. The final result is a long-term (15 to16 year) modeled record of surface irradiance at any location worldwideMORE..




Research by Murdoch Univ., James Cook Univ. and the Univ. of Waterloo in Canada has revealed flaws in the way that the widely used Ångström-Prescott equation links solar radiation to sunshine duration..more.. also read



Solar energy is free, clean, and usually available in abundance. However, solar radiation is also less predictable than many kinds of fossilfuel. Researchers at the Institute of Networked and Embedded Systems have developed a model that allows a more accurate prediction of hourly solar radiation.



The Government has initiated a comprehensive programme to augment solar radiation resource assessment in the country including Ladakh area. In Phase-I of this programme, one Solar Radiation Monitoring Station has been established at Leh through Centre for Wind Energy Technology, Chennai. The data from various stations is transmitted to a central server maintained at C-WET and is made available to various stakeholders after carrying out quality checks. As per data recorded through one of such stations, the peak value of solar radiation at Leh reaches up to seven kilowatt hour per day per square metre of area which is quite high as compared to other locations in the country. However, no assessment of the potential of grid fed solar energy in Ladakh area has been carried out taking into account availability of land area. 

As indicated by solar radiation data available for various parts of the country, several States, especially the Western States viz. Gujarat, Rajasthan, Maharashtra and Andhra Pradesh, and some parts of Tamil Nadu, Karnataka, Madhya Pradesh, have very good potential of setting up grid connected solar power projects in the country. However, a comprehensive survey of land for setting up of solar projects has not been carried out in any state. 






SRRA data for C-WET station-Annexure-A

List of SRRA stations with co_ordinates-Annexure-B

SRRA Stations


Solar Data Sharing and Accessibility Policy (SDSAP-2012)




* MNRE to install 60 more solar radiation monitoring stations !

The move is aimed at enabling states and developers of solar power projects take investment decisions based on scientific rationale. 

"We have already set up 51 solar monitoring stations for assessment of solar power in the country, which we are going to expand...60 more such stations shall come, and very soon entire country would be covered," the ministry Joint Secretary Tarun Kapoor said while addressing the 11th Green Power conclave-2012 organised here by CII.  source







 Solar radiation estimations over India using Meteosat satellite images






Free download





Solar radiation assessment is a critical activity for setting up Solar projects. The quality of the resource also impacts the type of technology which may be used at a specific place for solar power generation.

The measurement of this data should ideally be undertaken at the micro level through site specific ground based weather monitoring stations over a period of time (preferred time is between 12 to 18 months).

A micro level of assessment is required at this stage. This activity shall assess solar resource attractiveness of the proposed site. This shall include assessment of parameters like

  • Global Horizontal Solar Radiation
  • Diffused Horizontal Solar Radiation
  • Direct Normal Solar Radiation
  • Wind Speed/Direction
  • Rain Accumulation
  • Air Temperature
  • Atmospheric Pressure (SLP) and
  • Relative Humidity.

It is recommended that the micro level irradiation assessment be undertaken at the site by the developer (or any other agency). Preferred time is 12 to 18 months.




Technical experts with knowledge and experience of measuring irradiation levels using NASA and other data sets on solar irradiation level , India Meteorological Department (IMD), Solar Energy Centre, Center for Wind Energy Technology etc.



To improve availability of accurate solar irradiation data, several initiatives were taken by the MNRE:

  1. Update of data through a joint project between Solar Energy Centre (SEC) of the Ministry and IMD from 23 locations, monitoring solar irradiation parameters. The updated data has been posted on the Ministry’s website and is also available in IMD/MNRE Handbook of Solar Radiation.
  2. Cooperation between NREL (USA) and SEC of the MNRE has provided data which can be accessed in CD ROM form. These data sets contain high resolution solar resource maps in the form of NREL Solar Resource Maps and Toolkit for Northwest India.
  3. MNRE has taken an initiative to augment Solar Radiation Resource Assessment Stations (SRRAs) at sites of high potential for solar power generation, which is being implemented by C-WET, Chennai (Center for Wind Energy Technology). Around 51 stations have been set up that use high quality, high resolution equipment/instruments to assess and quantify solar radiation availability along with weather parameters to develop a Solar Atlas. Implementation of the project started in February 2011 and all stations have already been installed, completed and commissioned. The monthly average (daily) wise data received from each SRRA station is available with C-WET.
  4. Solar Insolation data made available by NASA under its Earth Science Enterprise program is also commonly used by the developers.

The India Meteorological Department (IMD) under the Ministry of Science & Technology is the nodal agency for setting up/monitoring weather stations.  There are around 45 radiation observatories. The measurements for global solar-radiation diffuse solar radiation and direct normal incidence is being carried out at 39, 23 and 21 locations respectively spread across India.


Till now availability of site specific data has been a challenge and therefore developers and financial institutions have been using macro level data sources like NASA. Going forward as better macro and micro level data becomes available; it would be better for developers to source and use this data for project planning.

The links below provides available database on solar resource assessment; Renewable Energy Laboratory/start.html





*Solar Radiation Resource Assessment

Ministry of New and Renewable Energy (MNRE) has initiated a major project on Solar Radiation Resource Assessment (SRRA) across the nation to assess and quantify the solar radiation availability along with weather parameters with a view to develop Solar Atlas. Centre for Wind Energy Technology (C-WET), Chennai is implementing the project by installing a network of 51 Automatic Solar Radiation Monitoring Stations (ASRMS) in the first phase in different States using high quality, high resolution equipment/instruments.


