Norms · DSTU HD 60364-7-712:2022
DSTU HD 60364-7-712:2022: the electrics of PV systems
How many panels can go in a string, when fuses are needed and what cable size to use — DSTU HD 60364-7-712:2022 answers these. It is the identical Ukrainian adoption of the European HD 60364-7-712:2016.
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Edition and status
DSTU HD 60364-7-712:2022 (HD 60364-7-712:2016, IDT) replaced DSTU IEC 60364-7-712:2019. Status as of 14.10.2026: in force per the norms register Solispec checked on 04.10.2026. The DSTU text is paid; we quote the formulas from the HD.
The official text: UkrNDNC, the national standards body (the standard’s text is sold). Solispec does not host the norm texts. Look for the current edition at the official source.
Voltage: Annex B.1
Current: Annex B.2
ISC MAX = KI · ISC STC, KI ≥ 1,25Under 712.512.1.2, ISC MAX is the design current for selecting devices. Under certain conditions, such as strong reflection, KI is increased, but the standard gives no number. For a bifacial panel over a bright surface this matters: the rear-side gain comes from the datasheet.
Fuses, cables, protection
- 712.431, 712.432: a string fuse is needed when more than two strings are in parallel and (Ns − 1) · ISC MAX > 1.35 · IMOD MAX OCPR; both poles are protected, 1.1 · ISC MAX ≤ In ≤ IMOD MAX OCPR.
- 712.433.101: the current rating Iz of the string cable is at least the string’s ISC MAX with one or two strings in parallel.
- 712.523.101: for cables heated from below by the modules, the ambient temperature is taken as at least 70 °C.
- 712.534 — SPDs, 712.54 — earthing and bonding.
How Solispec applies it
The Solispec engine computes UOC MAX per Annex B.1: with the panel’s α from the catalogue and the site Tmin, and without them 1.2 · UOC STC. It takes ISC MAX as 1.25 · ISC per string and compares it with the inverter input. For three or more parallel strings on one MPPT input it adds gPV fuses on both poles. It checks the DC cable size by current at 70 °C (a 0.91 factor on the datasheet Iz of H1Z2Z2-K cable).
Terms
- Maximum open-circuit voltage UOC MAXThe open-circuit voltage of a panel or string at the site minimum temperature; inverters, fuses and isolators are selected by it.
- Maximum short-circuit current ISC MAXThe design current of a PV array, I_SC MAX = K_I·I_SC STC with K_I of at least 1.25; cables and protection are sized by it.
- Site minimum temperature TminThe lowest ambient air temperature at the PV site; it sets the maximum open-circuit voltage of a string, U_OC MAX.
- String fuse (gPV)Protects a string from reverse current fed by parallel strings; under DSTU HD 60364-7-712 it is needed with three or more strings in parallel.
- PV DC cableThe cable between the panels and the inverter; its section is chosen by I_SC MAX at 70 °C and checked for voltage drop.
- PV stringA chain of panels connected in series: voltages add up, the current is shared; frost and the inverter MPPT window limit its length.
- MPPT and the inverter voltage windowThe inverter’s maximum power point tracker; its voltage range sets the minimum and maximum number of panels in a string.
- Surge protective device (SPD)A device that limits lightning and switching surges in PV circuits; its type depends on whether the building has lightning protection.
Other norms
- DSTU-N B V.1.1-27:2010: climatic regions and Tmin for PV stringsBuilding climatology for a solar plant: Ukraine’s climatic regions, the minimum temperature and why the string length depends on it.
- PUE:2026 for solar plants: what changedPUE:2026 replaced PUE:2017: scope, common earthing with the building and surge protection for a solar plant.
- DBN V.2.5-23:2025 (from 01.01.2026): what applies to solarThe new Ukrainian code for building electrical installations: lightning protection, SPDs, fire-rated penetrations, conductor sizing and PV cables.
Solispec’s calculation is preliminary: for a design it has to be checked by an engineer. The values and clauses follow the current editions of the norms on the date of the page.