Work out battery bank sizing instantly with clear inputs, formula shown and shareable results.
Bank energy is daily demand times days of autonomy divided by the permitted depth of discharge; dividing by system voltage converts it to amp-hours. Raising the system voltage cuts the amp-hour figure and therefore the cable size, which is why larger installations use 48 V rather than 12 V.
Battery bank
Wh = daily demand x autonomy days / DoD; Ah = Wh / system voltage
Electrical results are planning estimates only. Verify against the applicable wiring rules (IEC 60364, BS 7671, NEC or local code) and have all installation work designed and checked by a qualified electrician.
Two to three days for off-grid solar in temperate climates, more where cloudy spells are long, less if a generator or grid backup exists.
The same power needs a quarter of the current, so cables and losses shrink by a factor of sixteen in I squared R terms.