Rooftop Solar Generation by Indian City: What to Expect Where You Live

Solar output varies up to 45% across Indian cities due to sunlight, monsoons, and heat. A 3kW system yields ~5,100 units/yr in Jodhpur vs ~3,450 in Guwahati. Know your city's yield before evaluating quotes or PM Surya Ghar subsidies.

In this article,

• Why Your City Determines Your Solar Payback

• How to Read the Generation Table

• The City-by-City Generation Table

• Which Cities Have the Highest Summer Derating Risk

• How to Sanity-Check an Installer's Generation Estimate

• PM Surya Ghar ROI by City

• Frequently Asked Questions

A 3 kW rooftop system in India generates 3,450 to 5,100 units per year depending on location. This reference covers 11 cities across 10 states, with annual yield per kWp, monsoon impact, and summer derating risk for each. Zenergize publishes this as a standalone resource for homeowners and small-business owners comparing system options by location.

Why Your City Determines Your Solar Payback

The payback period on a rooftop solar installation is not a fixed number. It shifts with every degree of latitude, every monsoon pattern, and every dust corridor that runs across a state. An installer who quotes the same generation figure for Delhi as for Bangalore is working from a template, not from data.

Three variables control how much electricity a solar panel generates in a given location.

1. Global Horizontal Irradiance (GHI)

The total solar energy falling on a horizontal surface per square metre per year, measured in kWh/m2. Rajasthan registers GHI values of 2,000 to 2,200 kWh/m2 annually. Assam records 1,200 to 1,500 kWh/m2 in the same period. That gap flows directly into the kilowatt-hours a panel produces.

2. Monsoon duration and cloud cover

A city's annual GHI tells only part of the story. The months during which GHI drops to near zero determine how much of the year a system operates near rated capacity. Chennai faces two monsoon windows: the southwest (June to September) and the northeast (October to December), creating two separate low-production periods per year. Guwahati receives the heaviest annual rainfall of any major Indian city, with persistent cloud cover across five to six months.

3. Ambient summer temperature

Above 40 to 42 degrees C ambient temperature, standard silicon-based inverters reduce output to protect internal components. In Jodhpur, Ahmedabad, and Delhi, May afternoon temperatures routinely exceed 43 degrees C. During the peak generation window of 11am to 3pm, when a system produces approximately 60 percent of its daily yield, a thermally-derating inverter loses generation precisely when the solar resource is most available.

The combination of these three variables means two cities with similar annual GHI can produce very different real-world generation. Two cities with similar peak sun hours can have very different payback periods.

How to Read the Generation Table

The table in the next section presents five data points for each city.

Annual GHI (kWh/m2): Raw solar resource. Higher is better.

Peak sun hours per day: The number of hours during which solar irradiance equals 1,000 W/m2, matching Standard Test Conditions. A city with 5.5 peak sun hours receives 5.5 times more energy per day than a theoretical location receiving exactly 1 kW/m2 for one hour. This is the standard metric used in PM Surya Ghar subsidy calculators.

Annual yield per kWp (kWh): The kilowatt-hours a 1 kWp system is expected to produce per year, after accounting for a Performance Ratio (PR) of 0.80. PR captures real-world losses from inverter efficiency, temperature, wiring, and soiling. A 3 kWp system multiplies this figure by three.

Monsoon impact: A qualitative rating of how much cloud cover and rainfall reduce generation during monsoon months. Rated Minimal, Moderate, Significant, or Heavy.

Summer derating risk: Whether the city's summer ambient temperatures are likely to trigger thermal derating in a standard IGBT inverter. Rated HIGH (above 43 degrees C in May), MODERATE (41 to 42 degrees C), or LOW (below 40 degrees C).

One note on degradation: solar panels lose approximately 0.5 percent of output per year under standard conditions. Over 25 years, a system retains roughly 87 to 88 percent of its original capacity. All yield ranges in the table reflect Year 1 output.

The City-by-City Generation Table

Data sources: NREL NSRDB (June 2026), SolarCalculators.in regional generation calculator (2026).

Key findings from the data

Finding 1: Jaipur Performs Close to Jodhpur, With Higher Dust Risk

Jaipur's 1,600-1,750 kWh/kWp annual yield sits just below Jodhpur's 1,700-1,800. On a 3 kWp system, Jaipur generates approximately 4,950 units per year. The practical difference from Jodhpur is small (around 150 units annually, worth roughly Rs 1,200 at Rs 8/unit), but Jaipur carries equally high summer derating risk and comparable dust soiling pressure in the pre-monsoon months. Homeowners in Jaipur considering a standard IGBT inverter should factor the same summer derating losses that apply in Jodhpur.

