The short answer
In Delhi-NCR, Haryana, UP and Rajasthan, 1 kW of rooftop solar generates about 4.0–4.5 units per day averaged over the year — roughly 1,400–1,600 units per kW per year — with strong seasonality: ~5.0–5.4 units/kW in peak summer, ~4.0–4.4 in monsoon months, ~3.0–3.2 in December–January. MNRE's normative figure for planning is 4–5.5 units/kWp/day on clear sunny days. Plan on 10–35% below the sales pitch: dust, heat, shading and monsoon eat 10–35% of theoretical output.
TL;DR: Plan on ~4.2 units/kW/day annualized in Delhi-NCR (~15,000 units/year for a 10 kW system), summer peak ~5.0–5.4 units/kW, winter trough ~3.0, monsoon dip 30–50% month-on-month. A 500 kW industrial plant on a clean NCR roof generates ~7.7 lakh units a year at a 75–80% performance ratio; quarterly cleaning, temp-coefficient-aware design and honest PR assumptions separate good plants from bad ROI models.
The annualized norms by region
MNRE/PIB normative guidance: on a clear sunny day, 1 kWp generates 4 to 5.5 units. Annualized, North-Indian plants at good PR:
| Region | Units/kW/day (annualized) | Units/kW/year |
|---|---|---|
| Delhi-NCR, Haryana | 4.1–4.4 | ~1,500–1,600 |
| Western UP (Meerut, Ghaziabad, Lucknow) | 4.0–4.3 | ~1,460–1,570 |
| Rajasthan (Jaipur, Bhiwadi) | 4.3–4.6 | ~1,570–1,680 |
| Uttarakhand (plains) | 3.9–4.2 | ~1,460–1,570 |
| West Bengal (Kolkata) | 3.8–4.2 | ~1,400–1,530 |
| Coastal/monsoon-heavy markets | 3.5–4.0 | ~1,300–1,460 |
Delhi-NCR field data: a 10 kW system generates ~15,000 units/year (~42/day average), with per-kW daily output swinging from ~5.4 (May) to ~3.0 (Dec–Jan) — see the seasonal table below. MNRE's own CFA documentation uses 4–5.5 units/kWp/day clear-sunny-day planning norms.
The seasonal curve in North India
Monthly generation follows a predictable annual shape — plan cash-flow against it:
| Season | Per-kW daily yield | What drives it |
|---|---|---|
| Peak summer (May) | ~5.0–5.4 | Long days, high sun, but heat derates output per kWp |
| Pre-monsoon (April) | ~5.3 | Clear, hot, high yield |
| Monsoon (Jul–Aug) | ~4.0 (dips of 30–50% vs May on cloudy days) | Cloud cover; cleaning suspended |
| Post-monsoon (Oct) | ~4.4 | Clear skies return; so does dust |
| Winter (Dec–Jan) | ~3.0–3.2 | Short days, low sun angle, haze |
| Annual average | ~4.2 | — |
Two practical notes:
- Monsoon months (Jul–Aug) still generate 60–70% of clear-sky output — they do not zero out. Cloudy June–September months generate 30–50% less than May; the annualized number is what pays back the plant.
- Winter trough (Dec–Jan) at ~3 units/kW/day is a design constraint: if your plant must cover winter load (e.g., heating-heavy processes), size for winter, not summer.
Why your plant will not hit the brochure number
Sales collateral quotes STC output; real plants run at a performance ratio (PR) of 75–80% in North Indian conditions after:
- Heat losses: cell temperatures of 60–70°C cut output ~10–15% at peak — TOPCon modules lose less than PERC (full comparison in TOPCon vs Mono PERC).
- Soiling: NCR dust storms can cut output 5–15% within weeks; quarterly cleaning schedules recover most of it (cleaning schedule guide).
- Shading and orientation: true-south at latitude tilt (~26–28° in Delhi) — city-wise angles in our tilt and orientation guide.
