Solar OEM Fastener FAQs | Advantages of Using a Step Bolt Over a Carriage Bolt

Your projects combine electrical components with mounting systems made from aluminum, stainless steel and wood. Using the ideal fastener for the job is important for solar OEMs, and the subtle differences between a step bolt and a carriage bolt can make this choice somewhat confusing. Both of these bolts deliver advantages for certain stages of the project; the key is in knowing what those advantages are and where they come in.
Step Bolts 101
Step bolts and carriage bolts have a long shaft, often fully threaded with a square shoulder below the head. The blunt tip requires a pilot hole for installation and the typically round head found on both types of fastener sits on the joint surface. Both are generally used on wood applications, joining a wood structure together or mounting another material to the wood.
The differences between a step bolt and carriage bolt may be difficult to discern at first glance.
Notice that the step bolt has a lower profile head that holds the fastener in place and presents a smoother, more attractive joint surface. This works well for solar ground mount framing and can offer an advantage when using step bolts in a roof mount application. The larger, flatter head also resists pulling through, in cases where soft materials like plywood are being used.

Step bolts are commonly used in electrical towers and other structures within the power sector, making them a natural fit for the solar industry. Solar OEMs should be able to source this fastener quickly and affordably, although they are likely to find less selection in terms of length and diameter, when compared to the common carriage bolt. Ask your fastener distributor about stainless steel step bolts, an ideal fastener for many components of your solar projects.
Popular in the decking industry and in many outdoor structures, a carriage bolt comes in hot dipped galvanized and stainless steel. When the head size and smoothness of the joint surface is not an issue, carriage bolts may be the strongest, most available choice of fastener.
Solar OEMs are best to talk directly to their fastener distributor, examining the project specs together. If using a step bolt will present a more attractive finish or greater stability in high winds, put that fastener into your design. Your distributor might also recommend the common carriage bolt when the size and applications demands.