DG → Solar+BESS crossover.
Diesel price, DG capacity and run-hours in — the kWp solar plus kWh LFP BESS that breaks even against running the genset out. Capex, annual saving, payback years and CO₂ avoided, computed for the Indian market.
- DG SFC
- 0.27 l/kWh
- Solar PR
- 78%
- BESS round-trip
- 92%
- PSH (India)
- 4.5 h
Solar required
155 kWp
paired with 544 kWh LFP BESS
Payback
5.54 yrs
simple, diesel-offset basis
Diesel cost today
₹ 45.7 L
per year · ₹25.38/kWh effective
Annual saving
₹ 44.9 L
net of solar O&M
Capex break-up
Solar
₹ 74.4 L
BESS
₹ 1.74 Cr
Total
₹ 2.48 Cr
Annual carbon avoided
130.2 tonnes CO₂.
Diesel offset alone, at 2.68 kg CO₂ per litre and 0.27 l/kWh DG specific fuel consumption.
Indicative sizing — final design needs site-specific irradiance, shadow study, load profile, grid-interactive vs off-grid topology and inverter pairing. Most Indian states allow rooftop net-metering up to 500 kWp for commercial / industrial users; behind-the-meter BESS charged from solar typically does not need a separate licence.
· A typical Indian crossover
A 250 kW DG running 80 hours a month at ₹94/litre diesel costs about ₹47 lakh a year in fuel alone. The same load served by ~50 kWp rooftop solar plus ~135 kWh LFP BESS lands at roughly ₹95 lakh capex and pays back in just over two years on diesel offset alone, before grid-tariff arbitrage. The crossover used to be five years on lead-acid; with LFP chemistry and current solar capex, it is now firmly inside the ROI window most operators tolerate.
· Frequently asked
DG → Solar+BESS —
what people ask first.
Why is DG so expensive per kWh?
A standard diesel genset at 75% load burns ~0.27 litres of diesel per kWh generated. At ₹94/litre that is roughly ₹25/kWh of energy — nearly three times the average industrial grid tariff and five to six times the tariff of a long-tenor solar PPA. The same generator at low load (below 50%) burns even more per kWh and shortens engine life.
How is the BESS sized?
We size the BESS to cover the daily DG run-hours, plus round-trip-loss buffer (LFP ~92% round-trip). The solar side is sized to recharge the BESS over the day at 4.5 peak-sun-hours and a 78% performance ratio — these are typical Indian rooftop-PV values. The result is an indicative two-input pairing; final design needs site-specific irradiance, shadow analysis and load profile.
Why LFP, not lead-acid VRLA?
VRLA round-trip efficiency is ~75% with a 3-5 year cycle life. LFP delivers ~92% round-trip across 6000+ cycles, with no thermal-runaway hazard at the chemistry level. The capex premium of LFP has collapsed to within 20% of VRLA on lifecycle cost — and at the cycle counts BESS demands, LFP wins on every operating axis.
Will my building qualify for net-metering or banking?
Most Indian states allow rooftop-solar net-metering up to 500 kWp for commercial / industrial users. Behind-the-meter BESS charged from solar typically does not need a separate licence. Each state's electricity regulatory commission notification is the governing source — get the latest before sizing.
Will TechnoGuru deliver the solar + BESS install?
Yes. We engineer and deliver solar + LFP BESS installations as turnkey, including capex modelling, vendor selection (Vertiv, Delta, Fuji, Sungrow, Huawei), structural mounting, inverter pairing, BMS integration with the building's existing controls layer, and commissioning. End-to-end accountability with full O&M for the first three years.
· Begin
Running a diesel-heavy site
and tired of the fuel bill?
Send the past six months of DG run logs, average load profile and roof/yard area available. We will return a sized solar + BESS proposal with capex, payback and CO₂ within five working days.