Diesel v/s Solar electric

Oceans, Electrified.

Compare the lifetime economics of diesel v/s solar-electric boats.

Inputs

Pick a vessel; values auto-fill by section. Edit anything to override — every tab updates live.

At 6 kn over 100 km/day: 10 kW propulsion, motor 30 kW, running 9.0 h/day, solar 7.0 kWh/day.
Operational
kW
Speed–power curve — up to 10 points
Speed (kn)Power (kW)
Duty cycle — between two recharges
One row per mode of operation in a recharge cycle: a speed with its distance. For a stop, set speed 0 and give the idle time in minutes. The battery is sized to one cycle; the recharge range is the total distance below.
Speed knDistance kmIdle min
Lowest 20-year cost

Assumptions & parameters

Everything except the operational duty cycle (which stays on the left). Values auto-fill from the vessel; edit anything to override — every tab updates live.

Solar
Advanced
Power train & capital
Advanced
% oversizing over the max power needed (at max speed), to allow for degradation and power margin.
Battery sizing
Total distance of the duty cycle above.
Aux (hotel) battery
Advanced
Efficiencies
Advanced
Fuel & energy
Advanced
Engine SFC rises off its best point (a bowl min at the optimal load). It's applied per duty-cycle mode using that mode's load = mode power \u00f7 engine MCR. The same bowl (same optimal load & %s) is applied to the aux genset at its own load, using the aux best SFC.
Battery life & cell costs
Prices
Advanced
Finance
Advanced
Resale / scrap value of the asset at the end of the analysis period, credited in the final year.
Revenue & crew (P&L)
Feeds the P&L tab only. Revenue and crew are the same for diesel and electric, so they don't change which is cheaper — they show whether the route itself pays back.
Crew
Emissions
Advanced

Selected system

The vessel, powertrain and energy store the model is currently sizing, with the key derived figures.

Range v/s speed — battery only and battery + solar

Endurance from the usable propulsion battery at each speed, converted to distance. “+ solar” adds one day’s solar-to-propulsion harvest to the usable energy.
Battery onlyBattery + solar

Range table

Boat cost

Total delivered cost = boat (ex-system) + the propulsion system. The hull & fit-out is shared; the system differs — a diesel engine v/s the solar-electric power train, battery, charging and solar.

Profit & loss — net present value

Revenue and crew are identical for both powertrains, so the NPV gap equals the cost gap — this view shows whether the route itself is viable, not which powertrain is cheaper (that's the Basic / Advanced tabs). All figures are present values in lakh INR over the analysis period.

Net present value — Diesel v/s Solar electric

Present value of revenue less all costs over the analysis period. A taller bar is the more profitable option; the difference is the cost saving.

Cumulative cost (incl. CAPEX) v/s cumulative revenue

Running total from year 0: each cost line starts at that powertrain's up-front capital, then adds every year's running and replacement cost (nominal). Where cumulative revenue rises above a cost line is that option's project payback.
Cumulative revenueDiesel cost + CAPEXSolar electric cost + CAPEX

Yearly revenue v/s running cost

Nominal (un-discounted) figures for each year: ticket revenue against the annual running cost (energy + maintenance + crew, plus battery replacement in replacement years). Revenue is the same for both powertrains.
RevenueDiesel costSolar electric cost

Diesel

20-yr total cost (undiscounted)
₹613.5 L
Break-even v/s diesel

Solar electric

20-yr total cost (undiscounted)
₹324.9 L
Break-even v/s diesel3.9 yrs

20-year total cost (no discounting)

Up-front capital plus every year's running and battery-replacement cost, summed in nominal rupees — not discounted to present value.

Where the money goes — CAPEX v/s lifetime OPEX

Same 20-year total, split into up-front capital and everything spent running the boat (fuel or grid energy, plus battery replacement).
CAPEX (up-front)Lifetime OPEX (running + replacement)

Cumulative total cost — year 0 to 20

Running total of money spent (capital, then each year's cost), undiscounted. Where an electric line crosses below diesel is the break-even point.
DieselLFPLTO

For the Marsel-10m-15pax, Solar electric has the lowest 20-year total cost (undiscounted). LFP's cumulative spend drops below diesel at about year 3.9. The Advanced tab shows the same comparison discounted to present value (NPV).

