Solar panel layout on the aerial photo, filled as you draw

Every array starts as a zone drawn on the map. pvSpline fills it with modules as you draw, at your spacing, orientation and power cap, and the layout it records is the one the simulation, the report and the permit plans use.

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Five ways to draw a zone

A layout that follows your hand

There is no layout button. While you drag a corner, the browser refills the zone on every frame; when you let go, the engine runs the same placer as the simulation and records its layout and the installed power. That power follows from the modules that fit, and the input is the zone’s power cap: the placer stops adding modules before the next one would exceed it.

Spacing, orientation and roof pitch

On a tilted roof the placer lays the rows out in plan, shortened by the cosine of the tilt, so the module count follows the slope.

Obstacles kept clear

Draw a chimney, a rooflight or a neighbour’s wall as an Obstacle: it is the one zone type that removes modules from the zones it overlaps, and it casts its shade on the array. Rectangle keeps a four-corner zone a true rectangle while you resize or rotate it.

Strings painted on the layout

With Draw strings on, every zone is wired into serpentine strings of the length you set, and rewired whenever the modules change. Switch it off to paint the strings by hand, in one stroke across many modules. A string left shorter than the rest at the end of a zone shows in the loss cascade if it falls below the inverter’s MPPT window.

From the layout to the deliverables

Lay out a roof in five steps

  1. Open the Map and zoom until the roof fills the view.
  2. Click Draw a polygon, then each corner of the roof, and the first corner again to close it.
  3. The zone fills with modules: its card shows the kWp, the module count and the panel.
  4. Set the azimuth, the tilt and the panel type, and adjust the column and row gaps until the layout matches the roof.
  5. Repeat for each roof plane: each plane is a zone with its own orientation.

Questions

Is the layout on screen the one the simulation uses?

Yes. Once you let go, the engine runs the placer the simulation itself uses and records its layout and installed power. The drawing during a drag is the browser’s estimate, and the panel says so.

Can I start from a CAD drawing?

Yes. Import a .dxf and its closed outlines become zones after a placement preview on the map. Export a DWG as DXF first.

How do I keep panels off a chimney?

Draw it as an Obstacle: the modules under it go, and its shade is counted.

The fastest way to judge a simulation tool is to run it on a project you already know.