raw · articles · ingested 2026-06-28
Maximum PV system voltage — NEC 690.7 ceilings and temperature-corrected Voc
Source: https://www.mayfield.energy/technical-articles/code-corner-2023-nec-690-7-and-690-31g/
Sources: Mayfield Renewables (2023 NEC 690.7 / 690.31(G)); Solar Permit Solutions; EC&M. Credibility: High (code-based engineering references). Confidence: high.
The voltage ceilings
- 600 V DC — one- and two-family dwellings.
- 1000 V DC — other buildings (commercial/multifamily); dc circuits in/on buildings.
- 1500 V DC — ground-mount / utility systems (via 690.31(G)); the current utility-scale standard.
- DC circuits >1000 V must comply with 690.31(G); 2023 NEC relaxed this to allow >1000 V on building exteriors within size limits.
How the max is computed
- Max system voltage = ΣVoc × temperature correction factor. Sum the series modules’ Voc, then correct upward for the coldest expected temperature (Table 690.7(A) for c-Si, or manufacturer TC_Voc, or stamped-PE design ≥100 kW).
- Voltage is inverse to temperature → size strings on coldest-expected Voc so they never breach the ceiling (protects inverters/conductors, preserves warranty).
Relevance
The voltage half of photovoltaic-array-electrical-output: the practical “maximum” array voltage is a code/equipment ceiling (600/1000/1500 V), set by series-string length and cold Voc.