Diesel

20-yr total cost
₹322.8 L
Capital₹57.0 L
Boat (ex-system)₹25.0 L
Power train₹32.0 L
ESS / energy₹0.0 L
Solar plant
Annual running (Yr 1)₹17.0 L
Battery pack
Battery replacement
Payback (simple)
Breakeven (NPV)
Lifetime saving (NPV)

Solar electric

20-yr total cost
₹218.7 L
Capital₹116.3 L
Boat (ex-system)₹25.0 L
Power train₹24.0 L
ESS / energy₹66.1 L
Solar plant₹1.2 L
Annual running (Yr 1)₹3.0 L
Battery pack84 kWh
Battery replacement₹46.7 L
Payback (simple)4.2 yrs
Breakeven (NPV)4.6 yrs
Lifetime saving (NPV)₹104.1 L

CAPEX breakdown

Boat shell is fixed per model; power train & ESS scale with motor and battery sizing.
Boat (ex-system)Power trainESSSolar plant

Cumulative cost (NPV basis)

Discounted cumulative cost. Where an electric line drops below diesel is the NPV breakeven.
DieselLFPLTO

How the yearly OPEX is built

Fuel/energy is summed across the duty-cycle modes, scaled to the operating year, then costed and loaded with maintenance. Costs rise each year from price escalation; the electric side also rises as the solar plant degrades and more grid energy is drawn. Electric energy is billed on grid energy after the solar offset.

Annual operating cost — Diesel v/s Solar electric

Each year's running cost (energy + maintenance, plus battery replacement in replacement years), nominal. Diesel escalates faster; the electric line also creeps up as solar output degrades, so the gap still widens over time.
DieselSolar electric

Cumulative operating cost

Running total of operating cost (excludes up-front CAPEX). The area between the lines is the lifetime OPEX saving.
DieselSolar electric

Year-by-year detail

All figures in lakh INR (nominal). “Repl.” is battery replacement in the years it falls due.

Sensitivity analysis

Pick one parameter and enter up to five alternative values. The chart and table show how each powertrain's 20-year NPV — and the saving between them — move as that parameter changes. Your current (default) value is included and highlighted.
Diesel NPVSolar electric NPV

Saving = Diesel NPV − Solar electric NPV (positive means electric is cheaper). Only the selected parameter changes; everything else stays at its current value.

Diesel

Lifetime CO2
828 t
Annual CO2 (yr 1)41.4 t
CO2 saved v/s diesel

Solar electric

Lifetime CO2
446 t
Annual CO2 (yr 1)22.1 t
CO2 saved v/s diesel383 t

Lifetime CO2 emissions

Diesel burns fuel; electric draws grid power for energy solar doesn't cover. Grid factor & solar size drive the result.

Annual CO2 emissions

Per-year CO2 — diesel from fuel burnt, the battery option from grid charging (net of solar). The electric line rises slightly each year as the solar plant degrades and more grid energy is drawn.

Energy contribution

Diesel runs on 100% fuel. The battery option's annual energy splits between on-board solar and grid charging.
SolarGridDiesel fuel

Diesel fuel use

Volume of diesel the conventional option burns — the battery option uses none.
15,457 L
Diesel burned per year
3,09,136 L
Over 20 yr (309.1 kL)

What the switch adds up to

Over the analysis period, choosing the battery option instead of diesel saves:
3,09,136 L
Diesel not burned
383 t
CO2 avoided over 20 yr
18,237
Trees absorbing CO2 for a year
83
Cars off the road for a year

CO2 reflects grid charging less the solar share; raise solar kWp or lower the grid factor to cut it further.

