OUTDOOR CHARACTERIZATION OF INNOVATIVE BIPV MODULES FOR ROOF APPLICATION

C. Polo Lopez1, F. Frontini1, P. Bonomo1, F. Cais2, D. Salvador2 1SUPSI, Institute for Applied Sustainability to the Built Environment (ISAAC), Lugano, Switzerland

2Tegola Canadese, Via dell'industria, 21 - 31029 Vittorio Veneto (TV) Italy

Mail to: francesco.frontini@supsi.ch; phone +41 (0)58 666 63 20 fax +41 (0)58 666 63 49

ABSTRACT: In the framework of the European project Construct PV, two different real scale roof mock-up have

been installed, one at SUPSI campus in Lugano (Switzerland) and one at Tegola Canadese Headquarter in Vittorio

Veneto (Italy). Purpose of this paper is the investigation of the BIPV solar shingle developed within the project that

consists of a durable laminated PV glass (containing crystalline solar cells) integrated onto a waterproofing back

membrane bitumen-based with the aim of ensuring an easy-mounting and on-site customization. The test-facilities are

aimed to demonstrate and to show the Construct PV technology (visits, professional development and student’s

training, etc.) as well as to monitor the main energy performance of the new BIPV shingle in comparison to other

BIPV roof systems already on the market. Electrical BIPV performances (energy production, performance ratio,

temperature of modules, etc.) and some building performances (watertightness, temperatures, ventilation, etc.) are

analyzed and discussed, showing strengths and weaknesses of the technology in a multicriteria perspective involving

both energy and constructive requirements. This paper presents the preliminary achievements of the monitoring

campaign carried out during the first months of installation.

Keywords: BIPV, Building Integration, Performance, Roof integration

1 INTRODUCTION

Renewable energy systems, such as Photovoltaics

(PV), play an important role in the scenario identified by

the European Directive on Net Zero Energy Buildings

(ED 2010/31/EU) [1], and are mandatory in order to

reduce the energy demand of buildings and to contribute

to a more rational use of the energy resources.

Within the European project Construct-PV

(http://www.constructpv.eu/) new solutions have been

developed with the purpose of achieving a cost-effective

integration of photovoltaic (PV) technologies in the

building envelope, both in roof and façade. Construct-PV

research project (FP7-ENERGY-2011-2) has the goal to

develop and demonstrate customizable, efficient and low

cost BIPV for opaque surfaces of buildings [2-4]. The

consortium involves selected partners, connecting all the

actors of the value chain, including manufacturers,

architects, research centers and contractors working on

PV and building sectors.

In a first part of the project a detailed analysis of the

BIPV market (WP1) has been performed in order to

evaluate the attractiveness of innovative BIPV solutions

and to understand their evolving opportunities and threats

[5]. Furthermore, other aspects as the Life Cycle Analysis

(LCA) and Life-cycle cost analysis (LCCA) have been

investigated to determine the most cost-effective options

among different competing alternatives [6]. All these

analyses contributed to identify the essential

requirements and features which have been translated

into product technical specifications during conceptual

and detailed design of Construct-PV solutions. The

process involves the manufacturing phase (WP2 and

WP3), the development and demonstration of a radical

evolution of BIPV opaque products, from BIPV-modules

to multifunctional building systems with added

functionalities (WP4), besides considering these new

components within an integrated approach of the whole

building process (WP5). For this reason, a set of

demonstrative installations have been realized within the

project, including two small scale test-facilities (that will

be discussed in this paper) for roof and a real-scale mock-

up, prepared by the coordinator of the project Züblin AG

for the façade systems, that will have a round-trip around

European events in next years [7]. Moreover, two real

scale buildings will also be used as large-scale

demonstrators in Athens and Stuttgart and they will be

completed in the next months to respectively show the

roof and façade BIPV technologies.

An important part of the process of product

development is undoubtedly establishing their technical,

technological and constructive requirements to meet the

recent new standards for BIPV products [8], such as the

essential building requirements as specified in the

European Construction Product Regulation CPR

305/2011, and the applicable electro-technical

requirements as stated in the Low Voltage Directive

2006/95/EC / or CENELEC standards. For this reason it

has been necessary to perform specific tests for the

electrical and constructive characterization of the

products also by defining proper standard references and

testing procedures for Construct-PV products.

