1. Understanding the Weight of Solar Systems
The total load a solar system adds to a factory roof includes:
- Solar panels: Typically weigh 18–22 kg/m² (approximately 2–2.5 kg per panel per square foot).
- Mounting system: Adds about 10–15 kg/m², depending on material and type.
- Ballasted systems: On flat roofs, ballasts may add additional load (up to 30–40 kg/m²).
- Wind and snow loads: Local weather conditions significantly impact structural stress.
Total estimated weight range:
25–45 kg/m², depending on mounting design and panel type.
2. Key Factors That Affect Load-Bearing Capacity
Before any solar installation, the following factors must be considered:
a. Roof Structure Type
Steel trusses, reinforced concrete, or lightweight metal sheeting offer different strengths. Concrete slabs generally provide higher load capacity than metal deck systems.
b. Roof Age and Maintenance
Older roofs may have degraded structural integrity or waterproofing. A pre-installation inspection is essential.
c. Load Distribution
The mounting system design determines whether the weight is spread evenly or concentrated. Engineers aim for uniform load distribution to avoid local stress points.
d. Environmental Conditions
Seismic zones, heavy snowfall, and strong winds require structural reinforcement or specialized mounting solutions.
3. Load Evaluation: Structural Engineering Is Mandatory
A certified structural engineer should conduct a roof loading analysis that considers:
- Dead loads (solar panel weight + mounting frame)
- Live loads (installation personnel, snow accumulation)
- Environmental loads (wind uplift, thermal expansion)
- Safety factor margins based on local building codes
This evaluation ensures the system won't compromise building integrity or violate code requirements.
4. How Solar Panel Load Compares to Other Equipment
| Equipment Type | Load per m² (Approx.) | Notes |
| Solar panels | 20–25 kg/m² | Varies with design |
| HVAC rooftop units | 30–50 kg/m² | Common on factories |
| Water tanks | 60–100+ kg/m² | Often centrally located |
| Walkways/platforms | 35–70 kg/m² | Required for maintenance |
Compared with these, solar systems generally impose a lower or comparable load, making them suitable for most industrial roofs with proper design.
5. Reinforcement and Retrofitting Options
If a factory roof isn't initially strong enough, upgrades can include:
- Strengthening beams or trusses
- Adding support columns
- Using lightweight solar modules
- Optimizing panel layout to reduce concentrated loads
6. FAQs
Q1: Can I install solar on a metal sheet factory roof?
Yes, but it requires appropriate mounting solutions and possibly reinforced brackets.
Q2: What if my roof cannot bear the load?
You can consider ground-mounted solar systems or reinforce the roof structure.
Q3: How long does a structural assessment take?
Usually 3–7 days, depending on roof complexity and required tests.
Q4: Do solar panels damage roofing materials?
Not if installed correctly. In fact, they can protect the roof from direct weather exposure.
Q5: Is ballasted mounting better for weak roofs?
It can reduce drilling but adds more weight. It's best used when structural load is still within limits.