Generators & Home Battery Backup
When the power goes out,
what needs to
keep running?
Refrigeration, heating controls, a well pump, communications, or business equipment— your backup-power plan starts with the loads that matter to you.
Terrell Electric, LLC helps you discuss generator and battery options, transfer equipment, capacity, installation requirements, and the way the complete system should operate.
Understand the Options
Generators make electricity.
Batteries store it.
Both can support backup power, but they have different strengths, limitations, and installation requirements.
Standby Generator
A generator produces electricity while an engine operates. Available fuel, equipment capacity, operating conditions, and maintenance affect how long it can serve the loads.
It can be an option for extended outages when the fuel supply and operating plan support the need.
Home Battery System
A battery supplies stored energy through compatible power-conversion and backup-control equipment. There is no combustion exhaust from battery discharge.
Runtime depends on stored energy, reserve settings, system losses, connected loads, and available recharging.
Coordinated Backup System
A compatible design may combine batteries, solar, and a generator. Each source has to operate within the approved control arrangement.
Do not assume equipment from different manufacturers can simply be connected and used together.
Define What You Need
Essential circuits or
broader property coverage?
The most useful backup system supports the loads you actually need, for the duration you are trying to prepare for.
Some customers prioritize a refrigerator, lighting, communications, and a pump. Others want heating and cooling or broader property coverage.
Larger loads and simultaneous use change the equipment requirements. Load management may allow selected equipment to pause while higher-priority loads are operating.
Two Ratings You Need to Understand
Power determines what can run.
Energy helps determine how long.
Kilowatts: Available Power
Kilowatts, or kW, describe power available at a particular moment. Continuous output and short-duration starting capability are different ratings.
A system must support both the running loads and the starting requirements of applicable equipment.
Kilowatt-Hours: Stored Energy
Kilowatt-hours, or kWh, describe an amount of energy. Battery energy capacity is not the same as inverter output power.
More battery storage can extend runtime without necessarily increasing the power available to start or operate equipment.
A Simple Runtime Example
If 10 kWh is actually available to supply the loads, a steady 1 kW load would use it in about 10 hours.
A steady 5 kW load would use that same energy in about 2 hours. Real-world runtime must account for losses, reserves, and changing loads.
Home Battery Equipment Examples
Compare complete systems—
not just battery capacity.
Tesla Powerwall, Enphase IQ Battery, and SunGoldPower wall-mounted batteries represent different equipment approaches. The exact model and approved configuration matter.
Tesla Powerwall
As an example, Powerwall 3 lists 13.5 kWh of nominal battery energy and configured AC output up to 11.5 kW per unit.
Actual output settings, backup equipment, solar connections, and expansion arrangements depend on the approved system design.
Discuss the complete installation, not only the battery unit.
Enphase IQ Battery
As an example, IQ Battery 5P provides 5.0 kWh of usable energy and 3.84 kW of continuous output per unit.
Backup operation requires compatible Enphase control equipment. Multiple batteries may be part of a system when supported by the selected configuration.
IQ Battery generations and controls are not automatically interchangeable.
SunGoldPower Wall-Mounted Batteries
As an example, the SG48100M is a 51.2-volt, 100-Ah wall-mounted battery rated at 5.12 kWh.
This is a battery component that requires a compatible inverter, protection, controls, and appropriate system integration.
Verify inverter communication, ratings, system approval, and backup functionality before purchasing.
These are equipment examples, not a statement that all models have identical features or can replace one another. Specifications and availability must be verified for the proposed project.
Battery Runtime & Recharging
What happens after
the stored energy is used?
A battery is an energy reserve, not a fuel source that continuously creates electricity.
Without a compatible charging source operating during the outage, the battery eventually reaches its operating limit.
Solar may recharge a battery during an outage only when the solar, inverter, battery, and controls support that operation. Available sunlight and ongoing loads determine whether there is energy left to recharge the battery.
Generator Selection
Size the generator
around the actual loads.