- Inverter clipping and DC/AC ratio: modest DC/AC ratios (1.2–1.3) trade some clipping for higher morning/evening yield.
- Cable and transformer losses, availability.
A plant that quotes 85%+ PR in a dusty NCR industrial setting is selling you a number that survives the PowerPoint, not the monsoon.
Turning units into rupees: the valuation side
Units only matter at the avoided tariff. Two adjustments matter:
- Net billing states (UP): exports are compensated below retail (Solar Injection Compensation), so the value of a solar unit = self-consumed units × retail tariff + exported units × compensation rate. Model self-consumption honestly — see NPCL net billing guide, UPPCL net billing guide.
- Net metering states (Haryana, Delhi, Rajasthan): surplus exports offset imports 1:1 within the settlement period, so even exported units are valued near retail (until banking caps bind).
A 500 kW plant in Faridabad (DHBVN HT) generating ~7.7 lakh units/year at 85% self-consumption against a ₹6.95/kVAh blended avoided cost saves roughly ₹45–48 lakh a year; the same plant in a net-billing state with 70% self-consumption earns less — which is why self-consumption is the first variable in any honest ROI model (see solar IRR calculation methodology and panel ROI/payback guide).
Monitoring, O&M and the PR audit
Treat the first 12 months as the baseline year: compare monthly generation against the month-by-month P50 forecast, and compute PR against measured irradiance. If PR runs below 75% with a clean plant, the usual suspects are undetected string faults, inverter derating, soiling or a wiring defect — see solar monitoring systems and panel maintenance. Our O&M seasonal best practices sets the cleaning cadence for NCR dust and monsoon.
Frequently Asked Questions
How many units does 1 kW of solar generate per day in Delhi NCR?
About 4.1–4.4 units averaged over the year — roughly 42 units/day for a 10 kW system (~15,000 units/year). Seasonally, peak summer (May) runs ~5.4 units/kW/day and December–January ~3.0–3.2; monsoon months dip 30–50% below clear-sky output.
How many units does a 100 kW solar system generate per year?
Roughly 1.5–1.6 lakh units a year in Delhi-NCR/Haryana at ~4.2 units/kW/day annualized, varying with roof orientation, shading and cleaning discipline. At ₹7–8/kWh avoided tariff, that's ₹10.5–12.8 lakh of annual savings.
Why does my solar plant generate less in monsoon?
Cloud cover cuts output 30–50% versus clear-sky in June–September across North India. This is normal and is already inside the ~4.2 units/kW/day annualized average. Cleaning before the monsoon recovers the dust loss; the monsoon dip is weather, not fault.
What is a good performance ratio for solar in India?
A well-built North Indian C&I plant should deliver 75–80% PR annualized. Below 72–75% PR sustained, investigate soiling, string faults, inverter derating or metering errors before blaming the weather.
How do I convert solar units to savings?
Multiply self-consumed units by your avoided retail/HT tariff (₹6–9/kWh across our North-India markets), and exported units by your state's export/settlement rate (retail-offset under net metering; a lower injection compensation under net billing in UP). Net-metering states bank exports; net-billing states pay them out below retail — so self-consumption is the first variable to optimise.
Sources
- MNRE/PIB FAQ on rooftop solar: 1 kWp generates 4–5.5 units on a clear sunny day; MNRE benchmark costs by capacity band (PIB, 2022).
- Delhi-NCR seasonal per-kW generation data and 10 kW case study (~15,000 units/year) — field-corrected city yield references, 2026.
- CEA/Global Solar Atlas city irradiance basis for per-kWp yields; CEA grid emission factor 0.82 kg CO2/kWh for CO2 accounting.
- MNRE net-metering/PM Surya Ghar documentation for settlement mechanics; state tariff orders (DHBVN, PVVNL) for avoided-cost tariffs.
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Sun Wave models plant output month-by-month from your interval data and local irradiance before you sign — see our savings calculator explainer or talk to our team for a binding generation forecast with your quote.
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