A 2024 revision to the International Building Code (IBC) would require more robust design standards for solar energy facilities. The proposed change from the International Code Council (ICC) would elevate design standards for solar facilities from Risk Category 1 to Category 2 in an attempt to increase their ability to minimize damage from hurricanes, tornadoes and other extreme weather events.

What It Means

This change would increase load factors by about 15% on average, meaning that components that are subjected to the most stress would need to be redesigned to withstand the greater force. The Category 2 risk standards essentially require that all components of the solar installation — piles, racking systems, trackers and modules — be able to withstand wind speeds of approximately 145 to 150 miles per hour (mph), versus approximately 135 mph — typically the upper limit on standard solar structures under Risk Category 1 standards. The likely outcome would be an increase in the size of piles as well as use of heavier gauge steel in racking structures, clips and other connectors.

How Will It Be Imposed?

In order for the code change to become effective, it must be published formally by the ICC. It is likely that publication will occur in the third or fourth quarter of 2023, based on historic publication dates for past IBC code changes.

Even after that step, the change is likely to only be applicable to a project if the code is formally adopted as a new building standard by the jurisdiction that has approval authority for a given solar project. These authorities having jurisdiction (AHJ) are primarily municipalities, counties, state agencies, tribal authorities and other government or quasi-government entities that have legal authority to enforce building codes.  

However, the new code requirements may also be imposed by other parties with a material interest in the project, such as insurers or financial institutions. These requirements may be imposed even if the AHJ has not yet adopted a change to Risk Category 2.

Waivers May Be Available

The impact to equipment may vary, depending on site conditions. Wind maps showing historical patterns of wind activity recorded for that specific geographic location are used to calculate the dynamic loading on equipment. In some geographic areas, the change from Risk Category 1 to Category 2 may result in loading that falls within the current design standards for loading of existing solar equipment products. In this case, the cost impact would likely be minimal. In other cases, the change to Risk Category 2 may result in dynamic loading that exceeds the existing equipment’s design capacity, requiring a modification to the equipment to resist the increased load. Under these situations, a cost impact to the system is expected.

A developer or owner may pursue an alternative approach by performing a wind study utilizing measuring devices placed in specific zones throughout the site. A study is generally performed to verify whether the wind patterns for that location vary from the broader wind map. If the study verifies that lower wind speeds are historically prevalent and other risk factors are low, the developer may seek approval from the AHJ to use lower speeds. However, the American Society of Civil Engineers (ASCE) requires the Wind Directionality Factor (Kd) to increase from 0.85 to 1.0 when using a site-specific wind study, which results in a 15% higher design wind pressure. Depending on the wind speed, a site-specific study could reduce the impact of the increase in loads from complying with Risk Category 2.

Cost Impact

Though costs would vary for each site, it is unlikely that the design changes imposed by a Risk Category 2 designation would increase total project installation costs by more than 1%-5%.

Total installed costs for solar facilities today average between $1 per-watt to $1.30 per-watt. Solar tracking systems are likely to require the most significant upgrades and typically cost between 10 cents to 15 cents per watt. The specifications calling for more steel and other hardened components are likely to increase costs by only a penny or two, translating to a small incremental increase in the cost of materials.

Moreover, any additional costs of complying with higher risk standards would be borne uniformly by all solar power developers, negating the possibility of any competitive advantage or disadvantage for any individual developer.

Why It’s Being Changed

The ICC initially proposed to raise the standards for all power generation facilities (including solar) to Risk Category 4, the highest level generally applied, because power facilities are deemed to be essential public infrastructure. Because they are subject to higher category risk levels, power plants that operate as baseload facilities must be designed and built with redundant systems so that they are nearly impervious to intense storms or other catastrophic events.

It seems likely the ICC raised the question of whether solar power had reached the same level of criticality as other sources of power generation because of its increasing penetration on bulk power grids nationwide, and thus merited design to withstand higher loads.

The solar power industry was successful in showing that while solar power is increasing in importance, storms that have damaged solar fields have not resulted in widespread power blackouts or any loss of life. The Risk Category 2 designation is a recognition that while solar has become a more critical energy resource and serves some of the same baseload capacity functions as conventional power plants, it still doesn’t pose the same level of risk.

According to the Solar Energy Industries Association (SEIA), the trade association representing the solar power industry, elevating solar power to a Risk Category 4 designation would have resulted in a 30% to 40% increase in costs of developing solar facilities, potentially crippling or even halting development of new solar facilities. Moreover, even with more resilience by solar facilities to severe wind storms, the step still would not have materially improved overall grid resilience, according to the SEIA.

Changes Will Come (Eventually)

Though it’s likely there will be a time lag before the new risk standards are uniformly applied across North America, developers should begin planning for the potential that most solar projects will need to be designed to accommodate increased loads from higher wind speeds. Though there would be some cost increases associated with these changes, the outlook currently is that they would be nominal.

Timing is still somewhat uncertain, but it is best to assume that many if not all solar projects will need to comply with the new standards in the near future. Even if your AHJ doesn’t adopt the 2024 IBC immediately, it seems likely that project insurers and/or financial backers will require compliance. You should begin preparing accordingly. 


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Sasha Weir is a staff structural engineer for Burns & McDonnell. She brings nearly 10 years of experience in structural steel and reinforced concrete design, with a focus on dynamic foundations and deep foundations for solar installations.