W. Folkerts

BIPV Products for Façades and Roofs: a Market Analysis

In this paper, the authors report on a jointly conducted analysis of the current status of the BIPV market starting from a comprehensive overview on the available product, discussing the application ranges and finally by giving the price levels. For this purpose a market survey was conducted among the various stakeholders in the BIPV sector, including architects, installers and BIPV product suppliers. The product survey was conducted for the general European Market and the price survey concerned only Benelux and Swiss markets. The most frequent products analysed were PV tiles and in-roof mounting systems (for residential roofs). Although crystalline silicon technology was most commonly used, thin film technologies gained considerable share in facade products. The data from the price survey showed that new buildings using BIPV products can be executed at very similar costs than projects involving conventional and/or building applied PV products.

Towards simulation-assisted performance monitoring of BIPV systems considering shading effects

Nowadays, the application of BIPV systems is growing very fast and among this type of technology, application of BIPV facade systems is becoming more common. A main question in this field is how we can ensure the intended performance of such systems considering different involved parameters over the systems life-time. To do so, we need to be able to predict normal behavior of BIPV systems in urban environments, considering the effect of shading from neighboring obstructions. This research investigates a combination of real-time shading simulation using Rhino and Grasshopper with BIPV performance monitoring to detect abnormal system operation. The application of this approach is demonstrated for a 12 m2 vertical BIPV system in the SolarBEAT test facility in Eindhoven, the Netherlands. We have conducted an experiment to better understand the impact of different partial shading scenarios on the I-V curve of a vertical CIGS BIPV panel. The results show that the simulation-assisted approach, coupled with data visualization and a decision tree can be a powerful tool for guaranteeing robust BIPV system output.

Outdoor degradation of CdTe modules at open circuit and at maximum power point

A combination of outdoor exposure and laboratory measurements were utilized to characterize the differences in degradation of commercial CdTe modules in two operating modes. The degradation mechanism was observed on an array of 8 CdTe modules operated outdoors in open-circuit conditions. In contrast, a similar array of 8 grid connected PV panels operated at the maximum power point did not show any degradation over the same period of time. Of the degraded panels, Voc and FF degraded 6% and 7% respectively. Electro-luminescence imaging showed large dark areas in the degraded modules. Spectral response measurements showed enhanced response at blue wavelengths but significantly reduced response at red and near infrared wavelengths. Results suggest that degradation studies at representative field conditions are equally important as the standard accelerated ageing methods and should be taken into consideration.

Bottom-up analysis of the solar photovoltaic potential for a city in the Netherlands: A working model for calculating the potential using high resolution LiDAR data

This paper presents a working model to estimate the solar photovoltaic potential using high-resolution LiDAR data and Geographic Information Systems. This bottom-up approach method has been selected to arrive at the potential as this gives a better estimate than a top-down approach. The novelty of the study lies in estimating the potential at high resolution and classifying the rooftop as suitable or not for solar photovoltaic installations based on factors like irradiation, slope and orientation. The city of Apeldoorn in the Netherlands has been selected as the study area. The model was able to successfully locate suitable sites for photovoltaic installations at rooftop level. In addition, the area feasible for the installations and the potential power output has also been calculated. We conclude that the city has a potential of 319 MWp capacity, which would yield 283.9 GWh/yr in relation to the 304 GWh/yr consumption from residential buildings in the area.

A Big Data Approach to the Solar PV Market: Design and Results of a Pilot in the Netherlands

In this paper we explore the value of a big data approach to the solar PV market in The Netherlands. As a pilot we choose a specific area on a scale of 200.000 inhabitants. Available data sets from different sources depicting a variety of relevant parameters were brought onto the same Geographical Information System base. We demonstrate how this approach can help in understanding, planning and controlling the energy system.

