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Solar Panel Installation Classifications

The installation of solar energy systems has become very popular in connection with both new construction and remodeling operations. This e-newsletter provides classification information for the most common residential solar energy systems.

Hot water solar collection panels absorb solar energy to heat water or heat transfer fluid that circulates through the panels. Heat transfer fluid is routed through pipes to a heat exchanger, and heated water is routed to pools, spas, storage tanks, hydronic heating systems or other plumbing systems. The installation, service and repair of solar water panels, and all piping, valves and plumbing fixtures that comprise the solar water heating system, is assigned to Classifications 5183(1)/5187(1), Plumbing.

Photovoltaic (PV) solar systems convert solar energy to electricity. Residential PV systems typically include roof-mounted PV panels that are connected by wiring to an inverter that converts direct current to alternating current. The alternating current is then connected to the circuit breakers that control the flow of electricity to the house. A “grid connected” system will include connections through an electric meter to route electricity to the public utility grid. Less common “off the grid” systems may route electricity to an array of storage batteries before converting to alternating current and connecting to house wiring.

The installation, service and repair of PV solar panels is included in the description of Classification 3724(2), Electrical Machinery or Auxiliary Apparatus:

ELECTRICAL MACHINERY OR AUXILIARY APPARATUS – installation, service or repair – including incidental wiring

This classification applies to the outside installation, service or repair of electrical machinery or auxiliary apparatus, including but not limited to automated security gates, transformers, generators, control panels, temporary power poles at construction sites, industrial fans or blowers, photovoltaic solar panels, wind powered generators and industrial X-ray machines.

This classification does not apply to the installation or repair of machinery or electrical apparatus at facilities both occupied and operated by the employer; such operations shall be assigned to the governing classification.

Shop manufacturing or repair operations shall be separately classified.

Operations performed in connection with the installation of aerial power lines, including erection of poles, stringing of wires, installation of service transformers on poles or on the outside of buildings, or the making of service connections shall be classified as 7538, Electric Power Line Construction.


Classification 3724(2) includes incidental wiring, meaning the wiring that pertains specifically to the electrical apparatus, in this case the PV system. The installation of the PV panels, inverter, battery arrays and any other components that comprise the PV system, and all wiring that pertains to these components, are classified as 3724(2). Installation of the main circuit breaker panel, electric meter and all electrical wiring within the building that is not integral to the PV system is classified as 5140/5190, Electrical Wiring.

Commercial solar electric systems, including systems that use solar steam generation to produce electricity, are more complex and varied in design, and may have operations that require additional construction or erection classifications.

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