Energy mass balanceCostingSolar
Floating PV plant on water body
Floating solar on a reservoir: mooring-driven CAPEX premium, net water effect on yield, water surface occupied and LCOE against the same plant on land.
Levelized cost
Levelized cost of electricity (LCOE)
Lifetime cost divided by discounted lifetime generation, at the plant gate
LCOE component: CAPEX
Turnkey installed cost spread over discounted lifetime generation
LCOE component: fixed O&M
Annual O&M annuitized over the lifetime, per discounted MWh
Reference LCOE of the same plant on land
Same site, same finance, ground-mounted CAPEX and ground-mounted yield
LCOE premium of floating over ground-mounted
What the water costs you, once the cooling gain is netted against the tilt penalty
Real discount rate applied to both the costs and the generated energy. World Bank runs FPV at 6/8/10%; NREL uses 5.1% real.
Economic lifetime used to levelize. HDPE floats are credited with 20-25 years; NREL and Fraunhofer ISE model PV over 30.
Annual performance loss. SERIS measured -0.5%/yr to -0.7%/yr on a large floating test bed, in line with nearby rooftop PV.
Log in to view this sensitivity chart.
Log in to view this sensitivity chart.
Floating CAPEX premium
Turnkey installed cost of an equivalent ground-mounted plant at this site. The floating premium is built on top of it, poste by poste.
Annual variation of the water level. It drives the mooring complexity and therefore the float-and-anchor cost, up to the 10 m saturation point of the NREL benchmark site.
Floats, anchoring and mooring, per kWp
Driven by the drawdown range and by plant size, the two things that move this line
Floating CAPEX premium per kWp
The three cost lines that differ from a ground-mounted plant, net of the racking credit
Floating plant CAPEX
Turnkey installed cost per kWp: ground-mounted reference plus the floating build-up
Floating CAPEX premium
Where this plant sits inside the 10-25% band the literature reports
Total installed CAPEX
Turnkey EPC scope, before any project-level indirects or contingency
CAPEX line: floats, anchoring and mooring
The single largest line that a ground-mounted plant does not carry
CAPEX line: marinised balance of plant
DC cabling with extra insulation and shielding, floating combiner boxes, monitoring
Annualized CAPEX
Installed CAPEX converted to an equivalent constant annual payment
Log in to view this sensitivity chart.
Log in to view this sensitivity chart.
Production and the water effect
Nameplate DC capacity of the floating array. Drives the water surface, the CAPEX and the annual generation.
Annual yield a conventional ground-mounted plant would deliver at this site. The floating tilt penalty and the cooling gain are applied on top of it.
Yield lost because floats impose a lower tilt angle than a ground racking system. NREL benchmarks 5%.
Performance-ratio uplift from the cooler module temperature over water. World Bank: +5% conservative, +10% optimistic; NREL/Dorenkamper: +3% (Netherlands) to +6% (Singapore).
Floating specific yield
Ground-mounted yield after the tilt penalty and the water-cooling gain
Net effect of being on water
Cooling gain minus tilt penalty; positive only when the cooling gain outweighs the flatter array
Capacity factor
Share of 8760 hours the plant would need at nameplate to deliver the same energy
Full-load equivalent hours
Annual generation expressed as hours at nameplate DC power
Annual net generation
Year-one AC energy delivered at the plant gate
Log in to view this sensitivity chart.
Log in to view this sensitivity chart.
Water body footprint
Reservoir surface covered per kWp installed. 10 m2/kWp = the 100 Wp/m2 area factor used in the World Bank global potential; Cirata (200 MWp on 225 ha) is 11.25.
Water surface occupied
Reservoir surface covered by the array, not a land footprint
Water surface intensity of the energy
Square metres of reservoir per MWh delivered each year
Log in to view this sensitivity chart.
Operating cost
Annual fixed O&M per kWp: cleaning, mooring inspection, insurance, monitoring. No water-body lease is included.
Annual fixed O&M
Cleaning, mooring inspection, insurance and monitoring; no water-body lease
About
Calculator context
About
Calculator context
A floating photovoltaic plant is not a ground-mounted plant that happens to be wet. Three things move: the cost of holding the array on the water, the yield of a flatter array cooled by the water underneath it, and the resource itself, which is reservoir surface rather than land.
