Published by: PSP Studio Odia

Category: Solar Energy • PM Surya Ghar • Solar Maintenance • Renewable Energy

Quick Answer

Solar panels continue generating electricity even during cloudy and rainy weather, but their output usually drops because less sunlight reaches the solar cells. Other factors such as muddy panels, shorter daylight hours, poor wiring, shading, and improper maintenance can further reduce electricity generation. Fortunately, following a few simple maintenance tips can significantly improve solar performance during the monsoon season.

📑 Table of Contents

Introduction
Why Does Solar Generation Drop During Rainy Season?
Reason #1 – Cloud Cover
Reason #2 – Mud, Dust & Dirt
Reason #3 – Shorter Daylight Hours
Solar Output Comparison
5 Proven Tips to Increase Solar Output
Special Tips for Off-Grid Users
Mono PERC vs Polycrystalline Panels
Solar Maintenance Checklist
Frequently Asked Questions
Official Resources
Final Thoughts

Introduction

The monsoon season has officially arrived across Odisha, bringing welcome relief from the scorching summer heat. However, for thousands of homeowners and business owners who have installed rooftop solar systems under the PM Surya Ghar Muft Bijli Yojana, the rainy season often brings a different concern:

Common Question

"Why is my solar system generating much less electricity during the rainy season?"

If you own an On-Grid Solar System, you may have noticed that your daily electricity generation suddenly drops during cloudy weather. If you use an Off-Grid Solar System, your battery may take much longer to charge, reducing backup time at night.

Many people believe this happens only because there is no direct sunlight. While that is certainly one reason, it is not the only one.

In reality, several environmental and technical factors work together to reduce solar panel efficiency during the monsoon.

In this comprehensive guide, you'll learn:

Why solar generation decreases during rainy weather
The science behind cloud cover and solar panels
How dust and mud reduce electricity production
Why daylight hours matter
How to maximize solar output during the rainy season
Special maintenance tips for both On-Grid and Off-Grid users
The best type of solar panel for low-light conditions

Whether you already have a rooftop solar system or are planning to install one under the PM Surya Ghar Scheme, this guide will help you understand how to keep your solar plant performing efficiently even during bad weather.

Cloudy weather reduces solar output, but proper maintenance can improve performance significantly.

Why Does Solar Power Generation Drop During the Rainy Season?

Before learning how to improve solar performance, it is important to understand why electricity generation falls in the first place.

Modern solar panels are designed to work in various weather conditions, including cloudy days. They do not stop producing electricity completely during the rainy season.

However, because the amount of sunlight reaching the photovoltaic (PV) cells decreases, the electrical output also drops.

Besides sunlight, several additional factors also contribute to lower performance, including:

Heavy cloud cover
Mud and dust accumulation
Reduced daylight hours
Shading from nearby trees
Poor wiring or loose MC4 connectors
Water ingress in damaged cables
Improper tilt angle
Battery charging limitations in Off-Grid systems

Let's understand each reason in detail.

Reason #1 – Cloud Cover Blocks Solar Radiation

The biggest reason behind reduced solar generation during monsoon is cloud cover.

Solar panels generate electricity using tiny particles of sunlight called photons. When these photons strike the photovoltaic cells, they create an electrical current.

During clear summer days, sunlight reaches the solar panels directly, producing maximum power.

During the rainy season, however, thick clouds scatter and absorb a significant portion of the sunlight before it reaches the panels.

Although some diffused sunlight still reaches the modules, the intensity becomes much lower.

Typical Solar Output During Different Weather Conditions

☀ Bright Sunny Day → 90–100% output
⛅ Partly Cloudy → 60–85% output
☁ Heavy Cloud Cover → 30–60% output
🌧 Continuous Rain → 10–40% output (depending on cloud density)

It is important to understand that your solar panels are not faulty if electricity generation decreases during rainy weather. This is completely normal and expected.

High-quality Mono PERC and TOPCon solar panels generally perform better in low-light conditions compared to older Polycrystalline modules.

Solar Generation Comparison

Weather	Sunlight Level	Expected Solar Output
Clear Summer Day	Very High	90–100%
Light Clouds	High	70–90%
Moderate Clouds	Medium	50–70%
Heavy Rain Clouds	Low	20–50%
Continuous Heavy Rain	Very Low	10–30%

Did You Know?

Solar panels actually operate more efficiently at cooler temperatures. During monsoon, the panel temperature decreases, which slightly improves electrical efficiency. However, the benefit is much smaller than the loss caused by reduced sunlight, so overall power generation still drops.

