To comply with the prescriptive requirements, all single-family buildings are required to have a PV system installed unless the building qualifies for an exception. The minimum qualifying size of the PV system is based on the projected annual electrical usage as described by the Equation 7-1 below.
Equation 7-1
kWPV required = (CFA x A)/1000 + (NDwell x B)
WHERE:
kWPV = kWdc size of the PV system
CFA = Conditioned floor area
NDwell = Number of dwelling units
A = Adjustment factor from Table 7-1
B = Dwelling adjustment factor from Table 7.1
Table 7-1 – CFA and Dwelling Adjustment Factors
|
Climate Zone |
A - CFA |
B - Dwelling Units |
|
1 |
0.793 |
1.27 |
|
2 |
0.621 |
1.22 |
|
3 |
0.628 |
1.12 |
|
4 |
0.586 |
1.21 |
|
5 |
0.585 |
1.06 |
|
6 |
0.594 |
1.23 |
|
7 |
0.572 |
1.15 |
|
8 |
0.586 |
1.37 |
|
9 |
0.613 |
1.36 |
|
10 |
0.627 |
1.41 |
|
11 |
0.836 |
1.44 |
|
12 |
0.613 |
1.40 |
|
13 |
0.894 |
1.51 |
|
14 |
0.741 |
1.26 |
|
15 |
1.56 |
1.47 |
|
16 |
0.59 |
1.22 |
Annual Solar Access: The annual solar access is the ratio of solar insolation including shading to the solar insolation without shading. Refer to Exceptions for Reduced Solar Zone Due to Shade, in Section 7.6.2, for an example of how to calculate solar access.
Effective Annual Solar Access: The effective annual solar access shall be 70 percent or greater of the output of an unshaded PV array on an annual basis.
Effective Annual Solar Access Roof Areas: Are roof areas that meet the Effective Annual Solar Access requirements and are at least 80 contiguous square feet.
Solar Access Roof Area (SARA): The area of the building’s roof, covered parking areas, carports, and all other newly constructed structures that are capable of structurally supporting a PV system per Title 24, Part 2, Section 1511.2. SARA does not include any roof area with less than 70 percent annual solar access.
There are five allowable exceptions to the prescriptive PV requirements as listed below.
Exception 1: may apply if there is limited unshaded roof space. For steep slope roofs, SARA shall not consider roof areas with a northerly azimuth that lies between 300 degrees and 90 degrees from true north. No PV system is required if the SARA is less than 80 contiguous square.
Exception 2: No PV system is required when the minimum PV system is less than 1.8 kWdc.
Exception 3: Buildings with enforcement-authority-approved roof designs, where the enforcement authority determines it isn’t possible for the PV system, including panels, modules, components, supports, and attachments to the roof structure, to meet the snow load requirements of Ch. 7 in the American Society of Civil Engineers (ASCE) Standard 7-16.
Exception 4: For buildings that are approved by the local planning department prior to January 1, 2020 with mandatory conditions for approval:
1. Shading from roof designs and configurations for steep-sloped roofs, which are required by the mandatory conditions for approval, shall be considered for the annual solar access calculation.
2. Roof areas, that are not allowed by the mandatory conditions for approval to have PVs, shall not be considered in determining the SARA.
Exception 5: may apply to buildings with a battery storage system. PV system sizes determined using equation 150.1-C may be reduced by 25 percent if installed in conjunction with a battery storage system. The battery storage system shall meet the qualification requirements specified in Join Appendix JA12 and have a minimum usable capacity of 7.5 kWh.
Example 7-1 Detached Building
Question:
Does a new detached building classified as occupancy U (like a pool house, rec room, art studio, etc.) on a residential lot need to meet the solar PV requirements in Energy Code Section 150.1?
Answer:
Yes. A conditioned, newly constructed building classified as U-building on a residential lot needs to meet the PV requirements in Section 150.1(c)14 of the Energy Code. Using the prescriptive method, the annual PV electrical output Equation 150.1-C allows for an input of zero for the number of dwelling units. Using the performance method, the PV calculation is automated to at least one dwelling unit.
Example 7-2
Question:
Answer:
The installed PV system must meet the applicable requirements specified in JA11.
For prescriptive path compliance, a PV system with module pitches greater than 2:12, or 10 degrees, must be oriented between 90 to 300 degrees from true north. Module pitches less than 10 degrees (low-slope) can be installed in any orientation since azimuth of low-slope modules has an insignificant impact on array performance.
When using the performance approach, the array may be oriented in any direction, including due north; however, the more the orientation deviates from the optimum orientation of southwest, the worse the system performs, resulting in a larger PV system size needed to achieve compliance. It is best to orient the panels as close to southwest as possible to maximize the system performance with the smallest array size.
To use the California Flexible Installation 1 (CFI1) simplified modeling option in the performance method, the PV array must be installed between 150 to 270 degrees from true north, with all modules at the same tilt as the roof for pitches up to 7:12.