The test facilities are aimed at both demonstrating

and disseminating the Construct PV technology (visits for

roof industries and associations, professionals and

student’s training) as well as monitoring the

performances of the new Construct-PV solutions and to

compare them with existing systems on the market.

2 SMALL-SCALE TEST-FACILITIES FOR

DEMONSTRATING THE ROOF BIPV SHINGLE

As mentioned before, a couple of small scale

facilities for testing and demonstrating the Construct-PV

roof shingles have been installed both at of Tegola

Canadese S.p.a. headquarter in Vittorio Veneto, Italy and

at SUPSI Campus, Lugano, Switzerland. These outdoor

facilities consist of two roof test-stands representing

different solutions to be monitored in parallel to compare

the ConstructPV shingle with another BIPV roof solution

already commercially available.

In Vittorio Veneto, the ConstructPV product (Figure

1, Stand 1) has been compared with another BIPV solar

shingle already developed by Tegola Canadese S.p.a

(large size solar modules TEGOSOLAR 136®) and

available on the market (Figure 1, Stand 2). Tegosolar is

a photovoltaic flexible membrane that uses thin-film

triple-junction amorphous silicon technology. Its

flexibility and lightness make Tegosolar an ideal solution

for any type of roof, with the possibility of installation on

pitch roof from 5° to 60°, offering high aesthetic and

production standards. In addition to that, Tegosolar offers

waterproofing of the roof as the supporting part

represents the bituminous membrane for roof covering.

STAND 1 STAND 2

TEGOLA HEADQUARTERS

Figure 1: The two test-stands of the outdoor test facility:

demonstration site at Tegola Headquarters (Vittorio

Veneto, Italy).

At SUPSI test-facility, the ConstructPV solar tile

(Figure 2, Stand 1) has been compared to the BIPV in-

roof system developed by Meyer Burger AG, also partner

of the project (large size solar tile, MegaSlate®),

commercially available (Figure 2, Stand 2). The

MegaSlate® solar roof system uses high-efficiency

monocrystalline cell technology being an architecturally

appealing product, especially suited to new buildings and

roof refurbishments. This system offers the possibility to

replace conventional roof covering with all the benefits

of a conventional roof and it is fitted to roofs with pitches

of 20° or more. Even lower pitches are possible if a sub-

roof for heavy-duty applications with sealed seams is

used.

STAND 1 STAND 2

SUPSI CAMPUS

Figure 2: Outdoor test facilities: demonstration site at

SUPSI CAMPUS (Lugano, Switzerland).

The object of the investigation is the BIPV solar

shingle developed within Construct PV consortium that is

mainly conceived as a roof active tile for an easy-

mounting and on-site customization. It consists of a

durable laminated PV glass (containing crystalline solar

cells provided by the partner Meyer Burger AG)

integrated and glued into a rear waterproofing back-sheet

layer made of a bitumen-based membrane.

Modules with different dimensions can be produced

as follows (Figure 3), but not only.

Figure 3: Construct-PV prototypes installed in the two

test stand (Type 3.1, 20 solar cells prototype installed in

Vitorio Veneto and Type 3.3, 10 solar cells in Lugano).

The main goals of these installations are:

Demonstrate the technology;

Show innovation system and identify

similarities / differences;

Detect and prevent manufacturing defects that

may result in new product development;

Benchmark the technology with other BIPV

solution;

Evaluate the construction and electrical

performance of the system;

Evaluate the temperature effects in the inner

layers of the building envelope.

3 OUTDOOR TEST-STANDS AT SUPSI CAMPUS

The two test stands (Figure 2) consist in two metallic

framed structures of anodized aluminum supporting an

orientable roof (1,8 x 3,0 m), including a complete

construction package, where BIPV solar systems are

integrated as the tiling external layer.

Figure 4: Planning and design of the test facility

developed at SUPSI campus, Switzerland.

The test facilities have been designed on the specific

purpose of testing other BIPV complete system solutions

(roof and façade) as well. SUPSI has truly experience to

investigate all aspects concerning BIPV photovoltaic

systems in the specific conditions of installation [10-13]

and other different testing and monitoring activities are

usually performed contributing to better development of

new products and providing support to industry. The

small demonstrators allow changing the tilt angle of the

roof to perform different test under real operation and

weather conditions (Figure 4).

