The most fundamental question any Indian homeowner asks before investing in solar is also the most practical: how many electricity units will my system actually produce? Not in an advertisement, not on a datasheet, but on your specific rooftop in your specific state. This guide answers that question with state-by-state data, real worked examples, and a named framework for calculating your own system’s expected output.
Understanding generation expectations before you buy prevents the most common source of post-installation disappointment: a system sized to the wrong state benchmark. For the basics of how a solar system works, see how does a solar power system work.
Why Solar Generation Varies So Much Across India
India stretches from latitude 8° N (Kanyakumari, Tamil Nadu) to 37° N (Ladakh), and from sea-level coastal humidity to high-altitude desert. The solar resource across this geography varies more than most homeowners realise.
Three factors drive state-to-state variation in solar electricity generation:
- Global Horizontal Irradiance (GHI): total solar energy reaching a horizontal surface per square metre per day, measured in kWh/m²/day. This is the primary driver of panel output.
- Cloud cover and monsoon intensity: cloud cover reduces irradiance from beam (direct) to diffuse radiation, cutting output to 15–40% of clear-sky values on heavily overcast days.
- Temperature: higher ambient temperatures reduce panel output. Silicon panels lose approximately 0.4–0.5% output per °C above 25 °C (the standard test condition temperature). Rajasthan’s summer rooftops reach 65–70 °C panel temperature, reducing output by 16–20% compared to datasheet ratings.
The net result of these three factors is the annual specific yield: units generated per kW of installed capacity per year. This number is the single most useful metric for comparing solar potential across Indian states.
5–6 kWh/m²/day. Average solar irradiance across most of India, one of the highest levels in the world for a major developing economy. Source - NREL India Solar Resource Data, 2024.
The State-by-State Solar Yield Table
The table below shows annual specific yield for each major Indian state, The GHI ranges are this guide’s approximate state-level figures (check your pincode with NREL’s PVWatts or an installer’s simulation), and every yield figure is calculated from them with the formula below at PR 0.78, south-facing, optimal tilt.
| State / Region | GHI (kWh/m²/day) | Annual Specific Yield (kWh/kW/yr) | 3 kW System Annual Generation | 5 kW System Annual Generation |
|---|---|---|---|---|
| Rajasthan | 5.8–6.5 | 1,650–1,850 | 4,950–5,550 units | 8,250–9,250 units |
| Gujarat | 5.5–6.0 | 1,570–1,710 | 4,710–5,130 units | 7,850–8,550 units |
| Madhya Pradesh | 5.3–5.8 | 1,510–1,650 | 4,530–4,950 units | 7,550–8,250 units |
| Maharashtra | 5.3–5.7 | 1,510–1,620 | 4,530–4,860 units | 7,550–8,100 units |
| Karnataka | 5.0–5.5 | 1,420–1,570 | 4,260–4,710 units | 7,100–7,850 units |
| Tamil Nadu | 5.0–5.5 | 1,420–1,570 | 4,260–4,710 units | 7,100–7,850 units |
| Telangana/AP | 5.0–5.4 | 1,420–1,540 | 4,260–4,620 units | 7,100–7,700 units |
| Delhi / Haryana | 4.8–5.2 | 1,370–1,480 | 4,110–4,440 units | 6,850–7,400 units |
| UP / Bihar | 4.8–5.0 | 1,370–1,420 | 4,110–4,260 units | 6,850–7,100 units |
| West Bengal | 4.5–5.0 | 1,280–1,420 | 3,840–4,260 units | 6,400–7,100 units |
| Odisha | 4.5–5.0 | 1,280–1,420 | 3,840–4,260 units | 6,400–7,100 units |
| Kerala | 4.0–4.8 | 1,140–1,370 | 3,420–4,110 units | 5,700–6,850 units |
| Assam / NE | 3.8–4.5 | 1,080–1,280 | 3,240–3,840 units | 5,400–6,400 units |
| Himachal Pradesh | 4.5–5.5 | 1,280–1,570 | 3,840–4,710 units | 6,400–7,850 units |
| Punjab | 4.8–5.2 | 1,370–1,480 | 4,110–4,440 units | 6,850–7,400 units |
GHI ranges: approximate state-level values used in this guide, see NREL India Solar Resource Data for the underlying resource maps. Yields calculated as GHI × 365 × 0.78.
The State-by-State Solar Yield Calculator
This four-step framework lets you compute your expected annual generation from any system size in any Indian state.
The State-by-State Solar Yield Calculator
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Look up your state’s GHI: Use the table above, or look up your location in the Global Solar Atlas (World Bank Group, Solargis). For precision, use your pincode-level irradiance from NREL’s PVWatts tool.
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Calculate your annual specific yield: Apply a performance ratio (PR) of 0.75–0.82 depending on system quality. Formula:
Annual Yield (kWh/kW) = GHI (kWh/m²/day) × 365 × PR. For Bangalore with GHI of 5.2 and PR 0.80:5.2 × 365 × 0.80 = 1,518 kWh/kW/yr. -
Multiply by system size: For a 5 kW system in Bangalore:
5 × 1,518 = 7,590 kWh per year(approximately 633 units/month average). -
Adjust for orientation and shading: South-facing = 100%. West-facing = subtract 12–18%. East-facing = subtract 15–20%. Partial shading = subtract 10–30% depending on severity. Final adjusted yield is your realistic annual generation estimate.
This framework produces a conservative, real-world estimate. Many installers quote the higher end of the range without accounting for PR losses, temperature derating, and shading, comparing your calculated estimate to their quote is useful quality control.
