When installing solar panels, many property owners and contractors are most concerned about the risk of leaks caused by drilling holes in the roof and damage to the roof structure. In fact, it is not always necessary to drill holes when installing solar mounting systems on a roof. Currently, the industry offers two established installation methods: hole-drilling and anchoring, and ballast-based mounting without drilling. These can be flexibly selected based on the roof material, the age of the building, the roof’s load-bearing capacity and the property owner’s requirements, making them suitable for a range of residential, commercial and industrial solar applications. 

Suitable applications for drilling and anchoring

For roofs with solid substrates and sufficient load-bearing capacity—such as flat concrete roofs, brick-and-concrete flat roofs, older cement-tile roofs, and steel-frame industrial buildings—the preferred method is Bracket with Hole-Mounting System.By firmly anchoring the photovoltaic mounting system to the building’s main structure with expansion bolts and chemical anchors, the system achieves deep anchorage and stable load-bearing points, resulting in superior overall resistance to uplift, slippage, wind, and seismic forces.

A drill-free solution requiring absolutely no drilling

For standing seam colour-coated steel roofing, older roofs with relatively low load-bearing capacity, and buildings where the property owner does not permit damage to the waterproofing layer, priority should be given to the use of clamps combined with counterweighted mounting brackets. This system relies on the clamps gripping the edges of the roof panels, whilst counterweight blocks at the base secure the mounting brackets. The entire process causes no damage to the existing roof structure or waterproofing; installation is quick, and removal later causes no damage to the roof, making it suitable for small-scale residential photovoltaic projects.

Key advantages and disadvantages of the two methods

Advantages of the drilling and anchoring method: high structural strength, high wind resistance rating, good bracket stability, no additional dead load, and a compact array layout; suitable for large-scale commercial and industrial projects and those in areas with high wind pressures.

Disadvantages of the drilled-hole anchoring solution: Installation involves penetrating the existing roof waterproofing layer; if the waterproof sealing process is not carried out to standard or details are not properly addressed, there is a risk of water seepage or leakage in the future.

Advantages of the no-drilling ballast solution: Zero damage to the roof; eliminates the risk of leakage at source; preserves the integrity of the original roof waterproofing; simplifies maintenance and dismantling; suitable for older roofs and buildings with high waterproofing requirements.

Disadvantages of the hole-free ballast solution: As the brackets are stabilised by the weight of the ballast, the overall weight is greater, placing certain demands on the roof’s load-bearing capacity; in areas exposed to strong winds or coastal typhoons, the ballast specifications must be appropriately increased to further enhance resistance to overturning and slippage.