The CAPEX here is built as a delta on a ground-mounted reference you enter for your own market, poste by poste, from the World Bank cost comparison of a 50 MWp floating plant against its ground-mounted twin: floats, anchoring and mooring replace the racking, the balance of plant is marinised, and design and commissioning cost more. Modules and inverters are identical in the source table, so they are never re-modelled. The mooring line is the one that actually moves: it is interpolated on the drawdown range of your water body, between the calm-reservoir case and the complex-mooring case, and it falls with plant size along a scale law fitted on four NREL float unit-cost points. That exponent is negative because it applies to a specific cost in $/Wp; the equivalent exponent on the total is 0.778.
On the yield side the calculator refuses the marketing shortcut. Floating does buy you a cooling gain, but it also imposes a lower tilt angle. NREL measures a floating array 5% below ground-mount before cooling and adds back 3%, for a net loss of 2%; the World Bank retains +5% to +10% on the performance ratio. Both knobs are exposed and the net effect is reported as its own number, which at the defaults is -0.25%: essentially neutral. A promoter who claims +10% because the plant floats, without deducting the tilt penalty, is five points optimistic.
At the defaults (50 MW, 1200 kWh/kWp ground yield, 5 m drawdown, 700 EUR/kWp ground reference, 25 years, 6% real) the plant costs 834 EUR/kWp installed, a 19.1% premium over the ground reference, between the World Bank's +17.7% at 50 MWp and NREL's +25% at 10 MWdc. It covers 50 ha of water, delivers 59 850 MWh a year at a 13.7% capacity factor, and levelizes at 68.6 EUR/MWh against 59.3 EUR/MWh for the same plant on land, a 15.7% premium. Costs and energy are discounted at the same rate and the generation is degraded year on year.
Out of scope, deliberately: water-body lease or concession fees, taxes and tax credits, grid connection beyond the plant gate, trackers, bifacial rear-side gain, hybrid operation with a hydropower plant, evaporation savings, residual value and decommissioning.
Model
74 variables — inputs, calculations and outputs, with their dependencies.
Model
74 variables — inputs, calculations and outputs, with their dependencies.
| Variable | Value | Unit | Depends on |
|---|---|---|---|
| 50 | MW | — | |
| 1200 | kWh/kWp/year | — | |
| 5 | % | — | |
| 5 | % | — | |
| 10 | m2/kWp | — | |
| 5 | m | — | |
| 700 | EUR/kWp | — | |
| 13.3 | EUR/kWp/year | — | |
| 0.5 | %/year | — | |
| 25 | years | — | |
| 0.06 | ratio | — |
| Variable | Formula | Unit | Depends on |
|---|---|---|---|
if((<=0)+(<=0)+(<0)+(>)+(<0)+(>)+(<=0)+(<0)+(<=0)+(<0)+(<0)+(>)+(<=0)+(<0)>0,1,0) | bool | ||
* | kWp | ||
-* | ratio | ||
+* | ratio | ||
* | ratio | ||
/max(,) | ratio | ||
* | m2 | ||
min(/max(,),) | ratio | ||
+*(-) | USD/Wp | ||
(/max(,))^ | ratio | ||
* | USD/Wp | ||
*/max(,) | EUR/kWp | ||
*/max(,) | EUR/kWp | ||
*/max(,) | EUR/kWp | ||
+ | EUR/kWp | ||
if(<,/max(,),(*(+)^)/max((+)^-,)) | ratio | ||
/max(,) | years | ||
(-*)/max(+,) | ratio | ||
(/max(+,))*(-^)/max(-,) | years | ||
* | MWh | ||
* | MWh/year | ||
* | EUR | ||
* | MWh |
| Variable | Formula | Unit | Depends on |
|---|---|---|---|
(-)* | % | ||
* | kWh/kWp/year | ||
* | h/year | ||
*/max(,) | % | ||
* | MWh/year | ||
/max(,) | ha | ||
/max(,) | m2/MWh | ||
*/max(,) | EUR/kWp | ||
-++ | EUR/kWp | ||
clamp(,,) | EUR/kWp | ||
*(-)/max(,) | % | ||
* | EUR | ||
* | EUR | ||
* | EUR | ||
* | EUR/year | ||
* | EUR/year | ||
/max(,) | EUR/MWh | ||
*/max(,) | EUR/MWh | ||
+ | EUR/MWh | ||
(+*)/max(,) | EUR/MWh | ||
*(-)/max(,) | % |
Assumptions
41 assumptions used in the calculations
Assumptions
41 assumptions used in the calculations
Guards every division and every clamp lower bound against a zero denominator.