Step 1 · Demand & duty cycleThe same energy requirement feeds both powertrains.
Power & energy
QuantityValueFormula
Propulsion power at cruise10 kWinterp. speed–power curve @ 6 kn
Power required at max speed25 kWinterp. speed–power curve @ 8 kn
Daily range100 kmtrips/day × trip distance
Duty cycle distance50 kmsum of segment distances (one recharge)
Recharges / day2daily range / cycle distance = 100/50
Running hours / day9 hduty-cycle run time × recharges/day
Idle hours / day0 h0-kn segments × recharges/day
Berthing time2 hinput (trips × embark min / 60)
Operating hours / day11 hrunning + berthing = 9 + 2
Propulsion energy (mech) / day90 kWhpropPower×runH = 10×9
Propulsion energy (elec) / day100 kWhpropMech/ηmotor = 90/0.90
Auxiliary energy / day11 kWhaux×opH = 1×11
Step 2 · Power trainMotor and engine are both sized from the power needed at max speed.
Power train — motor & engine
QuantityValueFormula
Motor rating (with margin)30 kWreqMax×(1+margin) = 25×(1+0.20)
Power train system (electric)Inboard-15kW-48V system · 15 kW × 2 setsauto-pick smallest system ≥ motor rating
Power train cost (electric)₹24.0 Lsystem price × 2 set(s)
Powering penalty vs electric+60 %traditional / efficient input
Diesel engine (interpolated)25 kW/set × 2 setsreqMax×(1+penalty)×(1+engine margin)/sets = 25×(1+0.60)×(1+0.25)/2
Diesel engine cost₹32.0 Linterp. diesel ₹/kW curve × sets
Step 3 · Battery sizingThe pack is sized to one recharge cycle, then rounded up to whole strings and sets.
LFP + solar
QuantityValueFormula
Recharge range50 kminput
Charge leg fraction0.5recharge range / daily range = 50/100
Solar credit for sizing (prop / aux)1.4 / 0.4 kWhsolar×consider% = solar×0.25
Battery energy for sizing (prop / aux)98.6 / 10.6 kWhmax(0, demand − solar credit)
Grid energy / day (full solar, prop / aux)94.4 / 9.6 kWhmax(0, demand − full solar)
Battery sized — prop / aux74 / 8 kWhbattE×leg/DoD×(1+buf); DoD=0.80, buf=0.20
Module (V / Ah / Wh)12.5 V / 105 Ah / 1,313 WhWh = V×Ah = 12.5×105
Battery voltage → series48 V → 4SNMS = ceil(sysV/moduleV) = ceil(48/12.5)
Step (one 4S string)5.3 kWhNMS×moduleWh/1000 = 4×1,313/1000
Separate aux batteryNo — with propulsioninput
Battery sets · min / set2 × 42 kWhceil((prop+aux req/sets)/step)×step
Selected / set → pack42 → 84 kWhsets × chosen pack/set
Total pack84 kWhaux load sized within the propulsion pack
Pack oversize factortotal pack / required = 84/82
Cost rate prop (cost / repl)₹80,000 / ₹60,000 per kWhinput
Cost rate aux (cost / repl)₹30,000 / ₹15,000 per kWhinput
ESS cost (incl. charging)₹66.1 Lprop kWh×₹prop + aux kWh×₹aux + charger
Capital₹116.3 Lboat + power train + ESS + solar
Energy cost / yr₹2.7 Lgrid kWh×days×CEEB = (gP+gA)×300×₹8.6
Maintenance / yr₹0.3 Lenergy cost × 10%
Annual running (Yr 1)₹3.0 Lenergy + maintenance ; escalates 3%/yr
Charge cycles per year600days/leg = 300/0.5
Life: cycle vs calendar6.7 yr / 7 yrcycle life/cycles-per-yr ; shelf life
Replacement every6 yr (cycle-limited)floor(min(cycle yrs, calendar yrs))
Replacement years6, 12, 18multiples of interval within period
Replacement (each event)₹46.7 Lprop kWh×₹replProp + aux kWh×₹replAux
Step 4 · Energy, fuel & running costSolar offset and energy price, then the diesel fuel burn over the duty cycle.
Solar & energy price
QuantityValueFormula
Solar generation / day7 kWhkWp×insolation×ηsys = 2×5.5×0.64
to propulsion / to aux5.6 / 1.4 kWh×share / ×(1−share), share=0.80
Cost of energy at battery (CEEB)₹8.6/kWhtariff/(ηbatt×ηcharger) = 7/(0.90×0.90)
Diesel — fuel & running cost
QuantityValueFormula
