BusinessDay
Oladehinde Oladipo
June 16, 2026
When the rains arrived in earnest last May, Chukwuemeka Obi’s solar setup in Lagos went from powering his entire household to struggling to charge his phones.
His inverter was alarming at odd hours, his batteries were draining faster than usual, and his panels, recently installed at no small cost, were producing a fraction of what the salesman had promised.
“I assumed the rain would clean everything,” said Obi, a pharmacy owner who invested N2,000,000 in a 1.5kVA solar system the previous December. “Nobody told me the rainy season is actually when the system needs the most attention.”
His experience is common. Nigeria’s solar market has grown sharply over the past three years, driven by chronic grid unreliability and the removal of the petrol subsidy that made generator fuel unaffordable for millions. The country now has one of the fastest-growing off-grid solar adoption rates on the continent, with the International Energy Agency estimating more than 4.5 million solar home systems currently in use nationwide.
But the investment comes with a largely unaddressed vulnerability: the six-month rainy season, which runs from April through October in the south and shorter windows in the north, actively degrades system performance in ways that owners rarely anticipate.

Clean the panels, rain doesn’t do it for you
The most widespread misconception in Nigerian solar ownership is that rainfall keeps panels clean. It does not. Rain washes loose surface dust away but leaves behind a film of mineral deposits, especially in areas with hard borehole water or industrial proximity.
In Lagos, Port Harcourt, and Onitsha, airborne particulates from traffic and industry mix with rain to create a residue that dries into a semi-permanent haze across panel glass.
That haze cuts energy output by between 15 and 30 percent, according to maintenance engineers at SolarNaija, a Lagos-based installer. The solution is a soft cloth or squeegee, clean water, and no detergent. Cleaning every three to four weeks during peak rain season is sufficient for most environments. Do it early in the morning, before the sun heats the glass, to avoid thermal shock cracking.

Check the mounting before the wind does it for you

Rainy season in southern Nigeria often arrives with squalls and sustained winds that probe every weakness in a rooftop installation. Loose mounting bolts, improperly seated panel clamps, and corroding brackets, often invisible during the dry months, become failure points the moment wind load increases.
Walk around the structure after every heavy storm. If panels have shifted position, even slightly, output drops and connector damage become likely. Tighten any loose hardware, replace galvanised bolts that show rust with stainless steel alternatives, and inspect roof penetration points for leaks. Water entering the roof around a mount is a slow catastrophe that most owners don’t discover until the ceiling caves.
Your battery and inverter need dry air
Humidity is the quiet enemy of charge controllers, inverters, and battery terminals. Lead-acid battery terminals oxidize faster in humid conditions, creating resistance that wastes charge and generates heat. Lithium systems are more tolerant but not immune.
At least once a month during rainy season, disconnect the battery terminals, inspect for white or greenish buildup, and clean with a dry cloth or fine wire brush. Do not use water. Ensure your inverter has adequate ventilation and is not mounted in a sealed cabinet. If you can hear the inverter fan running constantly, the ambient temperature in the room is too high — something that worsens when buildings retain humidity.

Monitor your numbers, not just your lights
Most inverters display daily generation figures. Write them down or photograph the screen weekly. A consistent drop of more than 20 percent against your dry-season baseline, on a day with partial sun, signals something is wrong, whether dirty panels, a failing battery cell, or a corroded cable joint.
Nigeria’s solar boom has produced a market full of smart buyers who did their research before purchase. The owners who protect that investment through rainy season are simply the ones who keep paying attention after the installation crew leaves.

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