A generator earns its place as backup, not as your main power source, and it only helps if it starts when you need it.
Backup, not primary power
The book is clear that many beginners make the mistake of treating a generator as their primary power supply. Generators are expensive to run, noisy, need regular maintenance and depend on a fuel supply. As a primary source they are neither economical nor sustainable, but as backup for long dull spells or equipment faults they can be very useful.
Why an inverter generator is usually the better backup
- It produces power that is safer for sensitive electronics.
- It runs much more quietly.
- It adjusts engine speed to the actual load.
- The book says it uses roughly 25 to 40 per cent less fuel than a conventional generator.
It suggests that a 2,000 to 3,500 watt inverter generator can run most off-grid appliances. Check that against your own audit rather than assuming, and note that starting surges of motors and pumps can exceed their running figure.
Maintenance that keeps it reliable
- Change the oil every 50 hours of running, or at the manufacturer's recommended interval.
- Replace the spark plug every year.
- Clean the air filter regularly.
- Run the generator under load at least once a month, even if you have not needed it, to keep the carburettor clean and moving parts lubricated.
- Expect larger servicing after about 1,000 to 2,000 hours of operation.
The book's warning is blunt: a generator left unused for a season without preparation will often refuse to start at the moment you most need it.
Plan the fuel like any other cost
Decide where fuel will be stored, how much you will keep and how you will rotate it. A generator you only run a few times a year still has running costs, so include fuel and servicing in your budget. For how a generator fits with your other options, see backup power planning.
A generator is only one layer of an energy strategy; the Off-Grid Energy Systems guide shows where it sits among solar, wind and micro-hydro. For the DIY approach to keeping the whole property running, see The Off-Grid Survival Manual.