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Solar panels: how to recognize good quality solar panels?

Photovoltaic panels appear more and more frequently on the roofs of Polish houses. The Poles are investing in photovoltaic energy, but not everyone knows how to recognize good quality solar panels. Here’s what to look for when choosing solar panels.

Solar panels: how to recognize good quality solar panels?

The photovoltaic market in Europe is developing extremely dynamically, the fastest of all the renewable energy sectors. The market can also boast very large power increases when it comes to generating electricity from the sun. In 2019, the total capacity of our photovoltaic installations approached 1,500 MW. In terms of energy growth, we were 5th in the European Union, ahead of us only Spain, Germany, the Netherlands and France. At the beginning of June 2020, the total capacity of Polish PV installations was 1953.1 MW. Everything indicates that, therefore, we will maintain the fifth position in Europe.

Of course, these successes would not have been achieved were it not for the growing interest of Poles in photovoltaics. However, such an installation on the roof of your own home is sometimes quite expensive, although it can be reduced thanks to increasingly generous state subsidies. However, PV is worth approaching as a long-term investment. This means that the facility will serve us efficiently for many years. For this to be possible, it is necessary, among other things, to select good quality photovoltaic panels.

How to choose a solar panel? What are the parameters that I should consider?

A photovoltaic panel consists of cells that are semiconductor elements. It is these cells that convert the energy generated from solar radiation into electricity. For the modules to be powered in a domestic installation, they must be connected in series in strings or, in the case of microinverters, in parallel strings, which is preferable.

It is good to know that one solar panel is not the same as the other. That is why it is so important to pay attention to the most important panel parameters:

  • Maximum power: the power obtained during the tests (STC), is similar to the power during optimal operation. In Polish climatic conditions, 10% of maximum power is most often obtained.
  • Power tolerance: the level between the maximum and nominal power of a given panel.
  • Efficiency: the relationship between the maximum electrical power and the power that the panel actually reaches when exposed to sunlight.
  • Short circuit current: called I  sc  and is the highest current that can generate a fire as a result of sunlight. This current determines the efficiency of the cells and should be as high as possible.
  • Voltage at the point of maximum power U  MPP  – thanks to this parameter it is possible to determine the level of energy losses (the difference between the voltage U  MPP  and the voltage registered in the system).
  • Open circuit voltage U  oc  – maximum potential difference between panel contacts, open circuit voltage (when there is no current draw).
  • Temperature Power Factor – The lower the value, the better. Determines the percentage of power decrease with a 1 °  C increase in temperature   (cell power decreases with temperature).
  • Fill factor FF: it should be as close as possible to 100%, it should not be less than 70%. This parameter determines the quality of the cells.

Learn how to choose the best solar panel

How to read the card and what are the most important parameters of the modules?

When looking for good quality photovoltaic panels, the product sheet should be one of the basic sources of information. This card usually consists of the following sections:

  • Mechanical specificity (eg dimensions, weight, coating).
  • Electrical parameters (minimum performance under standard STC test conditions and under normal NOC operating conditions, performance guarantee and temperature coefficients).
  • Parameters for system connection (eg Maximum system voltage, wind load).
  • Qualifications and certificates.

When comparing different solar panels, compare the information on the product sheets. The following aspects compare best:

  • Frequency of failure of photovoltaic panels: the panels must have the highest possible resistance to mechanical damage, shadows and high temperatures. This is usually guaranteed by reputable manufacturers. By the way, it is worth paying attention to the warranty – it should be as long as possible (for example, 25 years).
  • Temperature power factor: select the panel with the lowest value of this parameter.
  • Decrease in maximum power over time: every year the maximum power of the panels decreases and this is according to the laws of physics, it is not a defect of the panels. In the case of good quality panels, this decrease does not exceed 1% per year. It is worth comparing.
  • The power of panels obtained under conditions other than laboratory conditions (STC) – it is worth paying attention to additional information about the operation of panels under less favorable conditions.

What about the PID effect?

Finally, the issue is no less important than the parameters described above. These are the so-called PID Effect (Potential Induced Degradation). It is the degradation of the panels caused by the induced voltage. The current will go to the grounded frame of the panel and then to the ground. This not only causes losses, but also destroys the photovoltaic panels.

The PID effect occurs more frequently in low quality photovoltaic panels, there is no problem in the case of good quality panels. To eliminate the dangers of PID, it is best to buy good quality panels that have been PID tested. Information on the PID resistance tests carried out must be attached to the product sheet by the manufacturer.

The choice of solar panels should not be a coincidence. You must carefully analyze the data from the panels, and it is best to consult a specialist who will advise you on the selection of the best cells. Good quality panels mean better installation efficiency and more durable modules.