"must I have a grounding electrode
on the DC circuit"
I misspoke previously- when I said (Isolated = grounded = yes) I meant an electrode is required FOR the DC circuit, *not*- "on the" or "at the".
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Over the past few
Code cycles, the changes to 690.47 have been dramatic. In the 2011
Code, the changes made to 690.47 seemed well-received by the PV community, primarily due to the
deletion of the most difficult and controversial requirement, 690.47(D), which called for additional electrodes for array grounding. The 2011
NEC’s 690.47 has three subsections, with the third being the most widely used. The first two are for systems that exclusively produce and use DC or AC. The third subsection, 690.47(C), applies to systems that have both DC and AC electrical requirements—the majority of PV systems installed today. That third subsection is divided into three additional subsections for different installation scenarios.
All three of 690.47(C)’s subsections require that the DC grounding system be connected to the AC system’s grounding electrode. For grid-direct PV systems, this is generally the existing grounding electrode—a ground rod, water pipe, concrete-encased electrode, etc. A new DC grounding system connection to earth can be accomplished by:
- Establishing a new DC GE and bonding the new electrode to the existing AC GE.
- Connecting a new DC GEC from the inverter to the existing AC GE.
- Using a combined DC GEC and AC EGC (in one wire) from the inverter to the grounding bus bar in the associated AC equipment.
Each of these provisions has its own unique set of rules to follow. Grounding and bonding is always a complicated case.
https://www.homepower.com/articles/...n/code-corner-pv-grounding-and-bonding-part-2
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Wow, so this issue has been around since 1989.
Of course, this bolded means not grounding it to an electrode on/at the DC side.
In view of the prevalent practice, with apparent success, among European designers of
not grounding the
dc system, the quasi-axiomatic practice by U.S. designers of multiple-point grounding should be re-examined,
and a dialogue initiated between the two parties.
https://www.nist.gov/sites/default/files/documents/pml/div684/Photovoltaic.pdf
