30th, 2013 at cea ines, Le Bourget du Lac (France) summary

Keywords: photovoltaic double façade, natural ventilation, stack effect

- Jordi Cipriano (CIMNE, Spain): Evaluation of the electrical and thermal energy performance of a ventilated Building Integrated PV component in outdoor conditions

J. Cipriano^a, C. Lodi^b, X. Cipriano^a, J. Carbonell^a, Gonzalo Gamboa<sup>a

a</sup> CIMNE-Building Energy and Environment Group, Gaia Building-UPC Campus Terrassa,

^c Rambla St Nebridi 22. 08222. Terrassa, Spain

^b Department of Engineering_Enzo Ferrari_, University of Modena and Reggio Emilia, via Vignolese 905/B, 41125 Modena, Italy

Abstract

Experimental results of an extensive monitoring campaign of a ventilated double skin BIPV system are presented. Measurements have been carried out at the outdoor Test Reference Environment (TRE-L) for double skin applications of Building Integrated Photovoltaic (BIPV) located in Lleida (Spain). The TRE-L facility allows testing photovoltaic systems integrated as double skin components in outdoor conditions. The energy performance of the ventilated PV module placed at the TRE-L opening is compared with that of other two identical reference PV modules. One of the reference modules is fully insulated while the other one is kept under free-rack conditions. Several experiments, at different inclinations, forced ventilation regimes and laminar and turbulent airflow conditions are performed and a comprehensive sensitivity analysis of results is presented. Energy and exergy analysis of each situation is carried out. Attention is paid to the influence of different rear-facing materials on the thermo-electrical performance of the system.

Keywords: ventilated BIPV facades, monitoring campaign, sensitivity analysis, Test Reference Environment

ANNEX 4: DETAILED MINUTES

The workshop took place at CEA INES site (Lynx 4 – Room 107) from 29^th to 30^th of August 2013. 43 participants have attended this event, coming from France, Italy, Germany, Australia, Austria and Spain. The participants were composed of Research Engineers and Technicians, Architects, Industrials, Installers and Associations.

Day 1: Question: What are the Requirements of Solar Photovoltaics in Buildings?

On the first day, through the presentations, participants defined a list of requirements.

Current BIPV systems requirements in Europe
BIPV system imply to consider electricity production, Building energy regulation and construction requirements.

The requirements of BIPV systems come from different actors (architects, engineers, construction companies and workers, building users and operators and Building Authorities) and are related to quality standards.

Requirements related to actors
Building Authorities are important actors since they can interrupt the project at any time.

For successful projects of BIPV systems installations, many requirements are to consider: workers safety, fire safety, integration criteria and limits, shadings, kind of building, urban regulation, building thermal regulation and esthetics of the integration at the building and the city levels, payback time, recyclability. Also, knowledge is required on when energy is needed, where it is needed and in what form it is required.

In some cases, these requirements differ. PV modules are still not considered as construction products in each country.

There is a need to bring solutions to the deviations between the PV world and the Construction world.

Requirements related to standards

- The main requirements of BIPV are linked to mechanics, electrical safety, waterproofness, mechanical strengthening…

An analysis of existing Pr EN 50583 Building standard shows that some requirements are considered for a BIPV system.

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  Mechanical rigidity and structural integrity;
  
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  Primary weather impact protection; rain, snow, wind and hail;
  
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  Energy economy (shading, daylighting, thermal insulation);
  
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  Fire protection;
  
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  Noise protection which seems to work for BIPV.
  

No special electrical requirements exist for BIPV in Pr EN 50583 standard. CENELEC is currently defining new standards corresponding more to BIPV.

The question is: Won’t these standards correspond to free ranking PV modules too since they will not be realized in an integration configuration (higher temperature level, other safety requirements…)?
Improvement Ideas
The discussion shows that there is a need for harmonization of BIPV requirements in each country.
Standards:

- Development of standards adapted to BIPV systems and independent from previous official standards should be encouraged in order to meet the requirements of European Building Authorities;

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  Necessity of fire safety tests within the Euroclasses (e.g: Euroclass A2);
  
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  Necessity to adapt the standards to high temperature level;
  
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  Necessity of specific standards applied to BIPV components as building components (local and international).
  

