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Solar power has been gaining popularity over the last decade, and with that demand, the supply has also been ramped up. As a result, many manufacturers, especially from China, have jumped on the bandwagon and are churning out more photovoltaic panels than ever before.
The quality of solar panels is an essential factor to consider when planning a solar plant project on the roof or the ground. Photovoltaic modules of high quality ensure you get a long-term optimal production of solar energy, making for a profitable investment.
Common solar panel defects
As we talk about the quality of solar panels, it is crucial to start off with the common defects found on solar panels. These might be from the factory or appear during shipping.
Scratches on the glass
On average, more than 70% of independent third-party quality inspections reveal small and large scratches on the thin glass covers of the solar modules. Wherever found, these scratches are frequently a result of poor handling or unsafe and careless packing of the modules at the factory.
These scratches, both small and large, may result in output reduction of the affected module.
In some cases, scratches may impact the cells, severely damaging the anti-reflection coating, resulting in diminished light transmission. In addition, air, dust, and water may get beneath the damaged coating, which then lifts the rest of the coating, causing delamination.
Glue marks on glass
During manufacturing, glue holds solar cells together to form a panel. If care isn’t taken during the manufacturing process, excess glue marks might remain on the glass.
These, if not noted during inspection, can lead to the supply of a defective panel. This factor cannot be ignored since glue marks reduce sun exposure, thus reducing the overall efficiency of the solar panel.
Low output as compared to what is stated
Many poor-quality solar panels might have a lower power output than is stated on the label. This is called negative tolerance. Power tolerance is the amount of power output from a solar panel. Some panels might have a positive one, and others a negative one.
Poor sealing between glass and frame
Poor sealing and framing is another commonly seen problem, especially in lower-priced solar panels. The frame protects the PV cells and the glass, and if the seal between the glass and frame is poor, then there is a risk of glass damage and foreign bodies getting in between the glass and the cells.
Poor sealing can also result in the edge delamination of the solar panel if rainwater enters the gap and the solar panel heats up during long work hours.
How to choose solar panels?
With a plethora of solar panel options today, one might wonder where to start when choosing which solar panels to buy. Requirements and preferences will definitely differ from person to person as each house possesses different power needs.
However, one aspect that cuts across is quality and sustainability. We all want quality solar panels that can last a long time, regardless of the purpose and power requirements.
Solar panel quality checklist
Photovoltaic panel quality
Many components and processes go into the manufacturing of a complete solar panel, and oftentimes, it’s the seemingly little things that significantly impact the overall quality of the panel.
For example, parts such as the frame need to be strong so as to support the glass, and other parts like cables need to be top-notch as well.
Attention to detail during the manufacturing process is also important to minimise defects such as poor sealing and glue on the glass.
Technology used
The technology on which the solar panel is built has the biggest impact on its power output and longevity. Some panels are polycrystalline, some are monocrystalline, and others are amorphous thin film panels.
Read: Monocrystalline vs Polycrystalline solar panels
Each of these presents pros and cons, although it is generally accepted that monocrystalline panels are the best in terms of quality. This results in the highest efficiency and longevity of the three.
Price
Solar panel prices tend to vary depending on the technology used, power output and manufacturer.
The best way to really know which panel is the best value for money is to work out the cost coefficient using the cost of the panel per watt of energy generated as a metric.
Manufacturer
The manufacturer has an impact on the quality and, indeed, the price of the solar panel.
Manufacturers like LG, Sunsolar and Panasonic are well-known in the industry for making high-quality, efficient and durable solar panels.
Oftentimes though, you get what you pay for, and while these are some of the best solar panels in the market, they are also some of the priciest.
The guarantee period
A warranty is your first line of defence if there is a problem or defect. In fact, a good warranty also covers any damage during shipping. Most solar panels come with an average warranty of 25 years.
IEC (International Electrotechnical Commission) regulations
The International Electrotechnical Commission (IEC) dictates international standards for all electrical, electronic and related technologies. Their certifications are widely recognised quality standard certifications throughout the solar industry.
