Why roof direction and shading matter more than you think

South-facing roofs harvest the most annual energy in the northern hemisphere, but east-west layouts now perform within ten to fifteen percent and pair beautifully with morning and evening usage. North faces are the only genuinely poor real estate — and good designs simply avoid them.

On a traditional string inverter, shading one panel can drag down the whole string, the way a kink slows an entire hose. A chimney shadow crossing two panels each afternoon can cost far more production than its size implies. This is why shade analysis matters more than roof size.

Panel-level electronics let each module produce independently, so a partially shaded roof no longer disqualifies a home. The design answer is placement first — keep panels out of predictable shadows — and hardware second, using optimizers to rescue the areas that remain.

Professional designs use satellite lidar and on-roof measurements to model sun hours across the year, panel by panel. If a quote shows one production number with no shade study behind it, the number is a guess — and payback math built on guesses fails in the direction you'd expect.