biology

Potential-induced degradation

Potential-induced degradation is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Potential-induced degradation rather than just read about it. In short: Potential-induced degradation (PID) is a potential-induced performance degradation in crystalline photovoltaic modules, caused by so-called stray currents. This effect may cause power loss of up to 30 percent.

Key takeaways

Potential-induced degradation belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Potential-induced degradation to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Potential-induced degradation from memory before moving on to harder problems.

Reference excerpt

Potential-induced degradation (PID) is a potential-induced performance degradation in crystalline photovoltaic modules, caused by so-called stray currents. This effect may cause power loss of up to 30 percent. The cause of the harmful leakage currents, besides the structure of the solar cell, is the voltage of the individual photovoltaic (PV) modules to the ground. In most ungrounded PV systems, the PV modules with a positive or negative voltage to the ground are exposed to PID. PID occurs mostly at negative voltage with respect to the ground potential and is accelerated by high system voltages, high temperatures, and high humidity.

History The term "potential-induced degradation" (PID) was first introduced in the English language in a published study by S. Pingel and coworkers in 2010. It was introduced as a degradation mode resulting from voltage potential between the cells in the photovoltaic module and ground. Research in this field was pioneered by the Jet Propulsion Laboratory, focusing primarily on electrochemical degradation in crystalline silicon and amorphous silicon photovoltaic modules. The degradation mechanism known as polarization found in the first generation crystalline silicon high performance modules from SunPower in strings having positive voltage potential with respect to ground was discussed in 2005. Degradation of conventional front junction (n+/p) solar cell modules under voltage potential was also observed. The degradation by polarization was also covered in the trade journal Photon (4/2006, 6/2006, and 4/2007). In 2007, PID was reported in a number of solar panels from Evergreen Solar (Photon 1/2008 and 8 /2008). In this case, the degradation mechanism occurring in photovoltaic modules containing the more common front junction (n+/p) crystalline silicon solar cells when the modules were in negative voltage potential with respect to ground. PID was further discussed as a problem in ordinary crystalline modules (Photon 12/2010, lecture by solar energy company Solon SE at PVSEC in Valencia 2010). Statement of the solar module manufacturer Solon SE: "At 1000 V, a now quite common voltage for larger PV systems, it can be critical for each module technology". PID of the shunting type (PID-s), which is the most prevalent and most detrimental type of PID for crystalline silicon modules, was discovered to be caused by microscopic crystal defects penetrating the p-n front junction of affected solar cells. In 2013, only 4 major manufacturers according to ISE Fraunhofer of the existing 23 modules are considered to be not affected by the PID.

Detection Although, PID usually has no visual effect on the module, different photovoltaic module analysis techniques are available for detection and analysis. First, the power degradation can become visible in IV curves. infrared thermography and luminescence imaging techniques like electroluminescence and photoluminescence are also able to detect PID.

Prevention The PID-s that occurs in modules in negative polarity strings can be completely prevented if an inverter is used with the possibility of grounding (or effectively grounding) the positive or negative pole. This is possible if the inverter is galvanically isolated, e.g. using a transformer, if specially designed transformerless inverter topologies are used, or by altering the electric grid potential to ground. Which pole must be grounded, is clarified with the solar module manufacturer. The easiest and very effective method to prevent PID is to install a reversal device from the first day of installation. See Anti-PID manufacturers in the "Reversal" section below. The phenomenon does not affect photovoltaic installations with micro-inverters, as the voltages are too low to facilitate Potential Induced Degradation.

Reversal If the PID effect is present in the solar module, the effect can be reversed. Seven companies, ELETTROGRAF/ATEX , Huawei, OriSolar, VIGDU, iLumen, PADCON and Pidbull have made a device that can prevent and reverse this effect.

References

^ APID - AntiPID Solution from ELETTROGRAF/ATEX

^ Huawei PID Solution

^ PID Solution

^ PID Solution video

^ PID Solution

Worked examples

Example 1 — a first encounter with Potential-induced degradation

Start with the simplest possible case. Write down what Potential-induced degradation claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Potential-induced degradation before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Potential-induced degradation ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Potential-induced degradation

In research: Potential-induced degradation appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Potential-induced degradation in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Potential-induced degradation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Photovoltaics, Solar cells, so understanding it makes those chapters shorter.
In everyday life: Look for Potential-induced degradation outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Potential-induced degradation in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Potential-induced degradation means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Potential-induced degradation out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Potential-induced degradation in simple terms?

Why does Potential-induced degradation matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Potential-induced degradation?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Potential-induced degradation.