What does the efficiency of a PV installation depend on?

PV, or photovoltaic, is one of those sectors of the economy that is constantly developing. Scientists and investors related to the industry are trying to outdo each other in concepts aimed at increasing the efficiency of photovoltaic cells, and thus also the entire structure of modules. The key to success in most often, however, is not to obtain the highest possible efficiency of photovoltaic panels, but to maximize the profitability of their use, i.e. to optimize the quality / price ratio of the device. Below, we will answer the question of what factors the efficiency of a photovoltaic installation depends on and when it is worth considering the purchase of relatively high-efficiency photovoltaic panels.

The efficiency of photovoltaics throughout the year and its overall efficiency determined by many aspects

Before we get to the right answer to the previously asked questions, let’s explain what is basically understood by the efficiency of a photovoltaic installation. In the simplest translation, this term describes the efficiency of a device in terms of converting energy from solar radiation into electricity. The efficiency of PV panels as a percentage is obtained by calculating the ratio of the power of solar radiation incident on their surface to the electricity generated by them. The efficiency of photovoltaics varies throughout the year, and the quality of the above-mentioned process is, in turn, influenced by many non-uniform factors that can affect it both positively and negatively. The most important of them include:

• type of technology used in the production of PV modules,
• material used in the construction, in particular the crystal structure and properties,
• features of the glass and anti-reflective coatings used to protect the cells,
• the quality of the connections between the links included in the installation,
• atmospheric conditions specific to a specific work area, such as wind intensity, air temperature, and the intensity of solar radiation.

Due to the above-mentioned factors, with particular emphasis on the last one, the actual efficiency of photovoltaic panels with the same nominal efficiency is not uniform for different geographic areas and depends on the azimuths and angles of inclination of individual cells.

Maximum power of the photovoltaic installation depending on the technology used

We have already mentioned that the efficiency of a photovoltaic installation depends, among others, on on the type of module technology. However, this is such an important factor that it is worth devoting a separate part of the post to it. The monocrystalline and polycrystalline variants are distinguished from the most popular types of PV panels. As the name suggests, the first one consists of a monolithic (i.e. one whole) silicon crystal, while the second one consists of cells containing many crystals in their structure.

The monocrystalline module has a dark shade and very characteristic cut corners, which result from the specificity of the silicon wafer manufacturing process. The maximum power of a photovoltaic installation of this type is significantly higher than the power that can be obtained with their polycrystalline counterpart. Its efficiency ranges from 18 to 22%, while the efficiency of polycrystalline panels is in the range of 14-18%. Does this fact mean, however, that the use of single crystal silicon panels is always the best option? The answer is no. To understand this better, let’s move on to the answers to the second of the questions posed in the introduction – when is it worth considering the purchase of relatively high-performance photovoltaic panels?

How important is the nominal efficiency of photovoltaic panels?

Polycrystalline modules are actually characterized by lower efficiency than their monocrystalline counterparts, but this disadvantage is also accompanied by a very significant advantage in the form of a lower price, or more precisely, its better relation to quality than in the case of monocrystalline modules. This fact makes the first of the above-mentioned solutions much more popular not only in Poland, but also in other regions of the world. In practice, the maximum power of a photovoltaic installation plays an important role almost only when the investor has a space that is limited in relation to the needs of the PV modules. For example, by installing a panel with a nominal efficiency of 20% and an area of ​​1.5 m2 in a given area (assuming the solar radiation intensity at the standard value of 1000 W / m), we will get a power of 300 W. For a module with the same area, but the nominal efficiency is lower by 5% power will be only 225W.

Of course, when making such estimates, one must take into account the fact that the efficiency of photovoltaics varies throughout the year and the key factor necessary to estimate the energy potentially produced by the panels are the specificity of the installation area and the number of sunny hours characteristic for the place of their installation.