HelioSphera HS Atlas Series, Safety And Installation Instructions Manual

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10-SSI-001_rev.005_ENG
Page 31 of 51
In order to choose the most appropriate inverter the following criteria must be met:

The maximum open circuit voltage (Voc) of the PV generator must never exceed
the maximum input voltage of the inverter. Please take into account that Voc is
affected by weather conditions.

The maximum power point voltage (Vmpp) of the PV generator must always be
within the input voltage limits (window) of the inverter’s MPP Tracker. Please take
into account that Vmpp is affected by weather conditions. Operating voltage can
also impact the conversion efficiency of the inverter. Refer to inverter’s data sheet.

Input current (Impp. Isc) should never exceed the respective inverter’s input limit.

HS modules have, as all thin film modules, special behavior overtime. This means
that initially, approximately 10% higher power may be observed which needs to be
considered for system design. After few weeks of exposure stabilized nominal
power would be reached.

Most inverters used to have 1 MPPT. In this case all the modules must have
identical orientation, inclination and belong to the same type and power category.
However, nowadays, inverters tend to have
2 or more MPPT . In that case, all the
modules that belong to each MPPT must have identical orientation, inclination
and belong to the same type and power category. In general, it is preferable to use
inverters with more than 1 MPPT.
6.3 Bypass diode
Partial shading of an individual module can cause a reverse current across the shaded
module. Current is thus forced through the shaded area by the other modules.
When a bypass diode is wired in parallel with the series string, the forced current will flow
through the diode and bypass the shaded module, thereby minimizing module heating and array
current losses.
Because HS modules have all cells connected in series in a single string, a single bypass
diode is used between the module terminals. This diode is inside the junction box.