Time series data

The Time series data tab in the Outputs workspace exports per-timestep simulation results as a CSV file. For a walkthrough of the download process, see Viewing results.

The behaviour depends on the selected output mode. For the Summary output mode, most values are pre-computed during the yield solving loop and stored — the download reads these from storage and formats them into CSV rows, with only a few derived values computed on the fly (air mass, diffuse fraction, and solar elevation; see Atmospheric inputs and Solar position below). For the Individual cell output and POA equivalent irradiance output modes, the download triggers a new solving loop that recalculates the per-cell light-generated current from the stored ray tracing and spectral data.

For a description of how Summary values accumulate into the losses shown in the waterfall chart, see Waterfall loss chart.

Output modes

The output mode determines what data is available for export and whether any new calculations are performed.

Summary

The standard output mode. All values are read from the pre-computed results stored during the yield solving loop. No additional physics calculations occur (except the few derived values noted above). The remaining sections of this page — Request info, Inputs, Module output, String output, and Array output — describe the columns available in Summary mode.

Individual cell output

Exports the light-generated current density ( $J_L$ ) for every cell in every module at each timestep. Unlike Summary mode, this triggers a new solving loop at download time that:

Loads the stored environment data (weather, spectral irradiance) and the pre-computed ray tracing absorption matrices from storage.
For each timestep, interpolates the ray tracing results to the actual sun position and recalculates the spectral photocurrent absorbed by each cell, weighted by the cell’s collection efficiency (spectral response).
Outputs one row per cell per timestep.

The per-cell $J_L$ is the same quantity that was used internally during the yield solving loop to drive the electrical circuit solver, but it is recalculated here because the original solving loop does not store per-cell values. The calculation is performed at the reference temperature (25 °C) — no thermal model is applied, and the collection efficiency is not adjusted for operating temperature. See Using a plane-of-array sensor in SunSolve for a related workflow that uses per-cell output to extract POA irradiance.

The output columns are:

Date/time columns — timestamp in the selected format (same options as Summary).
ModuleX, ModuleY — the module’s position in the array grid.
CellX, CellY — the cell’s position within its module.
$J_L$ (A/cm²) — the total light-generated current density (front + rear), representing the combined spectral photocurrent from both sides of the cell.
$J_L$ front (A/cm²) — the front-side contribution only.
$J_L$ rear (A/cm²) — the rear-side contribution only. Zero for monofacial modules.

POA equivalent irradiance

Converts the light-generated current at each cell or module into an equivalent plane-of-array irradiance (W/m²) derived from ray tracing. Unlike the view-factor-based POA estimates available under Module info, this calculation uses the full ray tracing absorption results and therefore accounts for detailed optical effects such as incidence angle, inter-row shading, and structural shading. Like Individual cell output, this triggers a new solving loop at download time and is calculated at the reference temperature (25 °C) without thermal effects. The key difference from Individual cell output is that the cell’s wavelength-dependent collection efficiency is set to unity across all wavelengths. This makes the cell respond equally to all wavelengths in the modelled spectrum (300–1200 nm), approximating a broadband irradiance sensor.

The POA irradiance for each cell is then calculated as:

I_{POA} = \frac{J_{L,POA}}{J_{L,GHI}} \times GHI

where:

$J_{L,POA}$ is the light-generated current density in the cell with unity collection efficiency
$J_{L,GHI}$ is the equivalent photon current density of the global horizontal irradiance over the same spectral range (300–1200 nm)
$GHI$ is the broadband global horizontal irradiance from the weather file (which includes wavelengths beyond 1200 nm)

This ratio-based approach compensates for the limited spectral range of the optical model (300–1200 nm) by scaling to the full-spectrum GHI. For more background on the method and how to define a module that acts as a POA sensor, see Using a plane-of-array sensor in SunSolve.

Results can be output per cell or per module:

Per cell — one row per cell per timestep, with the columns:

Date/time columns — timestamp in the selected format.
ModuleX, ModuleY — module position.
CellX, CellY — cell position.
POA irradiance (W/m²) — total (front + rear) equivalent irradiance.
POA front (W/m²) — front-side contribution.
POA rear (W/m²) — rear-side contribution.

Per module — one row per module per timestep, with the columns:

Date/time columns — timestamp in the selected format.
ModuleX, ModuleY — module position.
POA front (W/m²) — the front-side POA irradiance, averaged across all cells in the module.
POA rear (W/m²) — the rear-side POA irradiance, averaged across all cells in the module.

The remaining sections on this page apply to the Summary mode.

Request info

The request info section configures how timestamps and rows are handled in the output.

Date type controls the time reference: UTC, Legal time (no daylight savings adjustments), or Solar time.

Date format controls the column format for timestamps, ranging from a single timestamp column to separate columns for year, month, day, hour, and minute.

Row filters control which timesteps are included: day, night, and/or error rows.

Set for PVSyst factor calculation

This button applies a preset that selects the columns needed for the bifacial factor extraction workflow. It sets the output mode to Summary with Legal time and a day-of-year date format, and enables a specific subset of weather, module electrical, and current generation columns. See Extracting bifacial factors for PVsyst for the full workflow.

