REC Solar Alpha Series Technology
What is the REC Alpha Series?
Born of a development partnership between REC and the Swiss
production equipment manufacturer Meyer Burger, the REC Alpha
Series builds on REC’s experience with n-type monocrystalline cells
and half-cut technology as well as Meyer Burger’s in depth process
knowledge in heterojunction cell technology (HJT). The two companies
have been working partners for many years, but the Alpha marks the
first time a development project has seen such game-changing results.
The REC Alpha Series (fig. ) uses heterojunction cells and an advanced
low temperature cell connection technology on REC’s innovative Twin
panel design where cells are cut into equally sized rectangles through
REC’s half-cut technology and connected in parallel.
Fig : The REC Alpha Series with HJT cells and advanced cell connection technology
What makes the REC Alpha Series different?
Based on REC’s unique cell technology and innovative panel design,
the leading status of the Alpha has already been acknowledged by the
granting of a design patent. It is the first solar panel to ever combine
the advantages of highly-efficient heterojunction cells, an advanced,
solder-free cell connection technology, the power benefits of half-cut
cells and the performance-boosting Twin panel design. All this means
that REC is able to deliver the world’s highest power density on a -
cell panel, with over more power compared to a conventional
panel - up to W/m
2
- a key consideration where space is limited, such
as on residential and small commercial rooops.
Fig : Power of the REC Alpha compared to conventional cell panels on a residential rooftop:
P-type multi P-type mono REC Alpha
Series
x Wp x Wp x Wp
4.6 kW 4.9 kW 6.1 kW
less power
than the REC
Alpha Series
less power
than the REC
Alpha Series
over
more power
in the same
area
What is heterojunction technology?
Heterojunction cell technology combines the advantages of crystalline
silicon cells and thin film technology within a single cell structure. This
means efficiency levels of over are now within reach.
Where a conventional crystalline solar cell uses a single material, silicon,
in an HJT cell, the junction is formed between two different materials:
crystalline and amorphous silicon, with the junction therefore referred
to as a heterojunction. This creates numerous performance benefits
compared to conventional cells.
What are the benefits of HJT technology?
The structure of an HJT cell plays an important role in improving panel
power and efficiency. Using two different materials results in huge band
gaps leading to the best available passivation technology. The amorphous
silicon layers make the contact layers ‘carrier selective’, allowing only one
kind of carrier to pass through and reach the contacts - either electrons
(negative charge) or holes (positive charge) - ensuring a major reduction
in recombination for beer cell efficiency and higher power.
Fig : Diagram of the REC Alpha cell structure:
Due to the symmetrical structure of an HJT cell, it is in fact a bifacial cell
and offers the highest bifaciality among all cell structure types. Other
structures have lower bifaciality due to absorption in one of the layers
or due to resistance losses. The bifacial structure means that HJT cell
technology is ideal for bifacial panel applications, but equally, even in
mono-facial panels, the bifacial aspect can be used to improve energy
yield through light capture at the rear of the cell.
Low temperature production
Conventional solar cells use a process called diffusion to create
thin doped layers in the wafer which form the p-n junction. While this
process is widely used and well-established, it needs high temperatures
consuming a lot of energy as well as requiring an additional wet chemical
process to clean the wafer. In an REC HJT cell, layers of intrinsic and
doped amorphous silicon are deposited on the crystalline silicon
substrate at low temperatures and does not require any subsequent
process steps, reducing the impact of the manufacturing process on
the cell for an improved build quality.
The REC Alpha Series:
Delivering ground-breaking new levels of power and creating a legacy of
sustainable energy
The launch of the REC Alpha Series in May , rocked the solar panel manufacturing industry with
the world’s most powerful -cell panel. With over more power coming from the same installation
area, the REC Alpha Series opens a big power gap beyond the commercially available power levels of
Tier competitors, but power is only one of the major advantages offered - there are many more:
Cell fingers printed on surface
Capture current and lead to wires
Transparent
Conductive
Oxide (TCO)
Provides extra
conductivity,
anti-reflective
layer & high
transmission
Silicon wafer bulk
N-type mono wafer,
doped with phosphorus,
for most efficient cell
technology
Amorphous Silicon –
Phosphorus doped (n+)
Creates the P/N
junction.Only negative
charges are transported
to the TCO layer.
Amorphous Silicon –
Boron doped (p+)
Creates the P/N junction.
Only positive charges
are transported to the
TCO layer.
Intrinsic
Amorphous
Silicon layers
Creates
passivation
layer