When the CFI2 option is selected in the performance calculation, the PV array must be installed between 105 and 300 degrees from true north, with all modules at the same tilt as the roof for pitches up to 7:12. Note, when selecting CFI2, the performance of the proposed system is derated by approximately 10 percent.
If the PV array does not meet either CFI1 or CFI2, then the actual orientation and tilt of the PV array shall be described.
Shading from obstructions must be limited to meet the performance or prescriptive requirements. For prescriptive compliance, if the PV system does not qualify for Exception 1 described above, then the weighted average annual solar access by panel count shall be at least 98 percent. Any obstruction located north of the array does not need to be considered. Obstructions include the following:
(a) Any vent, chimney, architectural feature, mechanical equipment, or other obstruction that is on the roof or any other part of the building.
(b) Any part of the neighboring terrain.
(c) Any tree that is mature at the time of installation of the PV system.
(d) Any tree that is planted on the building lot or neighboring lots or planned to be planted as part of landscaping for the building. (The expected shading shall be based on the mature height of the tree.)
(e) Any existing neighboring building or structure.
(f) Any planned neighboring building or structure that is known to the applicant or building owner.
(g) Any telephone or other utility pole that is closer than 30 feet from the nearest point of the array.
Example 7-3 Shading
Question:
What would be the impact of shading on the PV sizing requirement?
Answer:
Prescriptively the PV array cannot have any shading and the weighted average annual solar access as measured by an approved solar assessment tool must be at least 98 percent by panel count. Under the performance path, there is no minimum requirement for annual solar access, however the increase in shading (lower annual solar access)will necessitate in a larger PV size to meet the same TDV budget as a smaller unshaded PV system.
A solar assessment tool that is approved by the Executive Director must be used to demonstrate the shading conditions of the PV system or when claiming an exception based on limited amount of solar access.
The installer must provide documentation that demonstrates the actual shading condition of the installed PV system using an approved solar assessment tool. To be certified by the Executive Director, the solar assessment tool:
a. Must calculate the annual solar access percentage of each individual solar array and a weighted average of the PV system. The calculation must include all known obstructions, including any tree that is planted on the building lot or neighboring lots or planned to be planted as part of landscaping for the building.
b. Must not include horizon shading in the calculation by default,
c. Must produce a shade report with a summary of the PV system, including the address of the project, individual array panel count, orientation, annual solar access percentage, and a weighted average of the PV system as a whole.
d. Annual solar access percentage values must be comparable to on-site measurements, if the tool’s model shading condition is based on satellite or aerial images. Documentation must be provided to the CEC as proof.
The PV system must have a web portal and a mobile device application that enables the building owner, manager, or occupants to monitor the performance of their PV system to identify, report, and correct performance issues with the panels, inverters, shading, or other issues that may adversely impact the performance of the PV system. At a minimum, the occupants must have access to the following information:
(a) The nominal kW rating the PV system.
(b) Number of PV modules and the nominal watt rating of each module.
(c) Hourly (or 15-minute interval), daily, monthly, and annual kWh production in numeric and graphic formats for the system.
(d) Running total of daily kWh production.
(e) Daily kW peak power production.
(f) Current kW production of the entire PV system.
In addition to the requirements above, the PV system must also meet the following requirements in JA11:
Interconnection Requirements: All inverters in the PV system must comply with the CPUC Electric Tariff Rule 21, which governs CPUC-jurisdictional interconnections for all net energy metering (NEM) customers. Rule 21 requires that inverters have certain capabilities to ensure proper operation of the electrical grid as more renewables are interconnected. The inverters must perform functions that can autonomously contribute grid support during excursions from normal operating voltage and frequency system conditions by providing dynamic reactive/real power support, voltage and frequency ride-through, ramp rate controls, communication systems with ability to accept external commands, and other functions.
Certificates and Availability: The PV installer shall certify on the Certificate of Installation that all provisions of JA11 are met and provide a solar assessment report meeting one of the following conditions:
(a) A satellite, drone, or other digital image used in the solar assessment report must be created and dated after the PV system is installed.
(b) If the satellite, drone, or other digital image used in the solar assessment report is dated before the PV is installed, additional on-site pictures must be attached to clearly show that the installed system matches the system modeled in the solar assessment report
The Certificate of Installation shall be available on the building site for inspections.
Enforcement Agency Responsibilities: The local enforcement agency shall verify that the Certificate of Installation is valid complete and correct, and uploaded into a Commission-approved registry.
Example 7-4 Remote Monitoring
Question:
How do I implement monitoring to meet section JA11.5.1 including the current reading?
Answer:
There are multiple options. Many inverters can connect to the homeowner’s internet, via ethernet and/or wireless. Others use independent cellular connections. For cellular, the data should be updated to the monitoring portal periodically as allowed by the cellular plan.