Monthly Variation: Why Summer and Monsoon Matter
Annual averages conceal the dramatic month-to-month variation in solar generation across Indian states. Understanding this variation helps you budget for your electricity bill correctly and set realistic expectations.
3 kW system in Rajasthan, monthly generation (approximate):
| Month | Generation (units) | Notes |
|---|---|---|
| January | 380–420 | Low sun angle, clear skies |
| February | 420–460 | Improving angle |
| March | 470–510 | Peak generation season |
| April | 500–540 | High irradiance, warm panels |
| May | 510–560 | Peak irradiance, some temperature derating |
| June | 420–480 | Monsoon onset, intermittent cloud |
| July | 320–380 | Full monsoon, significant cloud |
| August | 330–390 | Monsoon continues |
| September | 400–450 | Clearing up |
| October | 450–490 | Good generation, lower angles |
| November | 400–440 | Winter approaching |
| December | 360–400 | Shortest days |
| Annual total | 4,960–5,520 | Average: 413–460/month |
In Kerala, the June–September monsoon months can produce as few as 250–350 units per month from a 3 kW system, roughly half the annual average. This seasonal variation affects net metering credit accumulation and bill management strategies.
171.05 GW. India’s cumulative installed solar capacity on 30 September 2026, of which 33.41 GW was grid-connected rooftop solar. Source - MNRE capacity data as reported by Saur Energy, 8 October 2026.
Real Worked Examples: 3 kW, 5 kW, and 10 kW Systems
Example 1: 3 kW system in Jaipur, Rajasthan
- Annual specific yield: 1,750 kWh/kW/yr (middle of the Rajasthan range in the table)
- Annual generation: 3 × 1,750 = 5,250 units
- Monthly average: 438 units
- At an assumed ₹7.5/unit tariff: ₹39,375/year savings
- Self-consumption (70%, assumed): 3,675 units directly used
- Export (30%): 1,575 units at net metering credit
Example 2: 5 kW system in Bengaluru, Karnataka
- Annual specific yield: 1,500 kWh/kW/yr (middle of the Karnataka range in the table)
- Annual generation: 5 × 1,500 = 7,500 units
- Monthly average: 625 units
- At an assumed ₹8/unit tariff: ₹60,000/year savings
- Self-consumption (65%, assumed): 4,875 units directly used
- Export (35%): 2,625 units at net metering credit
Example 3: 10 kW system in Pune, Maharashtra
- Annual specific yield: 1,560 kWh/kW/yr (middle of the Maharashtra range in the table)
- Annual generation: 10 × 1,560 = 15,600 units
- Monthly average: 1,300 units
- At an assumed ₹9/unit tariff: ₹1,40,400/year savings
- Self-consumption (60%, assumed): 9,360 units directly used
- Export (40%): 6,240 units at net metering credit
The self-consumption ratio matters because exported units typically earn a lower return than directly consumed units in most net metering structures. Maximising self-consumption through load scheduling (running high-consumption appliances during the day) improves overall financial return.
What Reduces Solar Generation Below Expectations
Several factors can reduce actual generation below the theoretical estimates shown above. Understanding them helps you evaluate installer quotes critically.
- Soiling and dust: Dust accumulation on panel surfaces reduces generation by 5–20% in dusty regions (Rajasthan, UP, Delhi). Monthly cleaning in the dry season restores output. For tips on maximising output, see how to maximise solar output in Indian climate.
- Shading: A shadow covering just 10% of one panel can reduce that entire string’s output by 25–40% due to series connection physics. A thorough shade analysis at the site survey stage is non-negotiable.
- Panel degradation: Quality panels degrade at 0.5–0.7% per year. At Year 10, output is approximately 95% of original; at Year 25, approximately 80–85%.
- Inverter clipping: If your inverter is undersized relative to the panel array, it limits output at peak irradiance hours, the inverter effectively clips the peak. See inverter clipping explained for the diagnosis and fix.
- High ambient temperature: Panel output drops 0.4–0.5% per °C above 25 °C. On a 45 °C ambient day in Rajasthan, panel temperatures reach 60–70 °C, reducing nameplate output by 14–18%.
How to Use This Data When Evaluating Installer Quotes
Every reputable solar installer should provide a Detailed Project Report (DPR) or simulation software output that shows:
The string sizing calculator helps you verify whether the quoted panel and inverter combination is correctly matched for your state’s irradiance profile.
Where Qbits Fits in Maximising Your State’s Solar Yield
- On-Grid Inverters: Review the current product families and exact-model documents against the project design and utility requirements.
- Hybrid Inverters: Review current QBH model documents and confirm the exact battery, firmware, PV, backup-output, transfer, communication, warranty and project requirements in writing.
- Authorised Service Partners: Search the current directory, then confirm partner status, location coverage, service scope, response process and fees in writing.
Contact Qbits with the exact model, site inputs and documents relevant to the request. Confirm the responsible party, deliverable, fees and response time after submission.
Frequently Asked Questions
How many units does a 1 kW solar panel generate per day in India?
How many units does a 3 kW solar system generate per month?
What is peak sun hours and how does it affect solar generation?
How does monsoon affect solar generation in India?
Does panel orientation affect how much electricity solar generates?
What is performance ratio (PR) in a solar system?
How do I calculate how many units my solar system will generate?
How much electricity does a 5 kW solar system generate in India?
Keyur Rakholiya CTO, Qbits Energy
Listed by Qbits as its CTO. Current role, technical responsibilities and credentials require confirmation by the company owner.