No single power source is perfect year-round, so a sound off-grid plan decides in advance what keeps running when the main source falls short.
Start with what must keep running
Go back to your energy audit and mark the essential loads: usually refrigeration, lighting, water pumping and communication. Backup planning is about protecting those, not about powering everything. A shorter essential list needs a smaller backup.
Build in layers
- Batteries. The battery bank stores energy for nights and cloudy periods. Decide how many days of poor sun you want to cover and size around usable capacity (see solar battery storage basics).
- A second source where your site allows. The books discuss wind and micro-hydro as alternatives or complements to solar. Their usefulness depends on your site, so assess them as part of your property plan (wind, micro-hydro).
- A generator as the last layer. The book advises treating a generator as backup rather than primary power, preferring an inverter model and keeping it maintained (generator planning).
- Behaviour. Running heavy loads on sunny days and cutting optional use during poor weather (reducing demand) is the cheapest backup there is.
Plan for the hardest season
Solar output, water lines and even heating needs change with the seasons. Size your backup for the worst stretch you reasonably expect, not the average, and keep a simple written plan for what you switch off first when reserves run low.
Test it before you rely on it
- Run the generator under load on a schedule, as the book recommends.
- Check battery state and connections regularly.
- Keep spare fuses and basic parts for the equipment you cannot easily replace.
- Write down the shutdown order for non-essential loads so anyone in the household can follow it.
The Off-Grid Energy Systems guide sets out the full chapter on solar, wind, micro-hydro and generators. For a practical overview of everything a self-reliant property needs, see Off Grid Survival for Beginners.