India Solar Resource Maps

Posted on January 9, 2011


India Annual DNI solar map

I’ve got some old but exciting news!!

The U.S. National Renewable Energy Laboratory (NREL) in cooperation with India’s Ministry of New and Renewable Energy (MNRE), through funding from the U.S. Department of Energy(DOE) recently released solar maps for India; Now this is very exciting news considering the timing of the Solar India Project. I was ecstatic to find that they have made GIS data public which was not the case before. Up until now we have had only low resolution static maps to work with, but now with GIS data and high-resolution solar maps, one can extrapolate information for specific states and cities from this larger dataset.


The new dataset contains high-resolution solar resource maps and data for India. The high-resolution (10-km) solar resource data was 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.

The dataset includes monthly and annual direct normal irradiance (DNI) and global horizontal irradiance (GHI) maps. These maps were developed from hourly data spanning January 2002 to December 2008 generated through application of the SUNY satellite to irradiance model.

In English, it means that these maps show direct (normal) incident, diffuse (horizontal) and global (direct+diffuse) horizontal radiation data in Watt-hour per square meter (wh/m2). This data is also adjusted for the time zone difference (+5.5 GMT). I love the fact that you can download hourly data in a .csv format. You do this by typing in the longitude and latitude for the location of your choice. I downloaded data for my home town Hyderabad by typing in the geographical location: 17.366 N and 78.476 E and the closest cell of data available was 17.35 N and 78.45 E – pretty close eh!

The downloaded file has data for both un-shifted time and shifted time (i.e, applying the time zone difference). I created daily averages from the hourly data along with averages (Figure 1).

Obviously, from the solar applications perspective, it makes more sense to see the data for each month. So I calculated the monthly and annual average data (figure 2 and 3 below). The dashed lines indicate annual averages. So, Hyderabad receives 140  and 55 kWh/m2 direct and diffuse radiation respectively. It receives approximately 5 kWh/m2/day annual global incident radiation.

Hyderabad Solar Data
Source: NREL

Coming soon: A tool that can calculate the incident radiation at any given point in India!

I’m excited about this tool! I will post it as soon as it is complete, so look forward to it!

Until then,




Posted in: GIS, Solar, Solar Thermal