Peak Sun Hours & Shadow Calculator 2026

Lucknow solar resource

Annual Avg PSH

5.18

hours/day

Best Month

6.4 h

May

Worst Month

4.2 h

Dec

Annual Yield / kW

1437 kWh

After 5% shadow

Month-by-month peak sun hours

What this means for your system

A 1 kW system in Lucknow will generate roughly 1437 kWh/year. A 3 kW system generates ~4311 kWh/year, 5 kW generates ~7185 kWh/year.

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How to estimate solar yield for your city

Step-by-step guide to calculating peak sun hours and annual solar production.

Pick your city

Select the nearest major city from our list. Smaller towns inherit the closest metro's PSH.

Estimate shadow loss

Walk your roof between 10am and 2pm. Note shade from trees, buildings, tanks. 0-5% for clear roofs, 10-20% for partial shade.

Read annual yield per kW

The calculator outputs kWh/year/kW. Multiply by your desired system size.

Review seasonal chart

Note best and worst months. High seasonal swing means you'll net-meter a lot during summer and draw from grid in monsoon.

Size system for annual need

Use annual production ÷ your annual consumption. Aim for 90-100% offset with net metering.

The single most important number in solar

Everything in solar planning — system size, payback, EMI, subsidy value — depends on how much sun your specific location gets. That number is peak sun hours (PSH), and it varies from 3.5 to 6.0 across India depending on city and month. Sizing a system without accounting for your actual PSH is the fastest way to be disappointed six months after installation.

Why "India gets lots of sun" isn\'t specific enough

India averages ~5 PSH, but that hides a 40% swing across cities. A 5 kW system in Jaipur (5.5 avg PSH) produces 8,000 kWh/year. The same 5 kW in Kolkata (4.6 PSH) produces 6,700 kWh/year. That's a ₹10,000-15,000/year difference in bill savings — enough to change your payback period by 1-2 years.

Shadow is worse than you think

Shading one cell of a 72-cell panel can reduce the panel's output by 30%+ due to string effects and bypass diode behavior. A 10% shaded array can lose 25% of its yield. The fix is expensive (microinverters or optimizers) — the better solution is to avoid shading in the first place. Walk your roof between 10am and 3pm on a sunny day and note every shadow.

Once you know your city's PSH, lock in orientation using our Tilt Angle Calculator and Azimuth Calculator, then convert the final yield into rupees with the Payback Calculator.

Frequently Asked Questions

What are peak sun hours?

Peak sun hours (PSH) represent how many hours per day the sun delivers the equivalent of 1 kW/m² of irradiance. A "4.5 PSH" location means 1 kW of panel generates ~4.5 kWh/day on a tilted plane. PSH is the single most useful number for estimating solar output.

How many peak sun hours does India get?

India averages 4.5-6.0 PSH across the year, among the best in the world. North India (Lucknow, Delhi) averages 5.0-5.2; Rajasthan 5.5-6.0; Western India (Mumbai, Ahmedabad) 5.2-5.8; South India (Chennai, Bengaluru) 5.3-5.5. Our calculator has monthly data for 12+ major cities.

Why is June-August PSH lower in India?

Monsoon season. Cloudy days and humidity reduce direct irradiance by 30-40% in July-August for most of India. Mumbai gets 6.6 PSH in March but only 3.5 in July. This seasonal swing is why solar system sizing uses annual average, not peak month.

How do I calculate annual output from PSH?

Annual kWh per kW ≈ PSH × 365 × 0.8 (system efficiency). For Lucknow at 5.0 PSH: 5.0 × 365 × 0.8 = 1460 kWh/year/kW. A 5 kW system produces ~7,300 kWh/year. Our calculator does this math and applies a shadow loss if you have partial shading.

What is shadow loss?

Shadow loss is the yield reduction when trees, neighboring buildings, water tanks, or chimneys block sunlight during peak production hours (10am-2pm). Even a small shadow on one panel can reduce the whole string's output by 30-50%. Aim for shadow-free panels between 10am and 3pm.

How accurate is city-level PSH data?

City-level PSH (from MNRE, NIWE, and NASA SSE) is accurate within ±5% for well-sited rooftops. Micro-climate effects (valleys, high-rise shadow, dust accumulation) can deviate 10-15%. For financial planning, use the city average; for production performance, do an on-site irradiance survey.

How much does shading reduce my solar output?

Partial shade (5-10% of array) reduces output 15-25% due to string effects. Afternoon shade (4pm-6pm) reduces output ~5%. Morning shade on a westward-facing system reduces output 10-15%. The most valuable hours are 10am-3pm — prioritize clear access there.

Do solar panels work in cloudy weather?

Yes, but at 10-25% of clear-sky output. Light diffuses through clouds and modern panels still harvest it. Overcast days produce ~0.5-1.5 PSH vs clear days at 5-6 PSH. Most of India only has 20-30 truly overcast days per year.

Peak Sun Hours & Shadow Calculator

Location & shading