May. 26, 2020


Object-Based Image Procedures for Assessing the Solar Energy Photovoltaic Potential of Heterogeneous Rooftops Using Airborne LiDAR and Orthophoto


BGU Professors Arnon​ Karnieli and Isaac A. Meir, and their Ph.D. student, Arti Tiwari, developed a new method to assess the feasibility of roof utilization for Photo Voltaic (PV) installations, using the southern Israeli city of Kiryat Malachi as their test site and utilizing an orthophoto produced by the Survey of Israel in 2012. Digital Terrain Models and Digital Surface Models were created by an airborne light detection and ranging (LiDAR) map in 2015. After combining the data, an aspect-slope map was produced with a 97.39% accuracy.


AbstractAvailable renewable energy resources play a vital role in fulfilling the energy demands of the increasing global population. To create a sustainable urban environment with the use of renewable energy in human habitats, a precise estimation of solar energy on building roofs is essential. The primary goal of this paper is to develop a procedure for measuring the rooftop solar energy photovoltaic potential over a heterogeneous urban environment that allows the estimation of solar energy yields on flat and pitched roof surfaces at different slopes and in different directions, along with multi-segment roofs on a single building. Because of the complex geometry of roofs, very high-resolution data, such as ortho-rectified aerial photography (orthophotos), and LiDAR data have been used to generate a new object-based algorithm to classify buildings. An overall accuracy index and a Kappa index of agreement (KIA) of 97.39% and 0.95, respectively, were achieved. The paper also develops a new model to create an aspect-slope map, which combines slope orientation with the gradient of the slope and uses it to demonstrate the collective results. This study allows the assessment of solar energy yields through defining solar irradiances in units of pixels over a specific time period. It might be beneficial in terms of more efficient measurements for solar panel installations and more accurate calculations of solar radiation for residents and commercial energy investors.​

The project was reported in the Times of Israel (May 21, 2020) and on the Green Prophet site (May 21, 2020):

Read here recent article in Times of Israel:

Researchers develop system to measure solar energy potential of city roofs

Ben Gurion University team maps roofs across entire southern city of Kiryat Malachi with 97% accuracy

By Sue Surkes, May 21, 2020

Read here recent article in Green Prohet:

Calculate your cities' solar power potential
There are companies and apps that do it already from the comfort of your own home: you can check the solar panel potential output from your roof. Is the angle right? Are you on the grid? Are you in the right latitude or longitude or what does it all mean? What company do you choose? Type of solar panel?  Local or from the big city? Contracts? Loans? There are lots of things to think about. Rather than have the individual homeowner or business brave it alone a new project out of Israel, masters of solar energy innovation and implementation, helps cities decide if they should go solar.

By Karin Kloosterman, May 21, 2020