Eduardo Lorenzo

Quality Control of wide collections of PV modules : Lessons learned from the IES experience

This paper presents the Quality Control method for PV modules developed by the Instituto de Energia Solar (IES), an institution with almost 10 years of experience in the field of Quality Control of PV modules associated with supply procedures of PV projects. The method is easy and fast to implement. It consists of Technical and Contractual procedures, both closely related. Concerning the first procedure, detailed description is offered of the type of measurements performed, equipments used, data processing and steadiness control of the method. Regarding the Contractual procedure, after its detailed description an example coming from the Toledo PV plant is offered and commented. The paper then summarises the IES experience on Quality Control processes, together with additional information about time requirements and costs of the IES method. In addition, some reflections upon the possible adoption of the method by countries involved in PV Rural Electrification programmes are finally included. Copyright

Universal technical standard for solar home systems

The need for universally applied specifications for product and system quality is widely recognized as an essential factor for the success of large-scale photovoltaic rural electrification activities. This paper describes a THERMIE-B project that aims to elaborate a technical standard for solar home systems. The universal standard has been developed after a comparison of specifications used in some photovoltaic rural electrification programmes and circulation of the proposal among worldwide experts for a critical review.

SOLAR RADIATION IN MADRID

This work presents a up-date of the solar radiation data for Madrid. All the available data has been collected and systematically written in a computer readable form. This allowed us to create a daily and an hourly data base, containing 34 and 17 years respectively. From these data a Reference Year has been defined. The validity of different correlations between global radiation and its diffuse fraction, models to convert from horizontal to tilted surfaces and the solar energy potential over some representatives fixed and tracking surfaces have been analyzed.

From candles to PV electricity : A four-year experience at Iguape : Cananéia, Brazil

A PV rural electrification experience, based on the solar home system (SHS), is being carried out at a coastal region in the state of Sao Paulo (Brazil). Particular attention has been paid to aspects, relating to the integration of PV technology into the pre-existing social system. Regarding technical aspects, some special features have been designed: a ‘battery shelter’ made by the users; combined use of ‘high power’ fluorescent light with ‘low power’ incandescent light, etc. Regarding organizational aspects the technical training should be outlined. We initially decided to train one user in each community more intensively. This user was chosen from among those who appeared to be more skillful in relation to our requirements. This apparently common-sense oriented procedure was shown to be less than appropriate, because it interfered with social relationships that we knew very little about. We observed that later on the community decided who would be responsible for the maintenance; this time widely accepted by all the users. The technical and organizational aspects together conform to a particular rural electrification scheme that can be useful for general SHS projects. Copyright

Estimation of radiation incident on bifacial albedo-collecting panels

In this paper we present a method to predict the radiation incident on both front and back faces of a bifacial photovoltaic panel surrounded by several diffusely reflecting surfaces. The incident irradiance on the panel is obtained from a mathematical model that considers both the effect of the interreflections between the reflector surfaces and the effect of the collector shadow. The model was validated experimentally for several albedo reflector configurations. The results of applying this model to several configurations of reflector planes using data for Madrid are presented. It is shown that in some cases an increasement in annual radiation incident on bifacial photovoltaic panels of nearly 70% can be achieved when compared to the radiation incident on conventional monofacial panels.

3D simulation of complex shading affecting PV systems taking benefit from the power of graphics cards developed for the video game industry

Shading reduces the power output of a photovoltaic (PV) system. The design engineering of PV systems requires modeling and evaluating shading losses. Some PV systems are affected by complex shading scenes whose resulting PV energy losses are very difficult to evaluate with current modeling tools. Several specialized PV design and simulation software include the possibility to evaluate shading losses. They generally possess a Graphical User Interface (GUI) through which the user can draw a 3D shading scene, and then evaluate its corresponding PV energy losses. The complexity of the objects that these tools can handle is relatively limited. We have created a software solution, 3DPV, which allows evaluating the energy losses induced by complex 3D scenes on PV generators. The 3D objects can be imported from specialized 3D modeling software or from a 3D object library. The shadows cast by this 3D scene on the PV generator are then directly evaluated from the Graphics Processing Unit (GPU). Thanks to the recent development of GPUs for the video game industry, the shadows can be evaluated with a very high spatial resolution that reaches well beyond the PV cell level, in very short calculation times. A PV simulation model then translates the geometrical shading into PV energy output losses. 3DPV has been implemented using WebGL, which allows it to run directly from a Web browser, without requiring any local installation from the user. This also allows taken full benefits from the information already available from Internet, such as the 3D object libraries. This contribution describes, step by step, the method that allows 3DPV to evaluate the PV energy losses caused by complex shading. We then illustrate the results of this methodology to several application cases that are encountered in the world of PV systems design.