Region and units US ($, sq ft) UK (£, m²) Switching region reloads that region’s places, prices and units. Somewhere else? Pick “Enter sun hours” and type your own. Your numbers stay in this browser only. Electricity use per month (kWh) kWh Starting value: U.S. Energy Information Administration, FAQ "How much electricity does an American home use?", read 2026-09-20; edit it. Your bill shows the real figure; a yearly total divided by 12 works too. State Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware District of Columbia Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming Enter sun hours (anywhere) Peak sun hours per day h Starting value: Unbound Solar, "Peak Sun Hours by US State", table built from NREL's PVWatts data; "A peak sun hour is one hour of sunlight at an average intensity of 1,000 watts per square meter", read 2026-09-20; edit it.
Panel wattage (W) W Starting value: A 400 W panel is the middle of the Trina Vertex TSM-DE09 range and the common residential class in 2026; Trina Solar, Vertex TSM-DE09 data sheet, product range 390-405 W, read 2026-09-20; edit it. System losses (%) % Starting value: NREL, PVWatts Version 5 Manual, section 11 System Losses, Table 6, read 2026-09-20; edit it. Share of use to cover (%) % 100% sizes the system to produce a year's use over a year. A choice, not a published figure.
Result
Panels of 400 W 17
System size needed 6.48 kW
Installed size (whole panels) 6.8 kW
Roof area for the panels 352 sq ft
Electricity use per day 29.6 kWh
Production per year (installed size) 11,313 kWh
Share of the yearly use covered 105% Sized for Texas at 5.3 peak sun hours a day and 14% losses. Roof area counts the panels only (1.922 m² each, Trina Solar), not the gaps, walkways or the unusable edges of the roof. Estimates from published averages (NREL, EIA, Ofgem, industry cost surveys), each with its source and date: an installer's site survey and shading analysis replace them. Not financial advice.