Square footage alone does not establish the generator capacity your property needs.
Running demand, motor starting, simultaneous use, voltage, and load-management arrangements all affect selection.
Natural gas and propane ratings may differ for the same model. Manufacturer adjustments for site conditions also need consideration.
How Backup Power Takes Over
Automatic transfer is
part of the complete design.
Generator Transfer
An automatic transfer system detects a qualifying utility outage, starts the generator, and transfers designated loads once the generator supply is acceptable.
Starting and transfer take time. An engine-driven system is not an uninterrupted power supply.
Battery Backup Controls
A battery system uses compatible isolation and control equipment to supply designated loads during an outage.
Transfer performance varies. Equipment that cannot tolerate interruptions may still need a suitable dedicated UPS.
Return to Normal Operation
When utility power returns, the system reconnects according to its controls and approved operating sequence.
Generator cooldown, battery charging, and reserve settings depend on the selected equipment.
Safe Source Isolation
Backup power must not
backfeed utility lines.
Improperly connected equipment can energize utility wiring and endanger lineworkers and others.
Correct transfer and isolation equipment prevents an unintended connection between backup power and the utility supply.
Grounding, bonding, neutral connections, equipment ratings, and source controls must be reviewed together. Switching a neutral alone does not provide the required source isolation.
Never connect a generator through an ordinary wall outlet or use improvised connections to feed building wiring.
Natural Gas & Propane
The generator needs fuel
at the required flow and pressure.
Natural Gas
Review the meter, regulator, and piping capacity for the generator and other connected gas appliances operating together.
Natural gas availability during one outage does not guarantee availability during every emergency.
LP / Propane
Consider tank size, available fuel, regulator capacity, delivery access, and the tank’s ability to supply vapor under expected conditions.
Runtime depends on fuel consumption, generator load, and usable fuel available.
Fuel-System Coordination
Pipe length, fittings, pressure, other appliances, and supplier requirements affect the installation.
Identify who provides fuel work and any utility or supplier upgrades in the written scope.
Equipment Location
Generators and batteries
have different placement requirements.
Generator Placement
Standby generators need an approved outdoor location with proper exhaust clearance, ventilation, drainage, and service access.
Keep doors, windows, air intakes, neighboring buildings, and potential exhaust entry paths in the assessment.
Battery Placement
Indoor or outdoor suitability depends on the specific model, listing, environmental rating, and installation requirements.
Review temperature, mounting support, working clearances, flood exposure, impact protection, and applicable fire and building requirements.
The Entire Installation
Consider electrical routing, access to disconnects, communications, maintenance, and future equipment replacement—not only where the unit will physically fit.
Follow the selected equipment’s instructions and applicable local requirements rather than using one clearance rule for every system.
Generator exhaust contains carbon monoxide. Home battery systems do not produce combustion exhaust during normal discharge, but they still require appropriate electrical, environmental, and fire-safety planning.
Compare the Complete Project
The equipment price
is not the installed-system price.
Generator Project Costs
Include the generator, transfer equipment, fuel work, site preparation, electrical installation, permits, and startup arrangements.
Plan for fuel, exercise operation, and manufacturer-specified maintenance.
Battery Project Costs
Include batteries, compatible inverters, gateways or controllers, disconnects, mounting, electrical work, and any panel or load-management changes.
Review warranty conditions, expected capacity retention, and communications requirements.
Combined-System Costs
Additional controls and integration may be needed when combining batteries, generators, and solar.
Confirm supported operating modes, maintenance responsibilities, and exactly what happens during a prolonged outage.
Before You Choose Equipment
Questions that shape
a better backup plan.
Can one battery run the entire house?
It depends on the battery system’s output, available energy, motor-starting capability, and the loads operating. Capacity alone does not answer the question.
Will a battery last through a multiday outage?
Only if stored energy and supported recharging are sufficient for the loads over that period. Do not assume unlimited runtime from a