January rains are real — but “no sun = no savings” is a myth.
Afternoon thunderstorms, northeast monsoon clouds, and grey skies don’t mean your Malaysia Solar system stops working.
Modern PV still generates electricity from diffuse light, and rain can even help by rinsing dust off the panel surface in many cases. (More below.)
If you’re a homeowner or business owner watching your TNB Bill climb, it’s normal to worry when January brings frequent cloudy afternoons. The good news: solar doesn’t “turn off” during monsoon season — it simply produces less than on clear-sky days, and a well-designed system is built for that.
Solar ATAP is Malaysia’s rooftop PV program effective since 1 Jan 2026, allowing eligible consumers to install and operate PV for self-consumption while exporting surplus to the grid (subject to the program rules). Non-domestic capacity limits are set at up to 100% of Maximum Demand or 1 MW.
- Residential users worry: “Will I still save money on rainy weeks?”
- Business users worry: “Will cloudy days break my ROI model?”
Myth #1: “Cloudy weather = solar produces zero.”
Solar panels generate electricity from sunlight — including light that is scattered by clouds (diffuse irradiance). Output is lower than under direct sun, but generation does not drop to zero just because the sky is grey.
Myth #2: “Monsoon rains damage panels (so solar isn’t reliable).”
Rain itself doesn’t harm PV modules; in many real-world situations, rainfall can help wash away dust and debris that would otherwise reduce output. What actually reduces production on heavy-rain days is the darker cloud cover that blocks and scatters sunlight—typically a temporary dip that rebounds when the weather clears.
Myth #3: “All solar panels perform the same in low light.”
Panel technology matters during overcast periods. High-efficiency modules are generally better at converting available light, and some bifacial designs can gain additional energy from light reflected onto the rear side (helpful in bright, reflective environments). For homeowners and SMEs concerned about rainy afternoons, selecting quality modules and correct system design is often more important than “waiting for better weather.”
What to look for (simple checklist)
- High-quality modules from reputable manufacturers, sized correctly for your usage pattern.
- Inverter + monitoring app that shows real-time power (kW) and daily energy (kWh).
- Shading review (trees, parapets, water tanks) because shade hurts output more consistently than clouds.
- Clear expectations: rainy days dip; monthly savings still work when averaged across the year.
Interactive: “Is my system performing normally?”
Use the quick tool below to sanity-check your solar output on a rainy day versus a clear day, then decide whether it’s a normal weather dip or something worth checking (like shading, inverter alerts, or soiling).
Solar Performance Check (Monsoon Mode)
Tip: If your monitoring shows “0W at noon” for multiple days with no storms, that’s a stronger sign to investigate than a single rainy afternoon.
How to monitor your system (home & business)
Most modern solar inverters include apps that show production, consumption (if CT clamps are installed), and system health. Checking the same time window daily (e.g., 12pm–2pm) helps you compare “like with like,” especially during monsoon season.
3 practical monitoring habits
- Look at daily kWh (not just instant kW) to avoid panic during passing clouds.
- Set a weekly reminder to check for inverter notifications or abnormal dips.
- After long dry periods, consider professional cleaning if dust/soiling is visible (rain helps, but not always).
Does Solar ATAP still make sense if it rains often?
Yes—because your savings are evaluated over months and years, not single afternoons. Solar ATAP is structured for self-consumption and allows surplus export under the program’s mechanism, so daytime usage patterns still matter most for ROI.
FAQ
Will my solar produce electricity during cloudy or rainy weather?
Yes—solar panels can still generate electricity from diffuse sunlight when the sky is overcast, although output is reduced compared to direct sun. Heavy rain combined with very dark clouds can temporarily reduce generation further, but production returns when sunlight improves.
Can rain improve solar performance?
Rain does not harm panels and can sometimes help by washing away dust and debris that reduce efficiency. The trade-off is that the same rain often comes with thicker clouds that reduce sunlight intensity for a period.
How do I know if low output is “normal monsoon” or a system problem?
Compare today’s kWh against your own clear-day baseline, check whether the inverter/app reports faults, and look for consistent patterns (e.g., repeated midday zeros). If there are alerts or output stays abnormally low for multiple days without extreme weather, arrange an inspection.