Finding 2: Bhopal Sits in the Mid-Table Band with a Hidden Heat Risk

Bhopal at 1,500–1,600 kWh/kWp per year sits between Hyderabad and Bangalore in yield. What makes Bhopal notable is its May temperature: at 42–43°C, it sits at the boundary of MODERATE and HIGH derating risk. A standard IGBT inverter will derate intermittently rather than consistently, making generation losses harder to predict. A system in Bhopal should be evaluated with the same care given to Delhi or Nagpur regarding inverter selection.

Finding 3: Rewari Outperforms Delhi. But Carries the Same Heat Penalty

Rewari (Haryana) lies approximately 80 km southwest of Delhi and benefits from slightly lower pollution and humidity, resulting in marginally better GHI (1,700-1,800 vs 1,680-1,780 kWh/m²). Annual yield per kWp is estimated at 1,450-1,550 kWh. However, May temperatures in Rewari reach 43-45°C, placing it firmly in HIGH summer derating risk, identical to Delhi. The dust soiling profile is also comparable. Rewari homeowners should apply the same inverter selection criteria as Delhi homeowners.

Finding 4: Mohali/Chandigarh Has a Winter Generation Gap Others Don't

Most Indian cities see their lowest monthly generation during peak monsoon (July-August). Mohali/Chandigarh has a second low-production window: December and January, when dense fog across the Punjab plains can reduce effective peak sun hours to 2.5–3.0 hours per day for weeks at a time. Annual yield of 1,300-1,450 kWh/kWp reflects both the monsoon loss and this fog-season penalty. Homeowners in Mohali/Chandigarh should request a monthly generation profile from their installer, a flat annual estimate will overstate winter output.

Finding 5: The Rajasthan Premium Persists Across Both Cities

Jodhpur's 1,700–1,800 kWh/kWp annual yield versus Guwahati's 1,150-1,250 kWh/kWp represents a 36 to 57% advantage in raw generation per kWp installed. Jaipur's addition confirms this is a regional pattern, not a Jodhpur-specific outlier. On a 3 kWp system, a Jaipur homeowner generates approximately 1,500 more units per year than a Guwahati homeowner, worth Rs 12,000 at Rs 8/unit, or Rs 3.0 lakh over a 25-year system life.

Finding 6: Delhi's Counterintuitive Performance

Delhi receives higher GHI than Bangalore in winter months, yet annual yield per kWp lands in a similar range (1,400–1,500 versus 1,450–1,550 kWh/kWp). Two factors close the gap: Delhi's summer dust soiling is among the highest in the country, requiring cleaning every two to three weeks in May and June; and Delhi carries HIGH summer derating risk, meaning a standard inverter reduces output during the peak hours when Delhi's strong summer sun is most available.

Which Cities Have the Highest Summer Derating Risk

Standard IGBT-based inverters are rated to operate at full efficiency up to approximately 40 to 42 degrees C ambient temperature. Above that threshold, the inverter's internal protection logic reduces output to prevent component failure. This is thermal derating: the inverter deliberately generates less electricity to avoid overheating.

Industry documentation places the effective derating onset for standard inverters at sustained ambient temperatures above 40 to 42 degrees C. Three cities in this table routinely exceed that threshold during May and June: Jodhpur (May average peak: 46 degrees C), Ahmedabad (44 degrees C), and Delhi (43 degrees C). Nagpur and Lucknow fall into moderate risk, with May temperatures in the 41 to 42 degrees C range.

Quantifying the silent generation loss

On a 3 kWp system generating approximately 18 units per day during peak summer season, a thermally-derating inverter loses 8 to 12 percent of output during the 11am to 3pm window. That four-hour block contributes roughly 60 percent of the day's total yield. Over May and June combined:

Derating loss calculation (3 kWp system, HIGH-risk cities)

• Daily loss during derating hours: 1.4 to 2.2 units (8 to 12 percent of 18 units)

• Season length: May and June combined = 61 days

• Total seasonal loss: 85 to 134 units

• Lost savings: Rs 680 to Rs 1,072 per summer season (at Rs 8/unit)

• Over 10 years: Rs 6,800 to Rs 10,720 in generation value permanently lost to heat

This is generation that cannot be recovered. It occurs during the period when the sun is most available, peak tariff is often in effect, and households draw most heavily from the rooftop system to run air conditioning.

