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Planning the Installation
PV Array Voltage and MPPT Requirements
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| WARNING: Shock hazard |
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| Whenever a PV array is exposed to sunlight, a shock hazard exists at the output wires or |
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| exposed terminals. To reduce the risk of shock during installation, cover the array with an |
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| opaque (dark) material before making any connections, and always test for voltage before |
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| touching exposed wiring or devices. |
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MPPT operational | The MPPT software maximizes the output energy of solar arrays as long as the | |
window | operating voltage is within the MPPT operational window. Ensure that the PV | |
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| array used in the system operates within the MPPT operational window. |
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| Effects of array voltages outside of the MPPT operational window are shown in |
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| Table |
Table
Voltage | Effect of Array Voltage | Inverter Mode |
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Voc < 240 Vdc | Inverter not operating. | |
VMPP < 240 Vdc | Operating voltage shifts to 240 Vdc; the array is not at its | |
(Voc > 240 Vdc) | maximum power point. |
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VMPP 240 to 550 Vdc | Maximum harvest of solar energy. | |
VMPP 550 to 600 Vdc | Does not allow maximum harvest of solar energy. | |
VMPP > 600 Vdc | Inverter stops delivering power and shuts down. Inverter | |
(or Voc > 600 Vdc) | may be damaged. |
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Voltage | The maximum power point voltage of a string connected to the GT Inverter should |
requirements | preferably be above 240 Vdc. If it is less than 240 Vdc, the inverter continues to |
| operate, but it regulates the PV voltage to 240 V. Because the array is not |
| operating at its maximum power point, this may result in lower than expected |
| energy harvest. If Voc is below 240 Vdc, the inverter remains |
| deliver power. |
CAUTION: Equipment damage
To prevent damage to the inverter, the array voltage must never exceed 600 Voc (open circuit voltage) under any condition.
The open circuit voltage of the array under normal conditions should be above 240 Vdc.
The short circuit current (Isc) rating of the array at any temperature must not exceed the Isc rating of the inverter. For maximum solar energy harvest, it is recommended that the effective power output of the array be matched with the input power capacity of the inverter.