| Installation Planning |
DC grounding | The negative PV conductor must be bonded to the grounding system at |
| only one point in the system. See Figure 2-3for 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. |
Ground bar
(connect to solid earth ground)
Figure 2-3 Ground bar location
PV Array RequirementsMPPT operational window
Voltage requirements
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.
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.