Propulsion energy /day (diesel)144 kWhpropMech×(1+penalty) = 90×(1+0.60)
SFC bowl (best · load)250 g/kWh @ 80% MCRminimum SFC point
SFC rise 25% / 100% MCR+15% / +3%parabola through these points
Effective SFC (duty avg)279 g/kWhload-weighted over the duty cycle
Propulsion fuel / day47.2 LΣ modes: SFC(load)×kWh/(1000×ρ×load-factor)
Aux genset SFC301 g/kWhbest 300 @ 70% MCR on the bowl
Aux mech / fuel per day12.2 kWh / 4.3 Laux/ηalt × aux SFC
Annual fuel15,457 L(propFuel+auxFuel)×days ; aux includes idle hours = (47.2+4.3)×300
Fuel price₹100/Linput
Maintenance (% of fuel)+10 %input
Capital₹57.0 Lboat + power train = ₹25.0 L + ₹32.0 L
Fuel cost / yr₹15.5 Lfuel×price = 15,457×₹100
Maintenance / yr₹1.5 Lfuel cost × 10%
Annual running (Yr 1)₹17.0 Lfuel + maintenance ; escalates 5%/yr
Step 5 · Comparison & CAPEX splitAll money in lakh INR.
Diesel v/s Solar electric
MetricDieselSolar electric
Capital₹57.0 L₹116.3 L
Annual running (Yr 1)₹17.0 L₹3.0 L
Battery pack (kWh)84
Replacement (each)₹46.7 L
Payback (simple)4.2 yr
Breakeven (NPV)4.6 yr
Breakeven (undiscounted)3.9 yr
Residual value (yr 20)₹5.7 L₹11.6 L
20-yr TCO (undiscounted)₹613.5 L₹324.9 L
20-yr TCO (NPV)₹322.8 L₹218.7 L
CAPEX breakdown
BucketDieselSolar electric
Boat (ex-system)₹25.0 L₹25.0 L
Power train₹32.0 L₹24.0 L
ESS (battery + charging)₹0.0 L₹66.1 L
Solar plant₹0.0 L₹1.2 L
Total capital₹57.0 L₹116.3 L
Step 6 · Energy & emissionsAnnual energy split and CO2; fuel in litres, CO2 in tonnes.
Annual energy (LFP)
Energy from solar / yr2,112 kWh (6%)
Energy from grid / yr31,185 kWh (94%)
Total charged energy / yr33,297 kWh
Fuel & CO2
MetricDieselSolar electric
Diesel fuel / yr15,457 L
Diesel fuel lifetime3,09,136 L
CO2 factor2.68 kg/L0.71 kg/kWh
Annual CO2 (yr 1, t)41.422.1
Lifetime CO2 (t)828.5445.5
— electric lifetime basisΣ each year (solar degrades 1%/yr)
CO2 saved v/s diesel (t)383
Step 7 · 20-year cash flowCumulative cost, discounted (NPV) and nominal; lakh INR.
Cumulative cost — NPV v/s nominal
YearDiesel NPVLFP NPVDiesel nomLFP nom
Year 0₹57.0 L₹116.3 L₹57.0 L₹116.3 L
Year 1₹72.9 L₹119.1 L₹74.0 L₹119.3 L
Year 2₹88.5 L₹121.7 L₹91.9 L₹122.3 L
Year 3₹103.8 L₹124.3 L₹110.6 L₹125.5 L
Year 4₹118.8 L₹126.8 L₹130.3 L₹128.7 L
Year 5₹133.5 L₹129.2 L₹150.9 L₹132.1 L
Year 6₹148.0 L₹162.6 L₹172.6 L₹182.2 L
Year 7₹162.2 L₹164.8 L₹195.4 L₹185.8 L
Year 8₹176.1 L₹166.9 L₹219.4 L₹189.4 L
Year 9₹189.8 L₹169.0 L₹244.5 L₹193.2 L
Year 10₹203.2 L₹171.0 L₹270.9 L₹197.1 L
Year 11₹216.3 L₹172.9 L₹298.6 L₹201.1 L
Year 12₹229.3 L₹195.4 L₹327.6 L₹251.9 L
Year 13₹241.9 L₹197.2 L₹358.2 L₹256.2 L
Year 14₹254.4 L₹198.9 L₹390.2 L₹260.6 L
Year 15₹266.6 L₹200.6 L₹423.9 L₹265.1 L
Year 16₹278.5 L₹202.1 L₹459.2 L₹269.8 L
Year 17₹290.3 L₹203.7 L₹496.4 L₹274.6 L
Year 18₹301.8 L₹218.9 L₹535.3 L₹326.2 L
Year 19₹313.1 L₹220.3 L₹576.2 L₹331.3 L
Year 20₹322.8 L₹218.7 L₹613.5 L₹324.9 L
Step 8 · Profit & lossRevenue & crew are identical for both powertrains, so the NPV gap = the cost gap.
Revenue & crew (annual)
QuantityValueFormula
Annual revenue₹38.4 L20 pax×₹40×80%×20 trips×300 days
Crew cost / yr₹7.3 L₹1,000×2 crew×1 sets×365
Revenue escalation+5 %/yrinput
Net present value (PV over 20 yrs)
Present valueDieselSolar electric
Revenue₹603.5 L₹603.5 L
CAPEX−₹57.0 L−₹116.3 L
Energy−₹242.9 L−₹36.1 L
Maintenance−₹24.3 L−₹3.6 L
Crew−₹114.7 L−₹114.7 L
Battery replacement₹0.0 L−₹65.7 L
Residual value (+)₹1.5 L₹3.0 L
Net present value₹166.0 L₹270.1 L
Step 9 · Sensitivity — break-evenValue at which each key assumption flips the 20-yr NPV decision, others held. Full sweep & tornado in the Sensitivity tab.

