Solar mapping and monitoring (SolMap)

Project description

Title: Solar mapping and monitoring (SolMap)
Commissioned by: German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU)
Country: India
Lead executing agency: Ministry of New and Renewable Energy (MNRE), Government of India
Overall term: 2010 to 2015


In 2010, India launched its National Solar Mission, which is one of the major initiatives worldwide to promote solar energy. The Mission provides a policy framework that includes regulatory measures as well as financial and fiscal incentives for the deployment of solar systems which generate grid-quality power while meeting electricity and heat needs in off-grid mode.

The aim of the Mission originally was to establish 20,000 megawatts (MW) of grid-connected solar power by 2022, while also running 2,000 MW-equivalent of off-grid applications and gradually increasing the solar thermal collector area to 2,000 hectares. This target got enhanced subsequently to 100 gigawatts (GW) of grid connected solar power capacity by 2022.

The availability of reliable and accurate solar radiation data is crucial to achieving these targets. For feasibility assessments, power plant designing tasks and bankability concepts – in all levels the precise and accurate information on the available solar resource is fundamentally important to possess. India so far did not have the adequate infrastructure of a nationwide network on precise solar radiation measurement. Starting from understanding the basic characteristics of solar radiation over specific monitoring locations till estimating the variability of solar radiation for the grid operators, from high time resolution phenomena like fluctuations, ramps and peaks till long term climatological features like average values and interannual variations as found in solar atlases, a broad spectrum of knowledge should get opportunity to be accumulated for the first time in India.

Similarly, it is also important that project developers, operators and investors can evaluate the real life performance of the solar plants commissioned under the scheme. A benchmarking system for a country wide photovoltaic (PV) performance comes from an idea to collect PV plant operation data at a central location, do an automatic data analysis by calculation of performance indicators which can be used to compare plant performance and for sending appropriate feedback information to the plants for improving the performance.


A system has been established for collecting weather information and comprehensive data on solar radiation that can be used by a broad solar energy community for several purposes and also for the preparation of solar radiation resource maps of India. A performance benchmarking system has also been developed and tested for improving the solar power plants’ performance.


The project supported the Ministry of New and Renewable Energy (MNRE) in establishing a network of solar radiation data monitoring units around India, as part of the countrywide Solar Radiation Resource Assessment (SRRA) initiative. The units measure solar and other relevant meteorological parameters. To this end, the project enhanced the exchanges and cooperation between relevant institutions and experts to transfer German experience and know-how in the field of solar resource assessment. Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH supported the National Institute of Wind Energy (NIWE) in the development of an accurate and enhanced-value database for information on solar radiation and other weather parameters. Such a precise and bankable database is essential for designing and planning for solar power deployment in India. The SRRA network is operating successfully in India, and accumulating precise solar and weather related information.

The project also introduced a mechanism for the systematic evaluation and benchmarking of the technical performance of large grid-connected photovoltaic (PV) power plants. A performance benchmarking scheme is developed that enables an easy overview of the performance of solar power plants in different climatic zones, using different technologies, tracking options etc. In this way, a substantial knowledge pool is being developed, with which to estimate yields under real operating conditions, during the planning stage as well as to provide valuable feedback for individual plants to enhance their operating effectiveness.


  • 121 solar radiation measuring stations have been set up throughout India covering each State by MNRE/NIWE with support from GIZ. This is the world’s largest pyrheliometric measurement network with high precision data logging.
  • Sophisticated procedures have been introduced for the quality control, processing and dissemination of data. Quality controlled time series data streams have been generated for all the measuring stations, and monthly reports are also published.
  • The Solar Data Sharing and Accessibility Policy (2013) of MNRE was introduced with restricted access for the public in the beginning. Specific data products, on types of radiation in various temporal resolutions, have been made available to the public afterwards and these were being accessed and used increasingly by the solar energy industry. By the end of 2014, almost 230 of such solar data products had been procured by the users. In 2017 the entire data from the measurements stations were made completely freely accessible for the public.
  • The typical meteorological years (TMY) for a few locations, with particular emphasis of direct solar radiation for CSP technologies, have been established by combining data gained from the SRRA with satellite-based models.
  • Four advanced monitoring stations have been set up, with facilities to measure aerosol optical depth along with several other kinds of measurements. Those four advanced monitoring stations have been selected to be part of the prestigious BSRN (Baseline Surface Radiation Network) of WMO (World Meteorological Organisation). This is the first time when Indian measurement stations got accredited by the BSRN.
  • Calibration laboratory for solar radiation sensors was built and made operational in two locations
  • Ground measurements were combined with satellite-derived data and a precise Solar Radiation Atlas of India was launched in 2015. The atlas has several kinds of maps including GHI, DNI and DHI information for the last 16 years.
  • A procedure for undertaking PV performance benchmarking has been developed. Further testing concluded with samples of monitored data streams from 119 PV plants provided by MNRE. These were located across 12 of India’s federal states and, at the outset of 2014, comprised approximately 25 per cent of the country’s total grid-connected PV capacity. A working PV benchmarking analysis tool, with robust analytical features, has been demonstrated.
  • SRRA data are being used by several other projects in the domain of forecasting, balancing and grid integration of solar power.
  • About 70 research institutions are hosting the SRRA measurement stations. Significant progresses have been made concerning the awareness creation and usage of the solar radiation data among the academia in India. Several scholarly studies, thesis works and recent research initiatives have used the SRRA database.
  • The outcomes of the project have been published in more than 10 peer-reviewed academic journals and professional global conferences proceedings.
  • Overall the green energy community is getting continuous benefit from the data and scientific knowledge being generated out of this initiative.