Electrically conductive adhesive maximises panel durability
The SunPower Performance panel eliminates the use of
soldered cell connections—designing out one of the major
failure modes of conventional cells (figure 4). These metallic
connections expand and contract as temperatures rise
during the day, and cool at night. This repeated daily stress
can cause solder bonds to break and cells to crack. With
cracked cells no longer functioning properly, bypass diodes
are activated, limiting the amount of power the panel can
produce. If the diode fails from continued activation, current
will then be forced through the defective cells and ultimately
lead to hotspot formation and permanent power loss.
In place of these fragile solder bonds, the SunPower
Performance panel uses an advanced electrically conductive
adhesive (ECA) originally developed in the aerospace
industry. The ECA provides a robust solution with high
electrical conductivity. It has the ability to adhere to diverse
materials, bonding the edge of the front of one cell to the
rear edge of the next cell. This innovative approach increases
the number of cell-to-cell contact points, while reinforcing
each connection to withstand the stresses of daily
temperature swings and corrosion over time—while
removing toxic lead from the interconnection.
A recent study of site inspection results from Dupont
demonstrated that the predominant panel failure mode was
attributed to the weakness of the cell-ribbon bond on
conventional panels (figure 5).
4
Eliminating these
connections has been a critical factor in the low claim rate of
SunPower Performance panels—less than 50 failures per
million panels installed globally.
5
In addition, the glass-glass
architecture of the SunPower Performance 5 panel further
strengthens its resiliency in the field.
Figure 4: SunPower Performance panels eliminate the use of soldered cell connections–designing out one of the major failure modes of
traditional cells.
Figure 5: Inspection results from Dupont’s Global PV Reliability Field Analysis featuring key causes of panel failure amongst recently
installed conventional panels.
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