Sl. No States No.of ASRMS
Proposed Completed
1 Rajasthan 12 12
2 Gujarat 11 11
3 Tamilnadu 7 7
4 Andhra Pradesh 6 6
5 Karnataka 5 5
6 Maharashtra 3 3
7 Madhya Pradesh 3 3
8 Jammu & kashmir 1 1
9 Chhattisgarh 1 1
10 Pondichery 1 1
11 Haryana 1 1
  Total 51 51


Each ASRMS consists of two towers of 1.5 m and 6 m tall each. The 1.5 m tall tower houses a Solar Tracker equipped with Pyranometer, Pyranometer with Shaded Ring and Pyrheliometer to measure solar parameters, such as, global, diffused and direct radiation. The 6 m tall tower houses instruments measuring rainfall, ambient temperature, atmospheric pressure, relative humidity, wind speed and direction. Each ASRMS is totally powered by 160 Watt SPV Panels and consists of 13 equipments/instruments and records 37 parameters inclusive of both measured and derived. The data from each ASRMS averaged to 10 minutes will be transmitted to a Central Receiving Station established at C-WET, Chennai through GPRS mode. The implementation of the project has started from February 2011 and all stations have already been installed, completed and commissioned.  The monthly average (daily) wise data received from each ASRMS is available on C-WET website as test run. The quality checking process of the data is on.



To caluclate or to find the data arrived by C WET  starting from May to Oct for 2011 and you will results as given below.




Monthly Average (Daily) values, October 2011

STATE DOC Global Horizontal Solar Radiation Diffuse Horizontal Solar Radiation Direct 
Normal Solar Radiation
Wind Speed Wind Direction Rain Accumulation Air Temperature Relative Humidity Atmospheric Pressure
(Kwh/m2) (Kwh/m2) (Kwh/m2) (m/s) (o) (mm) (o) (%) (mb)
1 Karakudi Tamil Nadu 23-05-11 4.752 2.592 2.880 2.568 139.385 215.500 27.192 81.001 995.731
2 CWET Tamil Nadu 28-05-11 4.464 2.448 2.592 3.587 192.669 168.100 28.121 85.055 1,006.914
3 Ramanathpuram Tamil Nadu 03-06-11 4.320 2.448 2.592 4.713 199.639 281.500 27.765 80.095 1,004.731
4 Kayathar Tamil Nadu 10-06-11 4.896 2.160 3.168 4.285 200.660 374.101 27.835 73.526 996.310
5 Vellore* Tamil Nadu 23-07-11 - - - - - - - - -
6 Trichy Tamil Nadu 29-07-11 4.752 2.592 2.736 5.025 185.788 135.900 17.781 67.810 997.158
7 Erode Tamil Nadu 03-08-11 5.040 2.592 2.880 3.125 183.653 176.800 26.962 74.975 976.345


Disclaimer: The data are still under the process of quality checking and evaluation and are kept on test run basis.

DOC  Date of Commissioning 
SLP   Station Level Pressure 

         Accumulated rain fall recorded 
*       Due to communication problem data from these stations will be uploaded later






Solar Radiation data in India


India is endowed with rich solar energy resource since it is located in the equatorial sun belt of the earth. Theoretically India’s solar power reception is about 5000 trillion kWh/year with about 300 clear sunny days in a year. The daily average solar energy incident over India varies from 4 to 7 kWh/m2 with about 2,300–3,200 sunshine hours per year, depending upon location. This is far more than current total energy consumption.


The daily average global radiation is around 5 Kwh/m2 in north - eastern and hilly areas to about 7 Kwh/m2 in Western regions and cold desert areas.


The annual global radiation varies from 1600 to 2200 kWh/m2, which is comparable with radiation received in the tropical and sub-tropical regions. Although the highest annual global radiation is received in Rajasthan, northern Gujarat, Tamilnadu and parts of Ladakh region, the parts of Andhra Pradesh, Maharashtra, Madhya Pradesh, Karnataka also receive fairly large amount of radiation as compared to many parts of the world especially Japan, Europe and the US where development and deployment of solar technologies is maximum. Thus it is clear that solar power projects are commercially viable in most parts of India.





Solar radiation:


Solar radiation is electromagnetic radiation emitted by the sun. The sun is converting its mass into light particles called photons. The solar radiation that reaches on different locations of earth depends on several factors such as geographic location, time, season, local landscape, local weather etc. The Earth rotates around the sun in an elliptical orbit and is closer to the sun during part of the year. When the sun is nearer the Earth, the Earth's surface receives a little more solar energy. The rotation of the Earth is responsible for hourly variations in sunlight.


When sunlight passes through the atmosphere, it is subjected to absorption, scattering and reflection by air molecules, water vapor, clouds, dust, pollutants, forest fires etc. When a photon is absorbed, its energy is changed in to either electrical energy or heat. Scattering occurs when gas molecules and small particles diffuse part of the incoming solar radiation in different directions without any alteration to the wavelength of electromagnetic energy. Reflection of solar radiation is a process where sunlight is redirect by 1800 after it strikes an atmospheric particle. Mainly reflection is caused by clouds.



 Visit NASA  and assesses solar irradiation data for anywhere in your  town, city or state 

All you need to do is to point to your city  or your town  or village and submit for data.

WOW, there you get  

Air temperature,  Relative humidity,  Daily solar radiation, - horizontal Atmospheric pressure,  Wind speed,  Earth temperature,  Heating degree-days Cooling degree-days,     etc., 

In fact Maharashtra government has recently decided that they will go for 140 MW of solar power by 2016 and have chosen Northern Maharashtra, Vidharba and Maratwada based on NASA figures. It is believed that these parts of Maharashtra has solar irradiation similar to Rajasthan.



Solar radiation which we receive as heat and light can be converted to useful thermal energy or for production of electricity either through solar photovoltaic route or through solar thermal route.  Availability of reliable solar radiation data is vital for the success of solar energy installations in different sites of the country. For solar collectors which are flat in nature, solar radiation data in the form of Global Horizontal Irradiance (GHI) is useful whereas for solar collectors which are concentrating in nature Direct Normal Irradiance (DNI) data is required.  Solar thermal power plants are essentially Concentrating Solar Power (CSP) units. For designing solar thermal power plants, DNI data is therefore a pre-requisite.  


India Meteorological Department (IMD) is the principal government agency in matters relating to meteorology and over 45 ground stations are currently being maintained by IMD in its solar radiation network. Two solar radiation handbooks were published in 1981 and 1982 by IMD based on the data available from their ground stations. These handbooks mainly contain global and diffuse radiation data along with temperature and other meteorological parameters. These handbooks have so far been widely used for designing solar systems in the country.  