Outdoor Characterization of Three PV Architectures under Clear and Shaded Conditions

Building Integrated and Building Applied Photovoltaic (BIPV, BAPV) systems often suffer from low performance due to partial shading. New system arch itectures have been proposed to optimize the energy yield. The common approach of these new architectures is to tr ack the Maximum Power Point (MPP) of every solar mo dule individually. Three independent PV systems were ins talled in Eindhoven, a reference string inverter sy stem, a power optimizer (PO) system and a micro inverter system. We designed a sophisticated monitoring system that allows for a detailed comparison of the three PV systems. We cal culated system and component efficiencies and foun d a good agreement with data sheets provided by the manufact urers. Additionally, we analyzed the performance ra tio for DC and AC of the systems for different weather types b a ed on the clearness index. A pole shading coverin g 1 to 2% of the total system surface has been used to evaluate sys m performance under a specific type of partial shading. Module Level Power Electronics (MLPE) are capable of increasing the Performance Ratio (PR) up to 35% under certain partial shading conditions. However, the st ring inverter system outperformed MLPE under unshad ed operation conditions.

Annual Yield Comparison of Module Level Power Electronics and String Level PV Systems with Standard and Advanced Module Design

This study focuses on the partial shade-mitigating effects related to the insertion of additional ideal bypass diodes in residential-scale photovoltaic (PV) systems. For this purpose, quantification of the resulting energy yield benefits is carried out in a representative residential environment. It is widely recognized that partial shading inflicts disproportional losses to the energy output of PV systems. Increased granularity levels in cell groups are perceived as a potentially promising measure to increase the shade-tolerance of photovoltaic devices. The past years, introduction of module level electronics promise to reduce further shading losses. The developed model includes a shading evaluation of the installation with means of 3D modeling, insertion of additional by pass diodes resulting in smaller cell groups, irradiance calculations, PV cell modelling and finally an empirical power conversion model. Results suggest that in the reference case of 3 by pass diodes the micro inverter system is performing the best under partial shading. By increasing the cell group granularity the string inverter systems seems to benefit due to the wide maximum power point voltage window.

Self-Shading in Bifacial Photovoltaic Noise Barriers

There is a large market potential for Bifacial Photovoltaic Noise Barriers (PVNB) due to their high energy output for any road orientation. A crucial parameter affecting their energy output is the so-called self-shading. In this research we evaluate the effect of self-shading on the energy production of both an east and west facing bifacial PVNB. We followed an approach consisting of 1) Experimental investigation by accurately monitoring the power output of two bifacial PVNB prototypes, 2) Shading simulation using in-house developed simulation methods. Results show that in particular noise barriers on north-south aligned roads suffer from self-shading because the support structure of the noise barrier itself casts a shadow on the PV modules around noon. A strong correlation is found between clearness index and energy yield loss. On sunny days the energy loss can be as high as 5%. The year average for the loss is about 3%. Clear design guidelines for minimizing the impact have been derived. We conclude that our measurement method, simulation tools and derived design guidelines provide a way to assess and minimize the effect of self-shading on the energy output of bifacial photovoltaic noise barriers, leading to better energy yields and more market success for this type of application.

Yield modelling for micro inverter, power optimizer and string inverter under clear and partially shading shaded conditions

Building Integrated and Building Attached Photovoltaic (BIPV, BAPV) systems may suffer from lower performance than predicted as a result of unwanted partial shading. New system architectures have been proposed to optimize performance. The common approach of these new architectures is to track the Maximum Power Point (MPP) of every solar module individually. A simulation model is developed to quantify the benefits and drawbacks of different PV system architectures. The model includes a shading evaluation of the installation with means of 3D modeling, irradiance calculations, PV cell modelling and finally an empirical power conversion model. The energy yield of three leading architectures is confirmed (string inverter, power optimizer, micro inverter) for clear and partial shading conditions by means of an outdoor field test. Results show that there is a clear benefit for MLPE systems at higher irradiance when partial shading is present. The analysis method can be used by PV installers and system designer to determine which is the optimal system architecture for maximum energy yield especially when partial shading is present.