Do Solar Panels Work in Rainy Weather?
Yes, solar panels continue to generate electricity during rainy weather. While output drops to roughly 10–25% of peak capacity during heavy rain and overcast skies, modern photovoltaic cells still convert diffuse sunlight and ambient light into usable power. For Singapore homeowners, this means your solar system produces energy every single day of the year — rain or shine.
This is one of the most common concerns we hear from homeowners considering solar in Singapore. Given that the island receives an average of 167 rainy days per year, it's a perfectly reasonable question. The short answer: solar technology has advanced far beyond the point where rain is a deal-breaker. In fact, Singapore's tropical climate is surprisingly well-suited for solar energy production.
How Much Electricity Do Solar Panels Generate During Rain?
Solar panels typically generate 10–25% of their rated capacity during rainy or heavily overcast conditions, and 25–50% during light cloud cover. This is because photovoltaic cells respond to light intensity, not direct sunlight alone — and diffuse radiation still carries significant energy even when the sky is grey.
To understand how rain affects solar output, it helps to look at the physics. Solar panels convert photons — particles of light — into electricity. On a clear day, panels receive both direct beam radiation (sunlight travelling in a straight line from the sun) and diffuse radiation (sunlight scattered by the atmosphere). During rain, direct beam radiation drops sharply, but diffuse radiation persists. Modern solar cells, especially N-type monocrystalline panels, are engineered to capture this diffuse light efficiently.
Here's what you can realistically expect from a typical 10 kWp residential system in Singapore across different weather conditions:
| Weather Condition | Light Intensity | Output (% of Rated) | Estimated Daily Generation |
|---|---|---|---|
| Clear / Sunny | 900–1,100 W/m² | 85–100% | 38–42 kWh |
| Partly Cloudy | 400–700 W/m² | 50–70% | 22–30 kWh |
| Overcast / Heavy Cloud | 150–400 W/m² | 25–50% | 10–20 kWh |
| Heavy Rain / Thunderstorm | 50–150 W/m² | 10–25% | 4–10 kWh |
| Dawn / Dusk (Low Angle) | 50–200 W/m² | 5–20% | 2–5 kWh |
The key takeaway: even during Singapore's heaviest monsoon downpours, your panels are still working. They don't simply switch off when clouds appear. And because Singapore's rain events tend to be short, intense bursts rather than day-long drizzle, panels typically recover to higher output within an hour or two.
How Does Singapore's Tropical Rainfall Pattern Affect Annual Solar Generation?
Singapore's rainfall pattern — characterised by short, intense afternoon showers rather than prolonged overcast days — is actually favourable for solar energy. Panels generate strongly during sunny mornings, experience a brief dip during afternoon storms, and often recover before sunset.
Singapore receives approximately 2,340 mm of rainfall annually, spread across an average of 167 rain days. However, the typical rain event lasts only 1–2 hours, predominantly in the afternoon. This means morning solar generation (roughly 7 AM to 1 PM) is often uninterrupted, providing the bulk of daily output.
The table below illustrates how monthly rainfall correlates with solar generation across the year:
| Month | Avg. Rainfall (mm) | Avg. Rain Days | Avg. Peak Sun Hours/Day | Est. Monthly Generation (kWh) |
|---|---|---|---|---|
| January | 234 | 15 | 3.8 | 950–1,050 |
| February | 160 | 11 | 4.5 | 1,050–1,150 |
| March | 171 | 14 | 4.4 | 1,050–1,120 |
| April | 179 | 15 | 4.3 | 1,020–1,100 |
| May | 172 | 15 | 4.3 | 1,030–1,110 |
| June | 162 | 13 | 4.4 | 1,050–1,130 |
| July | 159 | 13 | 4.5 | 1,070–1,150 |
| August | 175 | 14 | 4.4 | 1,050–1,130 |
| September | 170 | 14 | 4.3 | 1,020–1,100 |
| October | 197 | 16 | 4.1 | 980–1,060 |
| November | 254 | 19 | 3.7 | 900–980 |
| December | 269 | 19 | 3.6 | 880–960 |
Notice that even during the wettest months (November–January, the northeast monsoon season), a 10 kWp system still generates 880–1,050 kWh monthly. The driest and sunniest period (February–March and June–August) sees generation peak at 1,050–1,150 kWh/month. The difference between the best and worst months is only about 15–20%, demonstrating remarkable year-round consistency.