At current inputs solar electric is cheaper by ₹104.1 L (20-yr NPV).

Break-even thresholds
ParameterCurrentBreak-even
Diesel price100 ₹/L61 ₹/L — electric cheaper above 61 ₹/L
Grid tariff7 ₹/kWh25.3 ₹/kWh — electric cheaper below 25.3 ₹/kWh
Battery prop cost80000 ₹/kWh220900 ₹/kWh — electric cheaper below 220900 ₹/kWh
Discount rate7 %22.4 % — electric cheaper below 22.4 %
Analysis period20 yrs5 yrs — electric cheaper above 5 yrs
Best SFC (engine)250 g/kWh144 g/kWh — electric cheaper above 144 g/kWh
Calculation flowHow the model gets from a vessel choice to the comparison.
Step 01
Pick vessel & duty cycle
Speed-power curve, trip profile, hours, solar size.
Step 02
Propulsion power
Interpolate power at cruise and max speed from the curve.
Step 03
Operating & running hours
From trips/day, distance and embark time.
Step 04
Daily energy demand
Propulsion (mech → elec) and auxiliary energy.
Step 05
Solar generation & credit
Usable solar offsets part of the per-charge demand.
Step 06
Battery sizing
Propulsion pack — and a separate aux (XDLE) bank if chosen — in whole module-strings per set.
Step 07
CAPEX
Boat + power train + ESS + solar plant.
Step 08
OPEX
Diesel fuel cost vs grid energy at battery (CCB).
Step 09
Emissions
Diesel CO2 vs grid CO2 for energy solar doesn't cover.
Step 10
20-year cash flow
Inflate OPEX, add replacements, discount to present.
Step 11
NPV cost & breakeven
Total NPV and the year electric drops below diesel.
Step 12
Compare
Diesel v/s LFP v/s LTO — lowest NPV wins.
Vessel librarySpeed–power curves and per-vessel defaults. Selecting one on the left loads its values.

