Installing solar panels on your roof is an excellent long-term investment — but before any panels go up, your utility company, local building department, and sometimes your HOA may require a PE-stamped structural engineering letter or full permit drawings. Here's what that means, what's included, and why it protects you.
Why Do Utilities and Building Departments Require a Structural Letter?
Solar panels add significant weight and wind load to a roof structure. A typical residential solar array adds 3–5 lbs per square foot of dead load, plus increased wind uplift forces. If your roof framing was not designed for this additional load — or if the racking attachment points are not properly spaced — you risk structural damage over time.
Utilities and building departments require a PE-stamped letter to confirm that a licensed engineer has verified the existing roof structure can safely support the proposed solar system.
What Does a Solar Structural Engineering Letter Include?
- Assessment of existing roof framing — rafter or truss type, size, spacing, span
- Structural analysis of dead load capacity and wind uplift resistance
- Verification that the proposed racking system attachment points are adequate
- Maximum allowable panel weight and array configuration
- PE stamp and signature — accepted by utilities and building departments in PA, NY, DE & TX
Did you know? Most utility interconnection applications in Pennsylvania and New York require a structural engineer's letter as part of the approval package. Without it, your solar installer's permit application will be rejected, delaying your installation by weeks.
Do I Need a Full Permit Package or Just a Letter?
It depends on your municipality. Some townships require only a structural letter; others require full permit drawings showing the roof plan, panel layout, attachment details, and load calculations. NEC Solutions provides both — we'll confirm what your specific jurisdiction requires and prepare the appropriate documents.
How Quickly Can I Get My Solar Structural Letter?
Solar structural letters are one of our fastest deliverables. Most are completed within 3–5 business days once we receive the system design specifications from your solar installer. Many of our solar clients are installers and developers who rely on us for recurring project support across Pennsylvania, New York, Delaware, and Texas.
What Information Does the Engineer Need?
- Property address and year home was built
- Roof type (shingle, metal, tile) and approximate pitch
- Solar system specs from your installer — number of panels, weight, racking system
- Photos of the attic/roof framing if available