glossary

IBC solar modules

IBC stands for “Interdigitated Back Contact.” In a traditional solar cell, the contacts are located on the front of the cell, which results in some loss of light and therefore lower efficiency. In an IBC solar cell, on the other hand, the contacts are attached to the back of the cell and there are so-called “fingers” on the front of the cell that capture the light and direct it to the contacts. This arrangement allows IBC solar cells to make better use of the incident light and thus achieve higher efficiency. IBC technology will mainly used in high performance solar cells. 

Shingled solar panels

Due to the smaller cells, shingle solar modules have less power loss within the solar cells. They also achieve better results with partial shading than comparable solar modules. The conductive adhesive (ECA - electrically conductive adhesive) is very flexible and copes well with the heating of the solar modules. Shingle solar modules are therefore considered to be very robust. 

Normal solar cells are connected to each other using so-called busbar technology. Depending on the manufacturer, 3 to 6 metal contacts (busbars) are attached to the cell. These are necessary for the flow of electricity. The more contacts there are, the better the current flow. But this also means that more busbars cover the surface of the cell and so less sunlight can be used. The power is reduced by 3.5% by the busbars. 

No busbars are required for shingle solar modules. The conductive adhesive replaces the metal contacts. Shingle modules make much better use of the available surface than conventional modules. In addition, there is no need to leave any space between the individual cells or strips. Therefore, more electricity is produced on the same area.

HJT solar modules

Heterojunction solar cells (HJT) are a combination of crystalline solar cells and thin film cells. The thin monocrystalline silicon wafer has a wafer-thin coating of amorphous silicon on the front and back. The advantage is that a broader spectrum of sunlight can be used. HJT solar cells therefore have high levels of efficiency.

Heterojunction means “heterojunction” in German. The term indicates that an electron transfer takes place between two different semiconductors in the HJT cells. The difference in the crystalline and thin-film cells is not only in the material, but also in the doping of the silicon. The different dopings are intended to passivate the cell so that the loss of free charge carriers is reduced and the efficiency is increased.

Half cell solar modules

Half cells are normal solar cells that are cut in half after production. A half-cell module therefore usually has 120 cells per module instead of the usual 60, but in principle consists of the same materials.
Half-cell modules are also often referred to as “half-cut” modules or HC modules. In contrast to this, classic solar modules in which the solar cells are completely retained are called full cell modules.

Like a classic photovoltaic module In a half-cell module, 20 solar cells are connected to form a so-called string. In order for a half-cell module to have the same performance as a standard 60-cell module, six strings of half cells must be connected instead of the usual three strings. One cell string is connected in parallel at the top and one at the bottom and protected with a bypass diode. The cells of one half of the module are connected in series. 

Half-cell modules are significantly more powerful than normal modules, even though they are made of the same material. Fraunhofer ISE found that an average of 2-3% more module performance can be achieved with the same input cell when using half-cell technology.

Topcon solar modules

The basic idea The TOPCon concept is that the metal of the connection contacts does not come into contact with the silicon layer. This prevents charge carrier recombination, which typically causes performance losses at the rear of the cell. 

TOPCon = Tunnel Oxide Passivated Contact

Bifacial solar modules

Bifacial (or bifacial) modules enable a higher solar yield for the same area. With conventional modules, only the sunlight that falls on the front can be used. Bifacial modules also convert direct radiation onto the back into electricity, as well as photons that are reflected through the substrate onto the back of the module. Depending on the type and location of installation, 10-30% more performance can be achieved.

N-Type solar modules

Basically, n-type solar cells are similar to conventional p-type solar cells in how they work: both convert sunlight into electrical energy. This happens in different layers made of the semiconductor material silicon: The cells consist of a negatively doped n-layer, a positively doped p-layer and a boundary layer, the p-n junction. 

The crucial difference between p- and n-type solar cells is the material of the base - i.e. the thicker semiconductor layer: in p-type cells this consists of silicon that has been positively doped with boron atoms. For n-type cells made of silicon negatively doped with phosphorus or arsenic atoms. In both cell types, the p-n junction enables current to flow to the oppositely doped silicon layer.

The reverse design makes n-type solar cells less susceptible to power loss. With p-type cells, for example, there are always losses in performance when sunlight hits the modules for the first time. This is referred to as initial degradation. Experts suspect that this is a reaction of the positive boron doping with oxygen. Because most of the silicon in n-type cells is doped with phosphorus, the phenomenon does not occur in them. In addition, phosphorus and arsenic are less sensitive to metallic impurities that can arise during production than boron.

This technology can be used for PERC, TOPCon and HJT cells