by Gana Salieby

Solar energy has become a global cornerstone of the clean energy transition. Yet, even with decades of research and billions invested, most commercial solar panels still convert only about 20-24% of sunlight into usable electricity. The question is: Why?

While many point to surface-level issues like dust, heat, or shade — and these are critical — the core reason for low solar panel efficiency lies much deeper: in physics.

The Real Reason: The Physics of Photovoltaics

At the heart of every solar panel is a semiconductor — usually silicon — that converts photons (light particles) into electrons (electricity). But this process is inherently inefficient due to fundamental physical limits.

• Bandgap Limitations:
  Every semiconductor has a bandgap, the minimum energy needed to free an electron so it can contribute to electric current. For silicon, the bandgap is about 1.1 electron volts (eV).
  Photons with less energy than the bandgap pass through the cell with no electricity generated.
  Photons with more energy than the bandgap lose the excess as heat, reducing efficiency.
  This means a significant portion of sunlight is wasted before conversion begins.

• Thermalization Losses:
  High-energy photons, like ultraviolet light, excite electrons excessively — but the extra energy is lost as heat, reducing output and panel lifespan.

• Reflection and Optical Losses
  Even with anti-reflective coatings, about 2–3% of sunlight is lost due to reflection off the panel surface.

• Recombination Losses
  Excited electrons can recombine before reaching electrical contacts, wasting potential power.

What’s the Maximum Solar Panel Efficiency Possible?

In 1961, physicists Shockley and Queisser calculated a theoretical efficiency limit of 33.7% for a single-junction silicon cell — the Shockley–Queisser Limit. Today’s top commercial panels reach only about 24–25%.

Advanced multi-junction solar cells have reached up to 47% efficiency in labs but are not yet commercially viable for utility-scale solar projects.

Where DARBCO Comes In: Bridging Physics and Real-World Efficiency

We Can’t Beat Physics, But We Can Beat Inefficiency by minimizing real-world efficiency losses due to soiling, dust accumulation, and poor maintenance.

Solar panel efficiency is inherently limited by science. But most real-world energy losses come from neglect, soiling, and inefficient maintenance.
That’s the gap DARBCO closes with its innovative robotic cleaning and soiling monitoring solutions.
If you’re operating solar plants and wondering why your output doesn’t match expectations, it’s time to look beyond panels—into cleaning, soiling, and performance monitoring.

For more information, contact us: https://www.darbco.com/ContactUs