When your solar installer finishes the panels on the roof, the part that actually ties them into your home — and into Pepco’s grid — is electrical work, and it has to be done by a licensed electrician. David Williams handles the interconnection side of solar across Montgomery County: the main-panel tie-in, the outdoor AC disconnect, the conductor runs, and the Pepco net-metering wiring, with 30-plus years in the trade and Maryland license #11734 behind every connection. Up-front pricing, a 100% satisfaction guarantee, and an honest answer about whether your older Bethesda or Silver Spring panel can even take the load before anything gets ordered.
The electrical side of solar — what David actually does
Solar in Montgomery County involves two different crews doing two different jobs. One mounts the racking and panels on the roof. The other — the licensed electrician — ties that array into your home’s electrical system and into the Pepco grid so it’s safe, code-compliant, and approved to switch on. David Williams does the second part.
That work covers the main-panel interconnection (sizing the back-fed breaker against the NEC 120% busbar rule so your panel doesn’t get overloaded), the outdoor AC disconnect Pepco requires at the meter, the conductor runs between the inverter, disconnect, and panel, and the net-metering wiring that lets your meter run backward and credit you for what you send to the grid. If you’re going battery-ready, that also means a hybrid or string inverter feeding a protected backup subpanel — so the circuits you care about most keep running when the street goes dark.
What David does not do is roofing or panel-and-rack mounting. If you’ve already got an installer for the array, he’s the electrician who finishes it correctly. If you haven’t, he’ll tell you straight what the electrical scope looks like before you commit.
Older homes inside the Beltway and the 100–150A panel problem
A lot of the housing stock in Bethesda, Silver Spring, Chevy Chase, and the older parts of Rockville and Takoma Park was built decades before anyone planned for solar, heat pumps, and EV chargers all pulling from the same panel. Plenty of these homes are still on a 100-amp or 150-amp service with a panel that’s already close to full.
That matters because of the 120% rule: there’s a hard limit on how much solar a given busbar can legally accept through a back-fed breaker. On a tight 100A panel, the math often doesn’t work without a fix — and the honest fix is usually a line-side tap or a service upgrade, not cramming in a breaker that violates code. David checks the busbar rating, the existing load, and the meter setup first, in person, so you find out up front whether your panel takes the array as-is or needs work. That’s a conversation that should happen before your installer orders equipment, not after the inspector red-tags it.
Net metering and interconnection with Pepco
In Montgomery County your utility is Pepco, and going solar means going through Pepco’s interconnection and net-metering process. The application, the required AC disconnect at the meter, the production-meter coordination, and the permission-to-operate sign-off all have to line up with how the system is actually wired — and Pepco’s inspectors and the county both check the electrical work.
David wires the interconnection to match what the paperwork says and what the code requires, so the inspection passes and your net-metering credits start flowing the way they’re supposed to. With Maryland and the county both pushing hard on solar and electrification incentives, more homeowners in Gaithersburg, Germantown, Olney, and Potomac are adding panels — and the difference between a clean approval and a frustrating round of corrections is almost always the quality of the electrical hookup, not the panels themselves.
Battery-ready and backup that actually works in an outage
If you want your solar to keep the lights on during a Pepco outage — not just lower your bill — the wiring has to be planned for it from the start. A standard grid-tied system shuts off when the grid goes down, by design. A battery-ready setup with a hybrid inverter and a protected backup subpanel is what keeps your essentials running.
David sets up that backup subpanel deliberately: you decide which circuits matter — the fridge, the furnace blower, well pump, a few outlets and lights, the home office — and those get moved onto the protected side so a battery (now or added later) can carry them through a storm. Doing the subpanel work while the solar’s going in is far cheaper than re-pulling it later, which is exactly the kind of up-front, no-surprises planning DWE is built around, backed by the 100% satisfaction guarantee.
Frequently Asked Questions
Do I need a separate electrician if my solar company is handling everything?
Often, yes — and you should ask who's pulling the electrical permit. Many solar sales companies subcontract the interconnection, AC disconnect, and panel tie-in to a licensed electrician anyway. Hiring David Williams (MD #11734) directly for that scope means a Montgomery County tradesman with 30-plus years stands behind the connection, the inspection, and the Pepco sign-off.
My Bethesda house has an old 100-amp panel. Can it handle solar?
Maybe, but it has to be checked, not assumed. The NEC 120% rule caps how much solar a busbar can take through a back-fed breaker, and a lot of older inside-the-Beltway panels are already near capacity. David inspects the panel's busbar rating and existing load up front and tells you whether the array fits as-is or needs a line-side tap or service upgrade — before any equipment is ordered.
What's the AC disconnect Pepco keeps mentioning?
It's an exterior, lockable switch near your meter that lets Pepco physically isolate your solar from the grid for line-worker safety. Pepco requires it for interconnection in Montgomery County, and it has to be installed and labeled correctly to pass inspection. David installs and wires it as part of the standard solar hookup.
Will solar keep my power on during a Pepco outage?
Only if it's wired for that. A standard grid-tied system shuts off in an outage by code. To keep power, you need a battery-ready hybrid inverter feeding a protected backup subpanel. David can set up that subpanel and the protected circuits while the system is being installed so you're ready for a battery now or later — much cheaper than re-wiring it after the fact.
Which towns do you cover for solar electrical work?
David serves Montgomery County homeowners across Rockville, Bethesda, Silver Spring, Gaithersburg, Germantown, Potomac, and Olney, plus the surrounding communities. Call for up-front pricing and an honest assessment of your panel before you commit to a solar install.
Serving Montgomery County
David Williams Electric provides solar installations throughout Montgomery County, including Rockville, Bethesda, Silver Spring, Gaithersburg, Germantown, Potomac, Olney. Explore all Montgomery County electrical services or learn more about solar installations across Maryland. Call (410) 781-4357 for a free, up-front quote.
