Skip to main content
Library

Energy mass balanceCostingOther

Offshore wind HVDC export link: losses, HVAC/HVDC break-even distance and transmission cost per MWh

VSC-HVDC export of an offshore wind farm (500-2,000 MW): converter and cable losses, installed CAPEX against an HVAC export, break-even distance and transmission cost per MWh delivered, on DEA 2025 unit costs and the Härtel 2017 cost model.

Photo of Open Jack

Open Jack

Founder · OpenJack

Add to project
  • CurrencyEUR 2020
  • Battery limitinstalled
  • 60 documented assumptions
  • Updated2 Nov 2026

Mass and energy balance

What the asset draws and delivers for the case and load you choose.

Reference case

Share of the year at rated power equivalent; sets the energy carried. Default 42 %, the IRENA 2024 offshore wind average. When chained, the farm sets it.

Flows

  • In: Offshore wind electricity (at the offshore platform)—

Asset

Offshore wind HVDC export link (VSC)

  • Out: Delivered onshore electricity—

Annual quantities at the current usage.

Power the link is designed to export, in MW, normally the farm capacity. 500-2,000 MW: from one 500 MW AC circuit to one 525 kV bipole (DEA). The station cost follows the Härtel 2017 affine law calibrated on the DEA 2,000 MW price.

Average delivered power
— MW
Pole current
— kA
AC circuits needed
— circuits
HVDC link CAPEX
— MEUR

CAPEX

Specific cost at this size, what backs it, and how it behaves with scale.

Specific CAPEX at this size

—

Reference size 2,000 MW

Calibration (Härtel form x DEA level)

Model value: the Härtel affine law at the DEA 2025 level. Customized: your own cost for the converter station pair (offshore with platform plus onshore), per kW, used as entered at every size. A customized value is no longer sourced.

Converter station pair cost by rated export power

Log in to view this sensitivity chart.

  1. Ex-factory
  2. Installed· this figure
  3. Fully financed
CAPEX at the battery limit—
Working capital, contingencyproject level

Included

  • Equipment
  • Installation, civil works and engineering

Not included

  • Working capital
  • Contingency

Added at project level

  • Working capital layer, from the project settings
  • Contingency, from the project settings

Project figures

Values passed to project mode when this asset is added to a project.

Concept sketch, not to scale · drag to rotate

Offshore wind electricity (at the offshore platform) in
—
Delivered onshore electricity outMain product
—
CAPEX to the battery limit
—
Fixed O&M
—
Variable O&M, excluding feedstocks
0 EUR/year
Asset lifetime
40 years

Log in to add this asset to a project.

Transmission cost

A standalone indicator for a quick read. Project mode recomputes it for the whole system.

—

  • Transmission cost: capital—
  • Transmission cost: O&M—
  • Transmission cost: losses—

Linked to the balance above

Share of the year at rated power equivalent; sets the energy carried. Default 42 %, the IRENA 2024 offshore wind average. When chained, the farm sets it.

Submarine cable length from the offshore converter platform to the landfall.

Underground cable length from the landfall to the onshore converter station. Costed as 1.25 submarine km (Härtel 2017 Eq. 6; DEA gives 1.26).

Informative: sets the pole current reported for the bipole. The costs are those of the DEA 525 kV bipole reference and do not change with this value.

Price put on each MWh lost in the link. Default 80, inside the Fraunhofer ISE 2024 offshore wind LCOE range (55-103 EUR/MWh).

Real discount rate for the stand-alone transmission cost, as a fraction. Costs are constant 2020 EUR, so the rate is real. Default 4 %, the DEA real rate.

Years over which the CAPEX is annualised. DEA: 40 years technical lifetime for cables and substations (30-50).

Transmission cost by capacity factor of the farm

Log in to view this sensitivity chart.

Benchmarks

This model's figures against published references and reference cases.