Saved data

Vessels and standard curves you edit are stored in this browser automatically. Export to move them to another machine or keep a backup.

Slow — ≤ 8 kn

Displacement hulls. Dashed line = standard curve.

Medium — 8 to 16 kn

Semi-displacement. Dashed line = standard curve.

High — above 16 kn

Planing hulls. Dashed line = standard curve.
Speed–power curve points (knots → kW)
VesselS1S2S3S4S5
Estirar-7m-10pax4 → 35 → 46 → 67 → 98 → 13
Destiny-7m-10pax-Cat4 → 35 → 46 → 5.57 → 88 → 12
Marsel-10m-15pax4 → 45 → 66 → 107 → 168 → 25
Marsel-10m-20pax4 → 55 → 76 → 117 → 188 → 28
Limo-10m-15pax4 → 45 → 66 → 107 → 168 → 25
Barracuda-14m-20pax-med8 → 2710 → 6812 → 12514 → 22016 → 280
Limo-12m-25pax-slow4 → 55 → 76 → 117 → 188 → 28
Limo-30pax-slow4 → 65 → 86 → 12.57 → 188 → 25
Blueair-16m-56pax4 → 95 → 146 → 187 → 248 → 32
Esho-17m-55pax4 → 125 → 156 → 207 → 288 → 40
Aditya-21m-75pax4 → 105 → 126 → 167 → 258 → 40
Indra/Zayle-25m-100pax4 → 125 → 156 → 207 → 308 → 50
Apollo-25m-100pax med8 → 4010 → 10012 → 20014 → 34016 → 520
Custom (edit me)4 → 45 → 66 → 107 → 128 → 25
Per-vessel defaults
VesselDays/yrTrip kmTrips/chargeTrips/dayEmbark minAux kWPV kWp
Estirar-7m-10pax30051020612
Destiny-7m-10pax-Cat30051020612
Marsel-10m-15pax30051020612
Marsel-10m-20pax30051020612
Limo-10m-15pax30051020612
Barracuda-14m-20pax-med300154128210
Limo-12m-25pax-slow3005816823
Limo-30pax-slow3005816823
Blueair-16m-56pax300510208215
Esho-17m-55pax300510208216
Aditya-21m-75pax350612208220
Indra/Zayle-25m-100pax350612208325
Apollo-25m-100pax med350254810225
Custom (edit me)30051020612
Capital defaults (INR)
VesselBoat ex-systemCharge infraDiesel engine
Estirar-7m-10pax18,00,0002,50,0004,00,0004
Destiny-7m-10pax-Cat18,00,0002,50,0004,00,0004
Marsel-10m-15pax25,00,0003,00,0006,00,0005
Marsel-10m-20pax28,00,0003,50,0007,00,0007
Limo-10m-15pax25,00,0003,00,0006,00,0007
Barracuda-14m-20pax-med60,00,0006,00,00025,00,0008
Limo-12m-25pax-slow38,00,0004,00,0009,00,00010
Limo-30pax-slow42,00,0004,50,00010,00,00012
Blueair-16m-56pax70,00,0007,00,00025,00,00014
Esho-17m-55pax80,00,0008,00,00030,00,00014
Aditya-21m-75pax1,30,00,00012,00,00060,00,00014
Indra/Zayle-25m-100pax1,60,00,00015,00,00070,00,00018
Apollo-25m-100pax med1,80,00,00015,00,00095,00,00016
Custom (edit me)25,00,0003,00,0006,00,0005