Solar & battery
Solar Array Size Calculator
Array layout: panel count, rows, string configuration and the roof it occupies.
Result
String length is limited by the inverter's maximum input voltage at the coldest expected temperature, because panel voltage rises as it gets colder. A string sized on a summer figure can exceed the inverter's limit on the first frosty morning. Array dimensions here exclude module gaps, rail overhang and the fire setbacks code requires.
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About this calculator
How many panels can go in a string?
Whatever keeps the open-circuit voltage below the inverter maximum at your record low temperature. It is usually between 8 and 14 for residential inverters, and the cold-weather check is the one that matters.
Portrait or landscape?
Whatever fits the roof plane best with fewest wasted areas. Landscape often suits wide shallow roofs, portrait suits tall narrow ones, and the racking cost differs slightly between them.
The formula
panels = system watts / panel watts; rows = panels / panels per row
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