Solar Panel Diode Failure Diagnosis

Solar Panel Failures – Bypass Diodes

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If you are experiencing reduced solar panel output, buy a lottery ticket. Solar panel failures are exceedingly rare. Most people worry about their solar panel putting out less power over time, which is called degradation. That’s a relatively difficult thing to diagnose and hard to prove. However, bypass diode failures in solar panels are relatively easy to spot and diagnose using monitoring systems.

Using the Enphase Enlighten app, homeowner can detect bypass diode failures when one panel produces less power than adjacent panels every day. If the reduction of energy in percentage terms is the same every day and its not a shading issue causing it, the likely culprit is a bypass diode or diodes. This is especially true when the reduction in energy is a percentage like 1/3, 1/4, 1/2, or 2/3.

In this video, I discuss what to look for and how we detect failed bypass diodes and what to do about it.

Why Do Solar Panels Have Bypass Diodes

Solar panels are comprised of numerous photovoltaic cells connected in series to generate electricity. However, when part of a panel is shaded, whether by clouds, nearby structures, or foliage, the affected cells produce less electricity, leading to a drop in voltage across that section of the panel. This reduction in voltage can hinder the overall performance of the panel and even cause localized heating, potentially damaging the cells.

Bypass diodes are strategically integrated into solar panel circuitry to address this issue. Their primary function is to provide an alternate path for the flow of current when a section of the panel is shaded, effectively bypassing the shaded cells. By doing so, the diodes prevent the shaded cells from impeding the flow of electricity through the rest of the panel, thus maintaining overall performance.

When shading occurs, bypass diodes automatically redirect the current, allowing the unshaded cells to continue generating electricity. This minimizes the voltage drop across the shaded section and prevents hotspots from forming, which could otherwise lead to accelerated degradation or failure of the affected cells.

Furthermore, bypass diodes contribute to the longevity of solar panels by reducing stress on shaded cells and mitigating the risk of performance degradation over time. By preventing localized heating and associated thermal stresses, they help ensure the panel operates reliably for its intended lifespan.

Bypass diodes are indispensable components of solar panel systems, offering protection against shading-induced inefficiencies and safeguarding the overall performance and longevity of the panels. Their ability to seamlessly reroute current around shaded areas ensures that every ray of sunlight continues to be effectively harvested, driving forward the transition to a sustainable energy future powered by solar technology.

How To Do A Warranty Claim for Failed Bypass Diodes

First, it’s important to understand that you might have an uphill battle, which might not be worth the cost. You will need a solar power professional to diagnose the issue. If they are able to provide enough evidence from the monitoring system, it’s possible the manufacturer will replace the panel without further investigation. If a solar technician has to come out and there is a cost associated with that, you have to weigh how much energy you will lose for the remaining life of the panel and weigh that against the diagnostic and replacement costs.

Note that some manufacturers might cover the replacement labor costs but not the diagnostic costs for the solar dealer. This can be a substantial amount for a truck roll and getting people up to the roof to do diagnostic work, not to mention the administrative work necessary to file a claim.

If your system is in its infancy, then you definitely want to pursue a claim. If you have multiple panels with failures, that could also influence your decision. Your solar dealer should be able to help you file a claim and provide the necessary evidence. If it was your original installer, they will probably be much more interested in helping you. Unfortunately, if you are starting over with a new solar contractor, they don’t have a big incentive to help you other than collecting service fees, which are necessary to cover the costs of highly skilled workers.

Finally, you may not be able to get the same panel anymore, or even one that fits or is electrically compatible. You need to look at your warranty terms and determine what your options are.

Solar panel diodes don’t fail at high rates, but when they do, the results are manifested in obvious ways.  If you have a sophisticated monitoring system, that makes it easier to diagnose and prove cases of bypass diode failures.


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