ShadowsBuildings, trees and other structures in urban areas cast shadows on solar panels, which greatly affects their performance. An accurate estimation of this performance and the related cost-performance ratio of solar energy systems (PV systems), can ensure a better integration in the urban environment.
Much computing powerMultiple tools are used to simulate the energy production of PV systems. These use mathematical models that determine the amount of irradiation on the solar modules. By repeating these calculations for an entire year, these tools deliver an annual number for the irradiation received by the panels. However, it is not that easy to determine how much electricity a PV system generates in an urban area. Current simulations require much computing power, as the shadows cast by nearby structures change throughout the year as a consequence of the annual movement of the sun, have to be taken into account.
Two parametersA new approach simplifies this calculation and enables the user to asses the potential of solar energy in larger urban areas quickly and accurately. The method is based in the correlation between the skyline profile and the annual irradiation received at a particular urban location. This is explained and substantiated in a study that has been published in Nature Energy. The research shows that the total annual solar irradiation that a particular surface in an urban area receives, can be quantified based on two parameters derived from the skyline profile: the sky view factor (that part of the sky hemisphere that is visible from a particular location) and the sun coverage factor (measure for the amount of sun). The first parameter is used to estimate the amount of radiation due to diffused light, the second is an indication for the amount of radiation from direct sunlight. These two parameters are easily and quickly obtained from the skyline profile. The study demonstrates that using these two parameters significantly reduces the computational complexity of the problem.
Software toolboxThe research group Photovoltaic Materials and Devices (PVMD) has now integrated this method in a software toolbox that can accurately calculate the energy production of PV systems in any arbitrary location. The research was carried out as part of the program Solar Urban at the Technical University Delft. The research has been published in Nature Energy.
Source: TU Delft