Rev IM/GN-CM-EN/1.0 Copyright© October, 2020 Canadian Solar Inc. 6
A maximum of two strings can be connected in parallel without using an over-current protection device
(fuses, etc.) incorporated in series within each string. Three or more strings can be connected in parallel if
an appropriate and certified over-current protection device is installed in series within each string. And it
shall be ensured in the PV system design that the reverse current of any particular string is lower than the
module maximum fuse rating at any circumstance.
For high power bins modules such as CS1 series intended to be used on rooftop applications, in agreement
with IEC62548:2016 Photovoltaic (PV) arrays design requirements, blocking diodes should be used in each
PV array module string as exclusive mean of protection against reverse currents where three or more
strings are connected in parallel. Where permitted by your local electrical code, blocking diodes can also be
used for over overcurrent protection, in place of fuses or other OCPD devices.
Only modules with similar electrical parameters should be connected in the same string to avoid or
minimize mismatch effects in arrays.
To minimize risk in the event of an indirect lightning strike, avoid forming loops with the wiring when
designing the system.
The recommended maximum series fuse rating is stated in a table in the Annex C.
Modules should be safely fixed to bear all expected loads, including wind and snow loads.
A minimum clearance of 6.5 mm (0.25 in) between modules is required to allow for thermal expansion of
the frames.
The small drainage holes on the underside of the module must not be blocked.
Optimum orientation and tilt
To maximize your annual yield, find out the optimum orientation and tilt for PV modules in your region.
The highest yields are achieved when sunlight shines perpendicularly onto the PV modules
Avoid shading
Even minor partial shading (e.g. from dirt deposits) reduces yields. A module can be considered to be
unshaded if its entire surface is free from shading all year round. Sunlight should be able to reach the
module even on the shortest day of the year.
Constant shading conditions can affect module service lifetime, due to accelerated ageing of the
encapsulation material and thermal stress on the bypass diodes.
Reliable ventilation
Sufficient clearance (at least 10 cm (3.94 in)) between the module frame and the mounting surface is
required to allow cooling air to circulate around the back of the module. This also enables condensation or
moisture to dissipate.
According to UL 61730, any other specific clearance required for maintaining a system fire rating should
prevail. Detailed clearance requirements pertaining to system fire ratings must be provided by your racking
supplier.
