Site parameters

Site Parameters holds the settings that apply to the plant as a whole rather than to an individual table: how much ground is kept clear around the fence, whether lightning arresters are placed and how far apart, how much capacity one control room serves, and how wide a strip is cleared either side of a transmission line.

Two of them — the perimeter road width and the transmission line corridor — decide how much ground is available before a single table is placed. The rest decide what equipment is then placed on the ground that remains.

Screenshot pendinginputs/site-group.png

Site Parameters

What it shows

The whole group at its defaults, with the arrester option unticked and the protection radius therefore greyed out.

How to get there

Nothing changed from defaults.

At a glance

Perimeter road width

The plant boundary is shrunk inward by the perimeter road width to give the usable area — the ground the layout is allowed to occupy. Obstructions and terrain exclusions are then subtracted from it, and a table or tracker unit is placed only where it fits entirely inside what is left.

So this is not a road you design here. It is a setback, kept clear of modules around the whole plant, wide enough to take the internal ring road, the fence line and the working space a construction crew needs to get plant and cable drums around the perimeter. Widen it and every edge of the plant pulls inward at once; the capacity you lose is roughly the perimeter length multiplied by the extra width.

The band is computed once from the boundary and reused everywhere the plant is drawn — the plot on screen, the report, the Google Earth file and the CAD drawing — so the road you see on the screen is the road that reaches the contractor.

Entering 0 leaves no band at all, and tables are placed right up to the boundary. That is worth doing only when the boundary you supplied already excludes the road.

Place Lightning Arresters

Off by default. Lightning arresters (LA) are the masts that carry the plant's lightning protection over the array.

With the option off, no arresters are placed and the tables fill the whole usable area. Nothing is reserved for them, and the plant's capacity is the capacity of a fully packed field.

With the option on, arresters are placed on a square coverage grid once the tables are down, and every table overlapping an arrester's keep-clear footprint is removed. On a fixed-tilt plant that footprint is a rectangle of 30 m east–west by 7 m north–south, which is why the arrester count has a visible effect on capacity. On a tracker plant the arrester is a 1 m by 1 m pole marker snapped into the gap between tracker columns, and no tracker units are removed at all.

Arresters only ever sit inside the usable area, so the grid never puts a mast in the perimeter road band, in a water body or on excluded ground.

Because arresters cost capacity on a fixed-tilt plant, the usual sequence is to generate the layout with the option off, agree the field, and then turn it on for the run you issue. You can also leave it off and add arresters one at a time by hand in Sketch Mode — the plant totals are recomputed when you leave it, so a hand-placed arrester clears tables and changes the capacity exactly as an automatic one does.

The placed count appears in the summary's LA column. The arresters themselves are hidden on the plot until you turn the Lightning Arresters switch on. Lightning arresters covers the grid, the coverage circles and the footprints in full.

LA protection radius

Enabled only when Place Lightning Arresters is ticked.

This one field does two jobs at once:

1. It is the radius of the circular area one arrester is taken to protect, measured from the mast.
2. It is the spacing of the square grid the arresters are placed on.

Because the two are the same number, every point inside the array is within one radius of an arrester, and neighbouring protection circles always overlap. The grid alone can leave a table at the edge of the array uncovered, so after the grid pass any table whose centre lies beyond the radius from every placed arrester gets an extra arrester at the nearest valid position.

The consequence of tying spacing to radius is that the radius is the only lever on the arrester count, and it is a strong one: doubling it doubles the grid spacing in both directions, so roughly a quarter as many masts are placed. Halving it does the reverse. On a fixed-tilt plant that change in count feeds straight through to lost tables, because each arrester clears its own footprint.

ICR Block

An inverter control room (ICR) is the building that houses the plant's inverter and switchgear equipment for a block of the array. ICR Block is the DC capacity, in MWp, that one such room serves.

The count follows directly from it: the number of control rooms is the plant's DC capacity divided by the block size, rounded up to the next whole room. A plant whose capacity exceeds the block size by any margin at all gets another room.

Where the rooms go is not a grid. The placed tables are grouped spatially into blocks of roughly one block-size each, and a control room is put at the centre of each group — so every group of tables surrounds its own room rather than being cabled across the site to a distant one. Each room must fit entirely inside the usable area, and any table overlapping its footprint is removed. Because that removal reduces the plant's capacity, the required number of rooms is then re-checked against the reduced figure.

Choosing the block size is a cabling trade-off:

In Central Inverter mode there is a second constraint worth knowing before you set the block: a maximum of 4 central inverters are housed in one control room building. See Inverters and cable calculation.

The footprint and height of the room itself are not set here — they are in the Structures & Shadow group below. How the rooms are placed, and how to move one, is in Control rooms.

Transmission line corridor

A transmission line crossing the site is drawn in the boundary file as a line, not as a polygon, because it has no width of its own. This field supplies the width: the setback is applied to each side of the line, so the total cleared strip is twice the value you enter. At the default of 15 m per side, a line clears a 30 m strip through the array.

The same setback is applied to every line feature the boundary file carries — transmission lines, canals, drains and similar — so a line drawn through the middle of a plot splits the array into two blocks with a clear corridor between them.

Higher-voltage lines need more room. The application's own guidance is to raise the setback accordingly, for example 30 m per side for a 400 kV line. Set it for the highest-voltage line on the site, or split the work into separate runs if the site carries lines of very different voltages, because there is one corridor width for the whole plant.

The corridor is subtracted from the usable area before any table is placed, so it costs capacity in the same way the perimeter road does — but unlike the road it also breaks the array up, which matters for cable routing and for cleaning robot runs.

How to name and draw a line feature so it is recognised as a transmission line is in Boundary file requirements.

Where to go next