Reason #2 – Mud, Dust & Dirt Reduce Solar Panel Efficiency

Many people believe that rain naturally cleans solar panels. In reality, this is only partially true.

During the summer season, a layer of dust, pollen, bird droppings, dry leaves, and pollution gradually accumulates on the glass surface of solar panels. When the first heavy rain arrives, this dust mixes with water and forms a thin layer of mud instead of washing away completely.

This muddy layer blocks sunlight from reaching the photovoltaic (PV) cells, reducing electricity production significantly.

Expert Tip

Even a thin layer of dirt can reduce solar production by 5–15%. Heavy mud, bird droppings, or leaves covering one section of the panel may reduce production by 20–40% depending on the panel configuration.

This is because solar cells inside a panel are connected in series. If one section becomes shaded or dirty, the performance of the entire string may decrease.

Mud, bird droppings and dust can significantly reduce solar power generation.

Common Dirt Found on Rooftop Solar Panels

Cause	Impact on Generation
Dust	Low to Moderate
Mud after Rain	Moderate to High
Bird Droppings	High
Dry Leaves	Moderate
Tree Sap	Moderate
Algae or Moss	High

Reason #3 – Shorter Daylight Hours

Another major reason for reduced electricity generation during the monsoon season is the shorter duration of usable sunlight.

During summer, solar panels may receive strong sunlight from early morning until late evening. However, during the rainy season:

The sun rises later.
Cloud cover remains throughout the day.
Sunset occurs earlier.
Heavy rain interrupts sunlight repeatedly.

As a result, the total "Peak Sun Hours" available for electricity generation decrease considerably.

Peak Sun Hours Explained

Peak Sun Hours represent the equivalent number of hours when solar irradiance averages approximately 1,000 W/m². Even if daylight lasts for 10 hours, effective peak generation may occur only for 3–5 hours depending on weather conditions.

Typical Solar Generation in Odisha

Solar System	Summer	Rainy Season
1 kW	4–5 Units/day	2–3 Units/day
2 kW	8–10 Units/day	4–6 Units/day
3 kW	12–15 Units/day	6–9 Units/day
5 kW	20–25 Units/day	10–15 Units/day

Actual generation depends on location, panel technology, orientation, weather conditions, maintenance, and system efficiency.

Does Rain Damage Solar Panels?

This is another common question asked by many solar users.

The answer is generally no.

Modern solar panels are designed to withstand harsh outdoor environments, including heavy rain, wind, humidity, and temperature changes. Most certified panels are tested according to international standards before reaching the market.

However, poor installation or damaged components can create problems.

Potential Risks During Monsoon

Loose MC4 connectors
Broken cable insulation
Improper earthing
Water entering junction boxes
Damaged conduits
Weak mounting structures

These issues usually arise due to installation quality rather than rainfall itself.

Why On-Grid Users Notice Lower Generation

If you have installed a rooftop solar system under the PM Surya Ghar Muft Bijli Yojana, your system is most likely an On-Grid Solar System.

An On-Grid inverter synchronizes with the utility grid and converts DC electricity from solar panels into AC electricity for your home and the electricity network.

When sunlight decreases:

Solar generation falls.
Household loads continue consuming electricity.
Less surplus electricity is exported to the grid.
Your net meter records lower export units.
Grid import increases if your consumption remains high.

Example

Suppose your 3 kW solar system normally generates 14 units per day during summer.

During continuous rainy weather, it may generate only 7 units.

If your household still consumes 12 units daily, the remaining 5 units will automatically be imported from the electricity grid.

Why Off-Grid Batteries Charge Slowly During Rain

Off-Grid systems depend entirely on solar panels for battery charging.

When solar production decreases, the battery receives less charging current.

This causes:

Longer charging time
Reduced backup duration
Frequent deep discharge
Lower battery life if repeated continuously

Many homeowners mistakenly think their inverter or battery is faulty, whereas the real issue is insufficient solar energy caused by poor weather.

Important

If your Off-Grid inverter supports Grid Charging Mode, enabling it during extended rainy periods can help keep your battery fully charged whenever utility power is available.

How Much Power Loss is Normal?

Condition	Expected Output Loss
Light Cloud Cover	10–25%
Heavy Cloud Cover	30–50%
Continuous Rain	40–70%
Dirty Panels	5–20%
Tree Shading	10–80%
Cable Issues	Variable

5 Proven Tips to Increase Solar Power Generation During the Rainy Season

Although you cannot control the weather, you can significantly improve your solar system's performance by following a few proven maintenance practices. These recommendations are based on industry best practices and are suitable for both residential and commercial rooftop solar systems.

