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Web-based open source geospatial tool for estimating the solar power potential of cities

At the India Geospatial Forum in Hyderabad, I moderated a session on electric power. It turned out ot be an absolutely fascinating conversation with a wide range of speakers representing different aspects of the Indian power industry.

Alekhya Datta, a Research Associate at the Centre for Distributed Generation, part of The Energy and Resources Institute (TERI) in New Delhi, gave a presentation about a web-based open source geospatial application that has been developed to estimate the solar power generation potential of a city.

TERI promotes renewable energy and is working with the Ministry of Power to develop a roadmap for renewable energy for India. The objective is to install 20 GW of solar PV by 2020. As part of this effort 51 cities have been designated as "Solar Cities" and TERI is working with state governments to develop a program to encourage the installation of solar PV in these cities.

Chandigarh has been chosen to be the first solar city. Chandigarh is the first planned city post-independence and is in the North of India. Its population is about a million.

One of the projects to support the Solar City initative is to develop a high performance and flexible Web-GIS tool to estimate the rooftop solar power potential for a city. It is intended to be low cost, acessible to the public and to use widely available data sources.

Data sources

Satellite imagery (Pleiades-1A) is used for digitizing building rooftops. This is augmented by a digital surface model and meteoroloigcal information so that it can account for shadowing and cloud cover and includes the heights of buildings, trees and utiltiy poles. Rooftop solar analysis is simpler in Chandigarh than in North American and European cities because roofs are flat.

The total number of rooftops that were digitized is about 110,500. In addition about 14,000 buildings were surveyed and of these 50-60 were used for ground-based solar radiation measurement. For a subsample of 5-10 of these, solar pV panels were actually installed on the rooves and the generated power measured.

Estimating the solar potential of cities

The web-based tool was developed using open source geospatial libraries including Open Layers, GeoServer, PostGIS and TileServer and relies on OGC open standards. It is intended to be extended to enable it to be used in the other 50 solar cities including Delhi. It enables users to estimate the rooftop solar power potential of selected area for different types of PV technologies such as crystalline and thin-film. It also provides tools for estimating potential green house gas mitigation through solar rooftop PV systems for a specific area. The tool is available here and Alekhya Datta encourages people to try it.

It is envisioned that it will be used as a decision support system to perform pre-feasibility assessments of viability of devloping a rooftop PV program for a city for a particular region or area in the context of the possible business models and financial schemes that are available in that locality.