- Need for guarantees of products by European banks;

- Need for harmonization of standards, boundary conditions, security;

- Need of Standard tests surrounding new monitoring methods.
Products:

- Architects requirements (esthetics, low cost, energy production) are considered too far from reality according to some industrials. If architects exchange with industrials in order to match their requirements, some improvement of the situation should be possible.

- Industry: Lack of integration solutions, products: the cheapest, the best;

- Need to adapt the configuration, size of PV modules to BIPV system installation. We have to push the offer of products: color, size, integration structure. Need of suitable products.

Numerical models could be used to define new field of PV modules (with adapted optical properties, material, size…). For example, it is more efficient to change the backsheet of the PV modules than their color or their front side.
- To improve BIPV design at the building level: need for inputs for building energy simulation;

- Constructions: Need to take into account the cost and timeline (too much time before obtaining products certification).

Training sessions

- Proposal to realize training sessions after this workshop in order to diffuse its results.

The training sessions should be differentiated according to the audience. For example, architects are not interested to projects but to products. Technicians have other interests in the training…

- Common channels of communication must be used to inform people too. Webinar could be a solution to present the results of the workshop.

Day 2: Question: Do we need new testing and modeling methods, guidelines for BIPV systems studies?

Current situation
There is an urgent need for improvement since the topics of the first BIPV system projects (from nearly 20 years ago) are still relevant.

- The existing softwares and general equations, the usual time steps are not always suitable for BIPV systems.

- Industry: Need to demonstrate the performance (efficiency) of their systems by using simplified numerical models, macros or test methods of various kind of configuration (façade, roof, sunshade…)
Improvement Ideas
- Need for harmonization of testing and analysis (in IEC standards) methods.

- Need for more and more accurate modeling and testing methods concerning optical analysis:

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  Spectral transmittance and reflectance measurement at real operating angles of incidence;
  
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  Angular reflectance losses modeling for high angular losses.
  

- Good quality monitoring data is required for model validation;

- Simple linear models are reasonably accurate despite system complexity. Empirical models could be used to set guidelines for control systems.

- Proposal to contribute to 61215 and 62646 standards by introducing the ICT (fully insulated condition) test.

- Proposal to provide guideline offsets from NOCT/NMOT for pre-defined fully and partially insulated conditions (basis in existing JRC work).

- Proposal from to adapt DERlab Guidelines on testing methods to BIPV system in SOPHIA project framework;

Wrap-up discussion: Actions proposal

1- We must define priorities;

2- Action to harmonize building thermal regulation calculation methods and energy building simulation results: In the actual Building Thermal Regulation, the calculation of building energy efficiency doesn’t take into account BIPV systems. This calculation is different from the equations integrated into dynamic simulation tools such as Energy plus.

An action is proposed to convince CSTB or other regulation authorities in order to modify the regulation calculation by taking into account BIPV systems.

For that, we need to realize a comparison of several numerical models or softwares in order to define one which could be a reference for taking into account BIPV systems efficiency and thermal and electrical interaction with building.
3- Need for harmonization:

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  Targeting the audience,
  
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  Harmonization of standards: define or complete a list of limits concerning BIPV application: temperature level to be considered during testing. Combination of all EU standards to prove that some tests are current reference in other countries.
  
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  Harmonization of input/output parameters used in models.
  

4- Need to define a best practices document, certification: in the framework of SOPHIA project (such as GMPV-FFB guidelines for BIPV installations).

6- Realization of a European project on BIPV in order to find solutions to some problems: for example concerning interaction between integrated PV modules and building behavior.

7- Proposal to present a summary of the workshop at EUPVSEC in order to have more audience and opinion.

8- Possibility to join DERlab in SOPHIA project for the adaptation of their Guidelines to BIPV system: call for interested participants; send email to Vincent Helmbrecht and Brigitte.
- Brigitte has to send a minute of the workshop.

- This minute should be completed by participants in order to define an action plan. Each interested participant should send to ASSOA Ya Brigitte a list of requests concerning BIPV according to his activity.