Break-even distance HVAC/HVDC, km

50 DEA p.42

70 NSCOGI 2011

100 NSCOGI 2011

150 Chalmers 2024

Reference cases at this size and usage

Log in to compare the reference cases.

All results

Every model output at the current settings, grouped, with the sensitivity charts.

48 outputs · 6 groups · 13 also shown above, dimmed

Energy and losses

9
Full-load hours
Computingh/year
Offshore electricity carried
ComputingMWh/year
Converter losses
Computing%
DC cable losses
Computing%
Total losses of the HVDC link
Computing%
Energy lost in the link
ComputingMWh/year
Delivered onshore electricity
ComputingMWh/year
Average delivered power
ComputingMW
Offshore energy per MWh delivered
ComputingMWh/MWh

Link

4
Route length
Computingkm
Cost-equivalent cable length
Computingkm
Pole current
ComputingkA
AC circuits needed
Computingcircuits

HVDC CAPEX

11
Converter station pair cost
ComputingEUR/kW
Onshore converter station
ComputingEUR
Offshore converter station with platform
ComputingEUR
DC export cable
ComputingEUR
HVDC link CAPEX
ComputingEUR
HVDC link CAPEX
ComputingMEUR
HVDC link CAPEX per kW
ComputingEUR/kW
Cable share of HVDC CAPEX
Computing%
HVDC CAPEX with maximum owner's costs
ComputingEUR
Affine law over power-law summary
Computingratio
DEA onshore over offshore DC cable cost
Computingratio

HVAC alternative

7
Total losses of the HVAC alternative
Computing%
Energy lost, HVAC alternative
ComputingMWh/year
HVAC substations
ComputingEUR
HVAC export cables
ComputingEUR
HVAC alternative CAPEX
ComputingEUR
HVAC alternative CAPEX
ComputingMEUR
Transmission cost, HVAC alternative
ComputingEUR/MWh

Break-even

5
Break-even distance HVAC/HVDC
Computingkm
Break-even exists
Computingflag
HVAC beyond its practical length
Computingflag
HVDC saving against HVAC
ComputingEUR/MWh
HVDC cheaper than HVAC
Computingflag

Transmission cost

12
Capital recovery factor
Computing1/year
Annualised HVDC CAPEX
ComputingEUR/year
HVDC O&M
ComputingEUR/year
Value of energy lost
ComputingEUR/year
Total annual cost of the HVDC link
ComputingEUR/year
Transmission cost: capital
ComputingEUR/MWh
Transmission cost: O&M
ComputingEUR/MWh
Transmission cost: losses
ComputingEUR/MWh
Transmission cost
ComputingEUR/MWh
Transmission cost at the DEA 4 % rate
ComputingEUR/MWh
Transmission cost, low value of losses
ComputingEUR/MWh
Transmission cost, high value of losses
ComputingEUR/MWh

Sensitivities

5 charts
Transmission cost and losses against the offshore distance

Log in to view this sensitivity chart.

Transmission cost components against the capacity factor

Log in to view this sensitivity chart.

Break-even distance against the rated power

Log in to view this sensitivity chart.

HVDC and HVAC CAPEX against the offshore distance

Log in to view this sensitivity chart.

Converter station pair cost against the rated power

Log in to view this sensitivity chart.

Sources

60 documented assumptions · 7 sources

About

Calculator context

A screening model of the export link of an offshore wind farm by VSC-HVDC: an offshore converter station on its platform, a DC submarine and land cable and an onshore converter station, compared with an export by 220 kV HVAC circuits. It returns the losses, the energy delivered onshore, the installed CAPEX of both options, the HVAC/HVDC break-even distance and the transmission cost per MWh delivered, in real 2020 EUR.

Inputs. The rated export power (500-2,000 MW), the offshore and onshore cable distances, the DC voltage (informative), the capacity factor of the farm, the value of the lost energy, a reference case for the end losses, an optional customized converter station cost, and the real discount rate and lifetime of the stand-alone transmission cost.

