Residential 101


HelioScope is commonly used for designing residential solar arrays. In order to have the best experience, follow these best practices when doing residential layouts:

  1. Racking: set to “Flush Mount”
  2. Row Spacing: set to zero
  3. Azimuth: set automatically based on front of roof
  4. Use Keepouts for ridgeline setbacks
  5. Use “Align to Click” to fine-tune module layout
  6. Right-click to delete individual modules

For residential arrays on a pitched roof (slanted roof), the Racking Type should be set to “Flush Mount”, and the Row Spacing should be set to 0 (or a small number, such as 0.04’ for mounting clips).

The difference between Flush Mount and Fixed Tilt

As can be seen in the figures below, fixed-tilt racking assumes the modules are tilted up in rows along a flat surface. As a result they will shade each other without sufficient row spacing. This is why Fixed Tilt racking with Row Spacing of 0 will result in very high shading losses. For pitched rooftops, the Flush-mount racking assumes the modules are in the same plane as the roof – and therefore will never shade each other. 

If you do primarily residential designs, then make these your default settings. The easiest way to do that is to set your project profile to Default Residential when creating your project.

Azimuth (Orientation)

The Azimuth in HelioScope can be set automatically: right-click the midpoint on the top or bottom (ridgeline or gutterline) edge of the roof, and select “Set Top/Bottom Edge”. The modules will then face that edge of the roof.


The tilt represents the angle/pitch of the roof. For common pitch values (from 1:12 to 12:12), see the chart at the below for corresponding tilt values in degrees.

HelioScope assumes a top-down orthogonal view, so the module quantity that can fit a rooftop will change based on the tilt. In the example below, a rooftop at an 18.4º tilt can hold 26 modules, while at a 45º tilt it can hold 32 modules:

Ridgeline Setbacks

When the distance of code-mandated setbacks along the edges of a rooftop change, use straight-line Keepouts with a defined setback.

Staggered Rows

Staggering rows allows more flexible placement of modules while grid-alignment offers a more uniform appearance. HelioScope’s Alignment options at the bottom of the Mechanical section allow you to quickly toggle to find the best option for your roof.

Align to Click

Shift the modules in the Field Segment: right-click the spot where you want the top-left corner of a module to go, and select “Align to Click”. HelioScope will shift the module “grid” to that point, and adjust the module count as necessary. This can often help fit an extra row of modules in the array.

Obstructions Shadows in 3D

Keepouts with heights automatically remove modules on the winter solstice from 10am to 2pm. You can leave modules in the shade by unchecking the “Keepout from shade” checkbox on the Keepouts tab. Navigate to Advanced > Shading to calculate the shade loss for every module.

Delete Module

Right-click to delete individual modules. This can be done from the Mechanical or Keepout modes:

  • In Mechanical, right-click the module, and select “Remove this Module” from the menu.

  • In Keepouts, right-click the module and it will be eliminated immediately.

Optional: Orbit View in 3D to Confirm Correct Geometry

Click and drag the mouse to orbit the view in 3D. Dragging up and down tilts the perspective, while dragging right and left rotates the view. This can help confirm that your roof planes are lined up and oriented in the right direction