Specialty · Franklin County & St. Louis, MO
Adding solar to your home in the St. Louis area? The panels are only half the job — the electrical interconnection is where a lot of solar installs go sideways. CAS Electric handles the electrical scope of solar installations across Franklin County and the Greater St. Louis area — Pacific, Washington, Union, Sullivan, St. Clair, Eureka, Wildwood, Villa Ridge, and Marthasville, from inverter wiring through Ameren interconnection.
A grid-tied solar system generates DC power at the panels, converts it to AC at the inverter, and ties into your home's electrical panel — either through a dedicated backfed breaker or through a load-side tap or supply-side connection depending on your service size and panel condition. Getting that interconnection right (correct breaker size, correct location, correct labeling, correct disconnect placement) is what determines whether Ameren approves your interconnection application on the first submission.
We work with residential solar customers who've bought panels from a solar company or online and need a licensed electrician to handle the electrical scope, and with homeowners who want to hire the trades individually. We spec the interconnection, install the inverter and any AC disconnects, tie into the panel correctly, coordinate with Ameren on net metering, and handle the electrical permit and inspection.
If your panel can't support the backfed breaker or your service isn't sized right for the system, we'll tell you before you install — a service upgrade or a supply-side tap is usually the fix, and it's much easier to plan for before the panels are on the roof.
Electrical scope for a residential solar install (inverter wiring, AC disconnect, panel interconnection, permit) is quoted based on system size and interconnection method. We provide a free written estimate. Service upgrades are quoted separately if required.
We review your solar spec (panel wattage, inverter model, system size) and design the correct interconnection for your panel and service.
We help ensure the interconnection package meets Ameren Missouri's requirements the first time.
Inverter wiring, AC disconnects, backfed breaker or supply-side tap, panel tie-in, and all labeling per NEC 705.
Local inspector signs off, Ameren issues Permission to Operate, and your system goes live.
Yes — many of our solar customers buy panels/inverters separately or through an online installer and hire us for the electrical scope. We handle the interconnection, disconnects, panel tie-in, permit, and Ameren coordination.
Sometimes — depends on your existing panel's busbar rating and the size of your solar system. NEC 705.12 has specific rules about how much backfeed a panel can accept. We'll evaluate your panel first and tell you whether a service upgrade or supply-side tap is needed.
Ameren Missouri requires an interconnection application before the system goes live. Once approved and the local inspection passes, they issue Permission to Operate (PTO) and the system can be turned on. Net metering credits your account for excess generation.
We handle the electrical interconnection for battery systems too (Enphase, Tesla Powerwall, etc.) — including load panels, critical loads panels, and the AC side of the battery inverter.
No — that's a solar installer's role. We handle the electrical side: inverter wiring, disconnects, interconnection, panel tie-in, and permitting. We're happy to coordinate with your solar company.
Licensed, insured, owner-operated. We respond to all estimates within 1 business day.