Costs. The level is the Danish Energy Agency Technology Data for Energy Transport (2025 values, 2020 EUR): 0.32 MEUR/MW onshore converter, 0.75 MEUR/MW offshore converter with platform, 3.22 kEUR/km/MW DC submarine cable at 2,000 MW and 525 kV. The shape is the linear cost model of Härtel et al. 2017 (fixed term plus term proportional to power), with its average fixed terms and the proportional terms recalibrated to return the DEA level at 2,000 MW: a one-anchor calibration, declared medium. Onshore cable km count 1.25 submarine km (Härtel Eq. 6; DEA gives 1.26). The HVAC alternative uses DEA per-MW substation costs (0.25 + 0.60 MEUR/MW) and 4.51 kEUR/km/MW of AC cable with compensation. CAPEX covers purchase and installation; owner's costs (permits, planning, project management, up to +50 % per DEA) are excluded and shown only as a separate upper bound.

Losses. DEA rated-power values: 1-2 % per converter end (by case) and 1 %/100 km of DC cable; 1-2 % per transformer end and 5 %/100 km of AC cable. Applied to the annual energy, they over-state the cable losses at part load (Joule losses scale with current squared): a conservative choice.

Transmission cost. Annualised CAPEX plus O&M (DEA: 1.5 % of stations and 2.5 % of cables per year) plus the value of the lost energy, divided by the delivered onshore electricity. It excludes the value of the energy carried, so in project mode the link can be chained after the farm without counting the electricity twice.

Break-even distance. The all-sea route length at which HVDC and HVAC have equal annual cost, losses included. It falls as the power rises, the direction reported by Andersson and Johansson (Chalmers 2024), and sits mostly inside the 70-100 km NSCOGI/ENTSO-E range and above the generic DEA figure of about 50 km.

Limits. Härtel notes that average parameter sets strongly underestimate offshore wind connections, which is why only its fixed terms and linear form are used. The NSCOGI 2011 VSC prices imply stronger economies of scale: the affine law probably underestimates a 500 MW station; use the customized station cost when a quote exists. TYNDP 2022 project sheets give DC station costs about half the DEA level. Above about 100 km an AC route needs mid-route compensation, at the edge of the DEA domain.

Model

131 variables — inputs, calculations and outputs, with their dependencies.

131 variables shown of 131
VariableValueUnitDepends on
1——
1000MW—
120km—
20km—
525kV—
42%—
80EUR/MWh—
0——
1100EUR/kW—
0.04ratio—
40years—
VariableFormulaUnitDepends on
if((<)+(>)+(<=)+(<)+(<=)+(<=)+(>)+(<)+(<)+(>)+(<=)+(<)+(<)+(<)+(>)>,,)—
if(==,,)%
if(==,,)%
*ratio
-MWh/year
(*-)/EUR/MW
(*-)/EUR/MW
(*-)/EUR/(km*MW)
+*EUR
+*EUR
(+)/EUR/kW
(+)/((+)*)ratio
**EUR
+*EUR/km
(+)**(/)^EUR
*EUR/km
**EUR/year
**EUR/year
*EUR/year
**+**EUR/year
*EUR/year
+*1/year
+*1/year
*(-)+*+***(-)*EUR/year
*(-)+**(-)*/EUR/(km*year)
(**(+*)^)/max((+*)^-,)1/year
VariableFormulaUnitDepends on
**h/year
*MWh/year
+km
+*km
*%
*/%
+%
*MWh/year
-MWh/year
/MW
/max(,)MWh/MWh
/(*)kA
*+*/%
**MWh/year
ceil(/)circuits
if(>=,,clamp(*(*(/)^+-),,))EUR/kW
*/max(+,)EUR
-EUR
+*EUR
+EUR
/MEUR
/(*)EUR/kW
/max(,)*%
*(+*)EUR
(+)/max(,)ratio
/ratio
(+)*EUR
*EUR
+EUR
/MEUR
if(<,/,(*(+)^)/max((+)^-,))1/year
*EUR/year
+EUR/year
*EUR/year
++EUR/year
/max(,)EUR/MWh
/max(,)EUR/MWh
/max(,)EUR/MWh
++EUR/MWh
(++)/max(,)EUR/MWh
-EUR/MWh
if(>,,)flag
if(>,,)flag
if(>,max(,/),)km
if(>,,)flag
(*++)/max(,)EUR/MWh
(++*)/max(,)EUR/MWh
(++*)/max(,)EUR/MWh

