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Solar Panel Area

Free Solar Panel Area calculator with clear step-by-step results.

About Solar Panel Area

Panel count comes from target capacity divided by panel rating, rounded up because you cannot fit a partial module. Multiplying by panel area gives the glass area, and the spacing factor adds the row gaps, edge setbacks and access walkways that any real installation needs.

Formulas

Panel count

Panels = ceil(target kWp x 1000 / panel watts)

Roof area

Area = panels x panel length x panel width x row spacing factor

Worked example

With the default values below, Solar Panel Area returns Roof area required of 32.17. Change any input above and every figure here is recalculated in your browser.

Inputs used

Target system sizeminimum 0.1 kWp
6 kWp
Panel ratingminimum 50 W
430 W
Panel lengthminimum 300 mm
1,762 mm
Panel widthminimum 300 mm
1,134 mm
Row spacing and access factoraccepts 1–3 x
1.15 x

Results

Roof area required
32.17 m2
Panels needed
14 panels
Area covered by panels alone
27.97 m2
Power density of the installation
0.1865 kWp/m2

Step by step

  1. 1Values used
  2. 2Panel count
  3. 3Roof area
  4. 4Roof area required= 32.17 m2
  5. 5Panels needed= 14 panels
  6. 6Area covered by panels alone= 27.97 m2
  7. 7Power density of the installation= 0.1865 kWp/m2

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Roof-mounted solar affects structural loading, weathertightness and fire access, and is subject to permitting and grid connection approval. Have the design assessed by a qualified installer.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Roof-mounted solar affects structural loading, weathertightness and fire access, and is subject to permitting and grid connection approval. Have the design assessed by a qualified installer.

Frequently Asked Questions

What spacing factor should I use?

Around 1.05-1.15 for a flush-mounted pitched roof, and 1.5-2.5 for a flat roof with tilted rows where inter-row shading must be avoided.

Do I need fire setbacks?

Many jurisdictions require clear pathways along ridges and edges for firefighter access, which can reduce usable roof area substantially. Check local requirements before committing to a layout.

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