3.1 Set up and installation, assembly process.

The complete roof structure has been installed to

simulate the real behaviour of the systems under BIPV

tiling. The real building layering that includes

substructures, supporting layers, thermal insulation, and

ventilation air gap have been built onto the load-bearing

metal structure of the stands in order to simulate the real

building envelope conditions in terms of constructive,

architectural and technological aspects.

The new Construct-PV solar shingles are designed as

a replacement of the conventional roof tiling with

watertightness. They are installed with a constructive

procedure defined by Tegola Canadese mainly based on

the use of simple and safe operations in the construction

site such as bonding, nailing and sealing, not significantly

different from the installation of the conventional roof

tiles. Since these solar modules include waterproofing

membrane (BIPV back-sheet layer made of a bitumen-

based membrane), they are fixed onto a continuous OSB

rear wooden board with a similar overlapping to

conventional bitumen tiles, without additional auxiliary

frames normally used as a channel for water drainage and

retention hooks, as it happens in the roof solution with

MegaSlate.

The solar tiles are arranged so that they are double-

layer overlapped; the vertical and lateral overlapping

allows the rain to run off properly with good

watertightness. The installation has been carried out by

accredited roofers and skilled tradesmen of Tegola

together with the non-specialized staff of SUPSI showing

that they can be easily and quickly installed also because

the bitumen membrane allows to be cut directly on site to

better adjust the installation tolerances.

The outdoor test-stands have provided valuable

information to define the best process of installing the

new product and to detect and solve potential problems

during product assembly. The modular design ensures a

simple, speedy and therefore cost-effective installation as

well as a functional and aesthetically appealing roof-

integrated solution.

Six solar tiles BIPV modules have been installed in

each test facility:

Construct-PV prototypes: small solar tile Tegola with

10 SWCT monocrystalline cells (Figure 5, Stand 1);

MegaSlate®, BIPV in-roof system: large solar tile,

30 monocrystalline cells with three strips busbar

(Figure 5, Stand 2).

STAND 1: Construct PV BIPV STAND 2: MegaSlate® 3S

Figure 5: Assembly sequence of the demonstration site at

SUPSI (Lugano, Switzerland).

3.2 Monitoring equipment and test procedures.

Each module was equipped with a Maximum Power

Point Tracker (MPPT 3000) developed by SUPSI aimed

at measuring the electrical performances every five

minutes on the purpose of this task (Pm, Voc, Isc and IV

curves). The MPPT were adapted to the modules voltage

and current range to optimize measurement accuracy.

This aspect motivates that in the case of Stand 1, the

MPPT has to measure the power output of a couple of

Tegola BIPV modules installed by sets of two panels

connected in series to each MPPT (as similar to a large

solar tile of 20 cells, Type 3.1 Figure 3), while the MB

MegaSlate are monitored individually. Module

temperature was measured with a PT100 fixed on the

back of the module. In the case of Construct-PV Tegola

prototypes this sensor has been inserted between glass

and bitumen before manufacturing. Additionally, other

temperature sensors (PT100) have been positioned in the

different layers of the whole roofs' packages and also

behind the conventional tiles, as well as in different

positions at the top and bottom of the roof system (near

ridge and eaves) to check differences.

Furthermore, air flux meters for the evaluation of the

air speed velocity in the cavity of the roof were placed in

the middle of the ventilation chamber under the BIPV

modules and other water sensors were installed to survey

the tightness of the roof (even though a significant natural

ventilation was not registered since the limited dimension

of the roof pitches).

Meteorological data as global and diffuse horizontal

irradiance, wind speed and ambient temperature as well

as the module performance data were recorded

simultaneously with a resolution of one minute. Two

pyranometers were installed on the stand to monitor the

irradiance at roof planes. In order to achieve a high level

of reliability in the inter-comparison, improved data

quality control and advanced data analysis were used.

Main aspects analyzed:

• Outdoor characterization of BIPV modules electrical

performances (Pm, Voc, Isc and IV curves);

• Energy production (Final Yield FY, performance

ratio PR, temperature of modules Tbom, etc.);

• Performances of the whole roof system installed

(tightness, in-layers temperatures, ventilation, etc.).