Market range Not applicable (numerical parameter).
0.000001Numerical stability constant.Neutral element used to build the yield factors and the CRF without any inline literal.
Market range Exact.
1DSL convention: no magic number inside an expression.Converts a ratio into the percent convention used by every percent-labelled output.
Market range Exact.
100Unit convention: percents are carried 0-100, never as 0-1 fractions.Converts a percent input back to a fraction before it multiplies anything.
Market range Exact.
0.01Unit convention.Converts the nameplate capacity from MW to kWp, the unit every specific cost is quoted in.
Market range Exact.
1000kW/MWSI unit conversion.Converts the $/Wp line items of the World Bank cost table into $/kWp.
Market range Exact.
1000Wp/kWpSI unit conversion.Converts the occupied water surface into hectares, the unit reservoir operators use.
Market range Exact.
10000m2/haSI unit conversion.Reference time base for the capacity factor.
Market range 8760 (non-leap year); 8784 (leap year).
8760h/yearCalendar-year hours convention.A floating plant does not buy a ground racking system, so its cost is credited back before the floating structure is added.
Market range 0.10 $/Wp for a 50 MWp fixed-tilt ground-mounted plant (2018 basis).
0.1USD/WpWorld Bank cost comparison table, mounting-system line of the ground-mounted column.Cost of floats, anchoring and mooring on a calm reservoir, where the water level barely moves.
Market range0.15USD/WpWorld Bank reference case: 50 MWp, freshwater inland reservoir, maximum depth 10 m, minimal water level variation.Top of the observed float-and-mooring range, reached where the drawdown makes the mooring design complex.
Market range0.22USD/WpWorld Bank 2018 cost survey of HDPE floating structures including anchoring and mooring.Plant size at which the float-and-mooring anchors are quoted, and therefore the pivot of the scale law.
Market range 50 MWp reference case.
50MWAIScale law on the SPECIFIC float cost, hence negative: the $/Wp falls as the plant grows. The equivalent exponent on the TOTAL cost is 1 + (-0.222) = 0.778 and must never be swapped with this one.
Market range Equivalent total-cost exponent 0.778, inside the usual 0.6-0.9 band for modular equipment.
-0.222Least-squares fit of ln(unit cost) on ln(size) over the four NREL float unit-cost points: 0.40 $/Wdc at 2 MW, 0.36 at 5 MW, 0.30 at 10 MW, 0.20 at 50 MW (R2 about 0.98).Extra balance-of-plant cost of a floating array: DC cabling with additional insulation and shielding, floating combiner boxes, monitoring.
Market range 0.05 $/Wp premium at 50 MWp (2018 basis).
0.05USD/WpDifference between the FPV and ground-mounted BOS lines of the World Bank cost table (0.13 - 0.08 $/Wp).Extra design, construction, testing and commissioning cost of working over water.
Market range 0.01 $/Wp premium at 50 MWp (2018 basis).
0.01USD/WpDifference between the FPV and ground-mounted design+T&C lines of the World Bank cost table (0.14 - 0.13 $/Wp).Drawdown range at which the mooring cost reaches the top of its observed band. Above it the cost is held flat rather than extrapolated, because no source prices a deeper drawdown.
Market range 10 m at the NREL benchmark site; hydropower reservoirs routinely exceed it, which is why the model caps rather than extrapolates.
10mNREL benchmark model site: water level variation 10 m, water depth 50 m.Converts the dollar-denominated FPV cost literature into the euro basis of this calculator.
Market range1.0821USD/EUREuropean Central Bank annual average reference rate for 2024 (0.9241 EUR per USD).Plausibility floor on the installed CAPEX. A floating plant is never cheaper than the cheapest ground-mounted market.
