Recôncavo Solar Laboratory: different technologies available in the PV sector

A collaboration between UFRB (Federal University of Recôncavo da Bahia) and Amara Energia has enabled the creation of a photovoltaic solar energy laboratory with the aim of conducting studies of different technologies available in the photovoltaic sector under real conditions. The laboratory will also be of great value to the university's academics, who will be able to conduct research, develop articles and final course work using the laboratory's facilities. These facilities are often not easily accessible to the academic community.

16 photovoltaic modules were installed and commissioned, distributed in a string inverter (inverter A) and three microinverters (inverters B, C and D). All inverters work in the same climatic conditions, installed on the same electrical network and with modules facing the same direction.

The three microinverters are connected close to the modules, next to the installation's fixing structure, and the inverter is housed in a covered installation with the necessary technical requirements and 10 meters away from the photovoltaic modules. In summary, the following photovoltaic systems are located in the laboratory:

Table 1: Inverter technology and installed power of photovoltaic systems

As the objective of the laboratory is to analyze different photovoltaic module technologies, the following arrangements were carried out:

Table 2: Photovoltaic modules used in the systems

As indicated in Table 2, the connections between modules and inverters can be better represented through the following diagrams.

For a better understanding of the laboratory's lines of research, the construction characteristics of each module present in the plant are highlighted here:

Table 3: Cell types and module technologies used in the different laboratory systems

As a result, several research studies will be carried out in the laboratory with the aim of expanding practical knowledge linked to the theory of photovoltaic systems. Initially the following comparisons will be made:

• String inverters x microinverters;
• Polycrystalline modules x monocrystalline modules;
• Monofacial modules x bifacial modules.

It is important to highlight the structures used in the plant, both for soil: the Ecoground structure and a conventional single-pole structure. Each structure has different configurations and parameters that deserve to be analyzed, as well as their impact on energy generation. The following topics stand out here: height above ground, angle of inclination, spacing between rows and width between sheds.

For the systems analyzed here, the height above the ground and the angle of inclination will be the preponderant factors, as discussed in the article “EcoGround Structure – Differences and advantages compared to conventional soil structures”. For the monopole structure (Figure 6) the local inclination (13°) was used with the modules installed in portrait and for the Ecoground structure (Figure 7) the inclination of 15° was used (manufacturer's standard) with the modules installed in landscape.

These structures will be used to analyze the influence of the inclination and height of the modules in relation to the ground on the generation of the photovoltaic system. The effect of the presence of gravel at the installation site of the bifacial modules will also be studied, with the aim of increasing the albedo for greater capture of solar radiation on the lower face of the module. Factors such as these are described in more detail in the article “Albedo (reflection coefficient): definition and influence on bifacial modules".

In summary, this laboratory will present and study the main differences between photovoltaic systems connected to the electrical grid in a practical way. The results will be disseminated to society through articles and annual reports regarding the generation and efficiency of each system analyzed.