There are two practical ways to keep the lights on during a Northern Virginia outage without a permanently installed standby unit: a portable-generator hookup (a transfer switch or interlock kit plus an exterior inlet box) or a battery power station that AJ Long Electric supplies and installs. A portable hookup typically runs $900-$2,500 installed, an exterior inlet box adds $500-$1,200, and a battery power station with installation runs $2,500-$6,000 for a portable-unit setup or $6,000-$15,000+ for whole-home battery integration. This guide breaks down every cost factor across the DMV area.
Key Takeaways
- A code-compliant portable-generator hookup (manual transfer switch or interlock kit) typically runs $900-$2,500 installed
- Adding an exterior generator inlet box (power inlet) typically runs $500-$1,200 installed
- A battery power station supplied and installed typically runs $2,500-$6,000 for a portable-unit setup; whole-home battery integration runs $6,000-$15,000+
- Transfer switches and interlock kits prevent dangerous backfeed onto utility lines and are required for any code-compliant generator connection
- Battery stations are silent, fuel-free, and indoor-safe; portable generators must always run outdoors, away from windows, doors, and vents, because of carbon monoxide risk
Backup Power Options and Pricing
The right choice depends on how long you need to ride through an outage, whether you want a fuel-free indoor-safe option, and which circuits matter most. Both approaches are governed by NEC 702 (optional standby systems), and both require an electrical permit for the hardwired transfer-switch or smart-panel work — but neither requires a gas permit.
Planning Backup Power for Your Home?
Stay powered through the next outage. We install portable generator hookups — manual transfer switches, interlock kits, and exterior inlet boxes for safe, backfeed-free connection — and we supply and install battery backup power stations (EcoFlow, Bluetti, Anker SOLIX) for silent, fuel-free runtime. Call (703) 997-0026 for a free in-home assessment.
- Manual transfer switch or interlock kit: $900-$2,500 installed -- Lets you safely power selected circuits from a portable inverter generator. The transfer switch or interlock prevents backfeed, the leading safety hazard of an improvised generator connection.
- Generator inlet box (power inlet): $500-$1,200 installed -- The weatherproof exterior receptacle your portable generator's cord plugs into, wired to the transfer switch or interlocked breaker.
- Battery power station (portable-unit setup): $2,500-$6,000 supplied and installed -- A unit such as an EcoFlow Delta Pro, Bluetti AC500, or Anker SOLIX, set up to power essential loads with an inlet or a small transfer switch.
- Whole-home battery integration: $6,000-$15,000+ supplied and installed -- An EcoFlow Smart Home Panel or Bluetti EP900 system hardwired to your panel through a transfer switch to automatically power selected circuits, depending on capacity and number of circuits.
Portable-Generator Hookup Cost Breakdown
Transfer Switch or Interlock Kit ($900-$2,500 installed)
A manual transfer switch isolates a chosen set of circuits so they draw from the portable generator instead of the utility. A generator interlock kit is a lower-cost alternative that bolts onto your existing panel and mechanically prevents the main breaker and the generator breaker from being on at the same time. Either device prevents backfeed — energizing the utility lines from your generator — which can electrocute line workers and destroy your equipment. The number of circuits, panel condition, and run length drive the price within this range.
Generator Inlet Box ($500-$1,200 installed)
The inlet box is the weatherproof exterior power inlet your portable generator connects to with a heavy-duty cord. It is mounted on an exterior wall in a convenient, well-ventilated location and wired back to the transfer switch or interlocked breaker. Placement matters for carbon monoxide safety: the generator itself must sit well away from the house while the cord reaches the inlet.
Electrical Permit (typically $80-$165)
Hardwired transfer-switch and interlock work requires an electrical permit in all Northern Virginia jurisdictions. Fairfax County, Arlington County, Loudoun County, and Prince William County each have their own permit fees and inspection scheduling. There is no gas permit — a portable-generator hookup involves no fuel lines or tanks.
Carbon monoxide safety: Never run a portable generator indoors, in a garage (even with the door open), in a basement, or near open windows or doors. Portable generators emit carbon monoxide that can be fatal within minutes. Always operate the generator outdoors, at least 20 feet from the home, with the exhaust pointed away from windows, doors, and vents. Battery power stations carry no such risk and are safe to run indoors.
