Spacing and safety rules
The four spacing concepts every layout is built on — internal gap, service clearance, safety distance, boundary setback — and how gaps are shared.
Every distance in a generated layout traces back to one of four concepts. They are often conflated in early-stage site sketches, and conflating them either wastes land or produces an unbuildable plan — so the solver keeps them strictly separate, and so should you when reading a layout.
The four spacing concepts
| Concept | Default | Between what |
|---|---|---|
| Internal gap | 0.2 m | DC blocks inside one cluster (blind side to blind side) |
| Service clearance | 1–3.5 m | Working access around individual equipment: 3.5 m at DC doors, 2 m at DC cable ends, 3 m on all four sides of a PCS & MV skid, 1 m on all four sides of the E-house |
| Safety distance | 5 m | Between DC clusters — the fire/insurance separation |
| Boundary setback | 1.5 m | Equipment body to the site boundary — and the strip the fence-side aisle may use |
All four are configurable in Site details. The defaults are industry-typical starting values; your fire authority, insurer, and equipment manufacturer's install manual govern the real numbers, and the tool exists so you can test their impact on capacity in seconds.
The one exception is the PCS & MV skid: 3 m is a floor, not just a default. It applies to the 20 ft and the 40 ft skid alike, on all four sides, and the solver raises anything lower — including a layout you saved earlier at a smaller value.
Gaps are shared, not summed
When two pieces of equipment face each other, the gap between them is the larger of the two requirements — not the sum. A DC cable end (2 m) facing a PCS service side (3 m) produces one 3 m aisle that serves both. This single rule is the difference between a realistic layout and one that quietly wastes meters on every row.
The safety distance applies only where DC faces DC across cluster boundaries. A DC cluster facing a PCS & MV skid needs service clearance, not the fire gap — unless you set the optional DC↔AC fire distance in Site details, which then governs wherever a DC block faces a skid.
How spacing shapes the field
Inside a zone, the solver arranges BESS sections in pitch-aligned rows:
- Between rows: section height + whichever gap the facing sides require — the 5 m safety distance where cable ends face cable ends, a shared door aisle where doors face a skid.
- Between columns: section width + the 2 m cable-end clearance.
Because gaps are shared and the pattern repeats, small parameter changes compound: lowering the safety distance from 5 m to 4 m does not save one meter — it saves one meter per row, which on a large site can be an entire extra row of units. This is the single most valuable experiment to run when a site looks tight: adjust the safety distance in Site details and watch the capacity respond.
Roads and clearance
With the default perimeter ring, the Roads as service access toggle in Site details decides whether a road can double as the maintenance aisle for the equipment beside it. On: equipment packs tight to the road, and the road surface provides the working space. Off: the full service clearance stays inside the zone, and equipment sits back from every road. On matches how most operating sites actually work; off is the conservative reading some authorities require.
The fence on a no-road site
Choose No perimeter road (or a drive-through road) and the equipment along the site edge faces the fence directly — there is no road to absorb its service clearance. The rule the solver enforces there: no equipment's service clearance may cross the drawn boundary, whatever the parcel shape. The body sits inside the buildable area as always, and its working aisle may extend into the setback strip — the setback is usable ground, credited as aisle — but nothing reaches past the fence line itself.
This is a clearance floor on every fence-facing edge, not a default you can tune away: a fence-side unit is set back by however much its service envelope would otherwise overhang the boundary, minus the setback strip it is allowed to use. On a tight setback that costs a little capacity along each edge; widen the setback and the strip absorbs more of the clearance, so the edge units pack closer to the fence again. It holds identically on a rectangle, a concave (L-shaped or notched) parcel, and a parcel drawn at an angle.