Market range IRENA 2024 national averages: 525 $/kW (India) to 1058 $/kW (USA); global weighted average 691 $/kW.
450EUR/kWpSet below IRENA's lowest 2024 national average utility-scale PV installed cost (India, 525 $/kW, about 485 EUR/kW).Plausibility ceiling on the installed CAPEX, above the most expensive ground market plus a full floating premium.
Market range World Bank 2018 turnkey FPV 0.8-1.2 $/Wp; NREL 10 MWdc FPV benchmark about 1.32 $/Wdc.
1800EUR/kWpUSA utility PV 1058 $/kW (about 978 EUR/kW) plus the 25% NREL floating premium is about 1220 EUR/kWp; the ceiling sits well above it.Calibration anchor: the total FPV CAPEX the build-up must reproduce at the reference size.
Market range 0.73 $/Wp FPV vs 0.62 $/Wp ground at 50 MWp, i.e. +17.7%.
0.73USD/WpWorld Bank cost comparison, FPV column total.Calibration anchor: the ground-mounted total the floating delta is measured against.
Market range 0.62 $/Wp for a 50 MWp fixed-tilt ground-mounted plant (2018).
0.62USD/WpWorld Bank cost comparison, ground-mounted column total.Upper calibration anchor of the floating CAPEX premium, at a smaller plant size than the World Bank case.
Market range +0.26 $/Wdc, i.e. +25% at 10 MWdc.
0.26USD/WdcNREL bottom-up benchmark, 10 MWdc fixed-tilt FPV vs ground-mounted.External LCOE anchor for the floating case, used to judge whether the modelled result is defensible.
Market range 56.6 $/MWh without ITC (37.8 with).
56.6USD/MWhNREL benchmark, Kansas site, 1527 kWh/kWdc, 30 years, 5.1% real, no investment tax credit.External LCOE anchor for the ground-mounted reference, and therefore for the floating premium.
Market range 47.1 $/MWh without ITC; the FPV LCOE is about 20% higher.
47.1USD/MWhNREL benchmark, same site and finance as the floating case.External LCOE anchor from the World Bank FPV model, temperate climate at a 6% WACC.
Market range 7.53 c$/kWh at 6% WACC, 8.30 at 8% (base case), 9.26 at 10%; tropical 6.77-8.28; arid 4.90-6.01.
0.0753USD/kWhWorld Bank 50 MWp FPV LCOE table, conservative +5% performance-ratio case.Lower end of the European ground-mounted PV LCOE range, used to bracket the modelled result.
Market range41EUR/MWhFraunhofer ISE levelized cost study, utility-scale ground-mounted PV in Germany.Field cross-check on the surface intensity default, from the largest FPV plant built to date.
Market range 11.25 m2/kWp (89 Wp/m2), against the 10 m2/kWp (100 Wp/m2) planning factor.
11.25m2/kWpCirata (West Java): 200 MWp over 225 ha of the hydropower reservoir.Conservative end of the cooling gain, and the value NREL itself adopts.
Market range +3% (Netherlands) to +6% (Singapore); World Bank retains +5% conservative to +10% optimistic on the performance ratio.
3%Dorenkamper et al. (2021) measurements, adopted by the NREL benchmark.Upper cross-check on the degradation input; NREL applies the same rate to floating and ground-mounted plants.
Market range0.7%/yearNREL benchmark assumption table.Market cross-check on the ground-mounted reference CAPEX default.
Market range 779 $/kW in Europe (about 720 EUR/kW at the ECB 2024 average), 691 $/kW global weighted average.
779USD/kWIRENA 2024 cost survey, average utility-scale solar total installed cost across Europe.Costs and energy are discounted at the same real rate, and generation is degraded year on year. Discounting the costs but not the energy would understate the LCOE by roughly the ratio of the annuity factor to the discounted-energy factor.
Market range Not applicable (method rule).
—World Bank / NREL levelized cost convention.The CAPEX is not rebuilt from scratch: it starts from a ground-mounted reference the user owns, and only the three line items that actually differ are modelled. Modules and inverters are identical in the source table and stay inside the reference.
