Introduction to Bifacial Modules

and Modelling

Teresa W. Zhang, PhD

P. 2 | SunEdison Confidential

Brief History of Bifacial Modules

1966: U.S. Patent on a p+np+

solar cell

1977: Multiple presentations at

1st European Photovoltaic Solar

Energy Conference (PVSEC)

2000: Russia deploys 10 kW on

the International Space Station

2009: Sanyo (now Panasonic)

released first commercial bifacial

product

2015: >100 patents granted and

10’s of MWs deployed

P. 3 | SunEdison Confidential

(Soon to be) Active Bifiacial Suppliers

P. 4 | SunEdison Confidential

HIT Suppliers

HIT – Heterojunction with Intrinsic Thin Layer

a.k.a. HJT – Heterojunction Technology

a.k.a. HCT – Hybrid Cell Technology (Sunpreme)

P. 5 | SunEdison Confidential

PERT Suppliers

PERT – Passivated Emitter Rear Contact, Rear Totally Diffused

a.k.a. BiSoN – Bifacial Solar Cell on N-type (MegaCell)

Related to PERC – Passivated Emitter Rear Contact

Related to PERL – Passivated Emitter Rear Contact, Rear Locally Diffused

P. 6 | SunEdison Confidential

Modelling Challenges

𝐺𝑟𝑜𝑠𝑠 𝑀𝑎𝑟𝑔𝑖𝑛 = 𝑓𝑌𝑖𝑒𝑙𝑑

𝐶𝑎𝑝𝐸𝑥 = 𝑓

𝑀𝑜𝑑𝑢𝑙𝑒𝐸𝑛𝑣𝑖𝑟𝑜𝑛𝑚𝑒𝑛𝑡

𝑆𝑦𝑠𝑡𝑒𝑚 𝐴𝑟𝑐ℎ𝑖𝑡𝑒𝑐𝑡𝑢𝑟𝑒

P. 7 | SunEdison Confidential

Modelling Challenges

𝐺𝑟𝑜𝑠𝑠 𝑀𝑎𝑟𝑔𝑖𝑛 = 𝑓𝑌𝑖𝑒𝑙𝑑

𝐶𝑎𝑝𝐸𝑥= 𝑓

𝑴𝒐𝒅𝒖𝒍𝒆𝐸𝑛𝑣𝑖𝑟𝑜𝑛𝑚𝑒𝑛𝑡

𝑆𝑦𝑠𝑡𝑒𝑚 𝐴𝑟𝑐ℎ𝑖𝑡𝑒𝑐𝑡𝑢𝑟𝑒

Variables in Bifacial Flash Testing:

Front

Only

Back Front

vs. x

White

Black

vs.

vs.

None

1. Sides Flashed 2. Shield on the

opposite side

3. Distance to the

back of the flasher

+

P. 8 | SunEdison Confidential

Modelling Challenges

𝐺𝑟𝑜𝑠𝑠 𝑀𝑎𝑟𝑔𝑖𝑛 = 𝑓𝑌𝑖𝑒𝑙𝑑

𝐶𝑎𝑝𝐸𝑥= 𝑓

𝑀𝑜𝑑𝑢𝑙𝑒𝑬𝒏𝒗𝒊𝒓𝒐𝒏𝒎𝒆𝒏𝒕

𝑆𝑦𝑠𝑡𝑒𝑚 𝐴𝑟𝑐ℎ𝑖𝑡𝑒𝑐𝑡𝑢𝑟𝑒

Albedo:

Image courtesy of Colorado State University

P. 9 | SunEdison Confidential

Modelling Challenges

𝐺𝑟𝑜𝑠𝑠 𝑀𝑎𝑟𝑔𝑖𝑛 = 𝑓𝑌𝑖𝑒𝑙𝑑

𝐶𝑎𝑝𝐸𝑥= 𝑓

𝑀𝑜𝑑𝑢𝑙𝑒𝑬𝒏𝒗𝒊𝒓𝒐𝒏𝒎𝒆𝒏𝒕

𝑆𝑦𝑠𝑡𝑒𝑚 𝐴𝑟𝑐ℎ𝑖𝑡𝑒𝑐𝑡𝑢𝑟𝑒

Albedo:

Composite

Shingle White

EPDM

Unpainted

Metal Roof

White

Gravel

0 100 50 25 75

P. 10 | SunEdison Confidential

Modelling Challenges

𝐺𝑟𝑜𝑠𝑠 𝑀𝑎𝑟𝑔𝑖𝑛 = 𝑓𝑌𝑖𝑒𝑙𝑑

𝐶𝑎𝑝𝐸𝑥= 𝑓

𝑀𝑜𝑑𝑢𝑙𝑒𝐸𝑛𝑣𝑖𝑟𝑜𝑛𝑚𝑒𝑛𝑡

𝑺𝒚𝒔𝒕𝒆𝒎 𝑨𝒓𝒄𝒉𝒊𝒕𝒆𝒄𝒕𝒖𝒓𝒆

Mechanical Design:

P. 11 | SunEdison Confidential

Modelling Challenges

𝐺𝑟𝑜𝑠𝑠 𝑀𝑎𝑟𝑔𝑖𝑛 = 𝑓𝑌𝑖𝑒𝑙𝑑

𝐶𝑎𝑝𝐸𝑥= 𝑓

𝑀𝑜𝑑𝑢𝑙𝑒𝐸𝑛𝑣𝑖𝑟𝑜𝑛𝑚𝑒𝑛𝑡

𝑺𝒚𝒔𝒕𝒆𝒎 𝑨𝒓𝒄𝒉𝒊𝒕𝒆𝒄𝒕𝒖𝒓𝒆

Mechanical Design:

Image courtesy of gammasolar, via NREL

P. 12 | SunEdison Confidential

Modelling Challenges

𝐺𝑟𝑜𝑠𝑠 𝑀𝑎𝑟𝑔𝑖𝑛 = 𝑓𝑌𝑖𝑒𝑙𝑑

𝐶𝑎𝑝𝐸𝑥= 𝑓

𝑀𝑜𝑑𝑢𝑙𝑒𝐸𝑛𝑣𝑖𝑟𝑜𝑛𝑚𝑒𝑛𝑡

𝑺𝒚𝒔𝒕𝒆𝒎 𝑨𝒓𝒄𝒉𝒊𝒕𝒆𝒄𝒕𝒖𝒓𝒆

Electrical Design:

Optimal inverter capacity

Does the DC:AC ratio metric make

sense for bifacial modules?

Requirements for multiple MPPT

windows or string-/micro-inverters;

can they handle the additional

current?

Implications for DC wiring

Interpretation of electrical codes

Image courtesy of Sungrow

P. 13 | SunEdison Confidential

Modelling Challenges

𝐺𝑟𝑜𝑠𝑠 𝑀𝑎𝑟𝑔𝑖𝑛 = 𝑓𝑌𝑖𝑒𝑙𝑑

𝐶𝑎𝑝𝐸𝑥= 𝑓

𝑀𝑜𝑑𝑢𝑙𝑒𝐸𝑛𝑣𝑖𝑟𝑜𝑛𝑚𝑒𝑛𝑡

𝑆𝑦𝑠𝑡𝑒𝑚 𝐴𝑟𝑐ℎ𝑖𝑡𝑒𝑐𝑡𝑢𝑟𝑒