According to the Energy Market Authority (EMA), Singapore's annual average solar irradiance is approximately 1,580 kWh/m²/year, translating to around 1,580–1,620 peak sun hours annually. This places Singapore ahead of countries like Germany and the UK — both of which have thriving solar industries — despite our higher rainfall.
Why Do Modern Solar Panels Perform Better in Low Light?
Modern N-type monocrystalline solar panels feature advanced cell architecture — including heterojunction (HJT) and back-contact (ABC) designs — that dramatically improves energy capture in low-light and diffuse conditions compared to older P-type panels.
Solar panel technology has evolved significantly over the past decade. Older polycrystalline and P-type monocrystalline panels experienced steeper performance drops in cloudy weather. Today's premium N-type panels, such as the AIKO Neostar modules used in Sunollo's residential packages, incorporate several innovations that specifically address low-light performance:
- Higher bifaciality factor: N-type cells capture reflected light from the rear side, boosting generation by 5–10% even on cloudy days when light scatters in all directions.
- Lower temperature coefficient: N-type panels lose less efficiency as temperature rises — critical in Singapore's 30–35°C ambient conditions. A typical N-type panel has a temperature coefficient of −0.29%/°C versus −0.37%/°C for P-type.
- Superior low-light response: Advanced passivation layers in HJT and ABC cells maintain higher voltage output at low irradiance levels, meaning they start generating earlier in the morning and continue later into the evening.
- Reduced degradation: N-type cells are immune to Light-Induced Degradation (LID) and experience less Light and Elevated Temperature Induced Degradation (LeTID), maintaining higher output over the system's 25–30 year lifespan.
For Singapore homeowners, this means that investing in a system with premium N-type panels — like those in Sunollo's solar packages — delivers meaningfully higher annual yield compared to budget systems using older technology, particularly during the monsoon months.
Does Rain Actually Help Solar Panels?
Yes — rain provides a natural cleaning effect that removes dust, pollen, bird droppings, and atmospheric particulate matter from panel surfaces, which can restore 2–5% of output that would otherwise be lost to soiling.
Singapore's urban environment generates significant airborne particulates from construction, traffic, and regional haze events. Without periodic cleaning, a layer of grime builds up on panels and reduces light transmission. Rain events effectively wash this away for free.
Studies from tropical research institutions show that solar panels in equatorial regions that receive regular rainfall require less manual cleaning than those in arid climates. In Singapore, most residential systems need professional cleaning only 1–2 times per year, primarily to address stubborn deposits that rain alone cannot remove. For a deeper dive into upkeep requirements, see our complete guide to solar panel maintenance in Singapore.
Additionally, cooler temperatures during rainy periods can temporarily boost panel efficiency. Solar cells operate most efficiently at 25°C (the Standard Test Conditions reference temperature), and Singapore's rain showers can drop ambient panel temperatures by 10–15°C from their peak, momentarily increasing voltage output.
How Does Singapore Compare to Other Countries for Solar Despite the Rain?
Singapore receives 40–60% more solar irradiance than leading European solar markets like Germany, the Netherlands, and the UK, despite having significantly more rainfall. Proximity to the equator gives Singapore a fundamental advantage in total annual solar energy availability.
Many homeowners assume that Singapore's frequent rain makes it a poor location for solar energy. In reality, the opposite is true. Singapore's equatorial position (1.3°N latitude) means the sun passes almost directly overhead year-round, delivering consistently high solar irradiance even when factoring in cloud cover and rain.
