What is the difference between photovoltaic bolts and ordinary bolts?

Definition and Core Purpose Differences

Photovoltaic bolts are fasteners specifically engineered for use in solar power systems, particularly in photovoltaic (PV) mounting structures, panel frames, and supporting brackets. Their core purpose is not only to fix components together, but also to ensure long-term structural stability under outdoor environmental conditions. Ordinary bolts, by contrast, are general-purpose fasteners designed for a wide range of mechanical or construction applications without consideration for solar-specific stresses.

In a photovoltaic system, bolts are exposed to continuous sunlight, temperature cycling, wind loads, humidity, and sometimes corrosive atmospheres. Photovoltaic bolts are designed to maintain clamping force and mechanical integrity over decades, matching the expected lifespan of solar installations. Ordinary bolts may meet basic strength requirements initially, but they are not optimized for long-term exposure in PV environments.

Material Selection and Corrosion Resistance

One of the most critical differences lies in material choice. Photovoltaic bolts are commonly manufactured from stainless steel (such as SUS304 or SUS316), aluminum alloys, or carbon steel with high-performance surface treatments. These materials are selected specifically to resist corrosion caused by rain, salt spray, industrial pollution, and UV exposure.

Ordinary bolts are often made from standard carbon steel or low-alloy steel, with minimal surface protection such as basic zinc plating. While sufficient for indoor or short-term applications, these materials are prone to rust and degradation when used outdoors for extended periods.

Common Materials Used in Photovoltaic Bolts

• Stainless steel for superior corrosion resistance and strength stability
• Hot-dip galvanized carbon steel for large-scale ground-mounted systems
• Aluminum bolts for lightweight mounting structures

Structural Design and Functional Features

Photovoltaic bolts often incorporate specialized design features that are rarely found in ordinary bolts. These may include serrated flanges, integrated washers, anti-loosening threads, or custom head shapes that match PV rail systems. Such designs reduce installation time and improve load distribution across mounting components.

Ordinary bolts typically follow standardized head types and thread forms without any system-specific optimization. As a result, additional washers, lock nuts, or spring components are often required to achieve the same level of stability in a photovoltaic installation.

Load Performance and Long-Term Reliability

Photovoltaic bolts are tested to withstand dynamic loads such as wind uplift, snow pressure, and thermal expansion. These loads can fluctuate daily and seasonally, causing micro-movements that may loosen conventional fasteners over time. PV bolts are designed to maintain consistent preload and resist fatigue failure.

Ordinary bolts may meet static load requirements, but they are rarely tested for the cyclic loading conditions common in solar installations. Over years of service, this can result in loosening, deformation, or even structural failure.

Environmental Adaptability and Weather Resistance

Solar power systems are installed in diverse environments, including deserts, coastal regions, mountains, and industrial zones. Photovoltaic bolts are engineered to adapt to these conditions through enhanced coatings, higher corrosion grades, and temperature-resistant materials.

Ordinary bolts lack this level of environmental adaptability. In harsh climates, they may require frequent inspection, maintenance, or replacement, increasing long-term operational costs.

Installation Efficiency and Compatibility

Photovoltaic bolts are designed with installer efficiency in mind. Many are compatible with standardized PV rails and mounting slots, allowing for quick insertion and tightening without additional alignment steps. Some PV bolts are pre-assembled with washers and nuts to reduce handling time on-site.

Ordinary bolts often require multiple components and precise alignment during installation. This can slow down large-scale solar projects where thousands of fastening points are involved.

Compliance with Industry Standards

Photovoltaic bolts are typically manufactured to meet solar industry standards and certifications related to mechanical performance, corrosion resistance, and safety. These standards ensure compatibility with PV modules, mounting systems, and regional building codes.

Ordinary bolts may comply with general fastener standards, but they are not always tested or certified for photovoltaic-specific applications. Using non-certified bolts can introduce compliance risks in regulated solar projects.

Cost Considerations Over the System Lifecycle

At first glance, photovoltaic bolts may appear more expensive than ordinary bolts due to higher material and manufacturing costs. However, when evaluated over the full lifecycle of a solar installation, PV bolts often prove more cost-effective.

Their durability reduces the need for maintenance, replacements, and system downtime. Ordinary bolts may lower initial costs but can increase long-term expenses through corrosion-related failures and labor-intensive repairs.

Direct Comparison Overview

Practical Selection Guidance

Choosing between photovoltaic bolts and ordinary bolts should be based on application requirements rather than initial cost alone. For any permanent or semi-permanent solar installation, photovoltaic bolts provide measurable advantages in safety, durability, and compliance.

Ordinary bolts may be suitable for temporary fixtures or non-critical components, but they should not be relied upon for core structural connections in photovoltaic systems where long-term performance is essential.