A PHOTOVOLTAIC POTENTIAL MODEL WITH EXTENSION TO BUILDING FACADES S. Freitas 1,2, D. Martins 1, P. Redweik 3,4,5, C. Catita 3,4, C. Rodrigues 6, A. Joyce 6, M. C. Brito 3,5 1 SESUL – Centre for Sustainable Energy Systems, University of Lisbon 2 MIT Portugal - Sustainable Energy Systems Program 3 IDL - Instituto Dom Luiz, University of Lisbon 4 Centre of Geology, University of Lisbon 5 DEGGE – Department of Geographic Engineering, Geophysics and Energy, University of Lisboa 6 LNEG – Laboratório Nacional de Engenharia e Geologia

Why solar potential models for the urban environment? We need the sun… Cities as great consumers of energy Nearly Zero Energy Buildings (nZEB) Fast technological improvement of solar energy Decreasing costs of PV Increasing public acceptance However… Limited available area Insufficient solar radiation Unfavourable meteorological conditions Obstructions from the surroundings Regulating Energy Efficiency in Urban Contexts The design of modern cities must be oriented towards the taking of the full potential of the solar resource 2

SOL: the solar potential model Light Detection And Ranging (LiDAR) Digital Surface Model Typical Meteorological Year (SolTerm database) Mathematical sun-path model Sky View Factor Shadow algorithm: horizontal vs vertical surfaces Complete irradiation map (1 hour time step, 1x1m 2 ) 3 Redweik et al, Solar Energy 97 (2013) The algorithm:

SOL: the nouvel approach to vertical facades In modern cities, the ratio between roof area and facade area is high Redweik et al, Solar Energy 97 (2013) Vertical PV facades will produce relatively more power in winter and less in summer Different solar facades of a building will produce at maximum power at different times of the day Soiling rates will be much lower when PV panels are vertically installed Less maintenance will be required Solar potential doubles! What is interesting about facades?

SOL: Validation case study – LNEG Solar XXI building facade 5 IST

6 SOL: Validation case study - Methodology 12

1. Measured Radiation to Photovoltaic production SOL: Validation case study – LNEG Solar XXI building facade 7 Marion, B., Prog. Photovol: Res. Appl.10, (2002)

8 1. Measured Radiation to Photovoltaic production SOL: Validation case study – LNEG Solar XXI building facade Shadow events

9 1. Measured Radiation to Photovoltaic production SOL: Validation case study – LNEG Solar XXI building facade

10 SOL: Validation case study - Methodology 12

SOL: Validation case study – LNEG Solar XXI building facade Irradiance on vertical surfaces (30th November 3pm) South Digital Surface Model South Individual facade assessment VS Measured data

SOL: Validation case study – LNEG Solar XXI building facade 12 3 %

Main conclusions and next steps… 13 1x1m 2 radiation grid Interpolation and smoothening to a 0.2x0.2m 2 radiation grid Distribution of the strings on the facade Different spatial resolutions and smoothening of shadows

In the future…