N-Peak Technology Whitepaper
What is n-type technology and what benefits does it offer?
REC modules have to date been based on p-type multi wafer technology.
The market however, demands ever higher power and higher efficiency
modules and the move to a mono wafer platform allows REC to address
this demand. The P in p-type stands for positive where the cell bulk is
doped with boron, which has one less electron than silicon creating a
positive electron imbalance and stimulating the flow of electricity.
N-type on the other hand, sees the cell bulk doped with phosphorus,
which has one more electron than silicon, creating a negative charge
and stimulating the flow of electricity. As mono cells are generally more
efficient than their multi counterparts, n-type technology has so far
been used exclusively on mono to make best use of its high efficiency
properties and reach ever higher wa classes.
More importantly however, such a construction avoids the coming
together of boron and oxygen in the bulk. This combination is the
main cause of light induced degradation (LID) in the cell, and the
non-occurrence of this in n-type cells means they are free from any
permanent loss of power upon first exposure to sunlight.
Fig : Cross-section of an REC N-Peak cell showing negatively charged bulk and PERT layer
Market studies have shown that high power n-type products are
expected to grow to around of capacity over the next decade and
this is why REC has taken the step to leapfrog p-type mono technology
and provide n-type solutions. It is however, important to note that multi
technology is still expected to remain at around of the market up
until the mid s and therefore remain a major industry section.
What has REC put in place to achieve mono n-type production?
REC has purpose-built a new state of the art mono cell production plant
at its integrated module manufacturing facility in Singapore. Using all its
experience in half-cut cell technology and rearside cell passivation, REC
has invested heavily in ensuring n-type mono production comes under
its own quality control processes, with plans for further expansion.
ITRPV Ninth Edition , International Technology Roadmap for Photovoltaic Results
, www.itrpv.net/Reports/Downloads/
What is the REC N-Peak?
The REC N-Peak Series is a new solar module that builds on REC’s
multiple award-winning technology enablers and features innovative,
high efficiency cell technology for the highest power output. Based on
n-type monocrystalline (mono) silicon cells, the -cell REC N-Peak
Series achieves wa classes of up to Wp.
The first major characteristic of the REC N-Peak Series that sets it
apart from other REC products is the cell type, where REC has moved
into n-type monocrystalline cell production for the first time. The
N-Peak is based on standard sized mono wafers (. x . mm)
that have been cut into two equally sized pieces (. x . mm)
through our half-cut technology, to give separate cells in total.
Fig : The REC N-Peak Series module, with mono cells and ‘twin’ cell layout design
These cells are then split into two halves of cells, each with
three cell strings and the two halves then connected in parallel. This
layout is then supplemented by a collection of other enablers:
• Five bus bars
• PERT (Passivated Emier Rear Cell Totally Diffused)
• A split junction box
The REC N-Peak also features a new generation of frame design which
offers a thinner frame height, but with with support bars on the rear to
ensure durability, stability and increased load bearing capability.
What makes a mono cell different to a multi cell?
As the name suggests, multisilicon (multi) ingots are formed from
multiple separate crystals, whereas monosilicon is grown from a single
one. This means that, once sliced into wafers, mono has a higher level
of silicon purity, giving it a higher absorption efficiency, no visible cell
structure and a uniformly dark color. These differences have a decisive
effect on cell performance, giving a lower cell temperature coefficient,
which improves energy yield, especially in warmer weather.
The manufacturing process of a mono wafer differs from that used for
multi and it is this that creates the distinctive rounded corners seen on a
mono cell. The reason for this is that mono wafers are grown in cylindrical
ingots, rather than square or rectangular crucibles, before being sliced
and cut to make best use of the space available in the module.
REC N-Peak Technology:
How REC uses award-winning technology on an n-type mono platform to
provide long term power for lasting performance
The REC N-Peak Series is a brand new solar module from the leading European manufacturer that
builds on award-winning technology enablers and features an innovative module design with high
power output. Using a n-type monosilicon platform for the first time in REC’s mass production, the
REC N-Peak Series is available in wa classes of up to Wp and offers customers a product that
marries high power levels with the highest product quality in the market.
Si Nx anti-reflective layer
Si Nx anti-reflective layer
Front side contacts
Rear side contacts
PERT passivated rear side, means
electrons are free to migrate to emier
-ve charged polysilicon forms
second part of PERT layer
PERT layer: Tunnel oxide
layer forms upper part,
providing passivation and
separation of the two -ve
charged layers for increased
efficiency
P/N junction
+ve charged b-doped emier layer
-ve charged p-doped n-bulk layer
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