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Ground Mount Solar Calculator

Enter your land area and location — get optimal tilt angle, row spacing, panels that fit, and annual production estimate.

Site and system parameters
sq ft
kW
W
Ground mount system design
3.6 kW system on 500 sq ft
Optimal tilt angle29°
Row spacing (ft)10.5 ft
Ground coverage ratio40%
Area per panel55.3 sq ft
Panels that fit9
Land needed for target719 sq ft
Annual production5,676 kWh/yr
Est. system cost$10,620
Est. trench run61 ft
Your land fits 9 panels (3.6 kW). To reach 5 kW you need 719 sq ft. Consider higher-wattage panels or a smaller target.
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How to Use This Calculator

Enter your site details

Enter the available flat or gently sloping land area in square feet. A gentle slope (5-15°) is fine — racking systems can compensate. Then select your location, which determines latitude for tilt angle calculation and peak sun hours for production estimates.

Set your target and panel specs

Enter your target system size in kW and the wattage of the panels you plan to use. The calculator will check whether your land area can fit the target system and tell you the actual achievable size. If you're flexible, use 400W panels as a starting point — 450W+ bifacial panels are increasingly cost-competitive and reduce land needed.

Choose orientation

True South is optimal for maximum annual production in the northern hemisphere. East-West orientation with bifacial panels reduces land use (higher ground coverage ratio) and produces a flatter daily production curve — useful for commercial systems managing demand charges.

Interpret the results

The key outputs are: optimal tilt angle (to maximize annual yield), row spacing (to prevent inter-row shading at winter solstice), ground coverage ratio (panel area / total land used), land needed vs. available, annual production estimate, system cost, and a trenching estimate for underground conduit from the array to your electrical panel.

The Formula

Optimal Tilt = Latitude × 0.87 (fixed-tilt rule of thumb) Sun Altitude at Winter Solstice = 90° − Latitude − 23.5° Panel Shadow Length = Panel Height ÷ tan(Sun Altitude) Row Spacing = Panel Base Extension + Panel Shadow Length Ground Coverage Ratio (GCR) = Panel Width ÷ Row Pitch Area per Panel = Panel Length × Row Pitch Panels That Fit = Available Area ÷ Area per Panel Annual kWh = System kW × PSH × 365 × 0.80 Cost = System Watts × $2.95/W (roof base $2.80 + $0.15 ground premium)

Row spacing is calculated to prevent inter-row shading at the worst case — the winter solstice noon sun angle. This ensures year-round full production. The ground coverage ratio (GCR) of 0.40 is standard for south-facing fixed-tilt arrays — meaning 40% of the land directly under the array is covered by panels, and 60% is row spacing.

Example

Tom — 10kW ground mount on his Kansas farm property

Tom has a 2,000 sq ft section of flat pasture near his home in Kansas City (39.1°N). He wants to install a 10kW system using 400W panels facing true south.

Available land2,000 sq ft
LocationKansas City, MO (39.1°N, 4.9 PSH)
Target system10 kW
Panel type400W, true south orientation

Result

Optimal tilt34°
Row spacing~12.5 ft
Area per panel~55 sq ft (incl. spacing)
Panels that fit36 panels (14.4 kW) — land sufficient
Land needed for 10kW~1,375 sq ft
Annual production~14,350 kWh/yr
Est. system cost~$29,500

Tom's 2,000 sq ft can fit 14.4 kW — well above his 10 kW target, giving him flexibility to expand later. The 34° tilt angle maximizes annual production at his latitude. Row spacing of 12.5 ft ensures no inter-row shading even at winter solstice. Trenching conduit to his home adds roughly $1,500-2,000 to the total project cost.

FAQ

Ground mount systems typically cost $0.10-0.25/W more than equivalent roof mounts due to additional racking, posts, concrete footings, and trenching for underground conduit. A 10kW ground mount might cost $29,000-32,000 vs. $26,000-28,000 for a roof mount. However, ground mounts have advantages: optimal tilt angle (which roof mounts often can't achieve), easier access for cleaning, no roof penetrations, and ability to expand the array later without worrying about roof space.
As a rule of thumb, fixed-tilt ground mount systems at mid-latitudes (35-45°N) need roughly 100-150 sq ft per kW when accounting for row spacing. In the South (25-35°N) where rows can be closer together, it drops to 80-120 sq ft/kW. At northern latitudes (45°N+), the sun is lower so rows need more spacing — expect 150-200 sq ft/kW. This calculator computes the exact figure for your specific latitude.
Row spacing is calculated to prevent shading at the worst-case sun angle — typically the winter solstice at noon. The formula: Row Spacing = Panel Height × (cos(tilt) + sin(tilt) / tan(sun altitude at winter solstice)). Sun altitude at winter solstice = 90° - latitude - 23.5°. For Dallas (33°N) at a 29° tilt: the sun altitude is 33.5°, giving row spacing of about 10 feet. For Seattle (48°N) at a 42° tilt: sun altitude is only 18.5°, requiring about 17 feet of spacing.
Yes, almost always. Ground mount solar requires building permits (structural engineering for footings and racking), electrical permits (for the DC/AC wiring and utility interconnection), and in rural areas potentially zoning approval if the system is classified as an accessory structure. Some areas also require setbacks from property lines (typically 3-5 feet minimum). A licensed electrician and solar contractor will handle the permits, but you should budget 6-12 weeks for the permitting process.
Single-axis trackers (which follow the sun east to west) increase annual production by 20-30% compared to fixed-tilt arrays. Dual-axis trackers add another 5-10%. But trackers cost $0.20-0.40/W more, require maintenance (motors, sensors, hydraulics), and are impractical for small systems under 50kW. For residential systems (3-25kW), fixed tilt almost always delivers better economics. Trackers start making financial sense for commercial or utility-scale systems where the extra production can be sold to the grid.

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