In order to have detailed solar resource information, the following initiatives have further been taken by the Solar Energy Centre (SEC): 

  1. SEC-IMD Collaborative Project on the revised handbook on solar radiation:

A book entitled “Solar Radiant Energy over India” along with the CD containing various meteorological data is now available. The Handbook is available on MNRE website (

  1. SEC-NREL Collaborative Project on “Solar Resource Assessment” based on satellite imagery underIndo-US Energy Dialogue:

�         Solar Resource Assessment based on satellite imagery (SEC- NREL Project):

First phase has been completed.

Output: Solar maps (DNI & GHI) of North-Western India are available on MNRE website ( and also available in NREL website.

�         Solar Resource Assessment based on satellite imagery (SEC- NREL Project):

The Second phase of the SEC-NREL project for constructing solar maps for the rest of the country has now been completed.  The solar maps containing monthly and annual Direct Normal Irradiance (DNI) and Global Horizontal Irradiance (GHI) data have been developed from hourly satellite data spanning from January 2002 to December 2008.  These maps cover the entire country at 10 km x10km spatial resolution. Final Solar Maps (DNI & GHI) are available on MNRE website ( and also available in NREL website (


  1. A further recent initiative taken by the Ministry includes expansion of the network of solar radiation stations, especially at sites which fall in the zones receiving high direct solar radiation with a view to generate investment grade solar radiation data to enable States and the developers to take investment decisions backed up by scientific rationale.  The MNRE has recently assigned the task of solar radiation monitoring toC-WET, Chennai, which is an autonomous organization of the Ministry carrying out wind resource assessment in the country amongst other activities in the Wind Energy sector.  The basic configuration of the solar radiation monitoring stations has already been worked out, and soon basic work for procurement of the hardware by C-WET through competitive bidding would be completed.  To begin with, setting up of 50 such stations is being envisaged with centralized collection of data at C-WET. 

Expected benefits of Solar Mapping based on satellite imagery (Collaborative Project between SEC and NREL): 

Solar mapping of the entire country based on satellite imagery and duly validated by ground truth data will provide information of both Direct Normal Irradiance (DNI) and Global Horizontal Irradiance (GHI) on a continuum basis with an approximate accuracy of � 15%.  It is possible to identify the areas with higher solar radiation and set up ground stations for more accurate measurement of solar radiation and other meteorological parameters.  It can thus avoid setting up a large number of ground stations throughout the country, which is an expensive proposition. Investors are however required to set up their own ground measurement unit at the actual project site for more accurate estimation of data of input resources for their investment decisions. 


This page contains high-resolution solar resource maps and data for India. The high-resolution (10-km) solar resource maps and data were developed using weather satellite data incorporated into a site-time specific solar mapping approach developed at the U.S. State University of New York at Albany. The data were output as data in geographic information system (GIS) format and as static maps.

These products were developed by the U.S. National Renewable Energy Laboratory (NREL) in cooperation with India's Ministry of New and Renewable Energy, through funding from the U.S. Department of Energy.

Please contact Dr. Bibek Bandyopadhyay (, Dr. Shannon Cowlin (, Er. Alekhya Datta ( for any additional information.


 Solar Radiation Maps

 Direct Normal Irradiance


Annual average (JPG 1.6 MB)


 Monthly average (ZIP 9.3 MB)

 Global Horizontal Irradiance


Annual average (JPG 1.6 MB)


  Monthly average (ZIP 8.9 MB)

 GIS Data Layers


Direct Normal Irradiance (ZIP 2.7 MB)


 Global Horizontal Irradiance (ZIP 2.7 MB)


  State & District Boundary of India (ZIP 3.6 MB)


  Important Locations including State Capitals (ZIP 13 KB)

Solar Radiation Data (Monthly average, Lat/Long basis)


Direct Normal Irradiance (EXCEL 8.9 MB)


Global Horizontal Irradiance (EXCEL 8.9 MB)













Global solar radiation:


Global solar radiation measurement:


Global solar radiation is the total amount of solar energy received by the Earth's surface, usually expressed as W m-2. About 99 percent of global solar radiation has wavelengths between 300 and 3000 nm. This includes ultraviolet (300-400 nm), visible (400-700 nm), and infrared (700-3000 nm) radiation. Global solar radiation is the sum of direct, diffuse, and reflected solar radiation. Direct solar radiation passes directly through the atmosphere to the Earth's surface, diffuse solar radiation is scattered in the atmosphere, and reflected solar radiation reaches a surface and is reflected to adjacent surfaces.


The visible portion of the solar radiation spectrum provides energy for photosynthesis, which is the primary gateway for inorganic carbon to become organic and support life on the Earth. Infrared light heats the ground and maintains an ideal environment for life. Global solar radiation drives the global water cycle and weather patterns. In fact, about half of the solar radiation absorbed by the Earth's surface is consumed by evapotranspiration on a global scale. Solar radiation is also used to generate electricity. Measuring global solar radiation can be accomplished with pyranometers and pyroheliometers.


Solar radiation budget:


The solar radiation budget represents the balance between incoming energy from the sun and outgoing thermal and reflected energy from the earth. Globally, the budget is balanced. But locally, it is not balanced. The earth receives 1.8x1017W of incoming solar radiation continuously at top of its atmosphere. But only halt of it reaches the earth’s surface.


Instruments for measuring solar radiation:


Different instruments are used for measuring short wave and long wave solar radiation.


Instruments used

Short wave (0.3µ - 4µ)

Direct solar irradiance

Angstrom and thermoelectric Pyrheliometers

Global solar irradiance

Thermoelectric pyranometer

Diffuse solar irradiance

Thermoelectric pyranometer with shading ring

Reflected solar irradiance

Inverted pyranometer

Solar spectral irradiance and turbidity


Long wave (4µ - 100µ)

Net terrestrial radiation

Angstrom Pyrgeometer

Total (0.3µ - 100µ)

Upward  or downward radiation


Net radiation

Net Pyradiometer



Kipp & Zonen


The recently released SMP series of smart pyranometers offers a lot of extra features compared to the CMP series because of the integrated micro-controller and the RS-485 interface with Modbus® protocol. We have received many enquiries from customers who would like to evaluate the possibilities available, or to be able to use the new pyranometers in the field with a laptop computer to make comparisons with installed pyranometers, or for laboratory measurements and demonstrations.