Quick Summary

✔ Clean your solar panels regularly.
✔ Maintain the correct tilt angle.
✔ Inspect cables and MC4 connectors.
✔ Ensure proper earthing and lightning protection.
✔ Maintain Off-Grid batteries properly.
✔ Choose Mono PERC or TOPCon panels for better low-light performance.

Tip #1 – Keep Solar Panels Clean

The easiest way to improve solar output during the rainy season is to keep the panel surface clean.

Many homeowners assume rain automatically washes the panels. In reality, the first few rains often create a layer of mud by mixing dust with rainwater. Bird droppings, leaves, algae, and pollution can also accumulate over time.

This layer blocks sunlight from reaching the photovoltaic cells and directly reduces power generation.

Best Cleaning Practices

Use clean water whenever possible.
Use a soft microfiber cloth or sponge.
A rubber wiper can help remove excess water.
Never use hard brushes or metal tools.
Avoid strong chemical cleaners.
Clean the panels early morning or late evening when they are cool.

Safety First: Never climb onto a wet rooftop without proper safety equipment. If your roof is steep or slippery, hire a professional solar maintenance technician.

Cleaning mud, dust, and bird droppings helps restore solar efficiency. - PSP STUDIO ODIA

Tip #2 – Maintain the Correct Tilt Angle

Panel angle plays an important role in overall solar performance.

If panels are installed completely flat, rainwater may remain on the surface for a longer time. Dirt and mud are also more likely to accumulate.

A proper tilt angle allows rainwater to flow away naturally, helping keep the glass cleaner.

Recommended Tilt Angle for Odisha

Location	Recommended Tilt
Odisha	20°–25° Facing South

Your installer normally determines the best angle based on location, roof structure, and annual solar radiation.

Tip #3 – Inspect Wiring, MC4 Connectors & Earthing

Rain increases the possibility of electrical problems if the installation quality is poor.

While certified rooftop solar systems are designed to withstand rain, damaged wiring or loose connectors can still create safety issues.

Inspect the Following Items

MC4 connectors
DC cables
AC cables
Junction boxes
Earthing connections
Conduit pipes
Cable clips
Mounting structure bolts

If you notice damaged insulation, exposed wires, or water entering electrical boxes, contact your installer immediately.

Lightning Safety

Odisha experiences frequent thunderstorms during the monsoon. Ensure your rooftop solar system includes:

✔ Lightning Arrester
✔ Proper Earthing
✔ Surge Protection Device (SPD)

These components protect your inverter, solar panels, and household appliances from voltage surges caused by lightning.

Tip #4 – Maintain Off-Grid Batteries Properly

If you use an Off-Grid or Hybrid Solar System, battery maintenance becomes especially important during prolonged rainy weather.

Since less electricity is generated, batteries take longer to recharge.

Battery Maintenance Checklist

Check battery health regularly.
Inspect battery terminals for corrosion.
Maintain proper distilled water level (Lead-Acid batteries).
Avoid deep discharge whenever possible.
Enable Grid Charging Mode if available.
Monitor battery voltage regularly.

Lithium batteries require much less maintenance than lead-acid batteries, but regular monitoring is still recommended.

Tip #5 – Choose Mono PERC or TOPCon Solar Panels

If you are planning to install a new rooftop solar system, panel technology matters.

Modern Mono PERC and TOPCon panels perform significantly better under low-light conditions compared to traditional Polycrystalline panels.

Comparison Table

Feature	Poly Panel	Mono PERC	TOPCon
Efficiency	15–17%	20–22%	22–24%
Low-Light Performance	Average	Very Good	Excellent
Summer Performance	Good	Excellent	Excellent
Rainy Season Performance	Average	Better	Best
Cost	Lower	Medium	Higher

Extra Maintenance Tips

Task	Recommended Frequency
Panel Cleaning	Every 15–30 Days
Visual Inspection	Monthly
Cable Inspection	Every 6 Months
Earthing Test	Annually
Professional Maintenance	Once Every Year

Common Mistakes to Avoid During Monsoon

❌ Walking directly on solar panels.
❌ Cleaning panels during heavy rain.
❌ Using detergent or acid cleaners.
❌ Ignoring loose wiring.
❌ Allowing trees to shade the panels.
❌ Blocking drainage around rooftop installations.
❌ Ignoring inverter warning messages.

