Home›Off-Grid Systems›Floating Solar Calculator

Floating Solar Calculator

Enter your water surface area and site details — get system kW, cooling efficiency boost, evaporation savings, and payback period for floatovoltaics.

Water surface details
acres
Site & financial details
ft
$/kWh
Floating solar system estimate
110 kW on 0.50 acres
System capacity110 kW
Annual production208,780 kWh/yr
Cooling efficiency boost+8% (16,702 kWh/yr extra)
Water evaporation reduced75% (1.5 acre-ft/yr)
Annual energy savings$25,054/yr
Total system cost$203,000
ITC (30% federal credit)-$60,900
MACRS depreciation benefit-$20,300
Net cost after incentives$121,800
Payback period4.5 yrs
Link copied to clipboard

How to Use This Calculator

Enter your water surface area

Input the total water surface area available for floating solar panels in acres or hectares. Floating solar arrays typically cover 60–80% of a water body's surface — the calculator uses the full area you enter as the basis for sizing. A 0.5-acre irrigation pond can support roughly 110 kW; a 10-acre reservoir can exceed 2 MW.

Select water type and depth

Water type affects two key co-benefits: cooling efficiency (water keeps panels cooler, boosting output 5–10%) and evaporation reduction (shading water saves 65–80% of evaporation). Depth determines mooring complexity — shallow ponds use simple gravity anchors, while deep reservoirs need engineered cable systems costing 25–40% more.

Enter grid distance and electricity rate

Grid connection trenching runs about $10/ft and is often the largest site-specific variable. A remote reservoir 2,000 ft from the grid adds $20,000 in interconnection cost. Enter your commercial or agricultural electricity rate to calculate annual energy savings. MACRS 5-year depreciation and the 30% ITC are applied automatically for business installations.

The Formula

System kW = Surface Acres × 220 kW/acre Annual kWh = System kW × Peak Sun Hours × 365 × 0.80 efficiency Cooling Boost kWh = Annual kWh × Cooling Boost % (5–10%) Water Saved = Acres × 4 acre-ft/acre/yr × Evaporation Reduction % System Cost = System kW × 1000 × $/W (base $1.80 × mooring factor) + Trenching Net Cost = System Cost × (1 − 30% ITC − 10% MACRS benefit) Payback = Net Cost ÷ (Annual Savings + Cooling Savings)

The 220 kW/acre density is the industry standard for floating solar — approximately 1 MW per 4.5 acres with modern 400–550W bifacial panels on floating platforms. The cooling efficiency boost is a genuine, measured advantage: water evaporation under the panels keeps them 5–15°C cooler than ground-mounted equivalents, translating to 5–10% more energy output from the same panels.

Example

Central Valley Irrigation District — 10-acre reservoir, Phoenix

An irrigation district in Arizona has a 10-acre reservoir with medium depth (5–8 ft). The nearest grid connection is 500 ft away. They pay $0.12/kWh for pumping electricity.

Surface area10 acres
Water typeReservoir
DepthMedium (3–10 ft)
Grid distance500 ft
LocationPhoenix, AZ (6.5 PSH)

Result

System capacity2,200 kW (2.2 MW)
Annual production~4.18 million kWh/yr
Cooling boost+9% (~376,000 kWh extra)
Evaporation saved~32 acre-ft/yr ($6,400 value)
Annual savings~$502,000/yr
System cost~$4.5M
Net after ITC + MACRS~$2.7M
Payback~5.4 yrs

Floating solar on a 10-acre reservoir in the Southwest is extremely compelling. The combination of Arizona's exceptional sun, water-cooling efficiency gain, and substantial ITC/MACRS incentives delivers a sub-6-year payback — with 20+ years of additional production. The evaporation savings are a real secondary benefit for water-scarce regions.

FAQ

Floating solar (floatovoltaics) typically costs $1.50–2.50/W installed, about 10–25% more than comparable ground-mount systems ($1.20–2.00/W). The premium covers floating platforms, anchoring systems, waterproof wiring, and specialized installation. However, the premium is often offset by: (1) no land cost — water bodies are otherwise unproductive, (2) 5–10% higher energy output from water cooling, (3) evaporation reduction value in water-scarce regions, and (4) elimination of vegetation management costs.
One acre of floating solar produces roughly 220 kW of capacity, generating 300,000–500,000 kWh per year depending on location. In Phoenix (6.5 PSH), 1 acre generates about 418,000 kWh/yr. In Seattle (3.6 PSH), the same acre generates about 231,000 kWh/yr. The water-cooling effect adds an additional 5–10% on top of standard ground-mount production estimates.
Yes — studies consistently show 60–80% evaporation reduction under floating solar panels. A 2021 study of California reservoirs found floating solar covering 30% of reservoir surface reduced evaporation by over 70%. For water-scarce regions, this is a major co-benefit. One acre of open water evaporates approximately 4 acre-feet per year (1.3 million gallons). At $200/acre-foot for agricultural water, a 10-acre array saves $6,400/year in water alone — and far more in drought years.
Floating solar permitting is more complex than ground-mount. Typical requirements include: (1) Army Corps of Engineers permit if the water body is navigable or federally regulated, (2) State environmental review for impacts on aquatic ecosystems, (3) Local building permit for electrical installation, (4) Utility interconnection agreement for grid-tied systems. Private irrigation ponds and industrial wastewater ponds typically face the fewest regulatory hurdles. Budget 6–18 months for permitting on larger reservoir projects.
Yes — floating solar is fully eligible for the federal Investment Tax Credit (30% ITC) under the Inflation Reduction Act when installed for business or agricultural use. The system also qualifies for MACRS 5-year accelerated depreciation, which provides an additional 8–12% NPV benefit depending on tax rate. Combined, ITC + MACRS can offset 38–42% of total installed cost, dramatically improving project economics. Consult a tax professional for your specific situation.

Related Calculators

🌿 Agrivoltaics Calculator
Dual-use solar panels over crops — shade, yield, and energy output.
☀ Solar Farm Calculator
Large-scale ground-mount solar farm sizing and ROI.
💰 Solar Tax Credit Calculator
Calculate your federal ITC and MACRS depreciation benefit.
📈 Solar Savings Calculator
Annual bill savings and payback period for any solar system.

Embed This Calculator

Free to embed on your website. Just copy this code:

<iframe src="https://solarsizecalculator.com/floating-solar-calculator"
  width="100%" height="700" frameborder="0"
  title="Floating Solar Calculator"></iframe>