Glossary
Glossary of norms for solar power plants
The terms from the Ukrainian norms that Solispec’s calculation uses: snow and wind under DBN V.1.2-2:2006, frost and strings, lightning protection, the steel of the frames. Each term comes with its clause (where a norm defines it), a worked example and the calculator that computes it.
41 · Terms8 · Norms explainedStatus checked: 2026-10-14
Ground frame designer
Design the ground frame for your solar plant
Solispec picks the profiles and posts, checks the frame against snow and wind to the DBN and prices it down to the last bolt.
Snow and wind
- Characteristic snow load S₀The weight of snow cover per 1 m² of ground exceeded on average once in 50 years; under DBN V.1.2-2:2006 Kyiv has 1,550 Pa.
- Characteristic wind pressure W₀The mean wind pressure at 10 m height exceeded on average once in 50 years; Kyiv has 370 Pa under DBN V.1.2-2:2006.
- Limit design snow load SmThe snow load on the horizontal projection used for strength checks: S_m = γ_fm · S₀ · C under DBN V.1.2-2:2006.
- Limit design wind load WmThe wind load used for strength checks: W_m = γ_fm · W₀ · C, where C covers aerodynamics, height, topography and dynamics.
- Reliability factor for the limit value γfmThe multiplier on S₀ and W₀ that depends on the mean return period T: 1.00 at 50 years, 1.14 at 100 years (Tables 8.1, 9.1).
- Reliability factor for the serviceability value γfeThe multiplier for serviceability loads (deflections): at η = 0.02 snow 0.49, wind 0.21 (Tables 8.3, 9.3 of DBN V.1.2-2:2006).
- Altitude factor CaltThe correction for altitude: 1.4H + 0.3 for snow from 0.5 km, 2H for wind above 0.5 km, otherwise 1 (DBN V.1.2-2:2006).
- Operating conditions factor CeThe snow load factor for clearing and melting; without data on how the roof is operated C_e = 1 (cl. 8.9).
- Snow shape coefficient μThe conversion from ground snow to roof snow: μ = 1 up to 25°, 0 from 60°, linear in between (DBN V.1.2-2:2006, Annex Zh, scheme 1).
- Height factor ChThe wind correction for height above ground and terrain type, Table 9.01 of DBN V.1.2-2:2006: 0.7 at 5 m and 0.9 at 10 m for type II.
- Terrain type I–IVThe wind classification of a structure’s surroundings under cl. 9.9 of DBN V.1.2-2:2006: from open water (I) to dense urban areas (IV).
- Icing: ice thickness b and wind pressure WBIce-wind load under section 10 of DBN V.1.2-2:2006; Kyiv has b = 19 mm and W_B = 160 Pa, but it is not required for ground PV.
- Mean return period TThe period in years over which a load is exceeded once on average; γ_fm depends on it (Tables 8.1, 9.1 of DBN V.1.2-2:2006).
- Aerodynamic coefficient Caer (cf)The multiplier turning wind pressure into force on a shape; for panels Solispec takes c_f from Table 7.6 of EN 1991-1-4:2005, as cl. 9.8 of the DBN allows.
- Peak velocity pressure qpA Eurocode term from EN 1991-1-4:2005 (cl. 4.5): wind pressure including gusts; DBN V.1.2-2:2006 uses W₀ and C_h instead.
- Wind uplift and slidingThe two checks of a ballasted table: wind must neither lift the structure nor slide it across the ground or roof.
- BallastDead weight (concrete blocks, gravel trays) that keeps a PV table from wind uplift and sliding without anchoring into the ground or roof.
- Snow and wind zonesThe zones of maps Fig. 8.1 and 9.1 of DBN V.1.2-2:2006; for calculations the S₀ and W₀ values in Pa from the city table are easier to use.
Row layout
Climate
- Climatic region (DSTU-N B V.1.1-27)A region of Ukraine by building climatology; for PV it gives the absolute minimum air temperature used to check string voltage.
- 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.
DC and AC electrics
- 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.
- 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.
- DC/AC ratio (inverter loading)The ratio of the panels’ peak power to the inverter’s rated power; no norm sets it, it is an engineering choice.
- 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.
- Allowed connection powerThe power stated in the grid connection contract; the total power of the PV inverters may not exceed it.
Lightning, earthing, fire safety
- 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.
- PV earthing and equipotential bondingConnecting PV frames, rails and structures to the building’s earthing; under PUE:2026 the earthing must be common with the building.
- Separation distance s (lightning protection)The minimum gap between a PV array and lightning down conductors at which no spark flashes over (DSTU EN 62305-3:2021, cl. 6.3).
- Lightning risk assessmentThe DSTU EN 62305-2:2022 calculation deciding whether a building with PV needs external lightning protection; there is no "PV means LPS" rule.
- Fire-rated cable penetrationThe seal where a PV cable passes through a fire-rated wall or floor; its rating must be no lower than that of the construction.
- Combustible roofs and PV cablesNAPB forbids external wiring over combustible roofs; on bitumen shingle or onduline, DC cables run in metal trays or conduit.
Steel structures
- Thin-walled cold-formed C-profileA bent steel section with thin walls that buckles locally before yielding; it is designed to DSTU-N B EN 1993-1-3:2012.
- Profile perforation and bolts in slotsFactory slotted holes of a mounting C-profile; bolts go into the slots without drilling, and the maker confirms a slotted bolt’s resistance.
- Effective cross-sectionThe part of a thin-walled section that still carries compression after its walls buckle locally; computed per EN 1993-1-5 and EN 1993-1-3.
- Steel partial factors γM and γmFactors that divide the characteristic steel resistance: γ_M per Eurocode for C-profiles, γ_m per DBN V.2.6-198 for tubes.
- Buckling reduction factor φ (χ)A factor that reduces a compressed member’s resistance for flexural buckling: φ in DBN V.2.6-198, χ in Eurocode 3.
Norms explained
- DBN V.1.2-2:2006 “Loads and actions”: what matters for a solar plantThe clauses of the Ukrainian loads code a solar array needs: S₀, W₀, the factors, Changes 1 and 2, and a worked example for Kyiv.
- 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.
- DSTU HD 60364-7-712:2022: the electrics of PV systemsUkraine’s main PV electrical standard: U_OC MAX in frost, I_SC MAX, string fuses, cables under modules, SPDs and earthing.
- DSTU-N B EN 1993-1-3:2012: designing C-profiles for PV mountingWhy a perforated 41×41 C-channel is checked to Eurocode 3 rather than DBN V.2.6-198: effective section, γ_M factors, bolts in slots.
- DBN V.2.6-198:2014 “Steel structures”: tubes in PV framesHow the Ukrainian steel structures code applies to closed tubes in a ground PV frame: Ry, γm, the buckling factor φ and the checks Solispec runs.
- DSTU EN 62305-1…4: lightning protection for solar plantsThe four parts of DSTU EN 62305-1…4 for a solar plant: risk assessment, separation distance, SPDs. There is no rule that PV always needs lightning protection.
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.