Module specifications

The Module Specifications group describes the single PV module every other dimension in the plant is built from. Table size follows from the module dimensions, row pitch follows from table size, string length follows from the module's electrical data, and plant DC capacity is the placed module count multiplied by the wattage entered here. Get this group wrong and every figure downstream is wrong with it.

You can type the three numbers by hand from a datasheet, or load the manufacturer's .PAN file and have them filled in — along with the electrical data the energy model needs, which a datasheet reading would not give you.

Screenshot pendinginputs/module-group.png

Module Specifications

What it shows

The whole Module Specifications group at its defaults, including the Bifacial Options divider and the disabled bifaciality field.

How to get there

No module file loaded, so the row reads that none is loaded and the bifaciality field is greyed out.

The fields

All internal geometry is held in metres, projected to the site's own UTM zone, so the two dimensions are metres regardless of what the manufacturer's datasheet uses.

Length is the long side, width the short side

The two fields are named by the module itself, not by the compass. Length is always the long edge of the glass; Width is always the short edge. Neither field is tied to east–west or north–south on its own.

Which edge ends up running east–west is decided by the mounting orientation, one group further down the panel:

• On a fixed-tilt plant, Portrait puts the module's short side east–west and its long side north–south. Landscape reverses that. See Table configuration.
• On a tracker plant, P config (Portrait) puts the module's long side east–west, across the torque tube. L config (Landscape) puts the long edge north–south, along the tube. See Tracker configuration.

The practical consequence: swapping orientation does not change the module, but it does change the table's east–west width and north–south height, and therefore the row pitch, the ground coverage ratio and how many tables fit on the site.

Loading a manufacturer file

Load .PAN reads a .PAN module file — the module data file published for PVsyst — and fills the group in from it. This is the reliable route: it brings in electrical parameters that have no field in the input panel but that the energy model uses.

Screenshot pendinginputs/module-pan-loaded.png

Module group after loading a module file

What it shows

The same group after a bifacial module file has been loaded: the module name on the file row, the auto-filled dimensions and wattage, and the Bifacial checkbox now ticked with its factor filled in.

How to get there

Click Load .PAN and pick a bifacial module file. Capture before answering the modules-in-series question, or dismiss it with Manual first.

Callouts to add

Outline the three auto-filled fields and the ticked Bifacial checkbox.

What the file fills in

A file that declares the module bifacial turns the checkbox on for you and fills the factor with the manufacturer's value, so you do not have to know whether a given part number is bifacial to get the rear-side gain modelled.

Loading a file also recomputes Temperature losses in the energy settings and replaces the shipped default with a figure derived from this module. That calculation needs the module's temperature coefficient of maximum power, which is read from the file rather than typed anywhere. The module operating temperature it derives is displayed next to the loss row, with the working shown underneath it — see Temperature losses.

The nominal operating cell temperature comes from the file too

The nominal operating cell temperature — NOCT, the cell temperature the module reaches under standard nominal conditions — is read from the module file as well, and it is the figure the hot case of automatic string sizing works from. A file that declares no NOCT falls back to 45 °C, and the string sizing window will instead estimate one from the module's efficiency and say on screen that it has done so.

So the electrical data behind string sizing is not only the voltages: the cell temperature the voltages are evaluated at travels with the file too. Typing the three dimensions by hand leaves that figure to be estimated.

Metres or millimetres

Module files are published in both units. Dimension values are accepted either way and interpreted by magnitude: a value below 100 is read as metres, a value of 100 or more is read as millimetres. The same module described in metres and described in millimetres therefore lands as the same long side, and you do not have to convert anything before loading.

The modules-in-series question

Straight after a successful load, the application asks Calculate the number of modules in series automatically? with two buttons:

• Auto opens the string sizing window, which works the feasible number of modules in series out from the module's voltage data and the inverter's window.
• Manual leaves the string length to you.

The question appears because the module file is the first point at which automatic string sizing becomes possible. Full detail, including what the window needs from an inverter file, is on String sizing.

Viewing what the file contains

View opens a read-only window showing everything read from the module file. Nothing in it is editable — it exists so you can confirm you loaded the module you meant to, and check parameters the input panel has no field for.

Screenshot pendinginputs/pan-viewer.png

Module file viewer

What it shows

The viewer on its first tab, with the tab strip fully visible.

How to get there

Load a module file, then click View next to it.

The Graphs tab is the quickest sanity check on a file from an unfamiliar source: a curve with the expected knee near the maximum power point tells you the electrical data read cleanly.

Screenshot pendinginputs/pan-viewer-graphs.png

Module current and power curves

What it shows

The Graphs tab with both curves drawn and the axes readable.

How to get there

In the module file viewer, open the Graphs tab.

Bifacial options

A bifacial module generates from light reaching its rear face as well as its front. Two controls at the bottom of the group decide whether that is modelled.

Bifacial module is off as shipped. With it off, the module is treated as monofacial and no rear-side energy is added, whatever the module actually is. Tick it — or load a file that declares bifaciality — and the rear-side gain enters the yield calculation.

What the bifaciality factor means

Bifaciality factor (φ) is the rear-side efficiency of the module expressed as a fraction of its front-side efficiency. A factor of 0.70 means the rear face converts light to power at 70 % of the efficiency of the front face, so a given irradiance falling on the back is worth 70 % of the same irradiance falling on the front.

• Typical published values sit between 0.65 and 0.80. The field accepts 0.50–0.95, and ships at 0.70.
• The factor is a property of the module, not of the site. Take it from the datasheet or let a .PAN file fill it in; do not tune it to reach a target yield.
• Typical bifacial energy gain over the same plant built with monofacial modules is 5–15 %. Where a specific design lands in that band depends far more on the ground under the array and on how densely the rows are packed than on the factor itself.

Ground albedo lives with the energy settings

The factor alone cannot produce a rear-side figure. The rear irradiance the model uses depends on the ground reflectance — the albedo — the tilt of the module, and the ground coverage ratio, because closely packed rows leave less lit ground between them to reflect anything. Only then is the result scaled by φ.

Ground albedo (ρ) is therefore set in the energy settings, not here, and defaults to 0.25. The full rear-side model, and what to set albedo to for different ground cover, is on Bifacial gain.

What moves when these fields move

Nothing in this group is local to it. Before you change a value on a design you have already reviewed, know what else changes with it.

A module dimension change is a layout change, so the layout has to be generated again before any figure in the summary is trustworthy. A bifacial change is an energy change, so the energy calculation has to be run again, but the placed layout stands.

If you have no module file

Typing the three fields by hand is a complete input for layout purposes — the placement, the table geometry, the capacity and the summary all work from the dimensions and the wattage alone. What you lose is the electrical data behind two calculations:

• Automatic string sizing has no voltage window to work from, so the number of modules in series stays a value you enter.
• The temperature loss stays at its default percentage instead of being derived from this module's coefficient.

Both are usable defaults, not blockers. Load a file when you have one.

Where to go next