If you’re experiencing strong sunlight but weak solar power, you’re not alone.
Many homeowners notice that their solar panels seem to perform worst during the hottest part of the dry season — exactly when the sun is brightest.

So why is your solar system underperforming even though the weather looks perfect?

The truth is simple:
Solar panels love light, but they hate heat.

In this article, you’ll learn:

• Why excessive heat reduces solar efficiency
• The role of dust, harmattan, humidity, and roof temperature
• How high temperature affects battery charging and inverter output
• Practical steps to boost performance during hot weather

Let’s break it down.

---

🌡 Why “More Sun” Doesn’t Always Mean “More Power”

People assume hot sun = more energy.
But solar panels do not convert heat into electricity — they convert light (irradiance).
When temperatures rise too high, solar output drops immediately.

Here’s why:

---

⚡ 1. High Temperature Reduces Solar Panel Voltage

Solar panels are tested at 25°C in the factory.
But during the dry season, especially in Africa, panel surface temperature can reach:

• 60°C – 85°C on rooftops
• 90°C+ on metal sheets

When temperature rises:

• Panel voltage drops
• Power output drops
• Your batteries charge slower
• MPPT efficiency declines

This is known as “temperature loss.”

Most solar panels lose 0.30% – 0.50% power per degree above 25°C.

Example:

If your panel hits 70°C:

70 – 25 = 45°C above standard

45 × 0.40% = 18% power loss instantly

A 550W solar panel may produce only 450–480W in extreme heat.

---

🌬 2. Dust and Harmattan Block Sunlight

During the dry season:

• Dust settles on your panels
• Harmattan haze reduces sunlight intensity
• Panels get a brown or white layer that blocks photons

Dust alone can reduce solar output by 15–30%.

If you haven’t cleaned your panels in weeks, this is a major cause of low performance.

---

🔥 3. Hot Roofs Increase Panel Temperature

Mounting solar panels directly on:

• Metal sheets
• Low-quality roofs
• Black-coloured roofing

…causes heat to bounce back into the panels.

The hotter the roof, the hotter the panel —
and the lower your solar output.

---

🌀 4. Poor Airflow Under the Panels

If the installer did not leave enough space under the panels (at least 4–6 inches), heat gets trapped.

Low ventilation = high temperature = low power.

---

🔋 5. Batteries Charge Slower in Hot Weather

Lithium batteries prefer cool environments.
But during hot months, they experience:

• Reduced charging efficiency
• Reduced lifespan
• Protective slowdown from the BMS
• Higher discharge rates due to increased AC/fan usage

---

🎛 6. Your Inverter May Be Throttling Output

When panel voltage drops, the inverter may:

• Limit AC output
• Display under-voltage warnings
• Reduce charging amps
• Shut down temporarily

This is why your solar may perform worse in the afternoon than in the morning.

---

💨 7. Increased Home Cooling Load

During hot weather:

• AC runs longer
• Fans run 24/7
• Fridges cycle more frequently
• Freezers work harder

Your load increases by 20–40%, even though your solar system is producing less power.

This double effect creates the perfect storm for “hot sun, low power.”

---

✅ How to Boost Solar Performance During Hot Weather

Here are practical steps to fix the problem:

---

1. Clean Your Solar Panels Weekly

Use:

• Soft cloth or microfiber
• Mild soap
• Clean water

Avoid hard water that leaves mineral stains.

---

2. Improve Ventilation Under the Panels

Ensure at least 4–6 inches air gap between roof and panels.

Better airflow = cooler panels = more power.

---

3. Switch to Low Temperature Coefficient Panels

Panels with ≤ -0.30%/°C perform better in heat.
N-Type TOPCon or HJT panels are best for hot climates.

---

4. Install Panels on Raised Structure, Not on a Hot Roof

If possible:

• Avoid direct mounting on iron sheets
• Use aluminum rails
• Consider mounting on carports, ground mounts, or raised structures

---

5. Oversize Your Solar Array by 20–30%

This compensates for temperature loss.
Many professionals now recommend oversizing panels in tropical climates.

---

6. Keep Batteries in a Cool Room

Ventilate the battery room.
Avoid placing batteries in:

• Tight storage
• Hot outdoor spaces
• Unventilated wooden boxes

Heat reduces lithium battery lifespan.

---

7. Check Your MPPT Voltage Compatibility

Heat reduces voltage.
If your PV voltage rating is too close to the MPPT minimum, afternoon charging will be poor.

Raise your panel strings if necessary.

---

🌞 Final Thoughts

If your solar system is underperforming during hot weather, don’t panic.

This is a normal physical effect, not a system failure.

The main causes are:

• High temperature
• Dust & harmattan
• Poor ventilation
• Roof heat
• Increased household load

With good maintenance, ventilation, and proper panel selection, you can significantly reduce dry-season losses and keep your solar system performing at its best.