Solar Panel Shading Trainer
Learn how shade actually affects your solar array. Drag, toggle, and watch the electrical behavior change in real time.
This interactive training tool teaches you how shading affects solar panel performance, and more importantly, why your system responds to shade the way it does. It's not a production calculator. It's designed to help you understand the electrical behavior behind shading so you can make smarter decisions about panel placement, string layout, and component selection.
We built it for both customers designing their first off-grid installation and electricians troubleshooting commercial arrays. The tool uses the same equations as professional modeling software and demonstrates panels with single bypass diode configurations. Every panel, string, and operating point is calculated, not estimated, not simplified, not hand-waved. Because understanding why your system behaves the way it does is the first step toward making it better.
This tool runs under perfect irradiance and is for learning shading concepts only, not for real-world production calculations.
Solar Panel Shading Simulator
Explore how shading affects solar array performance
Array
Panel Specs
Panel Array
Power by Panel
IV & Power Curves
MPPT Optimization
How Shade Affects a Solar Array (It's Not What You Think)
Some people say, "Even a little shade kills your whole solar system," but this is a gross oversimplification and can lead to bad design decisions. The real answer depends on the panel technology, how you wire the strings, and what the MPPT (Maximum Power Point Tracker) does about it.
The training tool above shows the real effects. Drag the shade across the panels to see what happens to voltage, current, and power throughout the system.
What Happens When You Shade a Solar Panel
Cells inside solar panels connect to each other through a series connection, and all the panels in a single string also connect in series. This leads to two things.
First, the nature of a series connection limits the current flow from all connected parts to the lowest current output. In a solar panel, this means that even unshaded cells output the same current as their shaded neighbors.
Second, a shaded cell can also draw power from connected cells, turning that electricity into heat and potentially creating a hazardous electrical environment.
This is why we have bypass diodes.
Key Concept
In a series connection, current is limited to the weakest link. One shaded cell can drag down every cell connected to it.
Bypass Diodes: What They Actually Do
Every modern solar panel includes a junction box with bypass diodes. These diodes monitor groups of cells within a single panel. When one cell group produces less current, the bypass diode activates and reroutes the current around that group, essentially turning off those cells and ignoring them instead of reducing the output of every other cell group.
Here's what's counterintuitive: a fully bypassed panel doesn't produce zero power. Since the panel produces zero volts and the diodes consume some power, the final result is slightly negative (about -0.7V from the shaded panel).
The unshaded panels typically produce more than enough to make up for this voltage drop, and the MPPT continuously monitors this calculation. Should it restrict the power output from all panels to match the shaded panel, or should it completely bypass the shaded panel and take the voltage drop?
The training tool shows both options on the IV curve as separate power peaks.
Try it: Shade a single panel and look at the IV curve. You'll see two distinct peaks representing these two strategies.
Split-Cell (Half-Cut) Panels: Why They Handle Shade Better
Modern panels use split-cell (half-cut) technology, where the panel is divided into a top half and a bottom half. The cells in each half are wired in series, but the two halves are wired in parallel. This improves shade tolerance, but it's often improperly explained.
Here's what actually happens with a split-cell panel under partial shade:
If shade covers only one half (top or bottom), the current drops on the shaded half while the other half continues at full output. Since the halves are wired in parallel, the unshaded half still contributes its full current, and the panel operates at roughly 50% capacity instead of being fully bypassed. MPPTs often use this as the optimal choice.
If shade covers both halves, both bypass diodes may activate, and the panel is fully bypassed, just like a traditional panel.
Try it: Toggle the "Split-Cell Technology" switch, then shade one half of a panel. Compare the power curve to a traditional panel with the same shading. You'll notice a significant difference.
Why This Matters for Purchasing
Installations with partial shade often benefit significantly from split-cell panels. The real electrical advantage often justifies the additional cost.
MPPT and the Multi-Peak Problem
MPPT functions by constantly searching for the voltage where the array produces the most power. Under uniform conditions, there's a single clear peak. Partial shading creates multiple peaks in the power curve, each representing a different operating strategy:
The high-voltage peak: Running all panels at lower current so the shaded panels still contribute voltage. More panels producing, each one at reduced current.
The low-voltage peak: Running at higher current and bypassing the shaded panels. Fewer panels contribute, but those contributing run at full power.
Which peak is higher depends on how many panels are shaded and how severe the shading is.
A good MPPT tracker (one with global peak scanning) will find the true maximum. But some budget trackers get stuck on the lower peak and continually operate at the wrong voltage.
When purchasing an MPPT, always look for the Multiple Peak specification to avoid this issue.
