Your power. Your independence.

Pick one of three system types. Off-grid is a standalone, DC-coupled solar and battery system; the hybrid inverter must run without a utility connection. Hybrid is grid-connected with a battery for outages, so the grid can recharge the battery. On-grid is grid-tied with no battery: solar offsets your daily use and the grid-tie inverter shuts down during an outage.

1. Daily energy: add each appliance's watts × quantity × running hours, then divide by 1,000 for kWh.
2. Battery: average daily load × requested backup hours ÷ usable battery fraction ÷ inverter efficiency, plus your design reserve. LiFePO₄ uses 80% depth of discharge; lead-acid uses 50%. On-grid systems have no battery.
3. Solar: cover daily consumption and estimated storage losses, plus energy to recharge the backup allocation within your selected window (off-grid only; hybrid systems can recharge from the grid). Divide by peak sun hours, PV derating and inverter efficiency, then add your reserve. On-grid arrays are sized to cover your daily use.
4. Inverter: for off-grid and hybrid, total connected power + 25% headroom, rounded up. The separate surge figure assumes the largest single appliance starts while the rest are running. For on-grid, the grid-tie inverter is matched to the array, allowing up to a 1.2 DC/AC ratio, because the grid covers load peaks.

Battery modules: LiFePO₄: 5.12 kWh (51.2 V, 100 Ah) each. Lead-acid: 9.6 kWh per 48 V bank of four 12 V, 200 Ah batteries. Actual capacity and charge/discharge limits depend on the equipment.

Assumed storage round-trip efficiency: 95% for lithium, 80% for lead-acid. Battery use follows a uniform average-load model; it does not simulate an hourly schedule. No weather data is fetched. Starting values are editable planning assumptions, not a location-specific guarantee.

Background: Victron off-grid system planning · U.S. Department of Energy: solar and storage