Plumbing Vent Under Solar Panel (Important Planning)

Plumbing vents that exit on the roof of a structure can cause problems for installing solar panels, particularly if the vent is located in the optimal position for the solar panel. Is it possible to have the plumbing vent under the solar panel, or are there other options?

If you install solar panels and plumbing vents are in the way, you may have some concerns.

  • What role does a plumbing vent play?
  • Can a plumbing vent be trimmed?
  • Will installing a solar panel over a plumbing vent be a problem for the vent?
  • Will a vent under a solar panel be a problem for the panel?

Plumbing vents are usually installed according to the local building code. Depending on the relevant code, these codes may stipulate that the vent must protrude between 6 and 12-inches above the roof level. This regulation can limit the space available for solar panel installations, but some solutions are available for the problem.

Roof covered with solar panels hidden plumbing vents

Plumbing Vents And The Code

Plumbing vents are installed according to the various codes that govern the building industry. The codes can vary from region to region, depending on local conditions.

The generally prescribed height of a plumbing vent to protrude above the roof surface varies from 6-inches to 12-inches.

The intention for these heights above the roof surface for the vents is to protect the vent opening. In areas where snowfall is a common winter occurrence, the stipulated height is increased to allow the vent pipe to protrude above the snow accumulating on the roof.

In other regions where winter snow is less of a problem, a lower limit of 6-inches is required for vent pipes.

The intention for the height in both cases is to maintain the integrity of the opening of the vent pipe, which leads us to the purpose of these vents.

What Purpose Do The Plumbing Vents Serve?

The main purpose of the plumbing vents is to equalize the pressure in the plumbing system. Waste plumbing systems operate at very low pressures.

The vent system’s purpose is to restore the pressure in the system to as close to atmospheric pressure as possible. The plumbing vents supply this pressure release by opening to the atmosphere, allowing the pressure to equalize.

Thus, the opening of the vent pipe cannot be blocked. Otherwise, the system will not be able to vent adequately. This is the purpose of raising the upper end of the pipe a certain height above the roof surface to prevent the pipe from becoming blocked from debris on the roof.

Essentially, the vent pipe can be shorter if the risk of blocking the airflow is reduced, which is where our solar panel installation comes in.

See also: How to install solar panels (Detailed Step-By-Step Guide)

Can A Solar Panel Cover A Plumping Vent?

A solar panel can cover a plumbing vent. Solar panels are generally installed at the height of 5-inches above the roof. Vent pipes can be cut down to a height of 2-inches since the solar panel protects the vent opening from snow and other debris. The 3-inch gap provides sufficient space for airflow.

With solar power gaining popularity in many homes and businesses, the problem of vent pipes getting in the way of solar panels has come to the attention of the code regulators.

The heights of vent pipes were reviewed against the purpose of the height and the change in the roof dynamics with the installation of the solar panels.

Installing solar panels over plumbing vents was deemed to provide protection for the vent’s opening to allow the vent height to be lowered to accommodate the installation of the solar panel above it.

Can A Solar Panel Block A Plumbing Vent?

Solar panels installed correctly over a plumbing vent won’t block the plumbing vent. If the vent height is reduced to 2-inches above the roof and the panel is installed 5-inches above the roof, the airflow is sufficient for the vent to function to equalize pressure in the system.

If the vent height is reduced and the solar panel installed at the correct 5-inch height above the roof, the solar panel protects the vent opening from roof debris.

However, the likelihood of birds and rodents nesting under the solar panes and blocking the air vent or limiting its free access to the air to equalize pressure becomes more of a reality.

The code for these installation configurations requires that the vent pipe be terminated with an appropriate cover that allows for airflow but prevents bird and other animal nests from blocking the pipe opening.

Can A Plumbing Vent Under A Solar Panel Damage The Panel?

Plumbing vents under a solar panel will not damage the solar panel. The pressure in plumbing waste systems is very low. No high-pressure air or liquids is venting from the pipe that could cause a problem for the solar panel.

Plumbing waste systems operate at very low pressures, close to that of normal atmospheric pressure. Consequently, there is no air moving in or out of the vent pipe that could cause a problem for the solar panel.

Likewise, there are no fluids or acidic gasses the pass up the vent pipe that could damage the solar panel or its wiring.

What If The Code Does Not Allow A Plumbing Vent Under A Solar Panel?

Some locations do not allow a vent pipe to be shortened to have a solar panel installed over it. In this case, you have two options. Leave a gap in the solar panels to accommodate the vent or use a solar roof jack.

If your local legislation does not allow for the vent pipe to be shortened to accommodate your solar panel installation, then your options are limited. You can leave a gap in your solar panels to bypass the vent space, but this is often not feasible if you need to maximize the panels on your roof.

Another alternative that is allowed in some areas is the installation of a solar roof jack. A solar roof jack is an American-designed system that installs a plastic bend over the vent and re-directs it via an ABS pipe to a location on the roof out of the way of the panels.

The pipe re-directing the vent can be hidden under the solar panels. This allows for greater coverage of the roof area with solar panels without compromising the building code in your region by shortening the vent pipe.


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Elliot has 20+ years of experience in renewable technology, from conservation to efficient living. His passion is to help others achieve independent off-grid living.

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