What Affects Solar Panel Efficiency?

Solar panels have become a go-to solution for clean, renewable energy — but not all panels are created equal. If you're investing in solar, efficiency is one of the most important metrics to consider. So, what exactly affects solar panel efficiency? Let's break it down.

1. Sunlight (Irradiance and Duration)

Solar panels convert sunlight into electricity. Naturally, the more sunlight they receive, the more energy they can produce. Factors that impact sunlight include:

Geographic location

Time of year

Weather conditions

Shade from trees, buildings, or clouds

Even a small amount of shading on one panel can significantly reduce the performance of an entire string of panels.

2. Angle and Orientation

The tilt and direction of your solar panels play a huge role in their output. For example:

In the northern hemisphere, panels facing south typically generate the most power.

A tilt angle equal to your latitude often provides the best year-round performance.

Incorrect positioning can reduce efficiency by 10 – 25% or more.

3. Temperature

Yes, it's solar power — but too much heat is actually bad for efficiency. Most panels are tested at 25°C (77°F). When they get hotter, their output drops.

On average, panel performance decreases by 0.3% to 0.5% per degree Celsius above the test temperature.

So ironically, cool and sunny climates are often best for solar energy production.

4. Panel Type and Material

Not all solar panels are made the same. Efficiency varies by material:

Monocrystalline panels : ~20–23% efficient (high performance)

Polycrystalline panels : ~15–18% efficient (budget-friendly)

Thin-film panels : ~10–13% efficient (lightweight and flexible)

At Nurzviy , we use high-efficiency monocrystalline panels , known for their excellent performance and sleek, space-saving design. These panels are perfect for rooftops, RVs, off-grid cabins, and any setup where maximizing energy output per square foot matters.

Compared to polycrystalline or thin-film options, monocrystalline panels offer better performance in both high and low-light conditions, and they also degrade more slowly over time.

5. Quality and Age

Like any tech, solar panels degrade over time. Most panels lose about 0.5% of efficiency per year, meaning after 25 years, they may still operate at 80 – 85% capacity.

Higher-quality panels degrade more slowly.

Regular maintenance (like cleaning dust, pollen, or bird droppings) can also improve efficiency.

6. System Components

It ’ s not just about the panels — your system ’ s efficiency depends on everything working together:

Inverter efficiency: Most modern inverters are 95 – 98% efficient. 

Wiring and connections: Voltage drops from poor cabling can reduce output

Battery storage (if used): Adds energy loss during charge/discharge cycles

Proper system design ensures minimal losses throughout the energy flow.

Final Thoughts

Maximizing solar panel efficiency isn't just about buying the most expensive panels — it's about smart design, good installation, and proper maintenance. By  understanding these key factors, you can get the most out of your solar investment, whether you're powering a home, RV, or off-grid setup.