Inverter vs DG Backup for NCR Homes: Sanctioned Load Explained

Power cuts in Delhi NCR are shorter and rarer than they were a decade ago, but most households still want some form of backup. In a high-rise, that usually means the society’s diesel generator (DG) plus, in many flats, a home inverter. In independent houses and builder floors, the inverter is often the only option. At the same time, air conditioners, induction cooktops and electric vehicles are pushing many homes past the electricity load they were sanctioned years ago.

This guide compares inverter and DG backup, shows how to size an inverter with worked numbers, explains the pollution rules that now limit DG use, and sets out how sanctioned load works and how to raise it with discoms in Delhi, Uttar Pradesh and Haryana. Tariffs and charges change, so confirm current figures with your discom.

Inverter or DG: how they differ

An inverter stores grid power in a battery and converts it back to household AC when supply fails. Switchover takes a fraction of a second, it runs silently, and it has no fuel cost beyond the electricity used to recharge the battery. Its limit is the battery: it can run a few lights, fans and a router for hours, but not several air conditioners.

A DG set burns diesel or gas to generate power. In a society, one large set serves all flats and common areas, and each flat gets a fixed backup allowance, often a few kVA, recorded on a separate meter or register. DG backup can run heavier loads for longer, but it is noisier, more polluting, and billed at a rate the society sets, which is usually well above the grid tariff.

Pollution rules now limit DG sets

The Commission for Air Quality Management’s Graded Response Action Plan for NCR, in its schedule revised on 29 September 2026, lists DG controls from Stage I, the “poor” air quality stage. It says DG sets should not be used as a regular source of power and requires regulated DG operation across residential, commercial and industrial sectors under CAQM’s Direction No. 76 of September 2023.

• Sets running on gas or other clean fuels, and sets up to 800 kW built to the 2022 emission standards, have no restrictions.
• Older diesel sets between 19 kW and 800 kW must run in dual-fuel mode or be retrofitted with certified emission control devices to operate without restriction.
• Portable DG sets below 19 kW are not generally permitted, except for listed emergency services.
• Emergency services include lifts and escalators, hospitals, water pumping stations and sewage treatment plants, among others.

For residents, this means two things. If your society’s DG sets are not compliant, backup may be limited to lifts and pumps on bad-air days. And a small portable generator for an independent house is generally not an option. Ask your society or maintenance agency whether its sets are dual-fuel or retrofitted.

Sizing a home inverter: a worked example

Sizing has two parts: the inverter’s capacity, which decides how much load it can carry at once, and the battery, which decides how long it can run.

Step 1: list the loads you want backed up

Check the rating labels on your own appliances. Energy-efficient BLDC fans draw much less than older fans.

Step 2: choose the inverter capacity

Inverters are rated in volt-amperes (VA). Dividing watts by a planning power factor of 0.8 gives about 525 VA for this load. Adding headroom for motor start-up and future additions points to an inverter in the 900 VA to 1,100 VA range. Prefer a pure sine wave model: modified sine wave output can make fans hum, run hotter and work less efficiently.

Step 3: size the battery

Suppose you want 3 hours of backup at 420 W. That is 1,260 Wh of energy delivered. Allowing for inverter losses of around 15% raises the requirement to roughly 1,480 Wh drawn from the battery.

• A 12 V, 150 Ah lead-acid battery stores 1,800 Wh nominally. Using about 80% of it for planning gives 1,440 Wh, which is close to the target; heavy regular deep discharge shortens lead-acid life.
• A 24 V, 100 Ah lithium iron phosphate (LFP) pack stores 2,400 Wh. LFP tolerates deeper discharge, so it would cover 3 hours with margin, or more than 4 hours at a lighter load.

All percentages above are planning assumptions, not manufacturer figures. Use the datasheet of the battery you actually buy.

Lead-acid or lithium?

Lead-acid batteries release hydrogen and oxygen when overcharged, so keep them in a ventilated spot, not a closed cupboard. LFP is chemically more stable than other lithium chemistries but still needs proper protection electronics, as overcharging or physical damage can cause fires.

What DG backup costs a flat

DG rates are not set by the electricity regulator; they are fixed by the society or maintenance agency, usually linked to diesel cost and running expenses. In Uttar Pradesh, UPERC’s 2026-27 tariff order requires single-point society operators to meter DG supply separately and show DG units and rate on each bill.

As an illustration only: if a society charges ₹20 per DG unit against a grid tariff of around ₹6 per unit, then 40 units of backup a month cost ₹800 on DG, compared with about ₹240 at grid rates. A household that uses DG mainly for air conditioning during long cuts can see this add up quickly. Check your actual DG rate and backup allowance in the maintenance agreement before buying.

Sanctioned load: what it is and why it matters

Sanctioned load, or contracted load, is the maximum power in kilowatts your connection is approved to draw. It decides your fixed charge, the size of your security deposit, and whether you pay penalties when demand exceeds it. A home that adds two air conditioners, an induction hob and an EV charger can easily outgrow a 3 kW or 4 kW sanction.