To facilitate these applications we have created the SMP Starter Set that is perfect for demonstration, evaluation and testing. The SMP3 Starter Set has a convenient carrying case with the smart pyranometer and everything that you need to connect it to a USB port of your computer.

The SMP3 Starter Set contains:

  • SMP3 smart pyranometer with 10 m cable
  • RS-485 to USB isolated converter with USB cable for computer
  • CVP 2 universal 12 VDC power supply; with 100–240 VAC input and European, UK, USA and Australian mains plug adapters
  • Connection wires and terminal strips
  • Printed SMP instruction sheet and calibration certificate
  • CD with SMP instruction sheet, manual and Windows™ software
  • CD with RS-485 to USB converter drivers for Windows™
  • Instructions and wiring diagram for connecting SMP pyranometer, converter, CVP 2 and computer
  • Robust carrying case

The Starter Set is also available without a smart pyranometer so that you can choose your own combination of radiometer and cable length, or so that you can use one starter set with several smart pyranometers (for example to configure them).

To demonstrate a reasonable signal from the SMP pyranometer when using artificial light, a halogen desk lamp is advised. The average light level in an office or laboratory environment is less than 10 W/m2. A 20 Watt halogen lamp at a distance of 10-20 cm can give you an irradiance of 500 W/m2 or more.

The new SMP pyranometers are equipped with an extremely low power Smart Interface that provides industry standard digital and amplified analogue outputs within the well-known CMP series housings. The sensitivity is programmed so that all SMP pyranometers have identical output ranges, allowing easy installation and exchange for recalibration. source


Delta-T Services showcases SPN1 Sunshine Pyranometer

SPN1 has been designed to detect the most efficient sites for PV installations. IMage: Delta-T Services

Delta-T Services will be showcasing the SPN1 Sunshine Pyranometer at this year’s Intersolar Europe. The instrument is an important research device for PV developers because it measures both, global and diffuse radiation as well as sunshine state in the same instrument and can detect and identify the most efficient sites for PV installations.

After the installation of the PV system, the device monitors panel efficiency as well as calculating DNI (Direct-Normal Irradiance), an important feature in field trials, where panel efficiency is often compared to DNI. The device is designed for outdoor exposure and an effective meteorological instrument. source



*NRG Systems, a Vermont (US) based manufacturer of measurement equipment for the global renewable energy industry, has released the next version of its Solar Resource Assessment system, now with a choice of pyranometer to support ISO-compliant solar resource assessment campaigns.


(A pyranometer measures broadband solar irradiance on a planar surface solar radiation flux density. A typical pyranometer requires no power to operate.) The system is used to measure the potential of a given site to produce utility-scale photovoltaic (PV) solar power.

Along with the low-cost Li-Cor LI-200SZ photodiode pyranometer, NRG Systems now offers a ISO 9060-compliant Hukseflux LP02 thermopile pyranometer. Other sensors can be used with the system as well. The new system also includes plane-of-array booms standard with each pyranometer to allow for flexible configurations to match the prospective angle of the PV panels. At 2.3 meters (7 feet), the tower is also slightly shorter than the first version for easier maintenance and installation. more


Solar radiation in Rajasthan:

Rajasthan, the largest state in India receives maximum solar radiation intensity in India. According to US Department of Energy, Rajasthan receives the second largest amount of solar radiation in the world. Rajasthan is best suited for solar power generation since average rain fall is minimum. Solar radiation in Rajasthan is similar to California and Nevada in USA. Rajasthan has around 208,110 of desert land. Rajasthan has more than 325 sunny days in a year with solar radiation of about 6-7Kwh/sq-m/day. 


The direct normal insolation over Rajasthan varies from 1800 Kwh/m2 to 2600Kwh/m2. Mostly the western part of Rajasthan is blessed with abundant solar energy. Jodhpur in Rajasthan is receiving maximum solar radiation which is known as Sun City of India. Rajasthan is also blessed with abundant land, so it would be ideal for solar PV.


Solar Radiation in Gujarat:


Gujarat receives second largest amount of solar radiation in India. Gujarat receives 5.5 to 6 Kwh/sq.m/day with 300 sunny days/year. Most locations in Gujarat receive an annual Direct Normal Incidence (DNI) in between 1,800 - 2,000 Kwh/m2. 


Waste land of about 14.40 Million Acres is receiving largest amount of solar radiation. Northern part of Gujarat is receiving more solar radiation. The locations connected by the Rann of Kachch region of Gujarat receive the maximum DNI in the state.


Solar radiation in Maharashtra

Dhule and Jalgaon from north Maharashtra, Osmanabad and Aurangabad from Marathwada and Chandrapur and Wardha districts of Vidarbha have the highest exposure to solar rays.

Solar radiation in Tamilnadu:


After Rajasthan and Gujarat, Tamil Nadu receives the third largest amount of solar radiation in India. Tamil Nadu receives about 5.35Kwh/sq.m/day. Now some companies are taking initiative for solar power projects in Tamil Nadu. 


Solar Irradiance Calculator      

How to use the irradiance calculator:

Select your country from the list.

If you have selected America or Canada, select your state or province.

Select the town or city nearest where you live.
The irradiance calculator will then show monthly figures showing the average kWh per square meter per day for energy at your location.
You can multiply this irradiance figure by the wattage of your photovoltaic panels to give you an average daily amount of energy you can expect to generate with your system, measured in watt-hours.