Consider these comparative figures:
- Singapore: ~1,580 kWh/m²/year solar irradiance, ~2,340 mm annual rainfall
- Germany: ~1,050 kWh/m²/year solar irradiance, ~790 mm annual rainfall
- United Kingdom: ~950 kWh/m²/year solar irradiance, ~1,200 mm annual rainfall
- Netherlands: ~1,020 kWh/m²/year solar irradiance, ~850 mm annual rainfall
- Japan: ~1,300 kWh/m²/year solar irradiance, ~1,720 mm annual rainfall
Germany, with 50% less solar irradiance than Singapore, has installed over 80 GW of solar capacity and is one of the world's solar leaders. Singapore's higher irradiance means that a solar system here will consistently outperform an identical system installed in Berlin, London, or Amsterdam — even accounting for our tropical rainfall. To learn more about common misunderstandings, read our article on solar panel myths debunked for Singapore.
What Happens to Solar Panels During the Monsoon Season?
During Singapore's monsoon seasons (northeast monsoon from December to March, and southwest monsoon from June to September), solar generation decreases by approximately 10–20% compared to inter-monsoon periods, but systems continue producing substantial energy throughout.
The northeast monsoon (December–March) brings the heaviest and most sustained rainfall, with December and January averaging 250–270 mm each. During this period, expect your system's daily output to average around 30–35 kWh for a 10 kWp system, compared to 35–42 kWh during the sunnier inter-monsoon months of April–May and October–November.
Crucially, monsoon rainfall in Singapore still follows the pattern of intense, short-duration storms. Even on "rainy" days, there are typically 3–5 hours of usable sunshine. Extended multi-day overcast periods — common in temperate climates — are relatively rare in Singapore's equatorial climate.
Sunollo's system designs account for monsoon variability. Our energy yield projections use 10+ years of historical weather data from the National Environment Agency (NEA) to ensure that savings estimates are realistic and conservative, not based on best-case sunny-day assumptions.
Can You Maximise Solar Output During Singapore's Rainy Periods?
Yes — choosing high-efficiency N-type panels, ensuring optimal tilt and orientation, minimising shading, and adding battery storage are the most effective strategies to maximise solar output during rainy weather.
Here are proven approaches Singapore homeowners can adopt:
- Select premium panel technology: N-type monocrystalline panels (like AIKO Neostar) outperform P-type panels by 3–8% in low-light conditions. Over 25 years, this compounds to thousands of additional kWh.
- Optimise panel placement: Panels should be installed facing as close to due south or due north as the roof allows (in Singapore's near-equatorial location, east-west orientations also perform well). Minimise shading from trees, neighbouring buildings, and rooftop structures.
- Use microinverters or power optimisers: Unlike traditional string inverters, module-level power electronics (MLPEs) ensure that shading or soiling on one panel doesn't drag down the entire string's output.
- Add battery storage: A home battery system lets you store excess solar energy generated during sunny morning hours and use it during rainy afternoons or evenings, reducing grid dependency further.
- Keep panels clean: While rain helps, scheduling 1–2 professional cleanings per year ensures optimal light transmission, especially after haze season.
For a comprehensive understanding of total system value including savings analysis, explore our solar panel ROI and investment guide.
How Much Can You Save with Solar in Singapore Despite the Rain?
A typical Singapore household with a 10 kWp solar system saves $1,800–$2,400 per year on electricity bills, even after accounting for reduced generation during rainy periods. Most systems achieve full payback within 4–6 years.
The financial case for solar in Singapore remains compelling regardless of rainfall. Here's why:
- Grid electricity costs are rising: SP Group's regulated tariff has increased significantly over the past three years, and carbon tax increases under the EMA's framework will push prices higher through 2030.
- Excess solar is exported: Under Singapore's net metering scheme, excess energy your panels produce during sunny periods is exported to the grid and credited against your bill, offsetting times when generation is lower.
- System costs have dropped: Panel efficiency has increased while installation costs have decreased, making solar more accessible than ever.
Sunollo makes going solar straightforward with packages designed for Singapore's HDB, condo, and landed home rooftops:
- Radiance Package: From $14,500 (or $0 upfront from $99/mo)
- Abundance Package: From $15,000 (or $0 upfront from $99/mo)
- Abundance Pro Package: From $16,000 (or $0 upfront from $99/mo)
All packages include premium AIKO N-type panels, professional installation, system monitoring, and performance warranty. View all Sunollo solar packages to find the right fit for your home.
