The efficient use of energy and development of renewable sources has become an important aspect of the debate concerning global climate change and environmental politics.

Lidar, which stands for Light Detection and Ranging, is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth. These light pulses—combined with other data recorded by the airborne system— generate precise, three-dimensional information about the shape of the Earth and its surface characteristics.

SUN-AREA Method

Calculation of roof solar potential (SUN-AREA) : The aim of SUN-AREA, is to determine how the use of solar power can be optimised on urban roof areas using photovoltaic (PV) and thermal solar panels. A computer-aided analysis technique using Lidar and plan-view data can be developed to identify areas of high potential for the use of solar power.
A sequence of algorithms utilising grid and vector GIS functions is able to measure all necessary data, such as form, inclination, orientation and shaded areas of each roof. The algorithm yields the total energy which can be produced using solar power over the entire city and by each individual household. For solar potential analysis it is essential that even the smallest structures, such as dormers or chimneys, be taken into account; these areas are eliminated from the calculations as they reduce the total area available over which solar cells can be installed.

Lidar Data

Lidar data proved extremely useful for performing exact-site analyses of solar roof systems in large regions. High accuracy means homogeneous roof areas can be selected; roof superstructures such as dormers or chimneys can be identified, and site parameters such as roof exposition, roof slope, size of roof area and insolation energy determined.

Shading Analysis

Lidar data also allow calculation of an all-year shading analysis for the entire area. This is possible by taking into account any objects that create a shadow, such as vegetation, high buildings or objects like poles . Shadows cast by vertical objects onto solar panels can cause significantly greater power reduction than sub-optimal orientation of the generator. Even partial shading of a module can diminish the overall performance of the installation; any degree of solar generator shading should therefore be avoided.
The radiation-tracking algorithm determines changing strength of incident solar radiation on the roof throughout the day for different seasons. A roof pixel is classified as shadow if an obstruction cuts the beam. Every area of roof shaded during the period of observation is deemed unsuitable for PV use and thus excluded from further calculations.

Classifying Potential

In the final process of the methodology, polygons are generated representing homogeneous non-shaded areas of the roof in both slope and orientation. Parameters of solar energy potential are calculated for each suitable area: insolation, roof size, potential electricity generation, potential CO2 savings, power in kilowatts and investment volume.