These are the values of major cities in India


City                          Jan    Feb    Mar    Apr    May   Jun    Jul     Aug   Sep    Oct    Nov   Dec    Avg

Agra                         3.25   4.28   5.35   6.39   7.31   7.22   6.11   5.66   5.5     5        3.92   3.19   5.26

Agartala                   4.28   4.98   5.52   5.45   5.01   4.36   4.27   4.3     4.04   4.31   4.19   4.13   4.57

Ahmadabad             4.36   5.08   5.89   6.29   6.56   5.9     4.71   4.39   5.07   5.07   4.52   4.03   5.15

Aizawl                     4.39   5.06   5.5     5.42   4.95   4.46   4.3     4.37   4.26   4.34   4.28   4.19   4.62

Bengaluru                5.31   6.07   6.53   6.43   6        4.92   4.45   4.53   4.89   4.57   4.49   4.72   5.24

Bhubaneshwar         4.5     5.22   5.75   6.23   6.15   4.48   3.86   3.72   4.09   4.53   4.4     4.24   4.76

Chandigarh              3.5     4.58   5.65   6.66   7.39   7.08   5.86   5.43   5.54   5.25   4.22   3.4     5.38

Chennai                   4.89   5.83   6.56   6.61   6        5.12   4.63   4.71   4.94   4.37   4.02   4.21   5.15

Dehra Dun               3.67   4.47   5.58   6.61   7.39   6.69   5.33   4.8     5.17   5.38   4.38   3.63   5.25

Delhi                        3.71   4.64   5.73   6.17   6.39   6.04   5.19   4.78   4.99   4.79   4.07   3.45   4.99

Hyderabad               5.02   5.77   6.28   6.4     6.14   4.81   4.24   4.1     4.46   4.74   4.81   4.7     5.12

Imphal                     4.3     4.9     5.16   5.4     4.9     4.26   3.84   3.8     3.75   4.07   4.02   4.01   4.36

Jaipur                       3.9     4.67   5.4     5.99   6.35   6.21   5.08   4.68   5.05   4.75   4.04   3.66   4.98

Kolkata                    4.13   4.89   5.59   5.99   5.79   4.49   4.09   3.9     3.88   4.32   4.21   4.02   4.60

Lucknow                 3.62   4.63   5.68   6.19   6.54   5.88   4.78   4.45   4.45   4.83   4.14   3.52   4.89

Mumbai                   6.54   7.17   7.42   7.14   6.69   5.63   4.94   4.85   5.69   6.29   6.46   5.92   6.23


Patna                        4.06   5.21   6.19   6.81   6.87   5.71   4.55   4.54   4.37   4.92   4.57   3.97   5.14

Monthly Direct Normal Irradiance of India


January                                                 February                                     March


DNI Apr DNI May DNI June

April                                                      May                                      June


DNI July DNI Aug DNI Sept

july                                                   August                                     September



October                                                   November                                     December



Solar Radiation Resource Assessment across India:


MNRE has initiated a major project on Solar Radiation Resource Assessment (SRRA) across the nation to assess and quantify the solar radiation availability along with weather parameters with a view to develop Solar Atlas. Centre for Wind Energy Technology, Chennai is implementing the project by installing a network of 51 Automatic Solar Radiation Monitoring Stations (ASRMS) in the first phase in different states.



No. of ASRMS












Andhra Pradesh









Madhya Pradesh



Jammu & Kashmir













Each ASRM consists of two towers of 1.5m and 6m tall each. The 1.5m tall tower houses a solar tracker equipped with pyranometer, pyranometers with shaded ring and pyrheliometer to measure solar parameters such as global, diffused and direct radiation. The 6m tall tower houses instruments measuring rainfall, ambient temperature, atmospheric pressure, relative humidity, wind speed and radiation.


 Sun path chart program

This program creates sun path charts in Cartesian coordinates for: (1) "typical" dates of each month (i.e.; days receiving about the mean amount of solar radiation for a day in the given month); (2) dates spaced about 30 days apart, from one solstice to the next; or (3) a single date you specify. You can select whether hours are plotted using local standard time or solar time. In addition, there are a number of options available to allow you to alter the chart's appearance.
 Resulting charts are displayed in your Web browser window, and they are meant to be printed out. Two formats are currently available: PDF (Adobe) and PNG (a standard international graphics format). 


NOAA Solar Calculator



This very handy calculator allows you to zero in on your house using satelite images.  You can then see how your house lines up with south, find solar noon, sunrise and sunset times for any date. 




Here is a very new source of solar radiation data for India.


This source of solar radiation data for India is from new solar radiation database � SolarGIS.
I would like to inform that this company will change this situation in India, thanks to this new solar radiation database ( which is available already now) acknowledged by International Energy Agency.

Equally thanks to new online tools for the best site prospecting


&planning of photovoltaic projects

&Bankable reports for solar energy projects




This site gives sunset/sunrise times, as well as solar insolation, temperatures, precip, GAISMA



Climate Consultant,

UCLA Energy Design Tools



Surface meteorology and Solar Energy



NASA s01#s01






Measuring Solar Radiation




Industrial grade devices for measuring solar radiation are delicate and expensive. The "pyranometer" is basically a flat plate (covered with a transparent dome) that is coated with an extremely absorptive surface. As the sun strikes it, the surface gets hot. The temperature of the surface is measured with a thermopile, giving an output voltage related to the amount of solar radiation striking the surface.


You can build a "poor man's" pyranometer that works pretty well out of inexpensive and readily available components. Although it will not be of laboratory quality, it will suffice for comparative measurements and educational purposes.


Making the Meter


The obvious component to consider as the basis for our meter is a silicon photovoltaic cell. When sunlight strikes it, it produces electricity, and the more sunlight strikes it, the more electricity it produces.


At first glance, you might think that you could just hook a voltmeter up to it and measure the output voltage. Unfortunately, if you do this, you will get very erroneous results (visit the Appendix if you want to understand why).


Instead, you will need to measure the cell's output current. If you short out (hook a perfect wire between) the positive and negative terminals of your cell, a current flows through that wire. That is the current that you would like to measure. It varies linearly with the amount of sunlight striking the surface of the cell. This is actually a little trickier than one might think, for reasons that are explained in the Appendix.


You can measure the cell's current by measuring the voltage across a very small resistor. Here we show how to do this with a digital panel meter or digital VOM. This is shown in the following schematic:


Schematic Diagram of Meter

PV represents the PV cell, and M represents the voltmeter. Rsh is the resistor through which most of the current from the PV flows, and across which we will measure the voltage.


Following are the steps in making the meter.


Our goal is to make full sunlight give a 100 mVolt reading on the digital meter (full sunlight is about 1000 watts per square meter), so our meter will read 1 mVolt per 10 Watts/m2.