Assumptions

60 assumptions used in the calculations

  • Protects divisions in edge cases; far too small to move any result.

    Market range Not applicable (numerical parameter).

    0.000001
    Numerical constant

  • Converts capacity factor into full-load hours and annual energy into average power.

    Market range 8,760 (8,784 in a leap year).

    8760h/year
    Calendar convention

  • Avoids a literal 1 inside the formulas.

    Market range Exact.

    1
    Numerical constant

  • Avoids a literal 0 inside the formulas.

    Market range Exact.

    0
    Numerical constant

  • Converts the % inputs and the % loss and O&M figures into fractions.

    Market range Exact.

    0.011/%
    Unit conversion

  • Upper guard of the capacity factor (0-100 %).

    Market range Exact.

    100%
    Unit convention

  • Converts MW into kW for the EUR/kW station cost.

    Market range Exact.

    1000kW/MW
    Unit conversion

  • Reports CAPEX in million EUR.

    Market range Exact.

    1000000EUR/MEUR
    Unit conversion

  • Turns the %/100 km cable loss into a loss per km of route.

    Market range Exact.

    100km
    Unit convention

  • A point-to-point export link has two ends: one offshore and one onshore converter (HVDC) or substation (HVAC), each with its own loss.

    Market range Exact for point-to-point links (multi-terminal grids are out of scope).

    2stations
    Topology

  • Splits the transmitted power over the two poles of a bipole to report the pole current (P = 2 x V x I).

    Market range Exact for a symmetric bipole.

    2poles
    Topology

  • Integer id of the central-loss reference case.

    Market range Not applicable (identifier).

    1
    Selector identifier

  • Integer id of the upper-loss reference case.

    Market range Not applicable (identifier).

    2
    Selector identifier

  • Lower bound of the rated-power domain: one 500 MW AC export circuit is the smallest HVAC alternative the DEA unit costs describe.

    500MW
    Model domain

  • Upper bound of the rated-power domain: the 2,000 MW 525 kV bipole is the largest single DC link the DEA reference prices.

    2000MW
    Model domain

  • Onshore VSC converter station cost at the DEA reference size; anchors the onshore proportional term of the affine law.

    Market range 0.15 MEUR/MW (TYNDP 2022 project sheets) to 0.32 MEUR/MW (DEA 2025).

    320000EUR/MW
    DEA Table 7

  • Offshore VSC converter station cost, platform included, at the DEA reference size; anchors the offshore proportional term.

    Market range No independent range cited.

    750000EUR/MW
    DEA Table 7

  • DC submarine cable cost per km and per MW at the reference size; anchors the cable proportional term.

    Market range No independent range cited.

    3220EUR/(km*MW)
    DEA Table 5

  • Used only to cross-check the 1.25 underground-cable factor applied to the onshore route (ratio reported as an output).

    Market range No independent range cited.

    4070EUR/(km*MW)
    DEA Table 5

  • Size at which the DEA unit costs are quoted: the reference size of the scale law.

    2000MW
    DEA Table 4

  • Size-independent part of the onshore converter cost in the linear cost model.

    Market range No independent range cited.

    28380000EUR
    Härtel 2017 Table 1

  • Size-independent part of the offshore converter cost in the linear cost model.

    Market range No independent range cited.

    44810000EUR
    Härtel 2017 Table 1

  • Power-independent cost per km of DC cable (laying, protection) in the linear cost model.

