Roof Solar Panel Mount Weight & Wind Load Calculator

Calculator Inputs

Enter project assumptions below. The page uses one main column, while the calculator fields switch to 3, 2, and 1 columns by screen size.

Unit system

Number of panels

Panel length (m)

Panel width (m)

Panel weight each (kg)

Mount hardware weight each (kg)

Ballast or attachment weight each (kg)

Panel tilt from horizontal (°)

Roof slope from horizontal (°)

Mean roof height (m)

Basic wind speed (m/s)

Exposure coefficient Kz

Topographic factor Kzt

Directionality factor Kd

Pressure coefficient GCp

Roof zone multiplier

Safety factor on uplift

Allowable roof dead load (kPa)

Example Data Table

This sample helps you compare a realistic roof-mounted solar scenario before using your own project values.

Scenario	Panels	Panel Size	Wind Speed	Total Installed Mass	Dead Load Intensity	Vertical Uplift	Extra Ballast
Metric sample rooftop array	14	1.95 m × 1.13 m	42 m/s	756.00 kg	0.25 kPa	13.53 kN	1,312.95 kg

Formula Used

1. Total panel area
Area = panel length × panel width × panel count

2. Total installed dead load
Dead load = (panel + mount + ballast) × panel count

3. Velocity pressure
qz = 0.613 × Kz × Kzt × Kd × V²

4. Design pressure
Design pressure = qz × GCp × roof zone multiplier

5. Normal wind force
Wind force = design pressure × total panel area

6. Vertical uplift
Uplift = normal wind force × sin(panel tilt)

7. Horizontal shear
Shear = normal wind force × cos(panel tilt)

8. Extra ballast or anchor demand
Demand = max(0, uplift × safety factor − dead load)

This calculator is for preliminary screening and layout comparison. Final design should be checked against local code, manufacturer data, and stamped structural calculations.

How to Use This Calculator

Choose metric or imperial units.
Enter panel count, module dimensions, module weight, mounting weight, and ballast or attachment weight.
Set panel tilt, roof slope, roof height, and basic wind speed.
Adjust Kz, Kzt, Kd, GCp, and roof zone multiplier to match your project assumptions.
Enter a safety factor and your allowable roof load limit.
Click Calculate Loads to display results above the form.
Review uplift, shear, dead load intensity, and extra ballast or anchor demand.
Export the result table using CSV or PDF if needed.

FAQs

1) What does this calculator estimate?

It estimates installed mount weight, roof loading intensity, wind pressure, uplift, horizontal shear, downslope gravity, and extra ballast or anchor demand from your chosen assumptions.

2) Does this replace structural engineering review?

No. It is a screening calculator for planning and budgeting. Final attachment layout, connection design, code compliance, and safety checks should come from a qualified structural engineer.

3) Why include a roof zone multiplier?

Roof edges and corners usually see stronger localized suction. The multiplier lets you raise pressure demand when your array sits outside the central roof zone.

4) How does roof slope affect the result?

Roof slope adds a downslope gravity component. That helps you review sliding demand on attachments, rails, or friction-based ballast layouts.

5) What should I enter for ballast or attachment weight?

Enter the per-panel equivalent weight from your rack layout, ballast block plan, or attachment hardware estimate. Use conservative numbers when details are still changing.

6) Can I use this for flush-mount and tilted arrays?

Yes. For flush-mount systems, panel tilt often matches roof slope. For tilted racks on flat roofs, enter the actual rack tilt and roof slope separately.

7) Why compare dead load with uplift demand?

Wind uplift can overcome the installed weight of the array. Comparing both helps show whether ballast alone may work or whether anchors are still necessary.

8) Why is allowable roof load included?

Even when uplift resistance looks acceptable, the roof may still be overloaded. The allowable roof load check helps flag excessive dead-load intensity early.