Price per watt
By Priya Nair · Last reviewed Total system price divided by output capacity — the standard unit for comparing solar hardware value. Meaningful only within a configuration class: comparing a bare inverter, a complete kit and a battery system on price per watt produces nonsense, because the denominator buys different things.
Why it matters
Within complete grid-tied kits, price per watt cleanly exposes the transatlantic gap (roughly $1.60-2.50/W in the US against €0.50-1.50/W in Europe) and separates fair pricing from opportunism. WattRank rankings never compare the metric across classes — and buyers shouldn't either.