In the following table (Table I) the main

specifications of the BIPV modules monitored are

described: Construct-PV Tegola prototype couple of

modules in-roof (C5) and MegaSlate BIPV module (B3)

as seen in Figure 6. Another couple of ventilated free-

standing Construct-PV Tegola prototype module (D1)

has been located on the top of the Stand 1(Figure 6a) to

be used as reference (with free back ventilation).

Table I: BIPV modules monitored in SUPSI outdoor test

demo site have been measured in SUPSI accredited lab.

SUPSI

Demo

stands

BIPV

modules

monitored

Rated

Power

PSTC [Wp]

Module

Area

A [m2]

Temperature

Coefficient

γ(PMPP) [%/K]

STAND 1 Construct-PV

C5 / D1 (Tegola) 96.00 0.65 -0.39

STAND 2 MegaSlate ®

B3 (Meyer Burger) 135.00 0.84 -0.42

C5

D1

B3

a)

b)

Figure 6: Technical drawings of the outdoor test stands

at SUPSI: a) Stand 1, BIPV roof system Tegola

developed in ConstructPV project; b) Stand 2, BIPV roof

system MegaSlate®, developed and commercialized by

Meyer Burger AG.

Figure 7: Constructive detail, section of each roof

package with the position of the in-layers temperature

sensors.

3.3 First results of the monitoring campaign (SUPSI).

In the following graphics (Figure 8) the outdoor

energy yield measurements, Final Yield, Yf kWh/kWp,

the Performance ratio, PR % and the Energy Production

per square meter, EPV kWh/m2 are shown. The

monitoring period here presented consider the last four

months, from February to May 2016.

Figure 8: Results of the first months of the monitoring

campaing from the beginning of February to May 2016.

The final PV system yield Yf kWh/kWp is the net

energy output EPV divided by the real d.c power Pmax

G,STC (STC – Standard Test Condition 1000 W/m2, 25˚C,

AM 1.5), measured in the specialized and accredited

laboratory of SUPSI (Swiss PV Module Test Center).

Results have shown differences in Final Yield between

the big MegaSlate tile and the small tile Construct-PV

Tegola in a range of 7.9% to 10.9% (red line) while

differences between the same type of module full

ventilated (D1) or in-roof installed varies from almost

zero to 8.7% in May (blue line).

The Performance Ratio, PR % is essentially the

final yield divided by the reference yield (Yf/Yref). As

value independent from the irradiation is therefore useful

to compare systems. Findings from this first period of

monitoring have shown that the comparison between

MegaSlate and Construct-PV new prototype have been

up to 5.5% maximum while differences between the two

Tegola modules, in-roof and free-standing, depending on

the different installation conditions, have reached the

6.8% in May which can be attributed to higher

temperature of the unventilated module.

Nevertheless, the Energy Production per square meter

EPV kWh/m2, that is the energy delivered by the PV

modules considering the real module area (including also

not active parts), as expected, is higher in the MegaSlate

big tile than the small tile developed in the research

project reaching values from 22.1% to 24.6% of increase.

As in the following table (Table II), differences are

reduced by almost 7% if the larger Construct-PV solar

tile prototype of 20 cells is considered (Type 3.1, Figure

3) instead of the small solar tile prototype of 10 cells

(Type 3.3, Figure 3) as seen in Table III. In this case, a

greater impact on energy production per square meter is

observed due to as result of fewer cables ducts.

Table II: Differences in Energy production per area unit

performances kWh/m2 between MegaSlate® BIPV

module and Construct-PV prototype of 10 cells (Type

3.3) installed at Lugano, SUPSI Campus.

EPV

kWh/m2

Construct-PV

(mc-Si SWCT)

MegaSlate®

(mc-Si) EPV

%

FEB 6.58 8.45 -22.13%

MAR 11.26 14.67 -23.25%

APRIL 13.98 18.34 -23.79%

MAY 11.83 15.69 -24.62%

TOTAL 43.65 57.16 -23.63 %

Table III: Differences in Energy production

performances kWh/m2 between MegaSlate® PV

module and Construct-PV prototype of 10 cells (Type

3.3) and prototype of 20 solar cells (Type 3.1).

