Utility External Disconnect Switch Report
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This report documents the safe operation of photovoltaic (PV) systems without a utility external disconnect switch (UEDS) in several large jurisdictions. It explains the rationale for eliminating UEDS:
- Functionality is redundant
- Fails to provide the protection that is its justification
- Adds unnecessary cost to a PV system.
Why This Report is Important
Regulators must decide the question of UEDS requirements as they develop
or revise interconnection rules for small renewable energy generators.
The report includes important information on this topic and a recommendation
for regulators.
Issue
Some states and utilities require installation of UEDS between PV power systems and the utility grid as a device to ensure line worker safety. However, eight states and many major utility companies have recognized that safety devices and features already part of all Code-compliant PV systems make the UEDS redundant and have eliminated its requirement.
Solar America Board for Codes and Standards Recommendation
The recommendation of this report is to eliminate the requirement for UEDS for all small, inverter-based systems in all jurisdictions. With the inherent safety features built into all UL-listed PV inverters, the UEDS is functionally unnecessary and provides little, if any, additional safety.
For customers with self-contained meters (including almost all residential and small commercial customers), the meter itself is already fully capable of providing the functions required of the switch (i.e., a visible, physical, lockable separation of the system from the utility). At the very minimum, these customers should be excluded from any UEDS requirement.