The numbers behind the panel count
Five short reads, one per load-bearing concept. Each exists because a real question keeps arriving with a wrong number attached, and each hands you the right one with its sources showing.
Peak sun hoursWhat a peak sun hour measures (1 kWh/m²), why Phoenix gets 6.6 and Seattle 3.6, and how the figure turns panel watts into daily kWh.
Real panel outputRated watts are a lab number. Here is the itemized 23% between STC and your meter: soiling, wiring, mismatch, inverter conversion, and heat.
Read your billThe monthly kWh figure on your electric bill drives the whole solar decision. Where it hides, why one month lies, and how to build the 12-month average.
Roof factorsSouth beats west by ~15%, pitch matters less than everyone thinks, and one shaded chimney line can outweigh both. Percentages for each.
Off-grid sizingGrid-tied sizes to the annual average; off-grid sizes to the worst week of December. Why the same house needs a 2x bigger array off-grid, plus battery math.