How does rooftop solar work – and which mounting method fits your facility?
Rooftops are one of the most practical and cost-effective places to install solar panels on commercial buildings. If your building has unused roof space and a reasonably healthy roof structure, a rooftop system can help offset energy costs without disrupting operations or requiring additional land.
But not all roofs are the same – and neither are solar mounting systems. Choosing the right approach depends on your roof type, age, structural capacity, and site-specific factors like wind exposure and building height.
This section breaks down the three primary types of rooftop mounting systems and what makes each one suitable for different commercial projects.
- Efficient use of space on existing infrastructure
- Typically lower cost per watt compared to ground or canopy systems
- Lower visual impact for discreet sustainability upgrades
- Fewer permitting hurdles in most jurisdictions
- Roof provides easy access for wiring into the building’s electrical system
Rooftop Mounting Types
Mount Type: Ballasted Roof Mounts #
Used for flat or low-slope roofs, ballasted systems rely on weight (ballast blocks) – not roof penetrations – to secure the panels in place.
- Concrete blocks are placed on top of the racking to resist wind uplift
- Requires no mechanical attachments to the roof membrane (except for electrical conduit penetrations)
- Ideal for buildings with EPDM, TPO, or built-up flat roofs
- Load-bearing capacity of the roof must be verified by an engineer
- Simplifies waterproofing concerns and lowers install time
Panels are typically installed at a 10°–15° tilt to maximize year-round energy capture while minimizing wind load.
Mount Type: Standing Seam Roof Mounts #
For metal roofs with raised seams, special clamps are used to attach racking directly to the seams – eliminating the need for any penetrations through the roofing surface.
- Compatible with standing seam metal roof types (common in warehouses and industrial buildings)
- Clamps attach mechanically to seams using set screws – no drilling
- Panels can be flush-mounted or tilted with additional brackets
- Lightweight and easy to install with minimal impact on roofing warranty
This method is one of the most maintenance-friendly and durable rooftop options available.
Mount Type: Shingle Roof Mounts #
For pitched roofs with shingles (common in residential or small commercial buildings), mounts must be mechanically attached to the roof structure with proper flashing.
- Roof penetrations are required and must be sealed to prevent leaks
- Special mounting brackets and flashing hardware ensure weather-tight seal
- Typically installed flush with the roof slope for aesthetics and simplicity
- More common in small-scale commercial and residential buildings
Shingle mounts are proven and reliable – but involve more manual installation labor and roof penetrations.
Comparison: Rooftop Mounting Systems
| Feature | Ballasted | Standing Seam | Shingle Mount |
| Roof Type | Flat / low-slope | Metal (raised seam) | Pitched shingle roofs |
| Penetrations | None (except conduit) | None | Yes (with flashing) |
| Typical Tilt Angle | 10–15° | Flush or tilt-mounted | Flush to roof slope |
| Structural Load | Requires ballast weight (~4–6 lbs/ft²) | Minimal | Minimal |
| Aesthetic Visibility | Low (not visible from ground) | Moderate (tilted or flush) | Visible (flush-mounted) |
| Ideal For | Warehouses, big-box retail, distribution centers | Manufacturing or metal-roofed facilities | Small commercial, offices, or converted homes |
Rooftop Design Considerations
Before selecting a mounting system, Melink Solar performs a thorough rooftop assessment, considering:
- Roof age – Systems last 25–30 years, so the roof should be in good shape
- Structural integrity – Especially for ballasted systems, weight limits must be checked
- Setbacks and fire code access – Adequate space must be left around edges and rooftop equipment
- Shading – HVAC units, parapet walls, or nearby trees can reduce solar output
- Access for maintenance – Proper spacing and clear pathways are part of system layout
Not sure if your roof is solar-ready?
Melink Solar offers complimentary rooftop assessments and design feasibility analysis.
Want to compare rooftops with other system types?
Continue to Section 3.1.5: Ground Mount Systems or Section 3.1.6: Parking Canopies to evaluate alternatives.
Interested in how system performance is tracked using monitoring meters? Explore Section 5: How Do I Track, Maintain, and Maximize My Solar System’s Performance?