Get a 3 1/2 digit digital panel meter (try Marlin P. Jones, which sells such things for about $7...they do require a battery) that has a 0-199.9 mVolt scale (this is a common item). Or, just plan on using a digital multimeter on the 0-200 mVolt scale.

First, estimate how much current your cell will produce in full sunlight. A good first assumption is that your cell puts out about 0.025 amps per square centimeter. So measure your cell, calculate its area, and multiply by 0.025. For example, if your cell is 8 cm square, guess that your full sunlight cell current is 8 * 8 * 0.025 = 1.6 amps.

Calculate the resistance that is required to give 100 mVolt drop when I is flowing through it. Ohms law says that R = V / I, or 0.1 volt / I. For our example, this is 0.1 Volts / 1.6 Amp, or 0.0625 ohms.

Make the resistor. For very small resistors like this, a good way is to use a length of small wire. I used number 30 wire wrap wire. Appendix B shows the resistance per foot for various small copper wire sizes. Number 30 wire has a resistance of about 0.121 ohms per foot. So, to make a 0.0625 ohm resistor, only requires 0.52 feet, or 6.2 inches!

Connect your resistor across the PV cell. You will need to solder it, because of the very low resistances involved. And, bear in mind that wiring connected to the cell also has resistance, so either account for it or cut it short.

At this point, you should be able to connect your digital meter across the terminals. It should be configured for 200 millivolts full scale. Note that because the meter is measuring voltage now, the length of your meter wires is not too important. If you take your apparatus out into full sunlight, you will hopefully see a reading on your meter that is not too far from 100 mVolts.


At this point, you will want to calibrate your meter. The best way is to have a calibrated instrument of some sort. Lacking this, you do a fair job by finding a time when the sun is high (noon on a summer day) on a very clear day. Then assume that the solar radiation is 1000 watts per square meter.


The following steps show how to calibrate the meter by altering your resistor. It will assume that you are calibrating without a reference. If you have an actual reference instrument, then use whatever value it supplies instead of 1000.


In full sunlight, note the reading of your meter. We would like for it to be exactly 100 mVolts. It is probably something different.

We are going to make a new resistor wire of the proper length to make the meter read 100 mVolts.

Calculate Lnew = L0 * 100 / reading. (L0 is the original length of the resistor wire). For example if my original wire was 6.2 inches, and my meter reads 88, I need a new resistor wire of length Lnew = 6.2 * 100 / 88 = 7.05 inches.

Cut a new resistor wire and replace your original.

At this point, your silicon solar cell and digital voltmeter should be doing a fair job of measuring solar radiation.


Things to do With Your Meter




What is solar radiation?

The sun is the earth's major energy source and radiates its energy from a distance of 150 million kilometers, or 8.3 light minutes. This solar radiation reaches the outside of our atmosphere with an irradiance of about 1360 Watts per square meter (W/m2). It covers the spectrum from ultraviolet, through visible, to near infrared wavelengths. Most important solar irradiance spectral categories are presented in the table below.

Ultraviolet 100 nm ≤ λ < 280 nm UVC (ultraviolet C)
  280 nm ≤ λ < 315 nm UVB (ultraviolet B)
  315 nm ≤ λ < 400 nm UVA (ultraviolet A)
Visible light 450 nm ≤ λ < 500 nm blue
  70 nm ≤ λ < 591 nm yellow
  610 nm ≤ λ < 760 nm red
Infrared 760 nm ≤ λ < 1.4 μm IR-A (near infrared)
  1.4 μm ≤ λ < 3 μm IR-B (middle infrared)
  μm ≤ λ < 1 mm IR-C (far infrared)

TABLE 1: Some important solar irradiance spectral categories
(source: ISO 21348, Space environment (natural and artificial) — Process for determining solar irradiances)

Reference Solar Spectral Irradiance, credit pvresources

ASTM G173-03 Reference Solar Spectral Irradiance
(credit: Renewable Resource Data Center (RReDC): Standard Solar Spectra)

Sun, courtesy SOHO (ESA & NASA)  Sun, courtesy SOHO (ESA & NASA)  Sun, courtesy SOHO (ESA & NASA)

Sun's surface, image left shows large, eruptive prominence with an image of the Earth added for size comparison. Images courtesy of SOHO consortium. SOHO is a project of international cooperation between ESA and NASA.

Components of solar radiation at the Earth's surface

When solar radiation reaches the top of the Earth's atmosphere it can be considered as a parallel beam coming in a straight line from the sun. By the time this beam reaches the earth's surface, it has traveled through the atmosphere and changed its composition through scattering, diffusion and absorption. This is caused by gasses, water vapour, particles and clouds. Some of the absorbed energy is re-radiated in the far infrared. Light is scattered differently by the atmosphere depending upon its wavelength, and this results in the blue sky during the day and the red colour at sunrise and sunset. As a result of these effects, three components can be distinguished at the surface; direct, diffuse, and global solar radiation. The first are the solar rays travelling in a straight line from the sun which were not scattered or absorbed by the atmosphere. The second is solar radiation which has been diffused by the atmosphere and clouds and, as a result, is coming from all directions of the hemisphere. Finally, global solar radiation is the sum of the direct and diffuse solar radiation irradiating a flat horizontal surface. In this case, the contribution of the direct beam component is proportional to the cosine of the angle between the position of the sun in the sky and the normal (vertical) to the horizontal surface.

Why should I measure it?

Good quality, reliable solar radiation data is becoming increasingly important in the field of renewable energy, with regard to both photovoltaic (PV) and thermal systems. It helps well-founded decision making on activities such as research and development, production quality control, determination of optimum locations, monitoring the efficiency of installed systems and predicting the system output under various sky conditions. Especially with larger solar power plants, errors of a few percent can significantly impact upon the return on investment.

What do I measure with?

Global radiation is measured with pyranometers, which are radiometers designed for measuring the total (global) irradiance on a plane surface. Direct radiation is measured with a pyrheliometer that has a slightly larger view than the sun and its aureole and does not see the rest of the sky. To make measurements the pyrheliometer must point precisely at the sun and this is achieved by using an automatic two-axis sun tracker. A shading assembly on the sun tracker is used to block the direct radiation from a pyranometer so that it measures only the diffuse sky radiation.

