Shading Threats to Solar Efficiency: Unveiling the Hidden Risks of Self-Shading and Solutions to Recover 30% Energy Loss

There has been a lot of speculation regarding the question: "Do solar panels shade themselves with half of their work?" The answer is not a simple yes or no question, but what is certain is that shade from trees, chimneys, and even bird feces, which we almost always have to deal with, reduce energy production from the solar panels. Once we have established this, we can focus more closely on the effect of shade on solar panels.

The Science Behind Solar Panels

Solar photovoltaic (PV) energy works with the sun's light to create electrical energy through Solar PV cells, using semi-conductor material (Silicon), to allow for the release of an electron upon the impact of photons hitting the material and producing a direct current (DC) from this electron movement. The creation of alternating current (AC), which can be used, is made possible by the movement from DC to AC through inverting devices.
However, there is a catch: the way solar panels are wired. When solar panels are wired in series, pulling one solar panel away from the circuit for repair/maintenance or if it is shaded, affects the performance of the entire circuit. For example: When even 10% of a panel is shaded, the output of the solar panel can drop as much as 20% to 30%. A shading of 40% of a solar panel may only create the efficiency of around 20%.

Why Shadows Are Solar's Worst Enemy

a. The Domino Effect

When sunlight hits a shaded cell, it becomes a "weak link." Instead of producing energy, the cell starts acting like a resistor, generating heat and stressing neighboring cells. This phenomenon, dubbed the "hot spot effect,"can permanently damage panels if ignored.

b. Real-World Nightmares

Tree Trouble: One rogue overgrown tree branch that overhangs your roof can shade your solar panels during peak solar hours and can impact your solar output by a whopping 30-50%.

Roof Rascals: Winter sunlight moves quickly and can create large shifts in shadows caused by roof chimneys and skylight windows on the sloe of the roof.

Dust & Debris: A thin dust of dirt and debris can accumulate on the surface of the solar panels and mimic the effects of solar panels being electronically shaded. Panel dust can shade a solar PV system by 5-20%.

Outsmarting Shadows: Pro Tips

a. Tech to the Rescue

Bypass Diodes: Modern panels include these "safety valves" that reroute current around shaded cells. Three diodes mean shading 33% of a panel only cuts output by ~33%.

Microinverters: Unlike traditional string inverters, these tiny devices work per-panel. If one's shaded, others keep humming-preserving ~95% efficiency.

b. Smart Installation Hacks

Shadow Mapping: Use tools like Solar Pathfinder to identify seasonal obstructions before installation.

Angled for Attack: Tilt panels to minimize shade overlap. For example, lower angles in winter capture more daylight.

Bifacial Panels: These capture reflected light from surfaces like snow or water, compensating for shaded areas.

Final Thoughts

Do solar panels block half their work? Only if you ignore shadows. Using Smart Technologies, and planning ahead of time, this can reduce solar panel shading losses down to 10% or less! A recommendation to improve the shading loss would be to cut impaired growth (trees, brush) in the area around the Solar PV panel every three months, and consider combining Micro Inverters with Bifacial Solar Panels.