    Market range No independent range cited.

    680000EUR/km
    Härtel 2017 Table 1

  • Fixed cost of one cable branch in the linear cost model.

    Market range No independent range cited.

    700000EUR
    Härtel 2017 Table 1

  • Weights each onshore (underground) km as 1.25 submarine km in the cable cost. It is a cost equivalence only: cable losses use the physical route length.

    Market range 1.25 (Härtel) to 1.26 (DEA Table 5).

    1.25
    Härtel 2017 Eq. (6)

  • Exponent of the fixed term once the affine cost is divided by the rated power: the per-kW share of a fixed cost falls as 1/P.

    Market range Exact.

    -1
    Algebra of the Härtel linear model

  • Effective scale exponent of the station-pair cost over 500-2,000 MW, as implied by the Härtel affine law calibrated on the DEA 2,000 MW anchor. It is a one-parameter calibration on one anchor, hence medium evidence. The model applies the affine law itself; this exponent is its power-law summary, reported against it as a check.

    Market range 0.5 (implied by NSCOGI 2011 VSC prices) to 0.93 (Härtel/DEA affine law).

    0.93
    Calibration (Härtel form x DEA level)

  • Lower guard of the scaled station-pair cost; inactive inside the declared domain.

    Market range Model range 1,070-1,180 EUR/kW over 500-2,000 MW.

    500EUR/kW
    Numerical guard

  • Upper guard of the scaled station-pair cost; inactive inside the declared domain.

    Market range Model range 1,070-1,180 EUR/kW over 500-2,000 MW.

    3000EUR/kW
    Numerical guard

  • Onshore AC substation of the HVAC alternative, per MW of export.

    Market range No independent range cited.

    250000EUR/MW
    DEA Table 7

  • Offshore AC substation with its platform, per MW of export.

    Market range No independent range cited.

    600000EUR/MW
    DEA Table 7

  • AC export cable per km and per MW, reactive compensation included. Constant per MW because 500-2,000 MW is exported over 1-4 parallel ~500 MW circuits.

    Market range No independent range cited.

    4510EUR/(km*MW)
    DEA Table 5

  • Capacity of one 220 kV AC export circuit; sets the number of parallel circuits of the HVAC alternative.

    500MW
    DEA note 9 / Table 1

  • Central-case loss of one VSC converter end, at rated power.

    1%
    DEA Table 1

  • Upper-case loss of one VSC converter end.

    2%
    DEA Table 1

  • Central-case loss of one AC substation end (transformer).

    1%
    DEA Table 1

  • Upper-case loss of one AC substation end.

    2%
    DEA Table 1

  • DC cable loss per 100 km of physical route, at rated power.

    Market range No independent range cited.

    1%
    DEA Table 1

  • AC cable loss per 100 km at rated power, with compensation: the reason HVDC wins on long routes.

    Market range No independent range cited.

    5%
    DEA Table 1

  • Yearly O&M of converter stations and AC substations, as a share of their CAPEX.

    Market range No independent range cited.

    1.5%/year
    DEA Table 13

  • Yearly O&M of export cables, as a share of their CAPEX.

    Market range No independent range cited.

    2.5%/year
    DEA Table 13

  • DEA real discount rate, used for the transmission cost at the DEA reference rate shown next to the user-rate figure.

    Market range No independent range cited.

    4%
    DEA p.29

  • Upper bound of the owner's costs that the DEA CAPEX excludes; shown as a separate upper-bound CAPEX, never added to the model CAPEX.

    Market range 0 to +50 % (DEA).

    50%
    DEA datasheet note 8

  • Low value of the energy lost in transmission (offshore wind LCOE, low end); drives the low side of the transmission cost range.

    55EUR/MWh
    Fraunhofer ISE 2024

  • High value of the energy lost in transmission; drives the high side of the transmission cost range.

