Solar Access Roof Area: Solar Zone, Exemptions, and Plan Check

CALGreen solar-ready requirements make most new California buildings reserve unobstructed roof space, an electrical pathway, an inverter location, and structural load documentation so a photovoltaic system can be added later without tearing into finished construction. The core provisions sit in Section 110.10 of the California Energy Code (Title 24, Part 6) and are incorporated into CALGreen (Title 24, Part 11) through Section 4.211.4 for residential projects and Section 5.211.1 for nonresidential projects.¹

Which Buildings Are Covered

The rules split by occupancy type and story count. Nonresidential buildings of three stories or fewer are covered. Hotel, motel, and high-rise multifamily buildings are covered up to ten stories.² Single-family residences and low-rise multifamily buildings of three habitable stories or fewer also fall under Section 110.10.

One boundary worth flagging: since the 2019 Energy Code took effect on January 1, 2020, new low-rise residential buildings must actually install a solar photovoltaic system, not merely prepare for one.³ The solar-ready documentation still applies to those projects because the zone, structural notes, and pathway must appear on the plans regardless.

Additions trigger solar-ready compliance only when they add more than 2,000 square feet of roof area.² The 2025 Energy Code, effective April 1, 2026, carries these requirements forward, so confirm which code cycle applies based on your permit application date.

Solar Zone Size

The solar zone is the unobstructed roof area reserved for future panels. Minimum size depends on building type.

Single-family residences need at least 250 square feet, on the roof or an overhang. A reduced 150-square-foot minimum applies to homes with three or more habitable stories and 2,000 square feet or less of floor area, homes in designated Wildland-Urban Interface Fire Areas that include a whole-house fan, and homes where all thermostats have demand-responsive controls.⁴

Low-rise multifamily, nonresidential, and hotel/motel buildings need a solar zone covering at least 15 percent of the total roof area, excluding skylights. The zone can sit on the building’s own roof, on another structure within 250 feet, or on covered parking built as part of the project.⁴

Each subarea inside the solar zone has to meet minimum dimensions. No subarea can be narrower than five feet in any direction. On buildings with 10,000 square feet of roof or less, each subarea must be at least 80 square feet. On roofs larger than 10,000 square feet, each subarea must be at least 160 square feet.²

Orientation, Shading, and Obstructions

Only roof area that will actually receive sun counts. On steep-sloped roofs, the solar zone must be oriented between 90 and 300 degrees of true north.⁵ That range takes in east-, south-, and west-facing planes and excludes north-facing slopes.

Any roof area with annual solar access below 70 percent of the maximum possible sunshine cannot count toward the solar zone.² Trees, neighboring buildings, poles, and other external objects all count in the shading analysis. If nothing on the roof meets the 70-percent threshold, no solar zone is required, but the limitation must be documented on the compliance form.

Vents, chimneys, architectural features, and roof-mounted equipment cannot sit inside the solar zone.² Any obstruction near the zone must maintain a horizontal distance of at least twice the height difference between the obstruction’s highest point and the nearest point of the solar zone. A vent that rises four feet above the solar zone surface therefore needs at least eight feet of horizontal clearance.

Interconnection Pathway and Equipment Space

Panels are only useful if their output can reach the electrical system. Section 110.10 requires the construction documents to show an interconnection pathway from the solar zone down to the point where it will tie into electrical service.⁶ For single-family homes and buildings with central water-heating systems, a plumbing pathway from the solar zone to the water heater must also appear on the plans.

The plans must also designate a location for future inverters and metering equipment sized for a system that could cover the entire solar zone.² No conduit, piping, or mounting hardware has to be installed during initial construction. The requirement is to design and document the pathway so a future installer can follow it without guesswork.

Structural Load Documentation

The code does not require you to engineer the roof for the added weight of future panels. It requires that, for the area designated as solar zone, the structural design loads for roof dead load and roof live load be clearly noted on the construction documents.⁵ The Energy Code states that estimating collateral loads for future solar energy systems is not necessary.⁷ When a future installer arrives, the rated capacity is on the drawings, and any needed reinforcement can be assessed against a known baseline.

