Building Division Residential Rooftop Solar
and ESS Requirements
The City of Littleton has adopted the following codes with amendments:
Applicable codes are required to be notated on plans.
***All documents are required to be submitted electronically***
These requirements pertain only to residential rooftop photovoltaic (PV) energy systems, as administered by Littleton’s Building and Code Compliance Division. Additional permits, permissions, authorizations, fees, inspections, etc. may be required by other Littleton departments and/or outside authorities having jurisdiction.
All components of a project, such as design, fabrication, installation, and construction, shall comply with City of Littleton’s adopted building codes, ordinances, amendments, and Building and Code Compliance Division policies. As of December 1, 2022, Littleton’s Building and Code Compliance Division administers the 2021 International Code Council’s I-codes and the 2020 National Electrical Code (NFPA 70).
Common Design Considerations
Littleton Design Criteria
Littleton’s design wind speeds are based upon the most recent Colorado Wind Gust Map, as approved by the Structural Engineers Association of Colorado (SEAC). The appropriate wind speed is based upon the structure’s risk category and location within the City of Littleton limits. Ground snow loads shall be assumed to be 30 pounds-per-square foot minimum.
Pathways and Setbacks
Not fewer than two pathways, on separate roof planes from lowest roof edge to ridge and not less than 36 inches wide, shall be provided on all buildings. Not fewer than two (2) pathways shall be provided on the street or driveway side of the roof. For each roof plane with a photovoltaic array, a pathway not less than 36 inches wide shall be provided from the lowest roof edge to ridge on the same roof plane as the photovoltaic array, on an adjacent roof plane, or straddling the same and adjacent roof planes. Pathways shall be over areas capable of supporting fire fighters accessing the roof. Pathways shall be located in areas with minimal obstructions such as vent pipes, conduit, or mechanical equipment.
For photovoltaic arrays, not less than a 36-inch clear setback is required on both sides of a horizontal ridge and from the roof eaves and rakes. Not less than an 18-inch clear setback is required on both sides of a valley or hip No setback is required at roof-to-wall transitions or at changes in roof slope.
These pathway and setback requirements apply in all cases, regardless of the percentage of the roof dedicated to solar, roof slope, habitable or non-habitable structure, principle or accessory structure, presence or not of an automatic sprinkler system, or rooftop-mounted modular system or building-integrated photovoltaic system (PV shingle).
In the case of townhouses and multi-family buildings, the photovoltaic system, pathways, and setbacks shall be restricted to the roof area allocated to the individual dwelling unit. In other words, it is not permissible to fill your townhouse rooftop with photovoltaic and consider your neighbor’s abutting rooftop as providing the required pathway.
Electrical & ESS
Photovoltaic panels and modules shall be listed and labeled in accordance with UL 1703 or with both UL 61730-1 and UL 61730-2. Inverters shall be listed and labeled in accordance with UL 1741. Systems connected to the utility grid shall use inverters listed for utility interaction.
Any exposed grounding conductors on the roof shall be 6 AWG copper or larger. NEC 250.120(C)
If the existing grounding system consists of a single rod, pipe, or plate electrode, then a supplemental grounding electrode must be provided. Electrodes shall be spaced at least 6' apart. (IRC E3608.4)
Energy storage systems (ESS) shall be listed and labeled in accordance with UL 9540 and be installed per IRC R328.4, the NEC, and Littleton amendments.
ESS shall be installed only in the following locations:
· Detached garages and detached accessory structures.
· Attached garages separated from the dwelling unit living space.
· Outdoors or on the exterior side of exterior walls located at least 3’ from doors and windows directly entering the dwelling unit.
· Enclosed utility closets, basements, storage, or utility spaces within dwelling units with finished or noncombustible walls and ceilings. Walls and ceilings of unfinished wood-framed construction shall be provided with not less than 5/8” Type X gypsum wallboard.
ESS shall not be installed in sleeping rooms, or closets or spaces opening directly into sleeping rooms.
ESS located inside of dwelling units, basements, and attached garages shall be provided with interconnected smoke alarms or heat detectors, as appropriate.
ESS shall be provided with the required warning labels, operation and maintenance manuals, and contact information for qualified maintenance and service providers.
Structural Design Documents
A digitally stamped and signed letter from a State of Colorado-registered Structural Engineer shall be submitted as part of the Building Permit Application process. Such a letter shall clearly state that the Structural Professional Engineer has evaluated the existing, non-concealed elements of the structure, considered the proposed photovoltaic system improvements, and either verifies that no structural modifications are required or provides the design for such required structural modifications.
All sheets within the project drawing set that contain structural design or related information shall be digitally stamped and signed by a State of Colorado-registered Structural Engineer.
Electrical Design Documents
All sheets within the project drawing set that contain electrical design or related information shall be digitally stamped and signed by a State of Colorado-registered Electrical Engineer.
Electrical sheets should at least provide the following information:
· A cover sheet shall provide the basic project information: project address, project location map, designer/installer/contractor contact info, system capacity in both DC and AC, whether the system is interconnected with the utility grid, whether there is an energy storage system, etc.
· A dimensioned site plan shall show the location of the property and its relation to the street or main access road, solar array layout, required pathways and setbacks, and the location of associated equipment, such as a power storage system, disconnect, main electrical panel, meter, etc.
· A one- and/or three-line diagram shall provide a complete, schematic design for the entire photovoltaic system and wiring design.
· A roof attachment diagram shall show how the panels/modules attach to the existing roof structure.
· The required warning labels shall be shown on the plans.
· The electrical documents shall also contain calculations and other details necessary to demonstrate compliance with the National Electrical Code as adopted by the City of Littleton.
Contractor Requirements
Contractors and installers must be licensed to perform photovoltaic and electrical work within the City of Littleton.
Required Inspections
Rough Electrical, Rough Frame, Final Electrical, and Final Building – Close Permit
Please Note: Only 25% of panels may be installed prior to rough frame and rough electrical inspection.
The permit holder shall maintain a complete and current set of Littleton Building and Code Compliance Division-approved documents on-site at all times. Such documents must be printed in color and to a size large enough to be legible. Inspections will not be performed in the absence of such documents.
All work is subject to field inspection and shall not be covered prior to inspection.