Horizontal and tilted pyranometer, courtesy skytron-energy Pyranomer, courtesy Kipp & Zonen

Horizontal and tilted pyranometer (left, courtesy skytron energy)
Pyranometer CMP11 (right, courtesy: Kipp & Zonen)

What instruments do I need for my installed system?






Northwest India, Global Horizontal, Solar Irradiance, April

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur, bhilwara, kota, indore, bhopal, vadodra, gwalior, agra, meerut,



Northwest India, Global Horizontal, Solar Irradiance,May

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur,



Northwest India, Global Horizontal, Solar Irradiance, June

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur,





Northwest India, Global Horizontal, Solar Irradiance, July

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur, bhilwara, kota, indore, bhopal, vadodra, gwalior, agra, meerut,



Northwest India, Global Horizontal, Solar Irradiance, August

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur, bhilwara, kota, indore, bhopal, vadodra, gwalior, agra, meerut,





Northwest India, Global Horizontal, Solar Irradiance,September

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur, bhilwara, kota, indore, bhopal, vadodra, gwalior, agra, meerut,



Northwest India, Global Horizontal, Solar Irradiance,October

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur, bhilwara, kota, indore, bhopal, vadodra, gwalior, agra, meerut,




Northwest India, Global Horizontal, Solar Irradiance, November

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur, bhilwara, kota, indore, bhopal, vadodra, gwalior, agra, meerut,



Northwest India, Global Horizontal, Solar Irradiance, December

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur, bhilwara, kota, indore, bhopal, vadodra, gwalior, agra, meerut,



Northwest India, Global Horizontal, Solar Irradiance,  January

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur, bhilwara, kota, indore, bhopal, vadodra, gwalior, agra, meerut,




Northwest India, Global Horizontal, Solar Irradiance,  Feb

kWh/m2/ /Day - jodhpur, udaipur, ahemadabad, ajmeer, bikaneer, jaipur, bhilwara, kota, indore, bhopal, vadodra, gwalior, agra, meerut,

















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  • Joydeep
    Joydeep -

    Solar Irradiation data for India , solar hot spots in India, barren lands for solar plants in India, solar sites suitable for project developers in India by IISC

    IISC is a very reputed research organisation based in Bengaluru, India. 

    Indian Institute of Science. 

    They have recently concluded  a study on the regions in India with high solar energy resource. It reveals what they call Solar Hotspots. 

    The Energy and Wetland Group, Centre for Ecological Sciences and the IISc, collaborated in the research. 

    The paper  studies the solar energy potential in India and  also reviews the availability of barren, wasteland which could be easily used for setting up solar power projects. 

    This is pretty important, given the importance of land in India. 

    Information about the most suitable sites for project development is essential for developers, state level planners, consultants, etc., 

    The monthly average global insolation for all the states is more than 5.25 kWh/m2/day for three months - March, April and May. Whch makes India a destination for solar energy developers from all over the world to flock to India. India thus becomes a solar destinatin for many business entrepreneurs. 

     Punjab, Uttar Pradesh, Haryana, Rajasthan and some areas of Gujarat and coastal Maharashtra receive the highest solar insolation - between5.7 to 7.5 kWh/m2/day - during summer. 

    During the monsoon ie.,  June, July and August,  Jammu & Kashmir, Haryana, Punjab, Rajasthan Uttar Pradesh, Madhya Pradesh, Gujarat and Uttaranchal  receive the highest amount of solar insolation, in the range of 5.3 to 7.1 kWh/m2/day.

    This is also pretty attractive for solar energy generating companies to enter India. 

     During these months, the southern half of the country receives moderate to low solar energy insolation in the range of 3.5 to 5.5 kWh/m2/day.

    I wonder how this figure compares with the North Eastern states of India. 

     A small area on the south-eastern coast of Tamil Nadu receives high solar insolation during this period. 

    During the winter months, September to January, only moderate to low solar insolation is received by all regions across the country. 

    The only regions receiving relatively high solar insolation during various parts of this period are western Rajasthan, Jammu & Kashmir and lower western coast. Solar insolation during this period ranges between 2.3 and 5.9 kWh/m2/day. 

    Extreme weather conditions in  regions like Rajasthan adversely impacts the efficiency of the solar cells. 

    The overall system prices for solar PV projects were around Rs 500/watt for off-grid and Rs 250/watt for grid-connected projects.

    For solar thermal power projects, the paper notes that the the parabolic trough collector system dominates more than 90% of of the solar thermal market globally. 

    The parabolic dish collector systems, which have the high optical efficiency are generally used for off-grid applications due to the high cost factor. The linear Fresnel systems have lower installation and maintenance cost and require lesser land area.

     Some of the new technologies coming up the solar thermal sector include dry storage and integration of gas combustion systems. 

    The cost of generation from parabolic trough systems is Rs 5 to 7 per kWh. 


    The Central Electricity Regulatory Commission has mandated all state governments to procure a set minimum percentage of their power consumption from solar power plants.

     By 2022, all states must procure at least 3% of their annual power consumption from solar power plants. Which is pretty low as per my opinion.

    The utilities which fail to meet these targets will be required to buy renewable energy certificates from the solar power plant developers. 

    Country's REC Renewable Energy Certificate trading Exchanges are already been in operation with luke warm response, so far.


    1 Krishnadas G, Jain R, Ramachandra TV. Hotspots of solar potenial in India. Renewable and Sustainable Energy Reviews 2011; 17:3178-3186

    V, Solar Thermal

    For more information about this article, contact:


  • anna
    anna -

      India solar insolation figures during different seasons. IISC Like

  • anna
    anna -

    Rajasthan has the most barren land with 2,595 ha, followed by Gujarat with 2,295 ha and Andhra Pradesh (2,056 ha).       Maharashtra, Madhya Pradesh and Karnataka have 1,718 ha, 1,351 ha and 788 ha respectively.  All the above are Ideally suited for CSP.        India  has a vast potential for solar power generation � about 58 per cent of total land area (1.89 million km sq). �It receives an annual average global insolation above 5 kWh per metre sq per day (m sq), Like

  • barani
    barani -

    There is no doubt that plenty of solar energy is available. Even a cursory glance at numbers will show that solar energy shined on earth is at least ten times more than what is presently used by all the living systems on the planet.

