By Dan Felix, IronRidge training manager
In the realm of solar mounting, codes are “alive” in that they are constantly being updated to keep pace with an ever-changing industry. These codes protect installers from making dangerous mistakes and from scenarios that have led to failure in previous installations. Therefore, it is critical to keep up with changes that local authorities having jurisdiction (AHJs) have put into place.
Working in the solar industry necessitates understanding more than one type of code, unlike, for example, an electrician who may just need to know the National Electrical Code (NEC). Building codes (IBC), fire codes (IFC) and structural engineering codes (ASCE) also come into play when adding solar to an existing structure. Here are a few codes all solar installers should be familiar with when working on rooftop projects.
International Building Code
Flashings and attachments
The IBC states in article 1503.2 that “flashing shall be installed in such a manner so as to prevent moisture entering […] penetrations through the roof plane.” The IBC also states in article 1507.2.9 that “flashing shall be applied in accordance with this section and the asphalt shingle manufacturer’s printed instructions.”
To prevent moisture from damaging the roof or entering the structure, a sealant is typically placed in holes and underneath the flashing. To this end, the IBC code requires an attachment flashing and a sealant that meets the requirements of the roofing manufacturer.
In article IBC 1509.7.2, it says that “rooftop-mounted PV systems must not diminish the fire classification of the roof system.”
In order to meet the IBC code here, one must ensure the system and equipment used have a UL fire-tested class rating that either matches or exceeds that of the existing roofing material.
Structural loading considerations
IBC section 3403 says “alterations to the existing building or structure shall be made to ensure that the existing building or structure together with the addition are no less conforming with the provisions of this code than the existing building or structure was prior to the addition.”
This means that when adding solar to an existing structure, an installer cannot exceed what the building or structure was originally engineered to support.
Each jurisdiction seems to enforce this code differently to make sure the roof is not overloaded. For example, here are a couple stances IronRidge has seen AHJs take:
- Some authorities are rigid: “The maximum spacing of PV supports is stipulated to be twice the rafter spacing and alternating such that all rafters carry the proposed system.”
- Some authorities are flexible: “45 lbs has been used by some jurisdictions as a reasonable level, below which point loading of roof joists and trusses can be ignored.”
One should contact the local AHJ to understand the requirements for point-loading a system. And if in doubt, one can always contact a structural engineer to review the structure and the planned added weight of the proposed system.
One way to evenly distribute weight across a solar system is to stagger attachments to the structure. This is a best practice, since staggering attachments means there will be less weight on each rafter.
International Fire Code
The IFC states in article 605.11.3.2.1 that “modules should be located in a manner that provides access pathway for firefighters.” It also says in article 605.11.3.2.4 that “panels/modules installed shall be located no higher than 3 ft below the ridge to allow for fire department ventilation operations.”
Combined, these codes require a 3-ft clearance down from the ridge of a pitched roof to allow for fire departments to ventilate the building. Additionally, a clear 3-ft pathway needs to be available for firefighter access to the roof.
National Electrical Code
NEC 690 defines electrical safety requirements for PV systems.
Equipment grounding required: Exposed non-current-carrying metal parts of PV module frames, electrical equipment and conductor enclosures must be grounded.
Structure as equipment grounding conductor: Devices listed and identified for grounding the metal frames of solar modules or other equipment can bond exposed metal surfaces or other equipment to mounting structures. Metal mounting structures (other than building steel) used for grounding purposes should be identified as equipment-grounding conductors or have identified bonding jumpers or devices connected between the separate metal sections bonded to the grounding system.
PV mounting systems and devices: Devices and systems used for mounting PV modules that are also used to provide grounding of the module frames should be identified for the purpose of grounding solar panels.
Adjacent modules: Devices identified and listed for bonding the metal frames of PV modules can bond one panel to an adjacent one.
To ensure NEC requirements are met, one should follow the racking manufacturer’s torque specifications to tighten down all connection points. These connections provide the bonding and grounding for the system when assembled properly.
The UL listing of the racking system should be checked to make sure it has been tested and listed under UL 703 for the provision of bonding and grounding required within the codes.
It’s important to remember that all codes are written for protection from system failures that could risk life and property. National codes are not always adopted and enforced by all states or local jurisdictions, so solar installers should always research what exactly is required by each AHJ.
For more information on designing and installing a solar system, check out IronRidge’s free webinars—each valid for 1 NABCEP CE credit.