If you have installed solar panels on the roof of your house you should know the common faults in solar panels
Top 5 Common failures in solar panels
Are there problems with the solar panels? And why is the quality of a solar panel so important in the long term? And why not think that all solar panels are the same. Read here a top 5 problem with solar panels.
1 Incorrect performance figures
By far, the most common: a panel that does not reach the maximum power specified. This applies in particular to cheaper solar panels (source: Eternal Sun in Delft).
For example, it expects to buy a panel of 280 Wp, while in reality this does not exceed 260 Wp. With a difference of 4%, you will lose many hours of kilowatts. And it is almost impossible for you as a consumer to check the maximum power.
2 bubbles of air or moisture under the glass or between the layers.
To keep production costs as low as possible, some manufacturers take too long to laminate (join layers of glass, solar cells, backsheet) together.
Good lamination leads to a vacuum between the layers. A too short and careless process can cause unwanted air bubbles. This leads locally to higher temperatures, which reduces efficiency.
This can also cause moisture to get under the glass. The consequence of this is that the so-called delamination occurs. This means that due to the effect of moisture, the layers separate.
Oxidation of contacts can also occur. Ultimately, this can cause the solar panel to lose its efficiency or even become completely defective.
3 access points in solar cells
It is important that you choose an installer that handles the solar panels very carefully. If a solar panel is overloaded locally, cracks may appear in the cell.
These damages are called hotspots. The hot spots lead to additional resistance, as a result of which a cell becomes (also) locally hot.
This leads to problems because the efficiency of the solar panels is decreasing. On the other hand, moisture can penetrate, causing oxidation. The panel will obtain a greater resistance and will generate a lower performance. Ultimately, this can even lead to a defect. See also defective solar cells for new solar panels .
4 Losses due to poor insulation.
Between the solar cells and the solar panel frame, a potential difference of more than 100 volts may appear. If the glass plate is subsequently wet (due to rain or condensation), the same potential difference will arise between the glass plate and the solar cells.
Leakage currents arise that reduce efficiency. This only becomes evident after a few years. Therefore, it is important to choose a solar panel from a manufacturer that has been in the market for years. After all, they know the properties of their solar panel in the long term.
5 bad contact connections in the connection box
The so-called junction box is located under the solar panel.
It is a plastic connection box in which the wiring is attached.
With high solar radiation, the contacts and diodes in the junction box can get quite hot.
It is important that a good cooling element is mounted on each diode in this junction box. This is usually made of aluminum. A bad cooling ensures a high resistance and therefore a lower efficiency.
The quality of the junction box is sometimes saved, which means that there is a risk that arcs are formed and, therefore, everything becomes a fire risk.
Causes of loss of efficiency and defective solar panels
Because solar panels have no moving parts, they are less susceptible to interference than other systems that produce energy.
The useful life of a photovoltaic panel is determined mainly by the stability and corrosion resistance of the materials used. Panel manufacturers give guarantees for up to 30 years.
However, the panels may fail or degrade, reducing the output power, or the panel does not work at all. Almost all faults are caused by humidity or stress due to temperature (stress).
Temporary decrease in power output.
The performance of a photovoltaic panel may also be temporarily lower. For example due to the shade of the trees or the earth.
With the dirt deposits, the performance can be reduced by around 10%. Wiring faults can also occur, as a result of which the installation does not work optimally. These causes can be remedied.
Efficiency losses and causes of defective panels.
Aging leads over the years to a gradual decrease in the power output of a panel or a defect in the individual cells of a panel.
Aging of solar cells.
A gradual decrease in efficiency in the performance of a panel is caused by:
- greater resistance due to reduced conductivity between contacts or corrosion (due to humidity);
- decreased yield due to migration of metal between the pn compounds; or
- Aging of the antireflective layer.
Short circuit between the cells
Short circuits may occur with the connections between the cells. This is also a common defect with thin-film cells, since the contacts in the front and rear are much closer together, there is a greater risk of short-circuiting the terminals or in the vicinity of damaged (corroded) cellular material or damaged.
Interruption of connections in solar cells.
This is a common problem. That is why redundant contacts and bus bars are used, so that the cell continues to function. The rupture of fragile cells is caused by:
- stress by temperature (thermal stress);
- hail
- damage during production and assembly, as a result of cracks that occur, which are not visible to the eye, but occur later.
Interruption of connections between cells.
The cyclic temperature and the wind load lead to the interruption of the connections.
Interruption of connections between panels.
Connection defects can also occur in the panel itself, particularly in the wiring or junction box.
Although each module is tested before sales, panel short-circuits are often the result of problems during production. Weathering degrades protection, resulting in delamination, cracking or electrochemical corrosion.
Broken glass
The crushing of the hardened glass plate on the front can be caused by vandalism, thermal stress, transport, assembly, wind or hail. As with automobile windows, a small amount of damage can result in a completely broken panel.
Delaminated
The separation of the laminated pieces is a common defect in the first generations of panels. This is less common nowadays. The cause of delamination is that the applied adhesive loses its strength due to humidity, photothermal aging, humidity and temperature stress.
Hot spots
Poorly combined, cracked or shaded cells can cause hot spots (narrowing of the connections can cause them to overheat, which causes the panel to break (burn) despite redundancy).
Defective by-pass diodes
By-pass diodes are used to limit the performance losses that occur when the cells do not work optimally (due to dirt, shade or defects in the intermediate cells.) Diodes can also break due to overheating and because they have applied small diodes).
Problems with encapsulation (lamination)
By encapsulating the cells between the glass plate and the back plate, an adhesive is used, which is brought to the temperature up to about 80 degrees. This glue (EVA) contains UV absorbents and other stabilizers that prolong the useful life of the panel.
However, the glue layer loses its power slowly but surely through leaching and diffusion. At a certain time, when the concentrations fall below a critical level, rapid deterioration of the adhesive layer occurs.
The glue (EVA) turns yellowish brown and acetic acid forms, which considerably reduces the performance of the panel. Solar panels with concentrators (for example, with Fresnel lenses) have more problems with this.