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Calculator

Diesel Genset vs Grid — Running Cost Calculator

See exactly how much you pay per kWh from your DG set versus the grid — fuel, lube, and maintenance all in. Indian defaults for April 2026.

Inputs

Result

DG cost per kWh
₹26.05/kWh
Grid cost per kWh
₹10.50/kWh
DG premium over grid
₹15.55/kWh
Annual DG running cost
₹27.3 L
Same kWh from grid
₹11.0 L
Annual savings by shifting to grid
₹16.3 L
Diesel price at which DG = grid: ₹36.5/L
Annual kWh: 105000  |  CO₂ from DG: 75978.0 t  |  from grid: 75.6 t

How this works

The cost per kWh from a diesel generator is simply fuel cost per kWh plus a maintenance allocation:

DG ₹/kWh = (SFC × Diesel price) + (Maintenance ₹/hr ÷ Effective load kW)

Effective load = Rated kW × Load factor %
Annual DG kWh = Effective load × Hours/day × Days/year

Grid cost should be your all-in landed rate — include demand charges, electricity duty, fuel surcharge, and any cross-subsidy. Use your last three months' bills to back-calculate the true ₹/kWh, not the nominal slab rate.

Benchmarks & defaults

What typical numbers look like in India in April 2026.

Diesel pump price

₹90–94/L across most Indian metros (Apr 2026). Retail varies by state duty.

DG running cost (typical)

₹22–28/kWh all-in, depending on DG size, load factor, and maintenance discipline.

Industrial grid tariff

₹8.5–11/kWh landed (MH, GJ, TN, KA industrial LT/HT). Commercial slabs run ₹9–13/kWh.

Break-even

DG breaks even with grid at diesel around ₹37–45/L in most cases — a price not seen since 2008.

Grid emission factor (India)

0.72 kg CO₂/kWh (CEA 2024). Diesel: ~2.68 kg CO₂/L or ~0.74 kg/kWh at typical SFC.

Maintenance fraction

Lube + service typically 1.5–3% of fuel cost for modern well-maintained DGs; up to 8% for neglected fleets.

Worked example — pharma manufacturing unit

A pharma plant near Baddi runs a 500 kVA DG for 3 hours/day, 250 days/year, at 70% load factor. That is 280 kW × 3 × 250 = 210,000 kWh/year from the DG.

  • SFC 0.28 L/kWh, diesel ₹92/L → ₹25.8/kWh fuel alone
  • + ₹40/hr maintenance ÷ 280 kW = ₹0.14/kWh
  • Total DG cost: ₹25.9/kWh
  • Grid cost (HP industrial HT, ~₹10.5/kWh all-in)
  • Annual DG cost: ₹54.4 L | Annual grid cost: ₹22.0 L
  • Potential savings by minimising DG runtime: ₹32.4 lakh/year

Most plants do not realise the delta because they have never sub-metered the DG. The fuel register tells them how much diesel went in — but not how many kWh came out, and not at what load factor.

Measure the DG to manage it

The calculator above uses assumptions. Your actual numbers will differ. The only way to know your real DG running cost is to sub-meter the alternator output and reconcile against diesel consumed.

Titan on the DG breaker gives you kWh, kVAh, PF, and load factor logged to the cloud — on the same dashboard as your grid meter. A single Energy Monitoring view lets you see grid-vs-DG split in real time, calculate actual SFC (kWh produced ÷ diesel consumed), and flag when DG runtime exceeds budget. The Energy Intelligence Platform alerts you if DG runs when grid is available (common cause: auto-transfer switch fault), so you stop paying ₹26/kWh when grid is ready at ₹10.

Most meter vendors give you kWh and stop. We built Titan to give you the full split — grid kWh, DG kWh, solar kWh, load factor, SFC — from a single stack, so the plant manager does not need three spreadsheets to answer “did the DG really need to run yesterday?”

Frequently asked questions

Six questions on DG economics, measurement, and alternatives.

Almost never, once you count all costs. In April 2026 at ₹92/L diesel and typical SFC of 0.28 L/kWh, DG costs ₹25.8/kWh just in fuel — plus ₹0.5–2/kWh for lube and maintenance. Industrial grid tariffs in most states sit ₹8–12/kWh. DG is cheaper only if you face very high grid demand charges plus frequent outages, or your grid tariff exceeds ₹25/kWh (essentially only small commercial connections in deep peak slots). The case for a DG is reliability, not running cost.
Sub-meter the DG output with a 3-phase energy meter on the alternator breaker and separately track diesel consumption (daily fuel register or a flow meter on the fuel line). Divide total ₹ spent on diesel + maintenance by total kWh produced — that is your real number. Most operators find their DG is ₹2–4/kWh more expensive than they thought, because their SFC assumption was optimistic for their actual load factor.
Yes. A diesel engine is most efficient around 75–85% load. At 30% load, SFC typically climbs 25–40% above the nameplate number — meaning a 500 kVA DG running 30% loaded might consume 0.37 L/kWh instead of the 0.27 L/kWh at 80%. Oversized DGs (common because buyers size for worst-case surge loads) spend most of their life at poor SFC. Measure, do not estimate.
At ~80% load (best point): 125 kVA ≈ 0.30 L/kWh, 250 kVA ≈ 0.28, 500 kVA ≈ 0.26, 1000 kVA ≈ 0.25. Smaller engines are less efficient. At 30% load, add 30–40% to each. Also factor ~0.5% worse SFC for every 10 °C of ambient temperature above 25 °C — relevant across most of India.
For short grid outages (under 30 minutes) and small loads (<100 kW), yes — a Li-ion BESS is now cost-competitive on TCO vs DG once you count fuel, maintenance, lube, and capex-of-DG amortisation. For longer outages or larger loads, DG remains essential, but a hybrid DG+BESS setup (BESS handles the first 10–30 minutes, DG starts only for longer events) cuts DG runtime by 60–80% and halves fuel cost.
Solar usually lands at ₹3–5/kWh levelised (rooftop, India, 2026) — cheaper than both DG and grid. Net metering credits offset grid consumption one-for-one in most states; gross/group-captive arrangements can go further. Solar does not replace DG for backup (night outages), but it massively reduces the daytime kWh you buy from either source. A proper sub-metering stack is how you allocate savings across solar / grid / DG.

Related products & solutions

From the calculator to a production DG sub-metering stack.

Titan — Smart Energy Meter

Sub-meter the DG alternator with Class 0.5S accuracy. Cloud-connected, WiFi + RS485, DIN rail.

Learn More →

Energy Monitoring Solution

Real-time grid-vs-DG-vs-solar split across your facility with automatic SFC reconciliation.

Learn More →

Energy Efficiency Solution

Programs that cut DG runtime 40–60% by identifying avoidable switchovers and rightsizing loads.

Learn More →

Know your real DG running cost

Sub-meter your DG in under 30 minutes. Talk to our engineers.

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