PV Research Updates

1SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the National University of

Singapore (NUS), the National Research Foundation Singapore (NRF) and the Singapore Economic Development Board (EDB).

Armin ABERLE, SERIS, NUS

APVIA, Annual General Meeting 2020

18 August 2020

PV Research Updates



Learning curve for PV modules ($/W)Prices of c-Si PV modules

ITRPV =

International

Technology

Roadmap for

Photovoltaic

Limit for c-Si

modules 0.1 $/Wp

Aug 2020

23.5% - PV has fastest

learning rate of all

energy technologies

“Race to the bottom”

Source: ITRPV 2020



Silicon 8%

BOS*74%

Cell process 6%

Module process 9%

* BOS = Balance of system (inverters, mounting system, cables, labour,

interest rate, etc)

Sources: SERIS market research, Dec 2018

Cost breakdown of rooftop PV systemsSilicon wafer PV, Dec 2018, installed system cost = 1.2 US$/Wp

~10 kWp system, no subsidies, no tax

Wafer process 3%

BOS is strongly reduced via higher efficiency of PV modules.

→ Need highly efficient (> 25%) low-cost solar cells

System, $/Wp:



Silicon wafers

Shift to

mono-Si

Source: ITRPV 2020



Silicon solar cell efficiencies

Limit for

industrial c-Si

cells 26%

Shift from p-multi to

n-mono wafers adds

~3% (absolute) in cell

efficiency

“Race to the top”

Multi-Si

Mono-Si

Source: ITRPV 2019



Solar cells

Shift to PERx,

TOPCON and

HJT

Source: ITRPV 2020



PERC innovation to industrialisationPassivated Emitter & Rear Cell

~25% efficiency, late 1980s/1990s Industrial process, 2008 – 2010

~680 mV,

~22%

TEX

ANNEAL

DIF

WET

PRINT

r + f.PECVD

FIRING

Stabilisation

LASER

Blakers, Zhao, Green et al. (UNSW)

New Process

Optimised

Knobloch, Aberle et al. (Fraunhofer ISE)



Silicon heterojunction cells on the rise

❑ Processing at low temperature (< 200 ºC)

❑ Compatible with thin wafers (< 100 microns)

❑ Very high Voc → well suited for hot climates

❑ Best silicon solar cell ever made: 26.7% (79 cm2, Kaneka, 2017)

a-Si:H (p+)

rear metal

a-Si:H (n+)

a-Si:H (i)

a-Si:H (i)

TCO

metal grid

n-type Cz-Si

TCO



Silicon heterojunction cells on the rise

❑ HJ mass production: ~2% share in

2018, estimated ~15% in 2029

❑ Selected companies working on HJ

development: Tesla, SolarTech

Universal, Sunpreme, NSP, Hevel

Solar, Sharp, Kaneka, Panasonic,

CIC, Enel Group, EcoSolifer, ENN,

Tongwei, GCL, Jinergy, Hanergy,

CIE Power, GS Solar, REC, Meyer

Burger, … Source: ITRPV 2019

❑ 2018: GS Solar installed production capacity of 600 MW in China; ENEL set

up 200 MW production capacity in Italy

❑ 2019: REC installed production capacity of 600 MW of HJT cells & modules

in Singapore

❑ 2020: Meyer Burger announced to set up a 400 MW factory in Germany

for heterojunction cells & modules



Poly-Si/SiOx passivated contacts (“TOPCon”)History

19

83

20

13

-2

01

5

20

17

-2

01

9

Fraunhofer ISE

TOPCon

ECN

PERPolyISFH

IBC POLO

SERIS monoPolyTM

Jinko Solar,

Jolywood,

Trina Solar,

REC, etc.

Large-area, high-T contacts

Stanford

Poly-Si emitters

with thermal iOx

19

90

19

76

Sony

SIPOS

Introduction,

IEEE TED/JJAP

19

75

Siemens AG

Poly-Si emitter for

bipolar transistors,

IEEE IEDM

Pu

blic

atio

ns

19

80

19

85

Uni. of Florida

Model for poly-Si

in solar cells,

IEEE IEDM

Uni. of Florida

First cells with

Poly-Si,

IEEE EDL

Bell Labs

(Yablonovich)

720 mV SIPOS

+ thin SiOx,

APL

Carleton

Poly-Si

emitter solar

cells,

IEEE EDL

UNSW

(Green)

Si solar cells with

MIS structures and

poly-Si layers,

Solar Cells



SERIS’ monoPolyTM celle.g. rear-side monoPolyTM scheme

Front PECVD

passivation/ARC stack

Screen-printed

(& fired) front metal

contact

Diffused

junction

Screen-printed

(& fired) rear

metal contact

Rear PECVD

passivation

n+:monoPolyTM

layer

Interfacial

oxide



Upgraded PERT/monoPolyTM PlatformPassivated Emitter & Rear Cell

monoPolyTM Industrial

Platform ~2017

710 mV, ~23.5%

TEX

DIF

WET

PRINT

PECVD n-doped layer*

FIRING

Anneal

r. + f. Passivation/ARC

➢ Screen-printing &

➢ High-T fired contacts

➢ Bifacial cell

➢ Industrial process

690 mV, ~23.0%

TEX

DIF

WET

LPCVD poly-Si

POCl3

pClean process*

PECVD Process* LPCVD Process*

PRINT

FIRING

r. + f. Passivation/ARC

* SERIS proprietary



Perovskite thin-film PV

❑ Rapid development in less than 10 years

❑ Lab cell: 25.2% (KRICT/MIT, July 2019)

