NEC 690.12 and Solar Panel Orientation: Is There a Connection?

Understanding NEC 690.12 Requirements

NEC 690.12 requires that the solar system’s maximum power point tracker (MPPT) can rapidly shut down the system in the event of a fault. This rapid shutdown capability is necessary to prevent electrical shock or arc faults in the event of a fault on the system. The MPPT’s ability to rapidly shut down the system is also affected by the temperature of the solar panels, which in turn is affected by the panel’s orientation.

Solar Panel Orientation and Temperature

The efficiency of the MPPT is affected by the temperature of the solar panels, which is influenced by the panel’s orientation. In general, solar panels oriented towards the south will receive more direct sunlight and thus will be hotter than panels oriented towards the east or west. A study by the National Renewable Energy Laboratory (NREL) found that panels oriented towards the south will have a temperature that is about 5-10°F (3-6°C) higher than panels oriented towards the east or west. This temperature difference can affect the MPPT’s ability to rapidly shut down the system in the event of a fault.

Best Practices for Solar Panel Orientation

To minimize the impact of temperature on the MPPT’s ability to rapidly shut down the system, it is recommended that solar panels be oriented towards the south at an angle of between 15° and 40°. This orientation will provide the most direct sunlight and thus will help to minimize the temperature difference between the panels. Additionally, using a high-efficiency MPPT that can operate effectively at high temperatures can also help to mitigate this issue.