This tool runs the same four-step method a professional off-grid designer uses by hand: divide your daily load by system efficiency and peak sun hours to size the array, multiply load by autonomy and divide by usable depth-of-discharge to size the battery, then apply a continuous-load heuristic to size the inverter.
The peak sun hour default above is a broad regional average, not your site’s number — insolation can vary sharply between two sites twenty miles apart, especially in hill or valley terrain. For a real spec, swap in your own site’s worst-month PSH (PVWatts in the US, PVGIS in Europe) instead — a system sized to survive December, not July, is the one that doesn’t brown out in winter.
LiFePO4’s deeper usable discharge (80–90%, per the two options above) needs a smaller nameplate bank than lead-acid’s ≈50% for the same autonomy.
The inverter figure doesn’t include motor-start surge — a well pump or compressor can spike well above its continuous rating.
The installed cost range is hardware-plus-labor for a typical site, interpolated from our installed-cost data — it excludes site-specific extras like long wire runs, difficult terrain, or permits.
The numbers above map straight onto real hardware. Picked on merit from what’s on the market right now — street prices, checked July 2026.
EG4 6000XP — 6kW split-phase all-in-one inverter, dual MPPT, 10-year warranty — the DIY value benchmark this calculator's budgets assume. $1,500–1,700
EG4 6000XP complete kit — inverter + fourteen 450W panels + three 5.12kWh rack batteries — lands close to what this calculator returns for a small home. $5,000–8,000
Victron MultiPlus-II 48/5000 — the premium inverter/charger — deepest monitoring stack and the support network installers trust. $2,300+
Chosen on merit — nobody paid to be on this list, and several of these can never earn us a penny. If a link here ever earns Grid CEO a referral fee, it will say so — disclosure.
Victron MultiPlus-II 48/5000 — the European standard inverter/charger — 230V native, deep monitoring, installer support in every country. €1,600+
Growatt SPF 5000 ES — the 230V budget all-in-one that made whole-home off-grid a four-figure project. €800–1,000
Chosen on merit — nobody paid to be on this list, and several of these can never earn us a penny. If a link here ever earns Grid CEO a referral fee, it will say so — disclosure.
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