9.3 Solar Zone

The solar zone is a suitable place where solar panels can be installed at a future date - if the owner chooses to do so. A solar zone area is designed with no penetrations, obstructions or significant shade. The solar zone must comply with the access, pathway, smoke ventilation, and spacing requirements in Title 24 Part 9. Requirements from the other parts of Title 24, and those adopted by a local jurisdiction should also be incorporated in the solar zone design.

• Roof of another structure located within 250 feet (75 meters) of the primary building.

• Overhang of another structure within 250 feet (75 meters) of the primary building.

Other structures include, but are not limited to, trellises, arbors, patio covers, carports, gazebos, and similar accessory structures.

Multifamily buildings: Solar Ready requirements for low-rise multifamily buildings are located in both the Residential and Nonresidential Compliance Manuals. In the 2019 Energy Standards, the solar zone requirements for low-rise multifamily buildings are grouped with high-rise multifamily, hotel/motel and nonresidential in §110.10(b)1B.

9.3.1 Solar Zone Minimum Area and Exceptions

Total Area: The solar zone must have a total area of at least 15% of the total roof area, after subtracting any skylights. See Example 9-4.

Multiple areas: The solar zone may be composed of multiple subareas if they meet the following minimum size specifications:

2. If the total roof area is equal to or less than 10,000 square feet, each subarea must be at least 80 square feet.

3. If the total roof area is greater than 10,000 square feet, each subarea must be at least 160 square feet.

Example9-1

Question:

A roof with no skylights has an area of 10,000 sq. ft. A neighboring building shades the roof, so 7,500 sq. ft of the roof has less than 70 percent annual solar access. How big does the solar zone have to be?

Answer:

If the entire roof had an annual solar access of 70 percent or greater, the minimum solar zone would be 1,500 sq. ft, or 15 percent of the total roof area (10,000 sq. ft.). However, the since the potential solar zone is 2,500 sq. ft, the minimum solar zone can be reduced to half the area of the potential solar zone, or 1,250 sq. ft.

Example 9-2

Question:

The total roof area is less than 10,000 sq. ft., but the potential solar zone is less than the minimum size requirements for any subarea (less than 80 sq. ft. or narrower than 5 feet in the smallest dimension). Does the building still need to comply with the solar-ready requirements?

Answer:

No. If half the potential solar zone is less than 80 sq. ft. (if roof is less than or equal to 10,000 sq. ft) or 160 sq. ft. (if roof is greater than 10,000 sq. ft), then the building does not need to comply with the solar zone requirements.

Example 9-3

Question:

A portion of an office building will have six stories, and a portion of the building will have two stories. Is the new building subject to the solar zone requirements?

Answer:

No, the solar-ready requirements do not apply to office buildings that have more than three stories. The solar-ready requirements apply only to hotel/motel occupancies and high-rise multifamily buildings with 10 or fewer stories and all other nonresidential buildings with 3 or fewer stories.

Example 9-4

Question:

A new warehouse has a total roof area of 80,000 sq. ft. Skylights cover 2,560 sq. ft. of the total roof area. What is the minimum solar zone area?

Answer:

The minimum solar zone area would be 11,616 sq. ft

Minimum Solar Zone Area=15% x (Total Roof Area-Area Covered by Skylights)

11,616 sq.ft= 15% x (80,000 sq.ft-2,560 sq.ft)

Example 9-5

Question:

Does the solar zone have to be one contiguous area?

Answer:

No, the solar zone does not have to be one contiguous area. The total solar zone can be composed of multiple smaller areas. A subarea cannot be narrower than 5 feet in any dimension. If the total roof area is 10,000 sq. ft or less, each subarea must be at least 80 sq. ft. If the total roof area is greater than 10,000 sq. ft, each subarea must be at least 160 sq. ft.

The image below illustrates a solar zone layout that is composed of eight smaller subareas. The sum of all the smaller areas must equal the minimum total solar zone area. In this case, the sum of all areas must be at least 11,616 sq. ft. The solar zones must also comply with fire code requirements, including, but not limited to, setback and pathway requirements. Current fire code requirements can be found in Ttile 24 Part 2 § 3111, Title 24 Part 2.5 §R331, and Title 24 Part 9 § 903.3.