A battery bank stores the day’s solar for the evening and night; a generator covers the gaps when the sun doesn’t. Many off-grid homes in Spain run without a generator, but a long winter storm is the test.
Compare batteries on usable capacity, depth of discharge and rated cycles, not headline kWh. If you add a generator, an inverter-charger that can start it automatically saves a cold walk at night.
Generators should be sized to recharge the battery in a sensible time and run your largest load at the same time. Petrol is cheap to buy; diesel and LPG models usually last longer and cost less to run.
Questions to ask before you sign
- What is the usable capacity and rated cycle life?
- Will the battery work with my existing inverter?
- Can the generator be started automatically?
- What fuel, and what does it cost to run per hour?