SolarCalculatorsSolar Panel Output in Winter & Fog — North India Guide 2026
Why Output Drops in Winter
- Shorter days: fewer hours of usable sunlight.
- Lower sun angle: light hits panels at a steeper angle and passes through more atmosphere.
- Fog, smog and haze: the biggest factor in the Indo-Gangetic plain; thick fog blocks most direct sunlight.
- Dust and soot on panels: winter smog leaves a film that also cuts output.
Cold itself is not the problem: panels are actually slightly more efficient at lower temperatures.
Typical Daily Output for a 3kW System (North India)
| Condition | Approx. units/day |
|---|---|
| Clear day, April–May | 13–15 |
| Yearly average | about 12 |
| Clear winter day (Dec–Jan) | 9–11 |
| Hazy / light fog day | 5–8 |
| Dense fog all day | 0–3 |
These are typical ranges; actual output depends on your city, tilt, shading and panel cleanliness. Compare your own inverter app readings with these numbers.
Does Net Metering Cover the Winter Gap?
Under net metering, extra units exported in spring and summer are credited against your bill. Many DISCOMs carry the surplus forward month to month and settle at the end of the year, so a sunny April can offset a foggy January. Check your DISCOM's settlement rules, because some settle surplus at a low rate at year-end.
What You Can Do
- Clean panels more often in winter: smog film builds up quickly; a rinse every 1–2 weeks helps.
- Check tilt: a tilt close to your latitude (about 25–30° in North India) balances summer and winter output.
- Trim new shade: the low winter sun casts longer shadows from water tanks and parapets.
- Size on yearly units, not winter units: sizing for the worst month leads to an oversized, expensive system.
Do You Need a Battery for Foggy Days?
Only if you face long power cuts. A battery stores daytime solar, but on a fully foggy day there is little to store. For grid-connected homes, net metering is usually the cheaper way to handle low-output days.
Month-by-Month Solar Generation in North India
For a 1 kW system in Delhi, Lucknow, Chandigarh or Jaipur, a typical pattern is:
| Months | Approx. units per kW per day |
|---|---|
| March–May | 4.5–5.0 |
| June–September (monsoon) | 3.5–4.2 |
| October–November | 3.8–4.3 |
| December–January | 2.8–3.6 |
| February | 3.8–4.3 |
Multiply by your system size: a 5kW system makes roughly 14–18 units on a clear winter day. Use our solar generation calculator for your city.
Is Rooftop Solar Still Worth It in Foggy Cities?
Yes. Fog affects a few weeks of the year, while the other months produce well. A 3kW system in North India still makes about 4,000–4,400 units a year, which is why payback stays around 4–6 years. See the 3kW solar panel price page for cost and savings, or check solar in Delhi and solar in Uttar Pradesh for state subsidy details.
How to Check Your System Is Working Normally in Winter
- Compare today's units with a clear day last week, not with May.
- Look for one string or panel producing far less than others (shade or dirt).
- An inverter error, not just low units, means you should call the installer.
Before you talk to installers, run your numbers on our free solar calculator to see the system size, cost after subsidy and payback for your bill.
Frequently Asked Questions
Do solar panels work in fog?
Yes, but output falls sharply. Light fog cuts output roughly in half; dense fog all day can reduce it to almost nothing.
How many units does a 3kW solar system produce in winter in Delhi?
On clear winter days roughly 9–11 units a day, lower on hazy or foggy days. The yearly average is about 12 units a day.
Are solar panels less efficient in cold weather?
No. Cold temperatures slightly improve panel efficiency. Winter output drops because of shorter days, a low sun and fog.
Should I clean solar panels more in winter?
Yes, in smog-prone cities a rinse every 1–2 weeks in winter helps, because soot and dust films build up faster.