27
Bifacial BIPV Challenges for glass and encapsulation Bernd Koll/ Kuraray Europe GmbH Bifi PV Workshop, Chambery May 26/27, 2014

17 bernd koll ok

Embed Size (px)

Citation preview

Page 1: 17   bernd koll ok

Bifacial BIPV

Challenges for glass and

encapsulation

Bernd Koll/ Kuraray Europe GmbH

Bifi PV Workshop, Chambery May 26/27, 2014

Page 2: 17   bernd koll ok

Content

5/27/2014 2

BIPV basics

Challenges for BIPV module glass

Challenges for BIPV module encapsulation

Glass and encapsulants for laminated PV safety glass

Summary

Page 3: 17   bernd koll ok

Which will be the preferred (bifacial ) PV solar panel in

about 25 years from now?

5/27/2014 3

Version A „Standard size“

OR

Version B „Custom Size/BIPV“

Page 4: 17   bernd koll ok

5/27/2014 4

BIPV basics

Page 5: 17   bernd koll ok

Building Integrated Photovoltaic (BIPV)

5/27/2014 5

Page 6: 17   bernd koll ok

Why BIPV – now?Transition from niche to mass market

Changing economic drivers

Establishing new PV supply chain

New also bifacial cell concepts

New PV products/solutions

Significant cost reductions

Multiple product benefits

Growing awareness

Proven test/case studies

5/27/2014 6

Page 7: 17   bernd koll ok

New design/aesthetics and

architectural solutions

Higher functionality of glazing

beside safety, security, sound,

shading...

Large building area with PV =

excellent energy balance

(cost saving)

PV module has function of

„electrical power producing

glass pane“

Building Integrated Photovoltaic benefits

Page 8: 17   bernd koll ok

Integration of BIPV in building process

5/27/2014 8

Synergy between Glass and PV industry

=> Team-up of PV company with supplier of glazing building

products

Glass production

Glass processing

Static engineering

Building standards

and codes

Cell production

Standard module

production

Long term module

reliability

IEC certification

Page 9: 17   bernd koll ok

5/27/2014 9

Challenges for BIPV module glass

Page 10: 17   bernd koll ok

PV glass developments for standard PV modules

5/27/2014 10

Current PV cover/back glass standard is 3.2 mm

low-iron tempered or heat strengthened

Target : panel with 2x 2mm glass based has similar

mechanical strength than panel with 2x 3 mm glass

AR coated front glass improves module efficiency

Better performance of G/G modules in extreme

(desert or tropical) climate

Tempering or heat strengthening of 2 mm glass

improves mechanical performance and minimises

deflection by static/dynamic load

G/G panels have much better fire resistance

Thin and stable G/G panels can be also frameless

But: 2 mm ultra clear glass is not cheaper than 3 or

4 mm glass and not easy in glass processing

Page 11: 17   bernd koll ok

Glass for architectural glazings

Standard architectural glass thickness is from 4 mm up to 25 mm float/annealed glass

In some cases also 3 mm float glass is used (double or triple Insulating Glass Units)

Standard clear glass is preferred, but also low ironglass is used (~ 1/3 of glass consumption)

Tempered (TG) or heat strengthened (HSG) glassimproves glazing stability

Laminated glass consists of minimum 2 x 3 mm float glass and 0.38 mm interlayer

Laminated glass has to fulfil several (EU) safetyglazing norms, regulations and building codes

G/G solar panels are generally not regulatedaccording to EU glazing standards and needtherefore (national) building products approval

5/27/2014 11

Page 12: 17   bernd koll ok

5/27/2014 12

Challenges for BIPV module encapsulation

Page 13: 17   bernd koll ok

PV module encapsulant properties

5/27/2014 13

Mechanical protection (by adapted

module component adhesion)

Optical coupling of glass/front sheet

to solar cell

Physical protection (weathering-

induced, environmental damage)

Electrical insulation

No corrosion/PID of module

components (Long-term reliability)

Low thermal conductivity

Control, reduce or eliminate moisture

ingress

Page 14: 17   bernd koll ok

5/27/2014 14

Encapsulant materials

Thermoplastics

(not cross-linkable)

Elastomers/Thermoset

(cross-linkable)

Polyvinyl butyral (PVB)

Thermoplastic

Polyurethane (TPU)

Ionomer

Modified Poly-Olefines

(TPO, EPDM...)

Ethylen Vinyl Acetate

(EVA)

Polyurethane cast resins

(TPU)

Polyacrylate cast resins

Silicones (2K)

Page 15: 17   bernd koll ok

(Bifacial) module encapsulants

Encapsulant film market is dominated by

(thermoset) EVA film, global market share > 90%

EVA is partly replaced by Thermoplastic Polyolefin

TPO (reasons: price, PID and corrosion resistance )

Both EVA and TPO are used for solar panel mass

production (standard 60 or 72 cells module)

Other encapsulants are Polysilicone, Ionomer and

PVB which are used mainly for niche application

(also for BIPV)

Encapsulant type use beside material costs is

influenced by module production size, throughput,

standard module size and lamination tools

5/27/2014 15

Page 16: 17   bernd koll ok

5/27/2014 16

Glass and encapsulants for laminated PV safety glass

Page 17: 17   bernd koll ok

Laminated modules for BIPV roof application

Have to be laminated safety glass

with high performance

Reason: no splinter loss in case of

destruction

Also high post-breakage behaviour

(public traffic areas)