Exemptions That Reduce or Waive the Solar Zone

Five exceptions can reduce or eliminate the solar zone requirement for multifamily, hotel/motel, and nonresidential buildings.

A permanently installed compliant solar PV system with a nameplate DC rating of at least 1 watt per square foot of roof area waives the solar zone requirement.
On high-rise multifamily or hotel/motel buildings, a permanently installed solar water heating system meeting prescriptive requirements can substitute for the solar zone.
Where existing buildings, trees, or other external objects shade the roof, the designated solar zone can be reduced to 50 percent or more of the potential solar zone area. If the potential solar zone is smaller than 250 square feet, it can be cut to half that area. If the entire roof falls below the 70-percent solar access threshold, no solar zone is required.
For multifamily projects only, the solar zone, interconnection pathway, and documentation requirements are waived if the building includes demand-responsive thermostats plus at least one qualifying feature such as ENERGY STAR appliances, a home automation system, alternative plumbing for irrigation use, or a rainwater catchment system covering at least 65 percent of available roof area. The project must also meet CALGreen’s electric vehicle charging requirements.
No solar zone is required if the roof is designed as a heliport or used for vehicular traffic or parking.

These exceptions are documented in the code and in the CEC’s nonresidential compliance manual.² The compliance form still has to be submitted even when an exception applies.

Compliance Forms and Drawings

Every covered project files a solar-ready compliance form with the building permit application. Under the 2019 and 2022 code cycles, nonresidential projects use the NRCC-SRA-E (Certificate of Compliance: Nonresidential Solar Ready Areas). Under the 2025 code cycle, that form has been consolidated into the 2025-NRCC-SAB-E (Solar and Battery) form.⁸ It must be submitted even when the project claims an exception.

The form captures total roof area, solar zone dimensions, azimuth of the designated area, and shading analysis results. Those numbers have to match the architectural drawings. The drawings themselves must delineate the solar zone boundaries, show the interconnection pathway from the solar zone to the electrical service point, indicate the reserved space for inverters and metering equipment, and note the structural design loads for the solar zone area.⁶

Documentation for the First Owner or Occupant

The builder must give the first owner or occupant a copy of the construction documents, or a comparable packet, showing the solar zone location, its minimum area, the azimuth range, the shading analysis, the structural load ratings, and the interconnection pathway including the reserved space for inverters and metering equipment.⁶ For single-family homes and buildings with central water heating, the plumbing pathway for a future solar water heating system must also be documented.

Plan Check and Inspection

Solar-ready documentation is submitted with the rest of the building permit package to the local building department or Authority Having Jurisdiction. During plan check, reviewers compare the compliance form, construction drawings, and structural load notes against Section 110.10. The most common corrections involve missing or incomplete compliance forms, subareas that miss the minimum dimensions, obstruction setbacks that ignore the twice-the-height rule, and drawings that omit the interconnection pathway or the inverter location.²

After plan approval, a field inspector verifies the physical work matches the approved plans: the solar zone is free of unplanned obstructions, the interconnection pathway is in place as designed, and the reserved equipment space is available. Passing this inspection is part of the overall building approval required before a certificate of occupancy is issued.⁹

1
California Department of General Services. CALGreen
2
California Energy Commission. 2019 Nonresidential Compliance Manual – Solar Ready
3
California Energy Commission. Solar Photovoltaic Systems
4
Energy Code Ace. Solar Zone Minimum Solar Zone Area
5
Energy Code Ace. Section 110.10 – Mandatory Requirements for Solar Ready Buildings
6
Energy Code Ace. Section 110.10 – Mandatory Requirements for Solar Readiness
7
Energy Code Ace. 7.6 Solar Ready Overview
8
Energy Code Ace. 2025 Nonresidential Energy Code Forms
9
California Energy Commission. Solar PV, Solar Ready, Energy Storage Systems, Electric Ready