Battery Power Station Cost Breakdown
Portable-Unit Setup ($2,500-$6,000 supplied and installed)
For homeowners who want a silent, fuel-free option, AJ Long Electric supplies and installs battery power stations from EcoFlow (Delta Pro and Delta Pro Ultra), Bluetti (AC500), and Anker SOLIX. These units are sized by storage capacity in kilowatt-hours (kWh) and continuous output in watts, rather than by genset kW. A typical setup powers essential loads — refrigerator, lights, internet, sump pump, medical devices — and recharges from the grid or from solar. App monitoring shows charge level, runtime, and load in real time.
Whole-Home Battery Integration ($6,000-$15,000+ supplied and installed)
Larger systems hardwire to your panel through a transfer switch or a smart home panel — the EcoFlow Smart Home Panel or the Bluetti EP900 home-integration system — to automatically power selected circuits the moment the grid drops. The final cost depends on total kWh capacity, how many circuits you want backed up, and whether you add expansion batteries. Because these systems involve a hardwired transfer switch or smart panel, they require an electrical permit but no gas permit.
Good to Know: Battery power stations are silent and produce no exhaust, so they can sit in a garage, utility room, or closet. They recharge from your home's grid power when it is available and from rooftop or portable solar, which can extend runtime indefinitely on sunny days. Runtime depends on the stored kWh and how much load you draw — your electrician can size the system to your essential circuits.
Portable Generator vs. Battery Power Station
Portable Generator Hookups
A portable inverter generator paired with a transfer switch or interlock kit is the lowest-cost path to backup power and can run as long as you keep fuel on hand. The trade-offs are noise, fuel storage, and carbon monoxide risk — the unit must always run outdoors, well away from the home. This option is a strong fit for homeowners who already own (or plan to buy) a portable generator and want a safe, code-compliant way to connect it.
Battery Power Stations
Battery power stations deliver silent, fuel-free, indoor-safe backup with no exhaust and no refueling. They start instantly, run sensitive electronics cleanly, and can recharge from grid or solar. The trade-off is finite runtime per charge, which is why larger EcoFlow Smart Home Panel or Bluetti EP900 systems add capacity and automatic circuit switching. For homeowners who want quiet, low-maintenance backup — especially for medical equipment, home offices, or refrigeration — a battery station is often the better fit.
The Installation Process
Site Assessment
The process begins with an evaluation of your electrical panel, the circuits you want to keep powered, and the best location for an inlet box or battery unit. For a portable hookup, your electrician confirms whether a transfer switch or an interlock kit suits your panel. For a battery system, they perform a load review to match kWh capacity and watt output to your essential circuits.
Permitting and Scheduling
After you approve the proposal, your contractor pulls the electrical permit and orders any equipment. Battery power stations and transfer-switch hardware are generally stocked or available within days, so most projects schedule quickly.
Installation Day
A portable-generator hookup is typically a one-day job: mounting the transfer switch or interlock kit at the panel, installing the exterior inlet box, and labeling circuits. A battery power station install covers placing the unit, wiring it through a transfer switch or smart home panel, configuring app monitoring, and testing an outage transfer. Whole-home battery integration may take one to two days depending on circuit count.
Inspection and Commissioning
The electrical inspection must pass before the permit closes. Once approved, your electrician walks you through operation: for a portable hookup, how to safely start the generator outdoors and switch circuits over; for a battery system, how to read the app, monitor charge level, and confirm automatic switching on larger units.
Ongoing Maintenance Costs
Battery power stations are nearly maintenance-free — there is no oil, filter, or spark plug to service. Budget for occasional firmware updates through the manufacturer app and an eventual battery-capacity check after several years. A portable-generator hookup itself needs no routine service; the portable generator follows its own manufacturer maintenance schedule. AJ Long Electric is available for periodic safety checks and any panel or wiring updates your system needs.
Get Your Backup Power Quote
Power outages in Northern Virginia are not a matter of if but when. Whether you want a safe, code-compliant way to connect a portable generator or a silent battery power station for your essential circuits, AJ Long Electric can help. Contact us at (703) 997-0026 for a free on-site assessment and detailed installation quote. We serve homeowners throughout Fairfax, Arlington, Loudoun, and Prince William counties with backup-power work backed by our workmanship warranty.