The training tool shows both peaks and highlights which one the MPPT should choose.
Shared MPPT vs. Per-String Optimization
Shared MPPT
Multiple parallel strings share a single MPPT. All strings operate at the same voltage. The MPPT finds the voltage that produces the maximum total power, but this voltage isn't optimal for every string individually.
Per-String Optimization
Microinverters or string-level optimizers let each string (or panel) find its own optimal voltage independently. This prevents a shaded string from dragging down the entire array's production.
The difference matters most when shading is uneven across strings. If one string is shaded and another isn't, a shared MPPT may choose a voltage that sacrifices production from the unshaded string. Per-string optimization eliminates this compromise.
Try it: Toggle the "Per-String MPPT" switch and shade one string while leaving the other clear. Watch how the total power output changes.
When Partial Shade Is Worse Than Full Shade
Here's the scenario that surprises most people: a panel with one half partially shaded can cause more power loss than a panel that's completely shaded.
Why? A fully shaded panel bypasses cleanly. The MPPT adjusts and the rest of the string runs at full power. A partially shaded panel may contribute some current, and the MPPT may adjust to a voltage that doesn't produce the maximum power for the entire system.
Try it: Shade one half of a single panel and watch the power curve develop two peaks close together. Then fully shade that same panel. You'll often see the total system power increase because the MPPT can make a clear decision.
This is also why shade patterns matter more than shade area. A narrow shadow crossing every panel in a string (like a wire or thin branch) can be worse than a large shadow covering two panels completely.
Real-World Takeaways
For System Design
Analyze shade before installing. A few panels in the wrong position can affect the entire string. If shade is unavoidable, isolate shaded panels to one string rather than spreading them across multiple strings.
For Troubleshooting
Morning or afternoon underperformance usually comes from partial shading, even when panels look mostly clear. Monitor per-string current to identify the problem string.
For Purchasing Decisions
Split-cell panels provide real electrical benefits in partially shaded installations. Always choose MPPT controllers with global peak scanning. Per-string optimization matters most when shading is uneven across strings.
Questions About Your Installation?
Whether you're designing a new system or troubleshooting an existing one, our team can help you make sense of shading, string layout, and component selection for your specific situation.
This Solar Panel Shading Training Tool is provided by Current Connected for educational and illustrative purposes only. It is designed to demonstrate the general concepts of how shading affects solar panel performance, including bypass diode behavior, split-cell technology, MPPT optimization, and string configuration effects.
This training tool is not intended for real-world production calculations, system design, or engineering decisions. All outputs are based on idealized conditions, including perfect irradiance, uniform panel characteristics, and simplified single-bypass-diode configurations. Actual solar array performance will vary based on factors not modeled here, including but not limited to geographic location, weather and atmospheric conditions, panel temperature and thermal coefficients, specific panel and inverter hardware characteristics, wiring losses, soiling, degradation over time, and roof orientation or tilt angle.
Limitation of Liability and Indemnification. No representation or warranty, express or implied, is made regarding the accuracy, completeness, or applicability of this tool's output to any specific installation. This training tool is provided "as is" and "as available" without warranties of any kind. By using this tool, you agree to indemnify, defend, and hold harmless Current Connected LLC and its subsidiaries, affiliates, officers, directors, agents, employees, licensors, and suppliers from and against any and all claims, liabilities, damages, losses, costs, and expenses (including reasonable attorneys' fees) arising out of or in any way related to your use of this tool, including but not limited to any decisions made, equipment purchased, installations designed, or actions taken based on the results or information provided by this tool. Current Connected LLC shall not be held liable for any direct, indirect, incidental, consequential, special, or punitive damages of any kind resulting from the use of or inability to use this tool.
Intellectual Property. This Solar Panel Shading Training Tool, including all underlying code, algorithms, mathematical models, visual design, educational content, and associated materials, is the exclusive intellectual property of Current Connected LLC. All rights are reserved. No part of this tool may be reproduced, copied, distributed, modified, reverse-engineered, decompiled, disassembled, embedded, framed, scraped, or otherwise used by any third party for any purpose, whether commercial or non-commercial, without the prior written consent of Current Connected LLC. Unauthorized use, reproduction, distribution, or creation of derivative works constitutes a violation of applicable United States and international copyright, intellectual property, and trade secret laws, and may subject the violating party to civil liability, injunctive relief, statutory damages, and criminal prosecution to the fullest extent permitted by law. Current Connected LLC actively monitors for unauthorized use and reserves the right to pursue all available legal remedies against any individual or entity found to be in violation of these terms.