❑ Mini-module: 18.1% (NTU, 5 serial cells,

21 cm2, 2020)

❑ Sub-module: 11.7% (Toshiba, 44 serial

cells, 703 cm2, 2018)

Image: Nature 2, 16190 (2016)

NTU, Singapore

Saule

Technologies



Perovskite/Si tandem cells

400 600 800 1000 1200 1400 16000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Po

we

r [a

.u.]

wavelength [nm]

400 600 800 1000 1200 1400 16000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Po

we

r [a

.u.]

wavelength [nm]

Single junction Double junctionThe most likely technology path to low-cost 30% PV modules

4-terminal:

❑ Fabrication flexibility

❑ Complex module integration

❑ More parasitic absorption

2-terminal:

❑ Fabrication limitations

❑ Easier module integration

❑ Current matching issue



Perovskite/Si tandem cells ❑ 2T tandem: 29.1% (HZB, 2020)

❑ 4T tandem: 27.1% (IMEC, 2018)

❑ Mostly small area (≤ 1 cm2)

❑ Scaling up depends on perovskite technology

❑ Stability issue: Same as single-junction perovskite

Perovskite evaporated on textured Si

(image: EPFL & CSEM)

Perovskite/silicon 2T cell

made by HZB, Germany



Update PV modules



3BB→ 5 or 6BB Multi-busbar Busbarless

Larger wafer Half or triple-cut cells Shingling

(“close the gap”)

Advanced

Traditional

Advanced

Traditional

Next

Generation

Next

GenerationUltimateUltimate

PV module technology trends



Wafers becoming larger and larger …

New dimension?

https://www.rena.com/en/products/large-wafer-wet-processing/

https://www.rena.com/en/products/large-wafer-wet-processing/



REC new product: 72-cell Alpha module



Longi new product

540 W



❑ Longi next-generation PV module: 2250 mm x 1130 mm

❑ 40-foot high-cube container: Door opening = 2.34 m x 2.59 m (height)

❑ Module size = door height (2590 mm) - buffer for loading (100 mm) -

pallet height (2x 115 mm) = 2x 1130 mm

❑ Wafer size = module width (1130 mm) – cell to edge (2x 15 mm) –

string gap (5x 1.5 mm) → 6x 182 mm wafer

182 mm wafer: The new standard?



Multi-wire moduleAdvantages:

❑ Round wires instead of flat

ribbons

❑ Optical gain in module

❑ Reduced silver consumption

❑ Normally 12-15 wires are

used

SERIS approach:

❑ Half-cut cells with round wires

❑ 6-wire design is good enough

instead of 12-wire

❑ Only slight modification to the

stringer (small cost)

❑ Beneficial for bifacial module

WireBusbar

* Solar cell efficiency: ~21.0%

state-of-the art

design

recommended

design

baselineIndustry standard

3 4 5 6 -- 120

2

4

6

8

12-wire

half-cut

ribbon full-cell

ribbon half-cut cell

wire full-cell

wire half-cut cell

rela

tive p

ow

er

gain

[%

]

no. of busbars/wires

12-wire

full-cell

6-wire

half-cut

300

305

310

315

320

module

pow

er

[W]



Meyer Burger – Module technology❑ IBEX – Stringer for SmartWire

❑ Process time: 45-55 s per module

❑ Throughput:

• Manual: 2500 cells/hour

• Automated: 5000 cells/hour



❑ High-efficiency module

➢ For the same glass size,

more cells can be

accommodated (10-15%

higher module efficiency)

❑ Main issues

➢ IP situation?

➢ Reliability: SERIS has

studied the reliability,

particularly hot-spot

issues.*Solar cell efficiency: ~ 21.5%

303

0

311.7

0

315.7

346.4

5-BB

(baseline)

5-BB

half-cut

6-BB

half-cut

wire

shingled

(68-cell)

290

300

310

320

330

340

350

sim

ula

ted m

odule

pow

er

[W]

Modules with shingled solar cells



❑ “Race to the bottom” for PV module prices continues

❑ Rapid shift to mono-silicon wafers underway (multi-Si is dying …)

❑ PERC is now the market-dominating PV technology, but TOPCon

and heterojunction are gaining market shares

❑ PERC cells ~22%, TOPCon cells 22-23%, SHJ 22-24%

❑ Si wafers are getting bigger and bigger. Will it stop at 182 mm?

❑ Perovskite and perovskite/silicon laboratory cells are improving

rapidly (but are still far away from being commercialized)

❑ Efficiencies of mainstream industrial silicon solar cells & modules are

improving at a rapid rate (while maintaining low $/Wp)

❑ PV modules are getting bigger & bigger (panels with > 500 W avail.)

❑ “Holy grail” of silicon PV in 2025: Modules < 0.2 $/W, modules > 21%

for p-mono, > 22% for n-mono (> 24% for TOPCon and SHJ),

lifetime > 30 years, very low LCOE

❑ Promising alternative solar modules (> 2025): Thin-film on Si tandems

Conclusions



Thank you for your attention!

More information at www.seris.sg

E-mail: [email protected]

We are also on:

http://www.seris.sg/

http://www.seris.sg/doc/publications/Annual-Reports/SERIS_AR2019.pdf

PV Research Updates

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