Reviewed September 2026.
The right backup system starts with the equipment your building must keep running and the duration of an outage you want to plan for.
Generators: fuel and maintenance matter
A standby generator can support extended outages when properly sized, maintained, and supplied with fuel. Runtime is not unlimited: fuel access, operating limits, service intervals, and equipment condition all matter. Automatic starting also involves a transfer interval.
Batteries: separate power from stored energy
Battery power output determines which loads can run together; usable energy capacity helps determine how long they can run. There is no universal one- or two-day runtime. Ask for an estimate based on your actual loads, reserve settings, and operating conditions.
Solar alone does not establish backup capability
Standard grid-connected solar generally stops supplying the building during an outage. Backup requires suitable equipment and controls. See the DOE explanation of inverter and grid functions.
Can you combine them?
Solar, batteries, and a generator can work together when the equipment and controls are compatible and the system is engineered for that arrangement. A generator cannot simply be connected to an existing solar or battery system. Transfer controls, supported loads, charging behavior, and utility isolation must be addressed in the design.
What to compare in proposals
- Critical circuits and starting demands.
- Supported power, usable energy, and a realistic runtime estimate.
- Fuel, equipment location, maintenance, and operating costs.
- Transfer behavior and any loads needing dedicated uninterrupted power.
Explore Commercial Energy or home backup planning.
Request an assessment with BD Electrical & Solar. Tell us about your property, existing equipment, and priorities so we can define the appropriate scope.