Why vent relocation is usually the smallest obstruction cost you'll face
What relocating a vent typically runs
Relocating two plumbing stack vents a medium distance typically costs around 810 dollars total, while a single attic exhaust vent moved a short distance runs closer to 275 dollars. Plumbing vents cost more due to the pipe extension work involved, making vent type the biggest single factor in the estimate. Cross-check this against shading loss estimator before deciding.
Why plumbing vents cost more than attic or exhaust vents
Plumbing stack vents connect directly to the home's drain waste vent system, so relocating one means extending or rerouting actual plumbing pipe through the attic space in addition to creating a new roof penetration. Attic exhaust vents and bathroom exhaust fan vents typically only need ducting adjustment, or in some cases no connection work at all beyond the roof opening itself, which keeps their relocation cost lower. A related check is the roof azimuth orientation calculator, which looks at the same question from the system sizing side.
Why distance matters more than it might seem
Moving a vent a short distance within the same roof plane keeps pipe or duct extension work minimal, while relocating it far across the roof, or to an entirely different roof plane, requires substantially more extension material and labor. Checking whether a nearby, less invasive relocation spot would still clear your solar layout is worth doing before committing to the most distant option. Check the residential roofing code if you want the authoritative numbers behind this.
Why bundling multiple vents saves money
Since much of the cost in any relocation job comes from crew setup, scaffolding or ladder access, and mobilization, tackling several vents in the same visit spreads that fixed cost across all of them rather than paying it repeatedly. If your solar layout requires moving more than one vent, scheduling them together is almost always the more cost-effective approach compared to separate visits. The chimney removal cost estimator and skylight relocation cost estimator cover other common roof obstructions that follow a similar relocation logic, and PNNL's overview of roofing components and performance covers the roofing side of coordinating this kind of work.
Relocated vents still need to meet the residential roofing code's clearance and placement requirements, so the shading loss estimator and the roof azimuth orientation calculator are worth a look once relocation is resolved and you're finalizing your panel layout.