News date: 09.08.2024.

Photovoltaic systems with single-axis tracking

Photovoltaic systems with monitoring, so-called “tracker systems” have been on the market for quite a long time, however, due to their construction cost, they were not that widespread. But as times change, equipment for photovoltaic systems has become more and more affordable, and so have monitoring systems.

What is a tracking system? It is actually a photovoltaic system on the ground that has a built-in mechanism for tracking the path of the sun in its substructure. In practice, we distinguish between two types of systems:

  • Systems with single axis tracking
  • Systems with dual axis tracking

Two-axis systems follow the path of the Sun from east to west, as well as the height of the Sun itself, so they change their orientation and inclination depending on the position of the Sun. Given that these types of systems are poorly profitable because they require a much larger area of ​​land per installed kWp of photovoltaic modules, they are practically not even installed anymore. They were replaced by single-axis systems and we will talk about them in more detail in this article.

Single-axis systems follow the path of the Sun from sunrise to sunset. For this reason, the tables in such photovoltaic systems are placed so that the modules face east (initial position), and not south, as is customary with fixed photovoltaic systems on the ground.

The monitoring mechanism is installed on the substructure of the photovoltaic modules itself. It is programmed depending on the location and is usually powered from the inverters themselves. Most modern inverters for onshore power plants have separate connections on them to power the monitoring system. How exactly does such a system work? As we mentioned, the initial position of the module is a slope towards the east (the sensing slope can also be determined according to the location, but mostly it is between 20° and 30°). The program that we inserted into the tracking system will, depending on the location, follow the path of the Sun from east to west, when the sun sets. The system remains in the westward orientation until the morning, when it resets to its initial position in the morning, as soon as the exchangers are energized. And so it repeats every day.

What are the benefits of single-axis systems? Through various studies and examples from practice, it was found that uniaxial system have approx. 30% higher production on an annual basis. The price difference compared to fixed systems is currently approx. 15 to 20% higher, so single-axis systems are increasingly profitable. The following figure shows the difference between the production of fixed systems (colored yellow) and single-axis tracking systems (colored blue) in one day.

The negative side of single-axis and tracking systems in general is that a larger area is needed to install the same amount of kWp modules compared to fixed systems, and this is the reason why in Croatia, considering the land prices, these systems have not yet taken off to a large extent.

Single-axis systems are widely used in agrosolar power plants in gardening and agriculture. In Germany, such systems are very widespread. In gardening, such systems provide the plants with the necessary shade during the day. During rainy days, they supply the plants with additional rainwater by rotating them. In Germany, there are also examples of single-axis systems on grain fields.

Such examples are not possible in the Republic of Croatia according to the current legislation. One of the conditions for the construction of agrosolar power plants in the Republic of Croatia is that the plantations must be permanent (fruits and the like), and not seasonal (cereals, gardening and the like).

In Germany, there are also examples of single-axis systems on grain fields, as can be seen in the picture below.

Such examples are not possible in the Republic of Croatia according to the current legislation. One of the conditions for the construction of agrosolar power plants in the Republic of Croatia is that the plantations must be permanent (fruits and similars) and not seasonal (cereals, gardening and similars).