Consequently, certified solar panels are better in terms of quality, adhere to regulations, and meet the requirements set by the IEC. Therefore, it is best to look out for certified solar panels.
Efficiency rating
Higher-efficiency solar panels can have an efficiency rating of up to 20%, while an efficiency rating of 12-14% is typical for a standard panel. As such, it is crucial to understand the panel’s efficiency rating because it indicates the amount of sunlight it will absorb.
For context, if a panel has a 17% efficiency rating, it will absorb 17% of the sunlight that strikes it. This means you may need higher-efficiency panels if you have shorter days, or if you want to generate the most electricity from a small roof surface area.
Temperature coefficient
Very high temperatures affect the amount of power solar panels produce. If the temperature coefficient is high, the panel produces less energy at the rated temperature. A temperature coefficient below 0.5% is good.
Read: How to calculate solar cell efficiency?
Power Tolerance
A solar panel’s power tolerance is the extent to which it can produce more or less electrical power than its rated capacity. For example, if you have a 200-watt panel with a tolerance of 5 percent, it may produce 195 watts or 205 watts.
The build of the frame
An excellent solar panel frame should have a superb visual appearance. Corrosion protection is ensured by angling connectors and anodising them. Furthermore, sharp edges and unrefined designs should be avoided in order to enhance the aesthetic appearance of the solar panel on the roof.
Quality of cables and bypass box
The quality of the solar panel can be limited by auxiliary components, such as cables, boxes, or inverters. Make sure you inspect the quality of those parts as well as the overall quality of the panel.
Look at the finish of the Bypass box to see if it is silicone and the appropriate cable diameter. Make sure the bypass diodes are installed correctly so that the solar panel can continue to generate even if part of it is shaded.
Quality of protective film
Always check the protective film on the back of the module for air bubbles and a perfectly flat surface. The appearance of the opposite should indicate poor quality.
How do you know if a solar panel is original?
The ever-increasing demand for solar panels worldwide has led to an influx of poor quality and often counterfeit solar panels. Many will state a higher power rating than they are capable of producing, claim to be a better technology or even claim to be a brand they aren’t.
Here are a some tell-tale signs that can guide you to know if a panel is original.
- Body defects: Substandard materials are used to make fake solar panels, resulting in peeling outer coatings. If you notice any visible blemishes, simply pretend you are on the phone and leave the shop as quickly as possible.
- Cracked or chipped solar cells: Lower-grade solar cells are susceptible to cracks, and this is common with panels that aren’t original.
- Alignment of solar cell string: While misaligned solar cell strings do not affect module performance or lifespan, they can indicate a poor manufacturing process.
- Abrasions on the glass: Poor quality glass is susceptible to scratches. Note that the scratches could be a result of poor handling rather than poor quality.
- Scribbled labels and barcodes: IEC standards require solar module manufacturers to put a barcode behind the glass to track devices. Fake solar panels try to avoid this by including illegible or damaged barcodes on the back of the device. If a module breaks, the buyer is at risk since the warranty on the gadget is nonexistent.
Are used solar panels of good quality?
If well maintained, most electrical products are good for years, if not decades, and this holds true for solar panels.
Their lifespan is usually over 20 years, and most come with a 25-year warranty.
Given that it is unlikely that you will be buying a 30-year-old solar panel, most solar panels on the used market fall well under the 25-year mark and, thus, will most likely be in good condition.
In addition, solar panels are made up of a small number of components and no moving parts. This means that possibility of failure is very low. As long as there is no physical damage that is clearly visible, the panel is most likely good.
The cost savings in purchasing a used solar panel can be significant, especially if you buy many. Inspect the panels thoroughly for some of the markers of damage and poor quality, and if there are none, you will have a great panel at a fraction of the price.
Conclusion
There’s a plethora of solar panels on the market today. Various manufacturers, technologies, power ratings, sizes and shapes exist, and the search for which one to buy can be daunting.
With regards to quality, this guide should help you on your journey to clean and renewable energy.
