Farm Solar Panel Calculator
Size a grid-tied solar PV system for your farmhouse, barn or irrigation load. Estimate system capacity, panel count, roof/ground area, annual generation, annual bill savings and payback period.
Results
How to Use This Calculator
Estimate your average daily kWh use from a year of bills, look up peak sun hours for your region (typically 4-6 h/day), choose a common panel wattage (350-450 W), apply 75-85% system efficiency losses, and enter local electricity price, installed cost per watt, and any subsidy. Click Calculate.
About This Tool
About
Applicability: Designed for farm equipment and energy planning in North American and European contexts.
How the Calculation Works
System kW = Daily kWh ÷ (Peak Sun Hours × Efficiency). Panels = System kW × 1000 ÷ Panel Wattage. Area ≈ panels × 2 m². Annual generation = Daily kWh × 365. Annual savings = annual kWh × price. Payback = (gross cost − subsidy) ÷ annual savings. For 40 kWh/day, 5 h sun, 80% eff, 400 W panels, $0.15/kWh, $1.60/W, $2,000 subsidy: system = 40/(5×0.8) = 10 kW, 25 panels, 50 m², 14,600 kWh/yr, $2,190/yr savings, gross $16,000, net $14,000, payback ~6.4 yr. Common mistakes: using peak sun hours too high, ignoring shading/soiling losses, and forgetting that battery storage adds 30-50% to cost.
Reviewed by Agricalc Editorial Team — Agricultural engineers and agronomists with 10+ years of field experience. Our team verifies every calculator formula against peer-reviewed extension publications. For site-specific advice, consult your local agronomist.
References
- NREL — Solar Resource and PVWatts
- US DOE Office of Energy Efficiency — Solar
- USDA Rural Energy for America (REAP)
Frequently Asked Questions
How many peak sun hours does my region get?
Most of the contiguous US averages 4.5-5.5 peak sun hours/day; the Southwest 6-7, the Pacific Northwest 3.5-4. Use a NASA PVWatts or NREL map for your specific latitude and orientation.
How much roof or land area do I need?
Roughly 2 m² per panel and 7-10 m² per installed kW. A 10 kW system needs ~50-70 m². Ensure south-facing orientation (Northern Hemisphere), minimal shading, and adequate structural load for rooftop mounts.
What payback period is good for farm solar?
6-10 years is typical in the US after subsidies, with system life of 25-30 years. Shorter payback (4-6 yr) in high-insolation, high-electricity-price areas. Compare the lifetime savings (20+ years free power) against the upfront cost and financing.
Should I add battery storage?
If you are off-grid or need backup, yes. If you have net metering, grid-tied without batteries is usually cheaper and simpler. Batteries add 30-50% to the installed cost but capture self-consumption of midday surplus.
What is agrivoltaics?
Agrivoltaics co-locates solar panels with crop or livestock production: elevated panels let forage, vegetables or grazing continue underneath, diversifying income from the same land. It is growing but requires careful panel spacing and crop choice.
