1. Upload a floor plan -- tap the blueprint icon to load a PNG, JPG, or PDF of the unit layout.

2. Align north -- tap Align, stand in the unit, point your phone toward the top of the plan, then tap Lock North. The plan will be correctly oriented.

3. Read the arc -- the arc shows the sun's path for the selected date. Hour labels mark each hour. The glowing dot is the selected time. The dashed ray shows which direction light enters the unit.

4. Compare seasons -- tap the compare icon to overlay summer and winter arcs, showing the full range of sun angles across the year.

5. Add buildings -- tap Buildings to add neighbouring structures. Their shadows are projected based on their height and the sun's current altitude.

6. Set location -- tap the pin to search for any city or use GPS for precise calculations.