Why winter output is the number worth arguing about

Annual yield hides the number that decides whether a commercial array carries its load. Winter output is the one to argue about.

Annual production is the number in every proposal. It is also the number least likely to match how a building actually uses power.

Why the annual figure misleads

A warehouse with a refrigerated night shift draws steadily through December. An array sized on annual yield can be 30% short in the month the demand charge is set, and nobody notices until the first winter bill.

What we model instead

Month-by-month production against month-by-month load, not a single annual total.
December and January output at the site's real tilt and shading, not a regional average.
Demand-charge months called out separately in every proposal.

On flat commercial roofs a shallower tilt usually wins on annual yield and loses in winter. Which one is right depends entirely on the load, and that is a conversation worth having before the racking is ordered.