By Meraj Uddin Provat · Last reviewed May 23, 2026 · Editorial Standards
Solar Panel Sizing Calculator
How many panels do you actually need? Size a system from your real electricity use, your region's sun, and a target offset.
Sizing estimate using regional peak-sun-hours and a standard 0.80 system derate (inverter, wiring, soiling, temperature losses). Actual production varies with roof orientation, shade, and weather. The 30% federal Residential Clean Energy Credit (Section 25D) ended for systems placed in service after December 31, 2025 under the One Big Beautiful Bill Act. Systems bought outright in 2026 receive no federal credit. A solar lease or power purchase agreement can still capture the 30% credit under Section 48E — the installer claims it and passes the value on through lower payments — for systems placed in service by the end of 2027. Not tax or financial advice.