Difference between Steel and Aluminium Canopy

When planning a solar canopy, most initial attention is placed on the solar panels, inverters, and expected energy generation. However, the supporting structure is just as important.

The choice between steel and aluminium can affect the canopy’s strength, appearance, usable space, installation requirements and overall project cost. As a solar canopy may remain in service for 25 years or more, the structural material should be selected based on the site conditions and long-term requirements rather than price alone.

Unlike a conventional rooftop solar installation, a solar canopy must function as both a power-generating system and a permanent structural feature. It must support the weight of the solar panels and mounting system while also withstanding wind, rain and other environmental conditions.

Before deciding between steel and aluminium, several key factors should be considered.

1. Number of Solar Panels and Overall Canopy Size

The number of solar panels affects the total size, weight and span of the canopy.

A larger system requires a wider and stronger supporting structure. As the canopy becomes longer or wider, the structure must carry greater loads while remaining stable and preventing excessive movement or deflection.

Aluminium structures commonly require additional bracing, such as Y-shaped supports or A-frame arrangements, especially for larger canopy designs. This is because aluminium is generally less stiff than structural steel.

These supports help strengthen the structure but may reduce the amount of clear space beneath the canopy. They can also affect vehicle movement, parking arrangements and the overall appearance of the installation.

For smaller systems, such as canopies supporting approximately 20 panels or fewer, alternative designs may be possible. For example, where the structure can be securely connected to an existing building wall, additional Y-shaped bracing may not always be required.

However, the final design must be assessed by a qualified structural engineer. The panel quantity alone does not determine the structural requirements. Other factors include:

• The length and width of the canopy

• The required distance between columns

• The height of the structure

• Local wind conditions

• Foundation and ground conditions

• The weight of the solar panels and mounting system

• Whether the canopy is connected to an existing building

• Vehicle clearance and access requirements

• Drainage and waterproofing arrangements

  
  

2. Steel or Aluminium

Strength and stiffness are two of the most important considerations when selecting the structural material for a solar canopy.

They affect how much load the canopy can support, how far the structure can span, the size and number of supports required, and the amount of usable space available underneath.

Steel Solar Canopies

Steel is generally stronger and stiffer than aluminium. This allows engineers to design longer spans and more open layouts with fewer intermediate supports or less bulky structural bracing.

Depending on the design and site conditions, steel may provide several advantages:

• Wider clear spans between columns

• Reduced need for visible Y-shaped or A-frame bracing

• More open and usable space beneath the canopy

• Greater flexibility for vehicle movement and parking

• A stronger and more robust structural appearance

• Better suitability for larger or taller canopy systems

• Greater flexibility for integrating lighting, drainage, EV chargers or other services

  
  

Steel canopies are often selected where the client wants a clean, premium appearance with minimal obstruction below the structure.

However, steel must be properly protected against corrosion. Depending on the environment, this may involve galvanising, protective coatings, appropriate paint systems and regular inspection.

Aluminium Solar Canopies

Aluminium is lightweight, naturally corrosion-resistant and easier to handle during installation.

Its lower weight may reduce transportation and installation requirements, and it can be suitable for smaller or more straightforward canopy projects.

The potential benefits of aluminium include:

• Lower structural weight

• Good resistance to corrosion

• Easier handling during installation

• Potentially lower upfront cost

• Reduced need for heavy lifting equipment in some projects

  
  

However, aluminium is generally less stiff than steel. To achieve the required strength and stability, an aluminium canopy may require:

• Larger structural sections

• More supporting columns

• Y-shaped or A-frame bracing

• Shorter distances between supports

• Additional reinforcement

  
  

These requirements can reduce the clear space beneath the canopy and may result in a busier or less streamlined appearance.

3. Usable Space and Appearance

The space beneath a solar canopy is often used for vehicle parking, loading and unloading, pedestrian movement or recreational activities.

The placement of columns and supporting braces can therefore have a significant impact on how practical the canopy is.

A steel structure may allow for fewer obstructions and wider clear spans, depending on the engineering design. This can make it easier to park vehicles, open car doors, move equipment or install EV charging stations.

By comparison, an aluminium structure with Y-shaped supports may create additional obstructions beneath the canopy. While the structure may still perform effectively, the braces could affect parking layouts, traffic flow and the overall visual appearance.

For projects where aesthetics and clear usable space are important, the structural layout should be reviewed carefully before choosing the material.

4. Cost Considerations

Aluminium can sometimes offer a lower initial cost, particularly for smaller or standardised canopy systems. Its lighter weight may also reduce certain transportation, lifting and installation expenses.

However, the material cost should not be considered in isolation.

Additional bracing, more supporting columns, larger structural sections and changes to the foundation design can affect the final project cost.

Steel will generally involve a higher upfront investment. This is due to factors such as:

• Higher material and fabrication costs

• Heavier transportation and lifting requirements

• More substantial foundations

• Galvanising or protective coating systems

• Custom structural fabrication

  
  

In return, steel may provide greater structural flexibility, wider spans, fewer obstructions and a more premium overall finish.

The decision should therefore be based on the total value of the design rather than simply comparing the cost per kilogram of material.

5. Long-Term Maintenance

Both steel and aluminium structures require proper inspection and maintenance throughout their service life.

Aluminium provides good natural corrosion resistance, although it may still be affected by unsuitable material combinations, coastal environments or contact with certain metals.

Steel requires an appropriate corrosion-protection system. Any damaged coating, exposed metal or early signs of rust should be addressed promptly to prevent further deterioration.

Regular inspections should include:

• Structural members and connections

• Bolts, welds and fasteners

• Corrosion or coating damage

• Foundations and anchor bolts

• Drainage systems and gutters

• Panel mounting systems

• Movement, vibration or visible deformation

• Water leakage or ponding

  
  

A properly designed and maintained structure should continue to support the solar system safely throughout its expected operational life.

Choosing the Right Material

There is no single material that is suitable for every solar canopy project.

Aluminium may be appropriate where the canopy is smaller, the spans are shorter, and cost or corrosion resistance is the main consideration.

Steel may be more suitable where the project requires:

• A larger solar system

• Wider distances between supports

• Greater structural strength

• Fewer visible braces

• More open usable space

• A cleaner architectural appearance

• Integration with EV chargers, lighting or other equipment

  
  

Although steel may involve a higher upfront cost, the additional investment may provide greater strength, better functionality and a more refined final appearance.

Ultimately, the correct solution should be determined through a proper site assessment and structural engineering design. The number of panels, canopy dimensions, wind loading, foundation conditions, vehicle clearance and long-term usage should all be considered before selecting the material.

A solar canopy is not only a structure for supporting solar panels. It is a long-term asset that should be designed to balance energy generation, safety, functionality, appearance and cost.