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Installation Planning
975-0053-01-01 2–7
DC grounding The negative PV conductor must be bonded to the grounding system at
only one point in the system. See Figure 2-3 for the location of the Sun
Tie XR ground bar. The size for the conductor is usually based on the size
of the largest conductor in the DC system. Negative/ground bonding is
accomplished by factory-wired PVGFP breakers.
PV Array Requirements
MPPT operational
window
The Sun Tie XR is optimized to work with 4-each, 12 volt nominal
crystalline PV modules in series (48 VDC nominal), or various
combinations of amorphous, thin film PV modules. Ensure the PV array
used in the system operates within the maximum peak power tracking
(MPPT) operational window.
Vo l t a g e
requirements
The solar array connected to the Sun Tie XR should have a minimum of
50 volts DC open-circuit in full sunlight conditions. Crystalline solar
arrays configured for 48 volts DC nominal will have an open-circuit
voltage of around 84 volts DC in full sunlight. The MPPT software
controls the output of the solar modules, under loaded conditions, in the
42–85 volts DC range (full inverter output power occurs between 52–85
VDC for the STXR1500 and between 52–75 VDC for the STXR2500).
Other array voltages will either not operate the inverter, may cause
damage, or will not allow maximum harvest of the sun’s energy.
Figure 2-3 Ground bar location
Ground bar
(connect to solid earth ground)