Inputs

The inputs section adds per-timestep values to each row of the output. These values are the simulation inputs that were used by the yield solving loop for each timestep. They are read directly from the stored environment data — the same values that drove the optical, thermal, and electrical calculations.

Simulation info

Timestep length — the period duration in hours.
Row flag — the classification of the timestep: day, night, sunrise, sunset, or error. Night and error rows can be filtered out using the row filters above.
Diagnostic message — any warning or error message associated with the timestep, such as missing data or solver convergence issues.

Solar position

Solar zenith and azimuth are the values that were used during the yield solving loop. They are either calculated from the site coordinates and timestamp using a solar position algorithm, or loaded directly from the weather file if it provides solar position columns.

Solar zenith ( $\theta_z$ ) — the angle between the sun and the vertical, in degrees.
Solar azimuth — the compass bearing of the sun, in degrees (0° = north, 90° = east, 180° = south, 270° = west).
Solar elevation ( $\alpha$ ) — derived at download time from the stored zenith:

\alpha = 90° - \theta_z

Atmospheric inputs

Atmospheric values are those that were used as inputs to the spectral irradiance model during the yield solving loop. Where the weather file does not provide a value, SunSolve uses a default or derives one from other available data. If any atmospheric input has been overridden via the weather options, the exported value reflects the override, not the original weather file value.

Air mass (absolute) — the pressure-corrected optical path length through the atmosphere relative to the vertical path. This is one of the few values computed at download time (not stored from the solving loop), using the Kasten and Young (1989)¹ formula for relative air mass, multiplied by a pressure correction to give absolute air mass:

AM = \frac{1}{\cos\theta_z + 0.50572 \,(96.07995 - \theta_z°)^{-1.6364}} \times \frac{P}{1013.0}

where $\theta_z$ is the solar zenith angle and $P$ is the surface pressure in millibars.

Precipitable water vapour (cm) — from the weather file. If not available, derived from relative humidity and ambient temperature. Default: 1.42 cm.
Ozone (atm·cm) — from the weather file or default of 0.34 atm·cm.
Aerosol optical depth at 500 nm — from the weather file or default of 0.084.
Relative humidity (%) — from the weather file. Reported as unavailable if not provided.
Far-field albedo (%) — the ground reflectance value defined in the simulation inputs.
Surface pressure (mb) — from the weather file or default of 1013.25 mb.

Weather inputs

Weather values come directly from the weather file uploaded by the user. They are the irradiance, temperature, and wind conditions that were applied at each timestep during the yield solving loop.

GHI (W/m²) — global horizontal irradiance.
DHI (W/m²) — diffuse horizontal irradiance.
DNI (W/m²) — direct normal irradiance.
Diffuse fraction — derived at download time as the ratio of diffuse to global horizontal irradiance:

k_d = \frac{DHI}{GHI}

Ambient temperature (°C) — converted from the stored value in Kelvin.
Wind speed (m/s) — wind velocity.
Wind direction (degrees) — compass bearing of the wind. Reported as unavailable if not provided in the weather file.
Opaque cloud fraction — fraction of sky covered by opaque cloud. Reported as unavailable if not provided in the weather file.

Module output

Module output columns are available when Module summary or Module details is enabled.

Module summary outputs a single aggregated set of columns representing the average or total across all modules in the unit system. Module details outputs a separate set of columns for each individual module, prefixed with a module identifier. When module details is enabled, the Group module results by option controls how modules are grouped: None, Tilt, Module X, or Module Y.

Module info

Module tilt (degrees) — the tilt angle of the module surface relative to horizontal.
Incident angle (degrees) — the angle between the direct beam and the module surface normal.
View-factor power for module temperature (W/m²) — plane-of-array irradiance estimates derived from a geometric view-factor model (not ray tracing). Reported as a total, and optionally broken down into front and rear components. These values are the irradiance inputs to the thermal model and can also serve as approximate POA irradiance values. See POA irradiance for thermal model for more detail on how these are calculated.
Module temperature (°C) — the operating temperature of the module as calculated by the configured thermal model, using the view-factor irradiance, ambient temperature, and wind speed as inputs.

Module DC electrical

These values come from the electrical solver that runs at each timestep. The distinction between the power columns is important:

Power at MPP, no mismatch, at 25 °C (W) — the sum of per-module, per-cell, per-subcell maximum power calculated at a nominal temperature of 25 °C (298.15 K). This provides the maximum available output power of the photovoltaic cells, before corrections due to temperature and electrical mismatch are calculated.
Power at MPP, no mismatch, at operating temperature (W) — the sum of per-module, per-cell, per-subcell maximum power at the actual module operating temperature. The difference from the 25 °C value is the temperature loss.
Power at MPP, with mismatch (W) — the power after cell-level circuit solving (SPICE), which captures the effect of non-uniform illumination across cells within each module. The difference from the “no mismatch” value at operating temperature is the cell-to-cell mismatch loss.
Voltage at MPP (V), current at MPP (A), minimum current at MPP (A), open-circuit voltage (V), short-circuit current (A) — reported as averages across modules (or per-module in details mode). Minimum current is the lowest Imp across all modules and is relevant for string current-limiting behaviour.