    103EUR/MWh
    Fraunhofer ISE 2024

  • Route length above which an AC export needs mid-route compensation: raises a flag on the HVAC alternative.

    100km
    NSCOGI 2011

  • Generic DEA HVAC/HVDC break-even for cable lines; lower external reference for the break-even distance.

    Market range About 50 km (generic).

    50km
    DEA p.42

  • Lower end of the NSCOGI AC practical length, where HVDC becomes the appropriate technology.

    70km
    NSCOGI 2011

  • Upper external reference for the break-even distance, for small farms.

    150km
    Chalmers 2024

  • Point-to-point VSC-HVDC export link: offshore converter station with its platform, onshore converter station, DC submarine and land cable. CAPEX is purchase plus installation (battery limit 'installed'); owner's costs are excluded and are never presented as an all-in figure. Project mode adds only its working-capital and contingency layers on an 'installed' CAPEX.

    Market range No independent range cited.

    —
    Method

  • Station cost = fixed term (Härtel) + proportional term x P, cable cost = B0 + (Bl + bp x P) x equivalent length. The proportional terms are recalibrated so that the law returns the DEA 2025 level exactly at 2,000 MW: np = (0.32 x 2000 - 28.38)/2000 MEUR/MW, sp = (0.75 x 2000 - 44.81)/2000, bp = (3.22e-3 x 2000 - 0.68)/2000 MEUR/(km MW).

    Market range No independent range cited.

    —
    Method

  • HVAC alternative: 220 kV circuits of about 500 MW in parallel, each with an offshore substation on a platform, an onshore substation and reactive compensation. Its cost per MW is constant because 500-2,000 MW is exported over 1-4 identical circuits (numbering-up).

    Market range No independent range cited.

    —
    Method

  • Losses are the DEA rated-power percentages applied to the annual energy: 2 converter ends plus 1 %/100 km of physical DC route (HVDC), 2 transformer ends plus 5 %/100 km (HVAC). This over-states the cable losses at part load (losses scale with current squared): a conservative choice, published as such.

    Market range No independent range cited.

    —
    Method

  • Break-even distance: route length at which the HVDC and HVAC links have the same annual cost (CAPEX annuity, O&M and value of the lost energy) on an all-sea route. Fixed-cost gap (stations versus substations, cable branch, converter versus transformer losses) divided by the per-km saving of the DC cable (cheaper cable, lower losses).

    Market range No independent range cited.

    —
    Method

  • Chaining: link the electricity outlet of the offshore wind farm upstream to this calculator's electricity inlet with a full coefficient, and set the farm's grid connection scope to 'chained' so that its AC substation and AC export cable are removed there. The export losses and the export CAPEX are then counted once, here. The outlet is the delivered onshore electricity, net of losses.

    Market range No independent range cited.

    —
    Chaining doctrine

  • All costs are constant 2020 EUR with no escalation, so the discount rate is a real rate. The fixed-bottom wind farm calculator of the same batch is in 2023 EUR: compare the two with a cited index, not at parity.

    Market range No independent range cited.

    —
    Method

  • Default capacity factor of the farm (42 %): IRENA 2024 global weighted average for offshore wind. Chaining replaces it with the farm's own net energy.

    Market range IRENA 2024 global average 42 %; North Sea sites higher.

    —
    Default value

  • Default value of the energy lost in transmission: 80 EUR/MWh, chosen inside the Fraunhofer ISE 2024 offshore wind LCOE range (55-103 EUR/MWh).

    Market range 55-103 EUR/MWh.

    —
    Default value

  • Default economic lifetime (40 years) and asset lifetime exported to project mode: DEA technical lifetime of cables and substations.

    Market range 30-50 years (DEA).

    —
    Default value

  • Limit: the NSCOGI 2011 VSC prices imply stronger economies of scale than the affine law; the model probably underestimates the station cost of a 500 MW link. Use the 'Customized' station cost when a quote is available.

    Market range No independent range cited.

    —
    Limit