Importing from PVsyst
Project import
PlantPredict can import a complete PVsyst project from a ZIP file. The PVsyst project (PRJ) becomes a PlantPredict project, and each calculation variant (VC#) becomes a separate prediction. Modules (PAN), inverters (OND), weather data (MET), and shade scenes embedded in the project are imported automatically—you do not need to upload them separately. To import: on the Project Library, click Import Project, then choose Import PVsyst ZIP (Beta) under Other Options and select your ZIP file. For the full walkthrough—review screen, what gets imported, and troubleshooting—see How to Import PVsyst Projects.Individual file imports
If you are migrating components piece by piece, each PVsyst file type has a dedicated import path:
For PAN file imports, PlantPredict re-solves the single-diode parameters after import to ensure internal consistency—see PAN file re-solve below for what to expect.
A PVsyst 3D scene can contain object types PlantPredict does not support; those objects are left out of the scene that gets built. For both import paths (project ZIP file import or 3D shade scene SHD file upload), PlantPredict reports which objects were omitted, naming the object types and their counts. Any shading effect from those objects is not included in the results.
Mapping from PVsyst to PlantPredict
Plant topology
PlantPredict’s plant hierarchy is richer than PVsyst’s. PVsyst describes a plant as a flat list of sub-arrays, each pairing an array of modules with an inverter. PlantPredict nests that same pairing—one or multiple DC Fields tied to one Inverter—inside an Array, and groups Arrays into Blocks. The DC Field is the lowest modeling unit, aggregating identical modules and strings behind a shared tracker or fixed-tilt array. Because PVsyst has no equivalent of the Array and Block layers, the importer gives each PVsyst sub-array its own Array and its own Block rather than merging them together. This keeps a one-to-one correspondence with the source variant and gives users maximum flexibility. PlantPredict also allows a single Inverter to serve heterogeneous DC Fields, differing in module, orientation, or tracker geometry. PVsyst does not: a sub-array is homogeneous by construction. An imported PVsyst project therefore always leads to one DC Field per Inverter.
See the Power Plant Builder pages for the full hierarchy.
Loss tree
PVsyst reports each loss line as a percentage of the value before that loss is applied, so losses compound multiplicatively throughout the tree. PlantPredict divides the loss tree into four groups, each normalized by a single fixed reference quantity. Within a group, nearly every line shares that denominator and the lines are additive—you can sum them directly. The reference changes only when moving from one group to the next:
Total plant output is consistent between the two conventions, but line-item percentages are not directly comparable—a PVsyst line and its PlantPredict counterpart will differ in magnitude even when the underlying physics is identical. See P50 Loss Tree for the per-line formulas.
The table below maps common PVsyst loss diagram lines to their PlantPredict equivalents.
Shade factor table
To compare direct beam shading results line-by-line against PVsyst, PlantPredict exports a Beam Irradiance Shade Factor Table on the same 10° sun height × 20° azimuth grid PVsyst reports, from the 3D Scene page via Export Shade Factor Table. Availability depends on the tracking and binning configuration—see 3D Scene for the current conditions.Electrical shading models
Both tools split the beam shading loss into an irradiance component and an electrical effect of shade component. PVsyst offers No shadings, Linear shadings (irradiance deficit only, no mismatch), According to module strings / partitions (mismatch computed from the string layout), and Module Layout. Module Layout is not available above 5 MWp, so it is not practical for realistic utility-scale power plants. PlantPredict offers four models: None, Linear, Fractional, and Step Fractional (V12+, 3D Site Level shading algorithm only).
The models are formulated differently in each tool, so their percentage inputs are not interchangeable. See Electrical Shading Effect for PlantPredict’s full formulation.
Step Fractional (V12+) accounts for bypass-diode circuits with configurable horizontal partitions per bay, representing the non-linear response of a partially shaded module more closely than the legacy Fractional model.
Simulation settings
The most common PVsyst-to-PlantPredict setting mappings, on the Simulation Settings and Environmental Conditions pages:Common Comparison Pitfalls
Azimuth convention
PlantPredict measures all azimuths clockwise from geographic North on the 0°–360° range: 0° = North, 90° = East, 180° = South, 270° = West. PVsyst measures azimuth from the equator-facing direction on a signed ±180° range: 0° faces the equator—South in the northern hemisphere, North in the southern—with positive values toward West and negative toward East. PlantPredict’s importer converts azimuth values automatically.String sizing temperature
PlantPredict derives string design temperatures from ASHRAE data, using the extreme annual mean minimum dry bulb temperature at the nearest ASHRAE station by default. PVsyst applies a fixed lower temperature for the absolute voltage limit, defaulting to −10 °C for most European countries. Both values are editable, and both are design-only. They do produce different string counts for the same module and inverter, so verify string lengths when manually reproducing a design from one tool to the other.Solar position algorithm
PlantPredict uses the NREL Solar Position Algorithm (Reda & Andreas, 2004), accurate to ±0.0003°. PVsyst uses a simplified model derived from the US Navy formulation, accurate to within a few arc-minutes. The resulting difference in sun position is negligible for energy totals but contributes to small systematic differences in time-series comparisons.Perez coefficient set
PlantPredict offers twelve Perez coefficient sets on Simulation Settings: five composites and seven location-specific sets from 1988. The default PlantPredict set corresponds to the All Sites Composite 1990 set. PVsyst does not publish the coefficient set it uses and does not make it selectable. Since version 8.1.0, the set of Perez coefficients used by PVsyst depends on the time resolution of the simulation. At hourly resolution the two tools give very close transposition results. The differences that remain at the time-series level come mostly from the different solar position algorithms rather than from the coefficients—see Solar position algorithm.Circumsolar default treatment
