Is it good or bad to install photovoltaic on the roof

Theoretically, rooftop photovoltaics (PV) are undoubtedly an excellent green energy solution. They utilize idle roof space, convert sunlight into clean electricity, save on electricity bills, and contribute to environmental protection—it sounds perfect. However, in reality, there are some negative voices: failure to meet power generation targets, component damage, and even safety concerns. The root of these problems often lies not in the PV technology itself, but in whether the entire process—from equipment quality to installation and operation & maintenance—is standardized. And all of this needs to be verified through scientific and rigorous testing.

So, whether rooftop PV is good or not isn't a simple "yes" or "no"; it depends on whether it is a high-quality, high-safety, and high-efficiency system. Below, we will peel back the layers of its mystery from the perspective of testing.

The First Layer of Testing: The "Keen Eye" for Hardware Quality
The core of a PV system is its hardware, primarily including PV modules (solar panels) and inverters.

PV Module Testing: More Than Just Appearance

• Power Degradation Testing: This is a core metric for measuring module quality. New modules have a nominal power rating when they leave the factory, but inferior modules can experience rapid power degradation under sun exposure and weather erosion, leading to a sharp drop in power generation. Professional testing institutions use solar simulators to measure the actual output power of modules under standard conditions, checking if it meets the promised values and evaluating whether the degradation rate after years of use is within the normal range (typically, high-quality modules degrade less than 2% in the first year and less than 0.55% annually thereafter).

• EL (Electroluminescence) Crack Detection: This is the "X-ray machine" of the testing world. Tiny internal cracks (micro-cracks) in the cells are invisible to the naked eye but can severely impact power generation efficiency and expand over time. EL testing involves passing a current through the module in a darkroom, causing it to luminesce. An infrared camera then captures images, clearly revealing internal defects like micro-cracks, fragments, and poor soldering. A responsible project must conduct sampling or full inspection of modules upon arrival before installation.

• Weathering and Reliability Testing: Modules need to withstand over 25 years of exposure to wind and sun on rooftops. Therefore, laboratories simulate extreme environments for accelerated aging tests, such as damp heat testing (high temperature and humidity), UV aging testing, and mechanical load testing (simulating snow, wind pressure). These tests are the cornerstone for ensuring the long-term stable operation of modules.

Inverter Testing: A "Cardiac" Check-up for the System

Inverters are responsible for converting the DC electricity generated by the modules into AC electricity usable in homes. The focus of testing is on conversion efficiency, Maximum Power Point Tracking (MPPT) performance, and reliability. An efficient inverter maximizes the power "harvested" from the modules, while an unstable inverter is a primary point of system failure.

The Second Layer of Testing: The "Precision Gauge" for System Design and Installation
Even if all hardware is top-tier, poor design and installation can ruin the entire system.

• System Compatibility Assessment: During the design phase, software simulation is necessary to ensure that the voltage and current of the string perfectly match the inverter's input range, avoiding power generation losses or even equipment shutdown due to "under-sizing" or voltage over-limits.

• On-site Installation Compliance Testing:

  • Earth Continuity Test: This is a lifeline for safety. It is essential to test whether all metal mounts and equipment are reliably grounded, ensuring that current can be safely directed into the ground in case of lightning strikes or leakage.

  • Insulation Resistance Test: This checks the insulation performance of DC and AC circuits, preventing leakage caused by aging or damaged wiring, which could pose a fire risk.

  • Shading Analysis: Are the installation angle and orientation reasonable? Are there surrounding objects like chimneys or trees that might cause shading? Even a small area of shade can seriously impact the power generation of an entire string of modules, akin to the "bucket effect." On-site survey and simulation before installation are crucial.

The Third Layer of Testing: "Health Monitoring" for Operation and Maintenance
Grid connection and power generation do not mark the end of testing; rather, they begin the "health monitoring" throughout the system's entire lifecycle.

• I-V Curve Testing: This is the most comprehensive "check-up" for a module string. Using specialized instruments to simulate and plot the current-voltage characteristic curve of the string on-site can accurately determine issues such as micro-cracks, hot spots, shading, or junction box failures within the string. It is the "ultimate tool" for diagnosing the causes of low power generation.

• Infrared Thermography Inspection: While the system is operating, using an infrared thermal imager to scan the entire PV array can easily identify "hot spot" modules that are abnormally heating up due to poor contacts, diode failures, or internal short circuits. These hot spots are not only black holes for power generation but also potential fire hazards. Regular infrared inspection is a key method for preventive maintenance.

• Data Monitoring and Analysis: A qualified PV system must be equipped with an online monitoring system. By comparing theoretical and actual power generation in real-time, system abnormalities can be quickly detected. For example, if a particular string's generation suddenly and consistently falls below others, it likely indicates a fault requiring timely investigation.

Conclusion: The Dividing Line Between Good and Bad Rooftop PV is "Scientific Testing"
Returning to the initial question: Is installing PV on the roof good or not?

A PV system that has passed all the above testing stages, possessing high-quality hardware, professional design and installation, and ongoing intelligent operation and maintenance, is undoubtedly "good." It is a safe, reliable, green asset that can bring long-term, stable returns.

Conversely, a system that prioritizes low cost, omits critical testing steps, and is hastily installed by non-professional teams is highly likely to be "bad." It could become a "troublemaker"—failing to meet generation targets, prone to frequent faults, and even harboring hidden safety risks.

As part of Yao Hua Laser, we deeply understand that advanced manufacturing processes, including laser technology, form the foundation for ensuring the high-quality production of PV equipment. Meanwhile, a meticulous culture of testing, run through throughout the entire project lifecycle, is the ultimate guarantee for delivering this high quality to the end-user.

Therefore, our advice to you is: Before deciding to install, be sure to choose a service provider with a good reputation and strong technical expertise. Inquire about details such as hardware sources, test reports, design standards, and O&M plans. A service provider that is willing and happy to demonstrate its testing capabilities and quality standards is more likely to install a truly "good" PV system on your roof.