Market range Not applicable (method rule).
—World Bank table 5.1 line-by-line comparison.A promoter who claims +10% because the plant floats, without deducting the tilt penalty, overstates the yield by about five points. Both effects are entered separately and the net effect is reported explicitly.
Market range Not applicable (method rule).
—NREL nets -5% tilt against +3% cooling for a net -2%; at this calculator's defaults the net is -0.25%.Every CAPEX source used here is a total installed, turnkey figure, so the asset declares battery_limit = installed. Declaring it ex-factory would let project mode add roughly 77% of indirects on top of a cost that already contains them.
Market range Not applicable (scope rule).
—World Bank total investment cost, NREL installed system cost, Fraunhofer specific investment, IRENA total installed cost.Fixed O&M per kWp is entered once and applied to both the floating plant and the ground-mounted reference, so the LCOE premium reported here is a pure CAPEX-and-yield premium.
Market range 9-20 EUR/kWp/yr across the European market.
—AINo reservoir lease, concession fee or water royalty is included. Where one applies it is a project-level cost, not an asset cost, and it varies by an order of magnitude between jurisdictions.
Market range Not applicable (scope rule).
—World Bank excludes it from its FPV LCOE for the same reason, noting it is generally cheaper than an equivalent land lease.The area output is the water surface covered by the array. It is not a land footprint and it does not depend on the drawdown: the drawdown drives the mooring cost, not the surface.
Market range 8-14 m2/kWp across reported projects.
—World Bank global potential methodology multiplies usable water surface by an area factor of 100 Wp/m2.Above the 10 m benchmark drawdown the mooring cost is held at the top of the observed band instead of being extrapolated. The drawdown chart therefore shows a deliberate plateau, not a modelling accident.
Market range Not applicable (modelling limit).
—No published source prices a mooring design beyond the NREL benchmark drawdown, and a linear extrapolation there would be invention.The -0.222 exponent is fitted on the specific float cost in $/Wp, so it is negative. Applying a positive six-tenths exponent to a specific cost would make the plant more expensive per kWp as it grows, which is the inverted-economy-of-scale defect; the equivalent total-cost exponent is 0.778.
Market range Total-cost exponents for modular PV equipment sit around 0.75-0.95.
—NREL float unit costs across four plant sizes.The asset has no inlet: sunlight is not a purchased commodity and is not chained. Its single electricity outlet therefore shares no commodity with any inlet, so no chaining coefficient rule is needed and none is written.
Market range Not applicable (chaining rule).
—OpenJack chaining doctrine: a rule is required only where an inlet and the main outlet carry the same commodity.The model is a fixed-tilt, monofacial floating array. Trackers, bifacial rear-side gain, hybrid operation with a hydropower plant and evaporation savings are all out of scope and would each change the yield or the value stack.
Market range Not applicable (scope rule).
—Scope decision: the reference cost tables used here are fixed-tilt monofacial.
Sources
6 external sources
Sources
6 external sources
- World Bank / ESMAP / SERIS (2019) - Where Sun Meets Water: Floating Solar Market Report (cost table 5.1, LCOE method ch. 5.2, area factor ch. 3)
- World Bank / ESMAP / SERIS (2019) - Where Sun Meets Water: Floating Solar Handbook for Practitioners (performance ratio uplift 5-10%)
- NREL (2021) - Floating Photovoltaic System Cost Benchmark Q1 2021, TP-7A40-80695 (float cost vs size, 25% CAPEX premium, tilt penalty and cooling gain, LCOE 56.6 $/MWh)
- IEA-PVPS Task 13 (2025) - T13-31 Floating Photovoltaic Power Plants: energy yield, reliability and maintenance (degradation, CAPEX premium drivers)
- Fraunhofer ISE (July 2024) - Levelized Cost of Electricity: Renewable Energy Technologies (ground-mounted PV CAPEX 700-900 EUR/kWp, OPEX 13.3 EUR/kW/yr, LCOE 41-69 EUR/MWh)
- IRENA (2025) - Renewable Power Generation Costs in 2024 (utility-scale PV total installed cost by market, global LCOE 0.043 $/kWh)