How Real Build Cost Is Calculated
Real build cost is the advertised price of a solar kit plus any required parts the kit leaves out. It answers one question: how much will you actually spend to turn this box into a working off-grid system? Below is the exact formula, the included-component rules, and three worked examples drawn from kits in the dataset.
The Formula
Only required components count toward real build cost. Optional upgrades — Bluetooth monitoring, wall-mount brackets, third-party adapters — are surfaced separately and do not inflate the total.
Included-Component Rules
Every kit is scored against seven component roles. A role is marked "included" only if the kit ships a working instance of that role — not a coupon, not a compatibility claim, not a cross-sell.
- Solar panels — rigid or folding, with the wattage the kit advertises.
- Charge controller — MPPT or PWM, sized to the panel array.
- Battery bank — usable Wh at the listed chemistry and voltage.
- Inverter — pure sine for AC appliances, modified sine only when the kit specifies.
- Wiring & cables — battery cables, PV cables, fuses, breakers.
- Mounting hardware — Z-brackets, tilt mounts, rooftop rails, or ground stands.
- Monitoring — LCD display, shunt, Bluetooth gauge, or integrated app.
Missing-Part Estimation
Estimates are anchored to the mid-market price of a compatible component — matching voltage, chemistry, and capacity — from major retailers. We deliberately avoid the cheapest listing on each marketplace; cheap components that underperform would understate real cost and mislead buyers.
Three Worked Examples
A $289 'starter kit' without storage or inversion cannot power a single AC appliance on its own.
Missing battery + inverter nearly doubles the sticker price before the system produces a single watt of AC power.
A fully complete kit matches advertised price — the metric rewards transparent bundling.
What Real Build Cost Is Not
- Not a quote — your specific hardware choices will vary.
- Not a total installed cost — excludes permits, labor, and sales tax.
- Not a bias against minimal kits — a panel-only kit is fine if you already own the rest.
The point of real build cost is comparability. Every kit on this site is scored by the same formula, against the same seven roles, using the same component price reference. Two kits advertised at $500 can have a $900 difference in what it takes to power anything with them. The metric surfaces that difference.