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Circuit Requirements
Maximum Voltage
Maximum Photovoltaic System Voltage. In a dc photovoltaic source circuit or output circuit, the maximum photovoltaic system voltage for that circuit shall be calculated as the sum of the rated open-circuit voltage of the series-connected photovoltaic modules corrected for the lowest expected ambient temperature. For crystalline and multicrystalline silicon modules, the rated open-circuit voltage shall be multiplied by the correction factor provided in Table 690.7. This voltage shall be used to determine the voltage rating of cables, disconnects, overcurrent devices, and other equipment. Where the lowest expected ambient temperature is below -40°C (-40°F), or where other than crystalline or multicrystalline silicon photovoltaic modules are used, the system voltage adjustment shall be made in accordance with the manufacture's instructions.
Table 690.7 Voltage Correction Factors for Crystalline and Multicrystalline Silicon Modules
| Ambient Temperature (°C) | Correction Factors for Ambient Temperatures Below 25°C (77°F)(Multiply the rated open-circuit voltage by the appropriate correction factor shown below.) | Ambient Temperature (°F) |
| 25 to 10 | 1.06 | 77 to 50 |
| 9 to 0 | 1.10 | 49 to 32 |
| -1 to -10 | 1.13 | 31 to 14 |
| -11 to -20 | 1.17 | 13 to -4 |
| -21 to -40 | 1.25 | -5 to -40 |
Direct-Current Utilization Circuits. The voltage of dc utilization circuits shall conform with 210.6.
Photovoltaic Source and Output Circuits. In one and two-family dwellings, photovoltaic source circuits and photovoltaic output circuits that do not include lamp holders, fixtures, or receptacles shall be permitted to have a maximum photovoltaic system voltage up to 600 volts. Other installations with a maximum photovoltaic system voltage over 600 volts shall comply with Article 690, Part I.
Circuits Over 150 Volts to Ground. In one and two-family dwellings, live parts in photovoltaic source circuits and photovoltaic output circuits over 150 volts to ground shall not be accessible to other than qualified persons while energized.
Bipolar Source and Output Circuits. For 2-wire circuits connected to bipolar systems, the maximum system voltage shall be the highest voltage between the conductors of the 2-wire circuit if all of the following conditions apply:
- One conductor of each circuit is solidly grounded.
- Each circuit is connected to a separate subarray.
- The equipment is clearly marked with a label as follows:
WARNING
BIPOLAR PHOTOVOLTAIC ARRAY.
DISCONNECTION OF NEUTRAL OR
GROUNDED CONDUCTORS MAY RESULT
IN OVERVOLTAGE ON ARRY OR INVERTER.
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