Modelling and simulation of bifacial PV modules by implementing the ray tracing technique

Louw, Jobert (2020-03)

Thesis (MEng)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: This thesis shows how ray tracing can serve as an accurate irradiance mod-elling technique for bifacial PV modules. The electrical behaviour of bifacial modules is also modelled through investigation and development of two electri-cal models. Bifacial PV modules can increase the power output per unit area when compared to monofacial PV modules. This is made possible by exposing the PV cells of a bifacial module to the incident irradiance on the front and the rear side. This potential increase in power output allows bifacial PV to be an important role player in the growth of PV technology in the renewable energy market. In order to advance bifacial PV as the primary technology in the solar market, it is necessary to accurately model and simulate bifacial mod-ules. Existing bifacial PV simulation software mostly implements view factors which proves to be ineffective in accurately modelling the rear side irradiance of modules. There are some uncertainties regarding the electrical performance of bifacial PV, which can be significantly reduced once an accurate model is established for the technology. An irradiance model is developed by implementing ray tracing to model the front and rear side irradiance of bifacial modules. The irradiance model is verified by comparing modelled irradiance with irradiance measurements from an experimental bifacial PV installation. Two one-diode electrical models are implemented for bifacial modules. The two models are verified by comparing modelled power with measured power of a single bifacial module in a bifacial installation. The bifacial PV simulation software is developed by integrating the irradiance and electrical models with the python development language. After verification, the simulation software is used to simulate the effects of tilt angles, tracking, module height, albedo and row spacing on energy performance and bifacial gain of bifacial modules. A comparison is also done with existing commercial simulation software in order to determine the difference in accuracy between view factor and ray tracing models.

AFRIKAANSE OPSOMMING: Hierdie tesis toon hoe 'ray tracing' kan dien as 'n akkurate bestralings model-lering tegniek vir tweesydige PV modules. Die elektriese gedrag van tweesydige modules word ook gemodelleer deur ondersoek en ontwikkeling van twee elektriese modelle. Tweesydige PV modules kan die krag uittree per eenheid area vermeerder in vergelyking met eensydige PV modules. Dit word moontlik gemaak deur die PV selle van 'n tweesydige module bloot te stel aan die inkomende bestraling van byde die voor en agter kant. Hierdie potensiële ver-meerdering in krag uittree veroorsaak dat tweesydige PV modules 'n belangrike rol speel in die groei van PV tegnologie in die hernubare energie mark. Om sodoende tweesydige PV te vestig as die primêre tegnologie in die son ener-gie mark, word akkurate simulasie en modellering van tweesydige PV modules benodig. Bestaande tweesydige PV simulasie sagteware implementeer meestal 'view factors' wat bewys dat dit oneffektief is in die akkurate modellering van die agterkant se bestraling. Daar is ook 'n reeks onsekerhede rakende die elek-triese gedrag van tweesydige PV modules, wat aansienlik verminder kan word sodra 'n akkurate model gevestig word. 'n Bestralings model word ontwikkel deur gebruik te maak van 'ray tracing' om die voorste en agterste bestraling van tweesydige PV modules te modelleer. The bestralings model word geverifieer deur die gemodelleerde bestraling te vergelyk met bestraling soos gemeet op 'n tweesydige PV installasie. Twee een-diode elektriese modelle word geimplementeer vir tweesydige PV modules. Die twee modelle word geverifieer deur gemodelleerde krag uittree te vergelyk met gemete krag uittree van 'n enkele tweesydige PV module in 'n tweesydige PV installasie. Die tweesydige PV simulasie sagteware word ontwikkel deur die integrasie van die bestralings en elektriese modelle met behulp van die python ontwikkelings taal. Na verifiëring, word die simulasie sagteware gebruik om die effekte te simuleer van kantel hoeke, opsporing, module hoogte, albedo en ry spasiëring op energie opwekking en tweesydige aanwins. 'n Vergelyking word ook getref met bestaande kommersiële simulasie sagteware om sodoende die verskil in akkuraatheid tussen 'view factor' en 'ray tracing' modelle vas te stel.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/107857
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