Module losses

Loss values represent the power difference between successive stages in the energy conversion chain. These are the per-timestep equivalents of the accumulated losses shown in the waterfall loss chart.

Temperature loss (W) — the change in power due to the module operating at a temperature other than 25 °C. This value is positive when the module is warmer than 25 °C (power decreases) and negative when it is cooler (power increases):

\Delta P_T = P_{MPP,25°C} - P_{MPP,T_{op}}

where $P_{MPP,25°C}$ is the no-mismatch power at 25 °C and $P_{MPP,T_{op}}$ is the no-mismatch power at operating temperature. See Apply temperature correction in the waterfall loss chart.

Cell-to-cell mismatch loss (W) — the power lost due to non-uniform illumination and electrical mismatch between cells within each module:

\Delta P_{c2c} = P_{MPP,T_{op}} - P_{MPP,circuit}

where $P_{MPP,T_{op}}$ is the no-mismatch power at operating temperature and $P_{MPP,circuit}$ is the power from the module-level circuit solve (with mismatch), also at operating temperature. Both terms are at the same temperature so that this loss isolates the effect of non-uniform illumination only. See Cell-to-cell mismatch loss in the waterfall loss chart.

Current generation

Front $J_L$ (A/cm²) — the light-generated current density on the front side of the module, averaged across all cells. This is calculated from the ray-traced spectral absorption and the cell’s external quantum efficiency at each timestep.
Front $I_L$ (A) — the front light-generated current (current density multiplied by cell area).
Rear $J_L$ (A/cm²) — the light-generated current density on the rear side, averaged across all cells. Only non-zero for bifacial modules.
Rear $I_L$ (A) — the rear light-generated current.

String output

String output columns are available when the simulation includes string-level solving and the array solve type is not “Module DC”. The same summary/details pattern applies as for modules.

String DC electrical

String-level values come from a circuit solve that connects modules in series within each string. The string solver accounts for module-to-module variations in current and voltage.

Power at MPP, no mismatch (W) — the sum of per-module maximum power points within the string, ignoring module-to-module current mismatch.
Power at MPP, with mismatch (W) — the actual string power from the string-level circuit solve, which accounts for module-to-module mismatch (the weakest module in a series string limits the string current).
Voltage at MPP (V), current at MPP (A), open-circuit voltage (V), short-circuit current (A) — string-level electrical parameters.

String losses

Module-to-module mismatch loss (W) — the power lost because modules within the same string operate at different current levels:

\Delta P_{m2m} = \sum_i P_{MPP,module_i} - P_{MPP,string}

where the sum is over all modules in the string. See Module-to-module mismatch loss in the waterfall loss chart.

Array output

Array output columns are available when the array solve type is “Array AC”. These values come from the inverter model that runs after the DC string-level solve.

Electrical – DC side

The DC side reports two operating points, because the inverter may shift the array away from its maximum power point (for example, during power clipping):

DC power, voltage, and current at the array MPP — the maximum power point of the combined DC array before any inverter constraints are applied.
DC power, voltage, and current at the inverter input — the actual operating point of the array as determined by the inverter model. This may differ from the MPP when the inverter is clipping or operating outside its optimal voltage window.

Electrical – AC side

AC output power (W) — the inverter’s AC output after all DC-to-AC conversion losses.

Losses – DC

DC losses represent power that is lost between the module-level DC output and the inverter input. See the waterfall loss chart for how these accumulate over the simulation period.

Ohmic wiring loss at MPP (W) — resistive losses in the DC wiring, calculated at the array maximum power point: $P_{wire} = I_{MPP}^2 \cdot R_{wire}$ , where $R_{wire}$ is the total DC wiring resistance.
Ohmic wiring loss at operating point (W) — resistive losses at the actual inverter operating point, which may differ from the MPP value when the inverter is clipping. See Correction to wiring loss at operating point in the waterfall loss chart.
Clipping loss (W) — power that cannot be exported because the DC array output exceeds the inverter’s AC power rating. The inverter shifts the operating point away from the MPP to limit output. See Clipping loss in the waterfall loss chart.
Pmin loss (W) — power lost when the DC input power falls below the inverter’s minimum operating threshold.
Vmin loss (W) — power lost when the DC input voltage falls below the inverter’s minimum voltage threshold.
Vmax loss (W) — power lost when the DC input voltage exceeds the inverter’s maximum voltage threshold.
Imax loss (W) — power lost when the DC input current exceeds the inverter’s maximum current rating.

Losses – AC

Conversion loss (W) — the power lost in the DC-to-AC conversion process within the inverter, determined by the inverter’s efficiency curve. See Inverter loss during operation in the waterfall loss chart.
Night consumption (W) — standby power consumed by the inverter during night-time timesteps when no solar power is available.

Kasten, F. and Young, A. T. (1989). Revised optical air mass tables and approximation formula. Applied Optics, 28(22), 4735–4738. ↩