There are five exceptions to the solar zone area requirement described in §110.10(b)1B. Some exceptions are limited to certain buildings, as noted in the individual exception details below. Submit an NRCC-SRA-E, the "Solar Ready Areas" Certificate of Compliance to the enforcement agency for all building projects subject to Solar Ready, even if using a Solar Zone Exception.
Exception 3 allows a reduced-size solar zone when solar access is limited by certain circumstances.
Exceptions 1, 2, 4 and 5 allow alternate efficiency measures instead of a solar zone, so the requirements for zone shading, azimuth and design load; interconnection pathway, and owner documentation do not apply either. Any installations must be inspected and verified prior to final approval by the enforcement agency.
Exception 1: A compliant solar electric system is permanently installed on high-rise multifamily, hotel/motel, and nonresidential buildings. The system must have a nameplate direct current (DC) power rating of no less than 1 watt per sq. ft of roof area. The nameplate rating must be measured under Standard Test Conditions. See Example 9-6. To verify compliance with this exception, NRCI-SPV-01-E Certificate of Installation: Solar Photovoltaic System must be submitted as a condition of final approval.
Exception 2: A solar hot water system (SWH) is permanently installed on high-rise multifamily, hotel/motel, and nonresidential buildings. The SWH system must comply with §150.1(c)8Biii, the prescriptive solar requirements for a system serving multiple dwelling units. To verify compliance with this exception, submit NRCI-STH-01-E Certificate of Installation: Solar Water Heating System.
Exception 3: Reduce the solar zone area when the roof is shaded by objects that are not part of the building project, and therefore beyond the designer’s control. The designated solar zone may be reduced to ≥ 50 percent of the potential solar zone area when solar access is limited as described below. When the “potential” solar zone is smaller than the 250 sq. ft minimum, the solar zone can be reduced to half the area of the potential solar zone. The reduced-size solar zone is called the “designated” solar zoneException 4: Allowed for multifamily buildings only. The solar zone, interconnection pathway, and documentation requirements do not apply when compliant thermostats and other energy efficiency features are installed during construction.
Exception for Reduced Solar Zone
Step 1: Determine the Annual Solar Access: For the solar ready requirements, solar access is the ratio of solar insolation including shading to the solar insolation without shading. Annual solar access is most easily determined using specialized software.
Solar Access= (Solar Insolation Including Shading)/(Solar Insolation Without Shading)
Solar access does not take into account shading from objects that are included in the building project because the designer has control of potential obstructions. Objects that are not part of the building project cannot be moved or modified as part of the project and include existing buildings, telephone poles, communication towers, trees, or other objects. Objects that are considered part of the building project are objects constructed as part of the building project and include the building itself, its HVAC equipment, outdoor lights, landscape features and other similar objects.
First evaluate whether there are any objects outside the building project that will shade the rooftop (or other prospective solar zone areas such as overhangs or parking shade structures). If an existing object is located north of all potential solar zones, the object will not shade the solar zone. Similarly, if the horizontal distance (“D”) from the object to the solar zone is at least two times the height difference (“H”) between the highest point of the object and the horizontal projection of the nearest point of the solar zone, then the object will not shade the solar zone (See Figure 9-2).
Step 2: Determine the Potential Solar Zone Area: On low-sloped roofs, the potential solar zone is the area where annual solar access is ≥ 70 percent.
On steep-sloped roofs the potential solar zone is the area where the annual solar access is
≥ 70 percent on the portion oriented between 90 and 300 degrees of true north.
Step 3: Determine the size of the designated solar zone. The designated solar zone must be
≥ 50% of the potential solar zone area. If the roof is shaded such that there is no potential solar zone area, then no solar zone is required. Document the method/tools used to demonstrate that the solar access is less than 70 percent in the compliance form NRCC-SRA-E (Minimum Solar Zone Area Worksheet).
In each dwelling unit, the thermostats must have demand responsive (DR) controls that comply with Section 110.12(a). The thermostats must be installed in the dwelling units before the local enforcement agency grants the occupancy permit.
§110.12 is a new section in the 2019 Energy Standards that specifies capabilities for demand responsive controls. A “demand responsive control” is defined in §100.1 as an “automatic control capable of receiving and automatically responding to a demand response signal.” The technical specifications for compliant demand responsive control thermostats are detailed in JA5.
In addition to the demand responsive thermostats, choose option A or option B (below).
A. Each dwelling unit must have one of the following four measures (1 – 4):
1. Install a dishwasher that meets or exceeds the ENERGY STAR® program requirements with either a refrigerator that meets or exceeds the ENERGY STAR program requirements or a whole-house fan driven by an electronically commutated motor.
2. Install a home automation system that complies with §110.12(a) and capable of, at a minimum, controlling the appliances and lighting of the dwelling and responding to demand response signals.
3. Install alternative plumbing piping to permit the discharge from the clothes washer and all showers and bathtubs to be used for an irrigation system. It must comply with the California Plumbing Code and local ordinances.
4. Install a rainwater catchment system that uses rainwater flowing from at least 65% of the available roof area. It must comply with the California Plumbing Code and local ordinances.
B. Meet the Title 24 Part 11, Section A4, 106.8.2 requirements for electric vehicle charging spaces.
Exception 5: Applies to multifamily, hotel/motel, and nonresidential buildings. If the roof is designed and approved to be a heliport, or used for vehicular traffic or parking, no solar zone is required. Therefore, interconnection pathway and documentation requirements do not apply.
If the solar zone is located on a steep-sloped roofs (the roof has a rise to run ratio of greater than 2:12), then the roof must be oriented between 110 degrees and 270 degrees of true north (not magnetic north). The orientation is important because it ensures a reasonable solar exposure if a solar energy system is installed in the future.
Figure 9-1: Orientation of Roof If Solar Zone Is Located on Steep-Sloped Roof
If a solar zone is located on a low-sloped roof (the roof has a rise to run ratio less than 2:12), the orientation requirements do not apply.
Obstructions such as vents, chimneys, architectural features, or roof-mounted equipment cannot be located in the solar zone. This requirement is in place so the solar zone remains clear and open for the future installation of a solar energy system.
Any obstruction located on the roof or any other part of the building that projects above the solar zone must be located at a sufficient horizontal distance away from the solar zone such that the obstruction will not shade the solar zone. Equation 9-1 and Figure 9.2 describe the allowable distance between any obstruction and the solar zone. For each obstruction, the horizontal distance (“D”) from the obstruction to the solar zone has to be at least two times the height difference (“H”) between the highest point of the obstruction and the horizontal projection of the nearest point of the solar zone.
Equation 9-1:
D ≥2H
Figure 9-2: Schematic of Allowable Setback for Rooftop Obstructions
Source: California Energy Commission
Obstructions located north of all points of the solar zone are not subject to the horizontal distance requirements. Obstructions not located on the roof or another part of the building, such as landscaping or a neighboring building, are not subject to the horizontal distance requirements.
The structural design load requirements apply if any portion of the solar zone is located on the roof of the building. For the areas of the roof designated as the solar zone, the structural design loads for roof dead load and roof live load shall be clearly indicated on the construction documents. This is required so that the structural loads are known if a solar energy system is installed in the future.
The Energy Standards do not require estimating the loads of possible future solar equipment.