What Should You Know Before Going Solar in Singapore's Climate?
The most important thing to understand is that Singapore's climate is proven solar territory — the country's solar capacity has grown from under 100 MWp in 2015 to over 1,100 MWp in 2025, precisely because the economics work even with tropical rainfall.
Before committing to a solar installation, consider these factors:
- Roof suitability: Your roof's orientation, tilt, available area, and shading profile all influence system size and output. A professional site assessment is essential.
- Realistic yield expectations: Reputable installers like Sunollo use conservative yield estimates based on actual Singapore weather data, not theoretical maximums. Ask for a detailed energy yield projection that accounts for rain, cloud cover, and seasonal variation.
- Warranty and performance guarantees: Look for manufacturers offering 25-year performance warranties and installers providing workmanship guarantees.
- Grid connection: All residential solar systems in Singapore connect to the grid via SP Group. Your installer handles the application process.
For a complete walkthrough of every step in the process, from assessment to activation, read our complete solar guide for Singapore homeowners in 2026.
Frequently Asked Questions
Do solar panels work when it's raining?
Yes, solar panels continue generating electricity during rain. They produce approximately 10–25% of their rated capacity during heavy rain and up to 50% during light overcast conditions. This is because photovoltaic cells convert all visible light — including diffuse light scattered through clouds — into electricity, not just direct sunlight.
How much solar power does Singapore get despite the rain?
Singapore receives approximately 1,580–1,620 peak sun hours per year, translating to an average solar irradiance of about 1,580 kWh/m²/year. Despite receiving ~2,340 mm of annual rainfall, Singapore's solar irradiance exceeds that of Germany (1,050 kWh/m²/year) and the UK (950 kWh/m²/year) — both leading solar markets.
Are solar panels damaged by heavy rain or storms?
No. Solar panels are engineered and tested to withstand extreme weather conditions, including heavy rain, hail up to 25 mm diameter at 80 km/h, and wind loads exceeding 2,400 Pa. Panels carry IEC 61215 and IEC 61730 certifications that require rigorous environmental stress testing before market release.
Do solar panels need to be cleaned after rain?
Generally, rain acts as a natural cleaning agent for solar panels, washing away dust and light debris. However, in Singapore's urban environment, periodic professional cleaning (1–2 times per year) is recommended to remove stubborn deposits such as bird droppings, tree sap, or haze residue that rain alone may not fully clear.
What type of solar panel works best in cloudy weather?
N-type monocrystalline panels (including HJT and back-contact designs) perform best in cloudy and low-light conditions due to their superior low-irradiance response and higher bifaciality. Sunollo uses AIKO Neostar N-type panels, which deliver 3–8% more energy in diffuse light compared to conventional P-type panels.
Does the monsoon season affect solar panel performance in Singapore?
The monsoon season reduces solar generation by approximately 10–20% compared to drier inter-monsoon periods. However, because Singapore's monsoon rain typically falls in short, intense bursts rather than continuous all-day drizzle, panels still generate meaningfully during monsoon months — typically averaging 880–1,050 kWh/month for a 10 kWp system.
Is solar power worth it in Singapore with so much rain?
Absolutely. A typical 10 kWp residential solar system in Singapore generates 12,000–13,500 kWh per year and saves homeowners $1,800–$2,400 annually on electricity bills, with payback periods of 4–6 years. Singapore's solar irradiance is 50–60% higher than top European solar markets despite the rain, making it an excellent location for solar investment.
How does Sunollo account for rainy weather in their solar estimates?
Sunollo uses over 10 years of historical weather data from NEA and satellite-based irradiance databases to model realistic energy yield projections for each home. These projections factor in average rainfall, cloud cover, seasonal variation, and site-specific shading to provide conservative savings estimates that homeowners can trust.
Sources
- Energy Market Authority (EMA) — Singapore solar irradiance data and installed capacity statistics
- National Environment Agency (NEA) — Singapore rainfall and weather data
- Sunollo — Residential solar system performance data and package pricing
