What electrical equipment should I document before starting a clean energy project?
Understanding your building's single-line diagram, service panels, switchgear, meters, and transformers helps solar providers deliver accurate proposals and avoid costly surprises.
Electrical equipment varies in type, size, and voltage rating, and documenting what's at your facility is one of the most valuable steps you can take before soliciting solar proposals. Here's what matters and why.
A single-line diagram (SLD) is a simplified drawing of your building's entire electrical system — think of it as a symbolic map showing all components, their ratings, and the path of power flow. If your building has one, it gives solar providers a head start on system design. If not, a provider or licensed electrician will typically need a site visit to inventory your equipment and create one. Having an SLD (or at least knowing whether one exists) saves time and can surface potential upgrade costs early.
Main service panels (also called panelboards or breaker boxes) are where utility power enters your building and gets distributed to circuits. The panel's amperage and voltage ratings determine how much additional load from a solar system it can handle. Panels under 200 amps may need upgrading.
Switchboards and switchgear are larger-scale versions of service panels. Switchboards handle higher busbar ratings (above 1,200A) and are accessible from two sides. Switchgear adds fault protection and power control, handling voltages up to 350 kilovolts in industrial settings. Switchgear upgrades can be expensive with long lead times — sometimes several months — so identifying this need early is critical.
Electrical meters measure your building's energy consumption and are used by utilities for billing. Documenting the quantity, location, and ID number of each meter helps solar providers size the system correctly and ensure proper grid interconnection. Meters may be located inside (usually near the service panel) or outside the building.
Transformers step voltage up or down to match your facility's needs. You might have a pad-mounted transformer (a large green or grey box outside), a pole-mounted transformer (attached to utility poles), or station/sub-station transformers for larger industrial applications. The transformer's kVA rating directly limits your maximum solar system size, making it one of the first things a provider will want to know.