A Zenergize SiC inverter carries a rated operating temperature of 55 degrees C ambient with zero derating at full load. In Jodhpur, Ahmedabad, and Delhi, the SiC variant captures the generation that a standard IGBT inverter sacrifices during the hottest two months of the year.

For a detailed breakdown of how thermal derating compounds over a system lifetime, see Solar Inverter Thermal Derating.

For a technical comparison of SiC versus IGBT inverter architecture in Indian rooftop conditions, see Why Indian Rooftops Need SiC Inverters.

How to Sanity-Check an Installer's Generation Estimate

Before signing an installation agreement, one calculation separates realistic quotes from inflated ones.

Divide the quoted annual generation by the system's kWp.

If a Delhi installer quotes a 3 kWp system producing 6,000 units per year, that implies 2,000 kWh per kWp annually. The table above shows Delhi's realistic range is 1,400 to 1,500 kWh per kWp. The quote exceeds documented irradiance data by 33 to 43 percent. Either the installer is misrepresenting performance or has not accounted for real-world PR losses.

The standard cross-check:

1. Take the quoted annual generation in units (kWh)

2. Divide by system capacity in kWp

3. Compare to the city's documented annual yield range in the table above

If the result exceeds the table's upper bound by more than 10 percent, request a written breakdown showing the irradiance data source, the PR assumption, and the soiling and shading loss estimates.

Red flags in a generation quote:

• Annual yield per kWp quoted above 1,900 kWh for any Indian city (NREL NSRDB data shows no major Indian city exceeds 1,850 kWh/kWp at realistic PR)

• No mention of Performance Ratio in the estimate documentation

• Generation estimate presented as a single number rather than a range

• Monsoon months not broken out separately in a monthly generation profile

A secondary reference check: SolarCalculators.in publishes a regional generation calculator (2026) that returns city-level annual yields. A Jodhpur 3 kW system returns approximately 6,800 units per year on that platform; a Guwahati 3 kW system returns approximately 4,600 units. The 48 percent difference is consistent with the irradiance data in the table above.

For a full checklist of inverter selection criteria including efficiency ratings and warranty terms, see How to Choose a Solar Inverter in India.

PM Surya Ghar ROI by City

The PM Surya Ghar Muft Bijli Yojana offers a central subsidy of Rs 78,000 on a 3 kW rooftop solar installation. At a gross system cost of approximately Rs 1.5 lakh for a 3 kWp system, the net cost after subsidy is approximately Rs 72,000. ROI depends entirely on annual generation, which depends on the city.

The following payback calculations use two tariff assumptions: Rs 6 per unit (conservative) and Rs 8 per unit (reflecting time-of-use or export tariff levels in some states). Actual tariffs vary by state and distribution company. These figures are for comparison purposes.

Three ROI observations:

1. The subsidy equalises access but not returns. A homeowner in Guwahati and a homeowner in Jodhpur receive the same Rs 78,000 central subsidy. After that, the Jodhpur homeowner generates 48% more electricity per year and reaches payback roughly 0.8 to 1.0 years sooner at equivalent tariffs.

2. Jaipur and Rewari are strong performers for their latitude. Both cities sit above the national median for annual yield despite being in northern India. Jaipur's Rajasthan location gives it a resource advantage; Rewari benefits from slightly lower urban pollution losses versus Delhi.

3. Mohali/Chandigarh homeowners should confirm winter generation figures. The fog-season suppression of December–January generation means the annual yield figure understates mid-year performance and overstates winter performance relative to a city at the same annual figure but without fog.

4. State tariffs matter more in low-irradiance cities. In Guwahati, where annual yield is lower, a higher per-unit export tariff has a proportionally larger impact on payback time. Assam's actual net metering rates should be confirmed with the state DISCOM before finalising ROI calculations. Similarly, Haryana's tariffs are relevant for Rewari, and Punjab/UT tariffs for Mohali/Chandigarh.

5. Delhi's derating risk creates a hidden ROI gap. Delhi's quoted payback assumes full generation during summer months. The Rs 680 to Rs 1,072 per summer season derating loss is not captured in the standard payback estimate. The same gap applies to Rewari and Jaipur at equivalent inverter specifications.

For a detailed guide on which inverters qualify for the PM Surya Ghar subsidy and how to submit the application, see PM Surya Ghar Subsidy: Which Solar Inverter Qualifies?.