PERC, TOPCon or HJT
PERC, TOPCon and HJT are the types of cell technologies used in photovoltaic panels. Each solution is characterized by its own parameters, efficiency level, as well as price. How do they differ from each other? What is the efficiency of each, and is it possible to say unequivocally which solar cell technology is best?
Photovoltaic modules available on the market can have different solar cell technology applied. Today's offered modules have been made with technologies designed to increase the efficiency of solar energy conversion, which provides better benefits from investments in renewable energy sources. Among the solutions available on the market, you can find PERC cells, TOPCon cells or HJT cells. They make up a large part of the market, so it is these 3 technologies that will be the subject of description and comparison of this article. So what are the characteristics of each solution?
Photovoltaic investment - proper preparation
Photovoltaic investment requires detailed design and adequate preparation. The decision concerns not only the choice of technology, but also a convenient location. With help comes LiDAR laser scanning, i.e. Light Detection and Ranging technology. This is a measurement method that allows you to acquire a 3D geometric model of the scanned object using laser light. It makes it possible to easily and quickly collect a large amount of data that will be needed at the stage of design work. It is worth considering using this solution when planning an investment in renewable energy sources.
What additional elements should be considered? One solution worth considering is investing in energy storage. If you use photovoltaics, it allows you to better use the energy generated by the panels for your own needs, instead of selling it to the grid and buying it back later. Energy storage can also provide an additional source of energy in case of grid failure.
Another decision to make at the initial stage of investment is the choice of photovoltaic modules. New generation photovoltaic modules can be equipped with different cells. It is about them and the differences between the various solutions that we write below.
PERC cells
PERC cells are a type of monocrystalline p-type cells. The name of this technology comes from the term Passivated Emitter and Rear Cell. This solution allows solar radiation to be reflected from the aluminium-coated layer on the underside of the panel with laser-cut holes (known as reflectors). The purpose of this mechanism is to increase the utilization of the energy potential of solar radiation. In practice, this means increasing the module's efficiency. PERC cells are characterized by high efficiency in both testing and real-world conditions.
TOPCon technology
Solar cells can also be made with TOPCon technology, which stands for Tunnel Oxide Passivated Contact. Although these are n-type cells, i.e. based on negatively doped wafers, among other things, the knowledge and experience of PERC (p―type) cells was used to develop them. The main novelty with TOPCon technology is the addition of a very thin oxide layer and additional silicon layers to the design. The use of the so-called tunnelling effect in their case is expected to result in an increased level of efficiency of the panels by minimizing energy losses caused by internal resistance.
HJT technology
Another commercially available solution is HJT cells. These are classic n-type monocrystalline cells, just like the TOPCon photovoltaic module. HJT modules are often classified as premium modules, but this is due not only to their slightly higher price, but also to their quality parameters. Their construction uses thin wafers of amorphous silicon. Combined with crystalline silicon, such a mixture allows for higher resistance and higher module efficiency regardless of temperature. Heteroionic technology is therefore characterized by the possibility of using both technologies or types of silicon.
Solar cell comparison
Comparison of different solutions
Of the three proposals under discussion, PERC solar cell technology is the most widespread. This is due, among other things, to its longest market seniority. One can even say that in recent years PERC cells have dominated the market, becoming the most popular solution. The introduction of TOPCon technology marked the beginning of a certain trend of change in photovoltaics, due to the improvement of modules, regular increases in their efficiency and technological development. Already at the time of its entry into the market, one of the main arguments in favour of TOPCon was the higher efficiency compared to PERC, resulting from greater tolerance to high temperatures. The youngest technology, with the shortest market seniority, is the HJT heteroionic technology. However, it is referred to by many market experts as the technology of the future.
In terms of processes, the main difference, aside from the type of cells (PERC - p-type, TOPCon and HJT - n-type), between the solutions discussed is the use of passivation. PERC cells use passivation of the underside of the cell, TOPCon uses polysilicon thin-film passivation, while HJT uses amorphous silicon passivation technology. This translates into differences in the performance of each solution. According to tests, as well as examples of real-world deployments, heteroionic technology achieves the highest efficiency among these 3 solutions, i.e. allows higher energy production.
However, it should be remembered that the prevalence of individual solutions, the length of time they have been on the market, as well as the level of design sophistication and manufacturing technology translate into the cost of photovoltaic modules using each technology. The cheapest solution at present is PERC, followed by TOPCon. However, the growing interest in HJT cells is making them more common, and thus they are expected to become cheaper in the future.