Pro Maintenance Tip

Most modern solar inverters provide daily generation data through Wi-Fi monitoring apps. Compare your daily production with previous weeks. If the drop is unusually high despite similar weather, inspect your panels or contact your installer.

Complete Solar Maintenance Checklist for the Rainy Season

Use this checklist every monsoon to keep your rooftop solar system operating safely and efficiently.

Maintenance Item	Status	Recommended Frequency
Clean Solar Panels	☐	Every 15–30 Days
Check Panel Glass	☐	Monthly
Inspect Mounting Structure	☐	Every 6 Months
Inspect MC4 Connectors	☐	Every 6 Months
Check DC Wiring	☐	Every 6 Months
Check Earthing	☐	Yearly
Lightning Arrester Inspection	☐	Yearly
Monitor Daily Generation	☐	Daily
Battery Maintenance (Off-Grid)	☐	Monthly

Frequently Asked Questions (FAQs)

1. Do solar panels work during rainy weather?

Yes. Solar panels continue generating electricity even during rainy and cloudy weather. However, electricity production is lower because less sunlight reaches the photovoltaic cells.

2. Why is my solar generation suddenly lower during monsoon?

The most common reasons include heavy cloud cover, mud or dust on the panel surface, shorter daylight hours, shading, and reduced solar irradiance.

3. Should I clean my solar panels during the rainy season?

Yes. Rainwater does not always clean the panels completely. Mud, leaves, bird droppings, and dust should be removed regularly to maintain good performance.

4. Can rain damage rooftop solar panels?

Quality solar panels are designed to withstand rain, wind, and harsh weather. Problems generally occur due to poor installation, damaged wiring, or loose electrical connections.

5. Which type of solar panel performs better in low-light conditions?

Modern Mono PERC and TOPCon solar panels generally perform better than older Polycrystalline panels under cloudy conditions.

6. Why does my Off-Grid battery charge slowly during rainy weather?

Because the solar panels generate less electricity, the battery receives less charging current, increasing charging time.

7. Should I turn on Grid Charging during monsoon?

If your Off-Grid or Hybrid inverter supports Grid Charging, enabling it during prolonged cloudy weather can help maintain battery backup.

8. Does temperature affect solar performance?

Yes. Cooler temperatures actually improve solar panel efficiency slightly. However, during monsoon the reduction in sunlight is much greater than the efficiency gain, so total generation still decreases.

9. How often should solar panels be cleaned?

For most residential systems, cleaning every 15–30 days is sufficient. Areas with high dust, bird activity, or pollution may require more frequent cleaning.

10. Is reduced solar generation during monsoon normal?

Yes. A reduction of approximately 30%–60% can be normal depending on cloud cover, rainfall, and local weather conditions.

Official Resources

For authentic information about rooftop solar systems and government schemes, always refer to official sources:

PM Surya Ghar Muft Bijli Yojana
https://pmsuryaghar.gov.in
Ministry of New and Renewable Energy (MNRE)
https://mnre.gov.in
National Institute of Solar Energy (NISE)
https://nise.res.in
Odisha Electricity Regulatory Commission (OERC)
https://www.orierc.org
TPCODL Official Website
https://www.tpcentralodisha.com

Rainy Season Solar Performance Summary

Problem	Solution
Cloud Cover	Normal; generation will reduce temporarily.
Dirty Panels	Clean regularly.
Mud Accumulation	Wash with clean water and soft cloth.
Loose Wiring	Inspect MC4 connectors and cables.
Poor Earthing	Inspect before every monsoon.
Slow Battery Charging	Use Grid Charging if supported.
Buying New Panels	Choose Mono PERC or TOPCon.

Final Thoughts

The arrival of the monsoon does not mean your rooftop solar system has stopped working. Lower electricity generation during rainy weather is completely normal and is mainly caused by reduced sunlight, cloud cover, mud accumulation, and shorter daylight hours.

Fortunately, regular cleaning, proper maintenance, correct panel installation, quality wiring, good earthing, and choosing modern solar technologies such as Mono PERC or TOPCon panels can significantly improve performance even during cloudy weather.

If you have already installed a rooftop solar system under the PM Surya Ghar Muft Bijli Yojana, following the maintenance tips shared in this guide will help maximize your investment and keep your electricity bills low throughout the year.

Why Does Solar Power Generation Drop During the Rainy Season? 5 Proven Tips to Increase Solar Output in Monsoon (2026 Guide)