Top 10 Questions for Photovoltaic Testing Technician (PV Testing Technician) Interview

1. Describe the process of conducting an IV curve test on a photovoltaic module.

The IV curve (current-voltage curve) test is essential for evaluating the performance of a photovoltaic module. The procedure involves:

• Setting up a testing system that includes a power source, load resistor, and data acquisition device.
• Connecting the photovoltaic module to the testing system and ensuring proper electrical connections.
• Adjusting the load resistance to vary the current flowing through the module.
• Recording the current and voltage data at various points to create the IV curve.
• Analyzing the IV curve to determine the module’s performance parameters such as maximum power, short-circuit current, and open-circuit voltage.

2. Explain how the temperature and irradiance affect the performance of a photovoltaic module.

Temperature Effect

• As temperature increases, the bandgap energy of the semiconductor material decreases, leading to a reduction in photovoltaic efficiency.
• Increased temperature also causes an increase in thermal energy, which can lead to recombination losses and further reduce efficiency.

Irradiance Effect

• Higher irradiance levels result in increased photon absorption and charge carrier generation, leading to higher current output.
• However, at very high irradiance levels, recombination losses can increase, reducing the overall efficiency of the module.

3. Discuss the different types of performance defects that can occur in photovoltaic modules.

Performance defects can include:

• Shorted cells: Electrical shorting between cells, reducing the overall current output.
• Broken cells: Physical damage to cells, causing complete or partial loss of functionality.
• Delamination: Separation of layers within the module, affecting electrical performance and durability.
• Hot spots: Localized areas of high temperature, typically caused by cell damage or defects, which can lead to further degradation.
• Mismatch: Differences in electrical characteristics between cells, resulting in reduced overall efficiency.

4. Describe the safety precautions that should be taken when working with photovoltaic systems.

Safety precautions include:

• Wearing appropriate personal protective equipment (PPE) such as gloves, eye protection, and arc flash clothing.
• Following proper grounding and bonding procedures to prevent electrical hazards.
• Using insulated tools and maintaining safe working distances from live components.
• Being aware of electrical hazards such as potential arc flash risks and taking necessary mitigation measures.
• Understanding the potential for high voltage and current in photovoltaic systems.

5. Explain the importance of proper grounding in photovoltaic systems.

Proper grounding is crucial because it:

• Protects against electrical shock by providing a low-resistance path for fault currents to flow to the earth.
• Prevents damage to equipment and components by diverting excess voltage and current to the ground.
• Improves system safety by reducing the risk of arcing and electrical fires.
• Ensures compliance with electrical codes and standards.

6. Discuss the different methods used to measure solar irradiance.

Solar irradiance can be measured using:

• Pyranometer: A dedicated instrument that measures the total solar radiation incident on a surface.
• Reference cell: A calibrated photovoltaic cell that provides a reference value for irradiance.
• Spectroradiometer: A device that measures the spectral distribution of solar radiation.
• Satellite data: Weather stations and satellites provide irradiance data over large areas.

7. Explain the purpose of a combiner box in a photovoltaic system.

A combiner box serves several purposes:

• Combines the outputs of multiple photovoltaic modules into a single output.
• Provides protection against overcurrent and overvoltage faults.
• Simplifies wiring and reduces the number of connections.
• Facilitates monitoring and troubleshooting by providing access to individual module outputs.

8. Describe the different types of inverters used in photovoltaic systems.

Inverters are classified into several types:

• String inverters: Connect to one string of photovoltaic modules and convert the DC output to AC.
• Central inverters: Connect to multiple strings of photovoltaic modules and handle the conversion in a centralized unit.
• Microinverters: Installed at the module level, converting the DC output of individual modules directly to AC.
• Hybrid inverters: Combine photovoltaic input with other energy sources, such as batteries or the grid.

9. Explain the concept of maximum power point tracking (MPPT) in a photovoltaic system.

MPPT is an algorithm used in photovoltaic systems to:

• Continuously monitor the IV curve of the photovoltaic modules.
• Adjust the operating point of the inverter to match the maximum power point (MPP).
• Maximize the power output of the photovoltaic system under varying conditions of irradiance and temperature.

10. Describe the different types of warranties available for photovoltaic modules.

Photovoltaic modules come with various warranties:

• Performance warranty: Guarantees the power output of the module over a period of time, typically 25 years or more.
• Product warranty: Covers defects in materials and workmanship, typically for shorter periods such as 5 to 10 years.
• Labor warranty: Covers the cost of labor associated with replacing defective modules.

The Photovoltaic Testing Technician is responsible for conducting performance, safety, and reliability tests on photovoltaic (PV) systems and components to ensure they meet industry standards and customer specifications. The technician will work in a laboratory or field setting, using a variety of test equipment and techniques.

1. Conduct performance tests

Conduct performance tests on PV modules, arrays, and systems to measure electrical characteristics such as power output, efficiency, and voltage.

• Set up and operate test equipment, including solar simulators, power analyzers, and data loggers.
• Record and analyze test data to determine the performance of the PV system or component.

2. Conduct safety tests

Conduct safety tests on PV modules, arrays, and systems to ensure they meet electrical safety standards.

• Perform insulation resistance tests, ground fault tests, and other safety tests.
• Review test results to identify any potential safety hazards.

3. Conduct reliability tests

Conduct reliability tests on PV modules, arrays, and systems to assess their long-term performance and durability.

• Design and implement reliability test plans.
• Monitor and record test data over extended periods of time.
• Analyze test results to identify any potential reliability issues.

4. Prepare test reports

Prepare test reports that document the results of performance, safety, and reliability tests.

• Summarize test data and findings.
• Provide recommendations for improving the performance, safety, or reliability of PV systems or components.

Interviewing for a position as a Photovoltaic Testing Technician? Here are a few tips to help you ace the interview and land the job.

1. Research the company and the position

Before you go to the interview, take some time to research the company and the position you are applying for. This will help you understand the company’s culture and values, and the specific requirements of the job. You can find information about the company on their website, social media pages, and Glassdoor.

• Practice answering common interview questions
• Be prepared to talk about your experience and qualifications

2. Practice answering common interview questions

There are a few common interview questions that you are likely to be asked. It is helpful to practice answering these questions in advance so that you can deliver your answers confidently and concisely. Some common interview questions include:

• Tell me about yourself.
• Why are you interested in this position?
• What are your strengths and weaknesses?
• What is your experience with PV testing?
• What are your salary expectations?

3. Be prepared to talk about your experience and qualifications

The interviewer will want to know about your experience and qualifications as they relate to the job requirements. Be prepared to talk about your education, training, and work experience. You should also be able to provide examples of your skills and abilities.

• Highlight your skills and experience
• Quantify your accomplishments

4. Highlight your skills and experience

When you are talking about your experience and qualifications, be sure to highlight the skills and experience that are most relevant to the job. For example, if the job requires experience with a specific type of PV testing equipment, be sure to mention that in your interview.

5. Quantify your accomplishments

When you are talking about your accomplishments, be sure to quantify them whenever possible. This will help the interviewer understand the impact of your work. For example, instead of saying “I managed a team of PV testers,” you could say “I managed a team of PV testers and increased productivity by 20%.”