Construct-PV

Type 3.3

C5 (10 cells)

Construct-PV

Type 3.1

C5 (20 cells)

EPV

%

FEB 22.13% 14.87% -7.26%

MAR 23.25% 16.10% -7.15%

APRIL 23.79% 16.88% -7.10%

MAY 24.62% 17.59% -7.03%

TOTAL 23.63% 16.51% -7.12%

It has been found also small Energy production

differences registered between D1 (free-standing module)

and C5 Construct-PV Tegola (in-roof module), that vary

from 2.8% to 9.0% (Figure 8).

These differences can be attributed to the different

operating temperatures of the modules, some mismatch

effects caused by series-connected of each couple of

modules measured by the MPPT tracker device and by

local shadows caused by the cable ducts at the edge of the

modules (Figure 9), aspect that needs to be further

investigated and that will be optimize later on.

a) b)

C/3

06/04/16, 09:40 CET

C5

D1

Irregular shadows and dust

06/04/16, 09:40 CET

06/04/16, 17:00 CET 09/03/16, 15:19 CET

C/5

Figure 9: a) Detail pictures of the test Stand 1 (C5 and D1

prototypes) in a clear sky day of March and April; b) 3D

simulation, shadowing analysis performed with Revit

software at different times of day.

Focusing on a short period of monitoring in clear sky

days (Figure 10), it is possible to observe the clear

differences in the back of module temperature of the

BIPV modules under discussion. As noticed, in Figure

11, when the ambient temperatures are higher the

difference in the back of module temperature increased.

Figure 10: Back of the module temperatures (Tbom)

monitored in a week period of March (18/03/16-

25/03/16) with clear sky conditions.

Figure 11: Comparision of the Tbom temperatures of the

BIPV modules regarding the outdoor ambient

temperature.

The period under investigation showed large

differences on temperatures of the back of the module,

Tbom [°C] (maximum differences more than 12 °C

between Stand 1 and 2). Regarding the temperatures of

the inner layers, of the roof packages (referred to Figure 7

temperature sensors) for the period reported here

(18/03/16 - 25/03/16) display great differences especially

at the level of the layer 2 under the ventilation chamber.

It has been noticed that in the case of Stand 2 with

MegaSlate BIPV modules the temperatures at this level

decreases up to even 11.3 ˚C (Figure 12). This condition

is mainly influenced by the general weak air flow in the

air gaps of the two stands and also by a customized

constructive detail of the roof in the Stand 1 at the ridge

joint, that further obstacles natural ventilation.

Figure 12: a) Inner layer temperatures of the Construct-

PV solar tile prototype (Tbom, TLay0, TLay1, TLay2, TLay3); b)

Inner layer temperatures of the MegaSlate BIPV module

(Tbom, TLay2, TLay3) monitored during the same period.

4 OUTDOOR TESTS-STANDS AT TEGOLA

HEADQUARTERS

On summer 2015 two small-scale demonstrators

(Figure 13) have been realized and installed on the roof

over the research center of Tegola Canadese

headquarters, in Vittorio Veneto (Italy).

The roof is regularly used as a testing center, in

which several products of TEGOLA production and

R&D have been installed to analyze behavior of the

building components with ageing. This roof is a

challenging demosite to analyse photovoltaics, since it is

a south east exposed roof, with 18% of slope.

First step of installation has been the roofing products

removal and the preparation of a flat waterproof

substrate, in order to reproduce a typical roof of southern

Europe. The test roof consists of two separate stands of

BIPV products, parallel installed by torch on procedure

on the roof. No retro ventilation has been provided to

BIPV that has been installed in direct contact with

bituminous waterproofing substrate.

The roof covered with BIPV was a normal concrete

roof that has been covered with 3 layers of waterproof

membrane (two old layers, one the brand new installed

on purpose for this demo site). Second step of installation

has been the positioning of the BIPV roofing products on

the test stand roof demo site:

Construct-PV prototypes: large solar tile Tegola with

20 SWCT monocrystalline cells (Figure 13, Stand 1);

Tegosolar 136®, a thin film technology PV shingle

(triple-junction amorphous silicon, a-Si) produced by

Tegola Canadese (Figure 13, Stand 2).

