Structures and shadow

Structures & Shadow describes every building and pole on the site. The numbers you enter here do two separate jobs.

First, they set the physical footprint of each structure — the rectangle it occupies on the ground. That rectangle is what is drawn on the plot, what is reserved out of the array, and what is carried into the exported drawings. Any table overlapping it is removed.

Second, the heights of the buildings and objects drive a year-round shadow footprint. The application sweeps the sun through a working window of the day, across the whole year, and takes the ground each structure's shadow covers at any point in that sweep. Tables inside that footprint are cleared rather than placed, so no part of the array sits permanently in a building's shadow.

Screenshot pendinginputs/structures-group.png

Structures and shadow

What it shows

The whole group at its defaults: the L / W / H column headers, one row each for ICR, MCR, USS and Object, the arrester height and pile diameter row, the shadow window row, the clear-tables checkbox, and the street light section.

How to get there

Nothing changed from defaults.

Callouts to add

Bracket the L / W / H columns and label them Length (east-west), Width (north-south), Height.

The four structures

Every footprint is entered as Length east–west by Width north–south, with a Height beside it. The layout uses the values in these fields, not any fixed size, so a room you size differently here is placed and drawn at the size you asked for.

ICR — inverter control room

The building that houses the inverter and switchgear equipment for one block of the array. One is placed automatically for each block of DC capacity, and the block size is set by ICR Block in Site parameters.

Control rooms are the structures that most often cost you tables, because there are several of them and each sits in the middle of the array it serves rather than off to one side. Every table overlapping a room's footprint is removed, and the plant capacity is recomputed afterwards.

MCR — main control room

The plant's central control building, and the point every medium-voltage circuit terminates at. Unlike the inverter control rooms it is not placed automatically — you place it yourself, once, by arming Place MCR and clicking a position on the plot. A position outside the boundary is refused.

Its footprint is the largest of the three buildings by default, so place it where the array is already interrupted — beside the entrance, next to the switchyard, or on ground the terrain or an obstruction has already excluded — rather than in the middle of a well-packed block.

Where you put it also sets the plant's medium-voltage cable length. Every inverter control room's circuit runs back to this building, and the circuits are routed as one shared network rather than as parallel runs, so nearby rooms merge into a single trench. A position central to the control rooms costs materially less cable than a corner does. The total is reported as soon as the building is placed, and again in the summary — so placing it, reading the figure, moving it and reading again is a quick way to settle the position. See Cable routing.

USS — unit substation

A local step-up substation for a plot that does not contain the main control room. See Unit substations in a multi-plot file below for when one appears.

Object

A generic structure you place by hand — a store, a pump house, a security post, a switchyard building, anything on the site the boundary file did not carry. Arm Place Object, click the plot, and repeat for as many as you need; Remove Objects clears them.

All three of its fields ship at 0, which means not configured. Set the length, width and height before placing objects, or you are placing a structure with no footprint and no shadow.

Once sized, an object behaves like a building in every respect that matters here: its footprint is reserved out of the array, tables overlapping it are removed, and its height casts the same year-round shadow a control room does. The group carries one set of object dimensions, so every object you place takes that same size. On a site with a large store and a small security post, size for the structure whose shadow you care about and draw the rest as annotations.

The heights of these four structures are used for shadow geometry. They are not a structural design, and nothing here is checked against a load case.

Unit substations in a multi-plot file

On a site made up of several separate boundaries, the medium-voltage collection cannot all run to one building without crossing ground you do not own. The application handles this the moment you place the main control room:

The remaining link — from each unit substation onward to the main control room — is an overhead line or a buried cable on a route only you can decide, across land the file does not describe. It is handled outside the automatic medium-voltage routing, so it is neither drawn nor included in the reported medium-voltage cable length. Add it to your own single-line diagram and your own schedule of quantities.

Multi-plot sites covers how several boundaries are laid out and summarised together.

Arrester height and pile

Two fields describe the lightning arrester masts themselves. They appear here because the mast is a structure; whether arresters are placed at all, and how far apart, is set in the Site Parameters group above.

The tables cleared around an arrester come from the arrester's own keep-clear footprint, which is a fixed rectangle for the mounting type rather than anything derived from the height — see Lightning arresters.

The shadow window

The window is set in solar hours, so 12.0 is solar noon at the site rather than noon on a clock. The first field is the start of the window and the second is the end, and they are constrained so the window always spans solar noon.

The default window runs from 9.0 to 16.0 — the seven hours around solar noon, the productive part of the day. Narrowing it shrinks the footprint, because the early-morning and late-afternoon shadows, which are the long ones, are excluded from the sweep. Widening it grows the footprint quickly, for the same reason.

Two things make the resulting footprint larger than the shadow you would see at any single moment:

• It is swept across the day, so it fans from the western side of the structure round to the eastern side.
• It is swept across the year, so it takes the winter shadow length, not the summer one.

In the northern hemisphere the swept area therefore lies on the northern side of the structure; in the southern hemisphere, the southern side. Placing the main control room on the equator-facing edge of a block costs fewer tables than placing it on the pole-facing edge.

Clear tables inside shadows

On by default. It removes every table or tracker unit falling inside the year-round shadow footprint of the inverter control rooms, the main control room and any objects you placed.

That list is exactly three structures. Arrester masts are not in it — no arrester shadow clears a table, at any height you enter — and street-light shadows are handled by the street-light option rather than by this one.

The reasoning is straightforward. A module that spends the productive part of every day in a building's shadow does not earn its place: it produces a fraction of what its neighbours produce, it drags the string it belongs to down with it through mismatch, and it still costs a full set of modules, piles and cable. It is better removed than placed. The plant's capacity, module count and bill of materials all report the smaller, honest number.

Turning it off places tables everywhere they geometrically fit, shadow or not. That is useful when you want to see the maximum capacity a site can carry, or when you have not yet decided where the buildings go. It is not the configuration to issue a design from.

Row-to-row shading between the tables themselves is a different matter — it is never a reason to remove a table, and it is handled as a loss in the energy model. See Shading losses.

Street lights

Off by default. Ticking it places perimeter lighting poles once the layout is generated.

With the option on, poles are placed along the perimeter, spaced by the span, just inside the fence, and any table their shadow touches is cleared.

The count follows from the span: it is approximately the plant perimeter divided by the pole-to-pole span. Raising the span thins the poles out and lowers the count; lowering it does the reverse. The figure appears in the summary's St.Lt column.

The setback is small — a fraction of a metre by default — so with a perimeter road of any usual width the poles land inside the road band rather than in the array, and the ground they stand on was already kept clear. What can still cost you tables is the shadow, which reaches inward from the fence line toward the first row of the array.

Site equipment covers the placed poles, the main control room and the objects on the plot.

Where to go next