Both tools let you choose whether circumsolar irradiance is treated as direct or diffuse. PlantPredict calls the options Direct and Diffuse; PVsyst calls them separate and with diffuse. They correspond directly: separate ↔ Direct, with diffuse ↔ Diffuse. Note that under PVsyst’s separate setting, circumsolar is treated as direct in every respect except the electrical effect of shade: it takes the beam’s IAM and the beam’s far and near shading factors, but it does not produce electrical shading losses. However, the defaults do not match. PVsyst’s default is separate (since v7.0), whereas PlantPredict’s default is Diffuse. On import, PlantPredict reads the setting from the PVsyst variant and selects the matching option, overriding the PlantPredict default if needed. This makes IAM a useful diagnostic: a gap of 0.5% or more between the two tools’ IAM losses is a warning sign that they are not using the same circumsolar treatment. Treating circumsolar as diffuse generally increases IAM losses.Albedo definition
PlantPredict uses a single albedo. The values set on Environmental Conditions—read from the weather file or entered by hand—feed the transposition model’s ground-reflected component and the bifacial backside calculation alike. PVsyst keeps two independent albedo inputs: the project-level albedo, which drives ground reflection on the front side, and a separate ground albedo inside the bifacial model definition. These values are independent of one another and can diverge without a warning from the tool.3D transposition and orientation grouping
PVsyst describes a field as a limited set of orientations, each carrying a single averaged axis tilt and azimuth. It groups the tables in a 3D scene into orientations automatically and computes transposition once per orientation. PlantPredict computes transposition per bay when a 3D scene is enabled, using each bay’s own rotation angle and axis tilt, including the terrain-corrected orientation under terrain-aware backtracking. See 3D Transposition. This changes the bookkeeping when comparing plane-of-array irradiance. PlantPredict reports the flat-terrain result on Transposition On POA and the bay-level adjustment separately on 3D Correction to Transposition On POA, which can be a gain or a loss. PVsyst has no second line—its Global incident in coll. plane already contains everything. To compare the two tools, take the PlantPredict POAI and apply the 3D transposition gain or loss to it; the resulting 3D-corrected POAI is what PVsyst’s figure should be measured against.Horizon shading scope
PlantPredict’s far (horizon) shading applies to beam only: when the sun is below the interpolated horizon profile, beam irradiance is set to zero. Sky-diffuse irradiance and ground-reflected irradiance are not reduced by the horizon. PVsyst applies far shading to beam, diffuse, and albedo components. At sites with a significant horizon elevation, PlantPredict will predict more annual diffuse and reflected energy than PVsyst, and the gap grows with horizon elevation. See Horizon Shading.PAN file re-solve
After importing a PAN file, PlantPredict re-solves the single-diode parameters (, , , , ) to ensure all parameters are internally consistent. The resulting values will differ slightly from PVsyst’s stored values. This is expected—not an import error.Temperature coefficient units
PVsyst PAN files store in mV/°C and in mA/°C. PlantPredict stores both in %/°C. The PAN importer handles this conversion automatically. If you are entering coefficients manually, convert to %/°C before entry.DC wiring loss attribution
PlantPredict and PVsyst differ in the order in which DC wiring (resistive) losses and inverter clipping losses are applied. PVsyst accounts DC wiring loss before clipping is applied. PlantPredict accounts it after, on the reduced current. The AC power leaving the inverter is the same either way—what changes is the split between the DC Wiring and Inverter Limitation lines. On a high DC/AC plant, expect PlantPredict to report a smaller DC Wiring loss and a correspondingly larger Inverter Limitation loss than PVsyst for the same design.AC ohmic loss reference power
Both tools express AC collection loss as a percentage, but the reference power against which that percentage is applied can differ. PlantPredict always uses the inverter’s rated AC apparent power (kVA). PVsyst lets you choose between the inverter’s nominal AC output power (PNom(Inv))—this option matches PlantPredict—and the array’s DC nominal power at STC, times inverter efficiency (PNomPV(ac)). Because the percentage is converted into a wire resistance, a larger reference power means a smaller resistance and a lower resistive loss in operation. On a high DC/AC site, a PVsyst variant using PNomPV(ac) will report lower AC collection losses than the same percentage entered in PlantPredict.Grid limit enforcement
PlantPredict applies the grid limit (LGIA) at the point of interconnection, after all AC losses, and reports it on its own Plant Output Limitation line. PVsyst enforces the limit at the inverter and reports it as clipping, unless Account as separate loss is enabled to break it out asEGrdLim.
P90 / uncertainty methodology
Both tools compute P-values by combining named uncertainty components via root-sum-of-squares into a single sigma, then applying a normal-distribution z-score to P50. The component taxonomies differ, so uncertainty inputs do not transfer directly between the two tools. PlantPredict’s Uncertainty Analysis uses five components: interannual variability, irradiance measurement accuracy, monitoring-period representativeness, spatial variability, and modeling accuracy. PVsyst uses a different set: weather data annual variability, PV module model and parameters, inverter efficiency, soiling and module quality loss, and long-term degradation. These do not map one-to-one and must be re-entered independently in each tool.References
- Reda, I., & Andreas, A. (2004). Solar Position Algorithm for Solar Radiation Applications. NREL/TP-560-34302. DOI: 10.2172/15003974