STAND 1: Construct-PV BIPV STAND 2: Tegosolar 136®,

Figure 13: Assembly sequence of the demonstration site

at TEGOLA Headquarter (Vitorio Veneto, Italy).

4.1 Monitoring equipment and PV module specifications

In the following table (Table VI) are described the

main specifications of the BIPV modules monitored are

described: Construct-PV Tegola prototype (Stand 1) and

Tegosolar 136 (Stand 2).

Table VI: BIPV modules monitored in TEGOLA

outdoor test demo site.

TEGOLA

Demo

stands

BIPV

modules

monitored

Rated

Power

PSTC [kWp]

Module

Area

A [m2]

Number of

BIPV modules

n. [ud.]

STAND 1 ConstructPV

(Tegola Canadese) 1.34 8.53 14

STAND 2 Tegosolar 136

(Tegola Canadese) 1.36 21.22 10

a)

b)

The stands have been equipped with a monitoring

system that allows a continuative analysis by

measurement different parameters, with installations of

two inverters of 1.5 kWp and a cluster controller,

supplied by SMA (Figure 14).

Figure 14: Assembly sequence of the demonstration site

at TEGOLA.

4.2 First results of the monitoring campaign (TEGOLA

HEADQUARTERS).

Preliminary results obtained by monitoring activity

are compared, showing strengths and weaknesses of the

technology; each stand was equipped with an Inverter

and a cluster controller that both allow Tegola Research

operators to investigate performances. The roof

temperature was measured with a PT100 fixed on the

close Tegola 200 kWp PV plant, and a pyranometer as

well gives an estimation of the irradiation.

In the following tables and pictures (Figures 15 to 17)

blue columns represent performances of Tegosolar BIPV

modules; red columns refer to Construct-PV Tegola

prototype. In clear sky days Tegosolar performs better

than ConstructPV prototype (Figure 15a).

a) TEGOLA

Demo

stands

BIPV

modules

monitored

Energy Production

EPV kWh]

(22/05/16)

Total Yield

Yf kWh/kWp]

April 2016

STAND 1 Construct-PV 7.74 5.49

STAND 2 Tegosolar 136 8.57 6.30

b) TEGOLA

Demo

stands

BIPV

modules

monitored

Energy Production

EPV kWh] (11/05/16)

Total Yield

Yf kWh/kWp]

May 2016

STAND 1 Construct-PV 0.81 0.60

STAND 2 Tegosolar 136 0.77 0.56

Figure 15: Daily Energy production, EPV values kWh

and Final Yield, Yf kWh/kWp measured in a clear sky

day and a cloudy day of May 2016.

Analyzing in detail the monitoring results during the

day, Tegosolar performs better especially in sunny day

mid hours, while in the morning or in the afternoon

Construct-PV prototype is equal or even better (Figure

15a). Besides in cloudy days Construct PV prototype is

more performant than Tegosolar (Figure 15b).

The following tables and pictures show the electrical

performance results of the monitoring campaign since

February to May 2016. Figure 16 shows the total monthly

Energy production, EPV values kWh and the Final

Yield, Yf kWh/kWp measured in February (16.a) and

March (16.b) 2016. Figure 17 shows the same values

(total monthly Energy production, EPV and tFinal Yield,

Yf ) registered in the months of April (17.a) and May

(17.b). Considering the entire period of analysis,

Tegosolar BIPV roof system performs better (Figure 18)

in terms of energy produced versus installed power.

Results have shown differences in Final Yield, Yf

kWh/kWp] between the Tegosolar system and the

Construct-PV Tegola new prototype in a range of 0.32%

in February to 9.34% in May (black line in Figure 18).

a) FEBRUARY 2016

TEGOLA

Demo

stands

BIPV

modules

monitored

Energy Production

EPV kWh]

FEBRUARY

Total Yield

Yf kWh/kWp]

FEBRUARY 2016

STAND 1 Construct-PV 38.850 28.91

STAND 2 Tegosolar 136 39.440 29.00

b) MARCH 2016

TEGOLA

Demo

stands

BIPV

modules

monitored

Energy Production

EPV kWh]

MARCH

Total Yield

Yf kWh/kWp]