    The real problem is how to absorb and store it. The Si solar cells by their inherent physics, cannot respond to different wavelengths. They are restricted by their 1.2eV bandgap. No amount of tweaking will be able to expand it into a broadband device. The present efficiency calculations are only around what is absorbable at that response wavelength. It isn't calculated over what is available across solar spectrum!

    For that matter, even the biological system (chlorophyll in leaf) has specific resonance frequency that enables it to absorb energy at only a specific frequency (actually there are two frequences, but that is just academic).  It is like sipping some water using a straw from river ganga! Rest of the energy goes elsewhere, mostly into thermal excitations.

    Therefore, there is room for everyone to do some research and find ways to trap the rest of the energy.


  • nidhish
    nidhish -

    Joydeep had written that the cost of generation from parabolic trough systems is Rs 5 to 7 per kWh. Does anybody know how this calculation is done? and how to compare this parabolic trough system with a Solar PV one? Like

  • Daniel
    Daniel -

    New source of Solar Resource Data for India
    Here is a link to new source of high-perfirming Solar Resource Data for India: system works very well - it is a fast way how to obtain the solar data for each location in India. 

  • sebastianduerr
    sebastianduerr -

    Just to add my 2ct to this: In Germany the feed-in tariff is a complex thing and can easily be understood in a wrong way.

    It was pointed out that: "
    Advanced countries such as Germany and the US have multiple tariff system based on the exposure of a particular region to solar radiation."

    Fact is that the feed in tariff in Germany is depending on the size of the installation and not on the exposure of a particular region. The dependency on size is a very powerful instrument if you want to promote for instance systems with a size of 10..30kWp. This was the idea behind this system in Germany. 

    If a smaller system is installed on a rooftop, the feed in tariff was/is very high. The limit is 30kWp. From >30kWp to 100kWp the feed in tariff is lower. Installations >100kWp ... 1000kWp will get a feed in tarif that is even lower.  

    If you install the system like a solar farm, you will get different feed in tariffs based on some frame conditions. 

    A very shot overview on this can be found at (sorry, only in German, but you will get a idea).

    About radiation data: Whenever you simulate a system, you should be aware that it is a estimate and nothing else. There are many factors that can't be or can be just in a very rough way simulated: Like MPP tracking dependency on voltage per string, losses within the system, aldebo / reflections, wind-chill factor, etc. Therefore it is good and great if you can get access to irradiation data but you also need temperature data to get better simulation results. 

    Much more on this can be found in the IEC 61724 - Performance Ratio Calculations for solar pv systems where information about the resolution of measured data is given. If you can get irradiation / temperature data with this resolution, you can really start to simulate a system. 

  • krupali
    krupali -

    SPN1 Sunshine Pyranometer for PV Applications

    Photovoltaic developers and triallists find the SPN1 Sunshine Pyranometer from Delta T Devices (UK) a valuable tool for research and for performance validation. When making PV investments, it is essential to identify the best sites. An SPN1 can be used to quantify the available global and diffuse radiation at potential sites. Later, after an installation has been completed and power is being generated, the SPN1 can help to monitor the short and long term efficiency of the panels, and these results can be fed back into improved PV panel design.

    The key advantage of the Sunshine Pyranometer type SPN1 is that it measures global (total) and diffuse radiation, and sunshine state – all in one instrument. It is also easy to use and needs no routine adjustment or polar alignment. Output from an SPN1 Sunshine Pyranometer allows calculation of DNI (Direct-Normal Irradiance) in sun tracking, horizontal and tilted installations. It is a common practice to compare solar panel efficiency to DNI, particularly in solar energy field trials.

    The SPN1 is a meteorological class instrument designed for long-term outdoor exposure, and is an affordable and effective alternative to traditional shade-ring pyranometers, the Campbell-Stokes and other sunshine recorders. It also provides some of the functionality of expensive pyrheliometers: Global (total) and diffuse horizontal irradiance in W.m-2, DNI (Direct-Normal Irradiance) calculation, Sunshine threshold to WMO definition: >120 W.m-2 in the direct beam, No moving parts, no shade rings, no motorised tracking needed, No routine adjustment or polar alignment needed and Works at any latitude.

    The unique design of the SPN1 Sunshine Pyranometer uses a patented array of thermopile sensors and a computer-generated shading pattern to measure the direct and diffuse components of incident solar radiation. The shading pattern and thermopiles are arranged so that at least one thermopile is always fully exposed to the solar beam, and at least one is fully shaded from it, regardless of the position of the sun in the sky. A microprocessor derives the global and diffuse radiation values, which allows an estimate of the direct beam, and hence sunshine hours, to be calculated. The SPN1 Sunshine Pyranometer is protected by patents EP 1012633 & US 6417500.

    I am not sure what pyranameter the Indian EPCs are using. To me it looked good and am just posting . If you know of other appropriate pyranameter pl do post here as a comment. It is welcome.


  • aathmika
    aathmika -

    Solar Irradiation in JLN Medical College, Hospital Road, Ajmer, Rajasthan 305001, India

      Solar Radiation

      Annual Average: 5.78
      Monthly Average

      Geographical Information

      Latitude 26.4691660
      Longitude 74.6354967
      View Map

      Wind Speed

      View Wind Speed in JLN Medical College, Hospital Road, Ajmer, Rajasthan 305001, India

  • Krisan
    Krisan -

    Hello Krupali,

    In response to your note about pyranometers: In general EPCs do not use an all-in-one instrument like that. In an increasingly mature Indian market, EPCs will use pyranometers that meet higher ISO and WMO standards . This improves measurement accuracy and allows them to deliver dependable, bankable data.

    C-WET opts for pyranometers in the top ISO 9060 category: secondary standard. The C-WET measurement stations use the SR20 secondary standard pyranometer for GHI/DHI measurements. It is made by Hukseflux Thermal Sensors in The Netherlands.

    - Like

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