Regulated in international building

codes and safety regulations

Static load stable (e.g. snow load)

Safety requirements regulated by

ball drop test acc. to standards EN

12543-4 and DIN 52338

5/27/2014 17

Page 18: 17   bernd koll ok

Minimum requirement for laminated (BIPV) safety glass

Ball drop test with 1 kg steel ball according to EN

12543-4 and DIN 52338

Minimum LSG glass/encapsulant make-up:

2 x 3 mm float and 0.4 mm film

Falling height is 4.0 m

Test at room temperature (23°C)

Test is passed, if steel ball does not fall through

the glass samples (3 test pieces)

Test fulfilled with the encapsulants: PVB,

Ionomer, TPU

Test not fulfilled with the encapsulants: EVA,

Polyolefines TPO, Silicones, cast resins

Conclusion: main PV module encapsulants like

EVA and TPO have low safety performance

5/27/2014 18

Above test passed, below not passed

Page 19: 17   bernd koll ok

Fall preventing glazing

Have to consist of laminated

safety glass (LSG with PVB

interlayer)

Reason: no glass splinter loss in

case of destruction

High residual strength

Mandatory near to public traffic

way

Germany: Technical Rule for fall

preventing glazing (TRAV, valid

since 2003)

Safety requirements according

to pendulum impact test acc. to

standard EN 12600 (class 1B1)

BIPV module for facade elements

Page 20: 17   bernd koll ok

Pendulum impact test standard EN 12600

Twin tyre 50 kg

Testing (laminated) glass size 896 x 1938 mm

Test with 3 falling heights:

- Class 1B1 1200 mm (100 % impact energy)

- Class 2B2 450 mm ( 40 % impact energy)

- Class 3B3 190 mm ( 15 % impact energy)

Determination of minimum glass thickness at first with

laminates made of float glass

Class 1B1 safely reached with PVB and make-up 33.2 and

44.2 (2 = 0.76 mm PVB)

TG and HSG offer more reserve to pass the requested

safety class compared to float glass of same thickness

Glass lower than 3 mm is currently not regulated to EU

building regulations/codes, same as LSG made of float

glass or HSG/TG (HSG= heat strengthened glass, TG =

tempered glass)

5/27/2014 20

Page 21: 17   bernd koll ok

Pendulum impact test results EN 12600 LSG with 2x2 mm HSG or 2x3 float/0.9-1.0 mm film

5/27/2014 21

Film type HSG 2 mm float HSG 2 mm cast float 3 mm

EVA

(Architectural)

2B2 2B2 2B2

EVA (Solar) 2B2 2B2 2B2

Polyolefine TPO 1 1B1*narrow 2B2 2B2

Polyolefine TPO 2 1B1*narrow 1B1*narrow 2B2

Ionomer 1B1 1B1 1B1

Silicone 2B2 2B2 2B2

Polyurethane TPU 1B1 1B1 1B1

PVB 1B1 1B1 1B1

Page 22: 17   bernd koll ok

Pendulum impact test comparison PVB/EVALSG made of 2 x 3 mm float glass, class 1B1 (1200 mm)

5/27/2014 22

PVB 1.00 mm, 1B1 passed EVA 0.95 mm, 1B1 not passed

Page 23: 17   bernd koll ok

BIPV Insulating Glass Unit (IGU) with bifacial cells

Integration of bifacial solar panel in double

or triple IGU unit possible

bifacial panel is inner pane for higher

module efficiency

can be combined with different features

like:

coated glass for heat absorption

colours/printing for window design

acoustic interlayer (preferred PVB) for

sound damping

specific safety or security properties by

improved glass/interlayer combinations for

both facade and roof glazings

5/27/2014 23

Page 24: 17   bernd koll ok

Buildings account for almost half of global CO2 emission. Yet there is

enough building surface to generate all our electricity needs

Still in infancy – less than 2% PV market share

Globally installed BIPV modules 2013: ~400 MW

Higher value/margins worth $5 bn in 2016

Constrained by:

Varying module certification and building standards

Different installation skills/processes

Lack of suitable products/supply chain

No mass production/custom size

New cell concepts like bifacial need 2 glass panes

Facade and roof glazing PV elements require valid safety & security standards safely fulfilled by PVB, Ionomer and TPU encapsulant combined withfloat/heat strengthened/tempered glass

5/27/2014 24

BIPV market as a chance for high performance encapsulants

Page 25: 17   bernd koll ok

5/27/2014 25

Summary

Page 26: 17   bernd koll ok

Challenges for Bifacial BIPV glass/encapsulants

Bifacial PV modules need double glass laminates

Thin (< 3mm) float glass is limited to be used in facade/roof glazing due to non regulation andlimited laminated glass strength

Extra clear thin glass still is more expensive thanthicker glass, capacity still limited

Chances for thin glass laminates in IGU glazing due to high transparency and low weight

Safety performance of PV encapsulants is not unique with thin glass elements in LSG norms

PVB, Ionomer and TPU outperform other encapmaterials which are used in PV panel massproduction

Future BIPV market will focus on glass andencapsulants which have best glazing standardperformance

5/27/2014 26

Page 27: 17   bernd koll ok

Thank you for your kind attention!

Your questions,please!

Photo: „The brain“ with courtesy of Ertex Solar, Austria5/27/2014 27