MARCH 2016

STAND 1 Construct-PV 108.91 81.04

STAND 2 Tegosolar 136 114.97 84.54

Figure 16: Monthly Energy production, EPV values

kWh and Final Yield, Yf kWh/kWp measured in

February and March 2016.

a) APRIL 2016

TEGOLA

Demo

stands

BIPV

modules

monitored

Energy Production

EPV kWh]

APRIL

Total Yield

Yf kWh/kWp]

APRIL 2016

STAND 1 Construct-PV 135.76 101.02

STAND 2 Tegosolar 136 146.74 107.90

b) MAY 2016

TEGOLA

Demo

stands

BIPV

modules

monitored

Energy

Production

EPV kWh]

MAY

Total Yield

Yf kWh/kWp]

MAY 2016

STAND 1 Construct-PV 153.92 114.53

STAND 2 Tegosolar 136 171.80 126.33

Figure 17: Monthly Energy production, EPV values

kWh and Final Yield, Yf kWh/kWp measured in April

and May 2016.

Construct-PV prototype, installed on the top of non-

ventilated roof, over a waterproofing membrane by torch

on method, is producing a power output of only 10.40%

less, in the worst case (May), referred to the benchmark

Tegosolar installed in the same conditions (Figures 16

and 17).

In addition, the Performance Ratio, PR %

differences in this first period of monitoring comparison

between Tegosolar system and new Construct-PV BIPV

roof have shown reaching values from 0.17% in February

(cold month) to 6.63% in May (mild climate).

Nevertheless, Construct-PV has a higher efficiency per

square meter, since area covered by the prototype is

mostly 50% of the installation area of the benchmark. As

seen in Table V the Energy Production per square meter

EPV kWh/m2, is significantly higher in the case of

Tegola Construct-PV new prototype (mc-Si SWCT

technology) than the Tegosolar BIPV module (a-Si

technology) reaching values from 55.1% to 59.1% of

increase.

Figure 18: Results of the first months of the monitoring

campaing from the beginning of February to May 2016.

Table V: Differences in Energy production performances

kWh/m2 between Tegosolar 136® PV module and

Construct-PV prototype of 20 cells (Type 3.1) installed at

Vittorio Veneto, Tegola Headquarters.

EPV

kWh/m2

Construct-PV

(mc-Si SWCT)

Tegosolar 136®

(a-Si) EPV

%

FEB 4.55 1.86 +59.19%

MAR 12.76 5.42 +57.57%

APRIL 15.92 6.91 +56.55%

MAY 18.04 8.10 +55.13%

TOTAL 51.28 22.29 +57.54%

5 CONCLUSIONS

The paper presented two demonstration sites where

two new PV shingles, developed within the Construct PV

European project, have been installed and monitored for

different months. Comparison with commercially

available BIPV systems have been presented. The

performances of the BIPV Construct-PV solar tiles

prototypes result influenced mainly by both the type of

installation (in-roof) and the dimension of the solar

shingle (small solar tile of 10 cells or large solar tile of 20

cells).

The small-scale installation does not allow relevant

natural back-ventilation, like in a real roof. This has an

impact on the operative temperature of the BIPV

prototypes. Moreover, for the monitoring period studied

so far, it has been found that the new BIPV Tegola

system compared to the conventional Tegola roof tile

(not PV) imply, an increase in the roof temperature of

about 10 ˚C at the back of the tiling layer (Layer1) and of

4 ˚C within the air gap (Layer 2). Since the test-stands

have a very small pitch (1.8 x 3.0 m) this does not allow

proper natural ventilation and air flow, so that the

temperature conditions can be considered worse than in

the real behavior. The ventilated chamber used in such a

roof installation, in fact, represents in real conditions one

of the most effective technical solutions for natural

ventilation in sloped roof so that lower temperatures are

expected in the air gap as well as possible consequent

improvement of PV performance (and of course of the

roof in summer).

Another point that could be remarked is that the

option of a large solar tile BIPV prototype is better than

the small one in terms of energy production per square

meter, EPV values, as the impact of the cable ducts

shadowing less affected module surface. Anyway, the

monitoring campaign still continues and will be

important to further analyze the following aspects:

1) Evaluate the soiling/shadowing and temperature

effects as function of the tilt angle;

2) Evaluate of possible effects of back ventilation;

3) Assess the impact of the mounting structure (metal

channel) and local shadowing that could be caused by

cable ducts.