Estimating what you need

Add up the loads likely to run at the same time. As a rough guide using typical ratings: two 1.5-ton air conditioners at about 1.5 kW each, a 2 kW geyser, a 2 kW induction cooktop and 1 kW of lights, fans and electronics come to about 8 kW if all run together. Realistic simultaneous use is often lower. A home EV charger adds a large block: common AC home chargers draw about 3.3 kW, and a single-phase Type 2 charger can draw up to about 7.2 kW at 32 A.

Delhi (BSES and Tata Power-DDL)

Delhi’s rules are in the DERC Supply Code and Performance Standards Regulations, 2017.

• Applying yourself: you can apply for load enhancement in the prescribed format, and the discom follows the new-connection procedure.
• Automatic annual review: the discom takes the highest average of maximum demand readings over any four consecutive months in the previous financial year. If that exceeds your sanctioned load, it must send a notice by 31 May, and the revised load takes effect from 1 July. For domestic consumers up to 5 kW, a lower computed load is applied automatically if you do not reply within 30 days; above 5 kW, a reduction needs your consent.
• Charges: you pay the additional security deposit for the higher load, and a differential service line charge only if the service line is actually changed.

Worked example: raising a Delhi connection from 4 kW to 7 kW for an EV charger. The deposit at 7 kW would be 7 × ₹1,200 = ₹8,400, against 4 × ₹900 = ₹3,600 already paid, so about ₹4,800 extra. If the service line must be changed, the differential charge is (₹3,000 + 2 × ₹500) minus ₹3,000, or ₹1,000. Loads up to 10 kW are normally supplied on single phase. These figures are from the 2017 schedule as published by Tata Power-DDL; confirm with your discom whether any later revision applies.

Uttar Pradesh (PVVNL, NPCL)

In Noida and Ghaziabad, the state discom is PVVNL; much of Greater Noida is served by NPCL. Under the UP Electricity Supply Code, an application for enhancement goes to the sub-divisional officer with the prescribed fee, a licensed electrical contractor’s work completion and test report, and the latest paid bill. If the meter does not need changing, the code provides for sanction within 7 days, with additional security and system loading charges payable for the extra load.

UPERC’s 2026-27 tariff order adds two points that matter:

• If a domestic consumer with a demand-recording meter exceeds the contracted load in a month, the excess demand is charged at 100% of the normal rate on top of the usual fixed charge.
• If recorded demand exceeds the sanctioned load at least three times in a financial year, the lowest of those monthly peaks becomes the new sanctioned load from the next financial year, with additional security payable. The order also advises EV owners to take adequate contracted load or face penalties.

The current domestic fixed charge in PVVNL areas is ₹110 per kW per month, so each extra kilowatt adds about ₹1,320 a year in fixed charges before duty. In a single-point society, load changes go through the builder or association, which holds the bulk connection.

Haryana (DHBVN)

Gurugram and Faridabad are served by Dakshin Haryana Bijli Vitran Nigam. Load enhancement is applied for through the discom, with additional security and any applicable charges. We could not access DHBVN’s website to confirm the current procedure and charges, so check them directly with your subdivision office before applying.

Putting it together

• Society flat with compliant DG: a small inverter for lights, fans and the router may be enough to bridge short cuts without paying DG rates.
• Society with restricted or costly DG: a larger inverter, preferably lithium, reduces dependence on DG during bad-air months.
• Independent house or builder floor: an inverter is usually the practical choice, since small portable DG sets are generally not permitted under GRAP.
• Adding an EV charger: estimate your new peak demand, apply for a higher load before installing, and agree with your society on wiring and metering.

If you are comparing homes in Noida or Gurugram, or browsing projects across NCR, ask for the flat’s sanctioned load, the DG backup allowance and rate, and whether the DG sets meet the GRAP dual-fuel or retrofit requirement.

Frequently asked questions

Sources

• CAQM: Graded Response Action Plan schedule (revised 29.09.2026)
• DERC (Supply Code and Performance Standards) Regulations, 2017
• DERC: Supply Code and performance standards regulations page
• DERC Schedule of Charges and Procedure 2017 (Tata Power-DDL copy)
• Tata Power-DDL: Schedule of charges and procedures
• UPERC: Tariff Order for State Discoms FY 2026-27 (2 July 2026), PVVNL copy
• UPPCL: Public notice of approved tariff for FY 2026-27
• UP Electricity Supply Code 2005 (PVVNL copy)
• Wikipedia: Lithium iron phosphate battery
• Wikipedia: Lead-acid battery
• Wikipedia: Power inverter
• Wikipedia: Type 2 connector

Updated 20 October 2026. This article is general information, not legal or financial advice; check current rules and project details before you decide.