4) Evaluate the behavior of the different installations in

the summertime, to see if the difference between

power outputs of Construct PV prototype towards

Tegosolar is increasing or remains stable.

5) Evaluate the real temperature coefficient of the

Construct PV prototype by those measurements in the

jobsite.

In conclusion, even though the systems developed

seem to have a bit lower performance in terms of energy

performance as compared to other high efficient products

available on the market, considering the strategy of a low

final cost of the installation that the producer aims at

achieving the cost-effectiveness of the product in its life-

cycle could be demonstrated with further investigation.

Finally, it is important to highlight that the new

system enables an easy and fast mounting having other

advantages as for example, can be nailed or welded,

could be used in roofs even with small slopes, as 10°, the

dimension can be adjusted in site, etc., all aspects that

allow a cost-effective installation as well as a functional

and aesthetically appealing roof-integrated solution with

regard to other BIPV solutions for roof.

AKNOWLEDGMENTS

Construct-PV: The research leading to these results

received funding from the European Community’s

Seventh Framework programme (FP7/2007-2013) under

grant agreement no 295981 [www.constructpv.eu]. The

authors would like to thank Mr. Christof Erban from

Meyer Burger AG for his collaboration in this research

and for providing the PV modules. We also would like to

thank the colleague of SUPSI, namely Domenico

Chianese, Gabi Friesen, Sebastian Dittmann, Enrico Burà

and Boris Margna for their valuable contribution and

support.

REFERENCES

[1] Directive 2010/31/EU of the European Parliament

and of the Council of 19 May 2010 on the Energy

performance of buildings. Official Journal of the

European Union.

[2] B. Van Berkel, T. Minderhoud, A. Piber, G. Gijzen.

(2014). Title: Design Innovation from PV-Module to

Building Envelope: Architectural Layering and Non

Apparent Repetition. Proceedings of the 29th

European Photovoltaic Solar Energy Conference and

Exhibition. Amsterdam, The Netherlands. Pages

3606-3612.

[3] F. Frontini, A. Scognamiglio, G. Graditi, C. Polo

Lopez, M. Pellegrino (2013). Title: From BIPV to

Multifunctional Building Component. Session

Reference: 5CO.8.1. Conference Proceedings at

European Photovoltaic Solar Energy Conference and

Exhibition. Paris, France. Pages 3757-3761.

[4] J. Bezler, K. Fath, R. Hecker. Title: Customised

photovoltaic modules for building envelopes –

Construct PV, Research, Developments, Innovation

2014/15 – Züblin-Strabag

[5] E. Delponte, F. Marchi, F. Frontini, C. Polo-López,

K. Fath, M. Batey (2015). Title: BIPV in EU28, from

Niche to Mass Market: An Assessment of Current

Projects and the Potential for Growth through

Product Innovation. Proceedings of the 31st European

Photovoltaic Solar Energy Conference and Exhibition

14-18 Sept. 2015 Hamburg, Germany. Pages 3046 -

3050.

[6] R. Manariti, G. Urbano, F. Marchi, E. Delponte.

Title: Life Cycle Analysis and Life Cycle Costing

Analysis of Building Integrated PhotoVoltaics,

Convegno dell’Associazione Rete Italiana LCA 2016,

Ravenna, Italy.

[7] 10th Energy Forum on Advanced Building Skins.

Special Session BIPV 6 - From Design Concepts to

Real Buildings: How Stakeholders Envision BIPV.

Bern, Switzerland, 03-04 November 2015.

[8] EN 50583-1:2016. Photovoltaics in buildings. BIPV

modules

[9] F. Frontini, G. Friesen, T. Friesen; C. S. Polo López

(2013). Title: Experience on the behaviour of

different BiPV solution: electrical and thermal

performance of roof and façade mounted micromorph

modules. Conference Proceedings at 28th European

Photovoltaic Solar Energy Conference and

Exhibition. Paris, France. Pages 4357-4360.

[11] F. Frontini, G. Friesen, T. Friesen, C. S. Polo López

Title: Experimental testing under real conditions of

different solar building skins when using

multifunctional BIPV systems. Energy Procedia V48,

December 2014, Pages 1412-1418.