Half-cut cell or half cell modules are an ongoing trend. And there are good reasons for that as they show striking advantages compared to standard modules.
PSC SOLAR UK gives you an overview about these advantages.
What is a Half Cell Solar Module?
Half cell modules are literally normal solar modules the cells of which have been cut in half. Instead of having 60 or 72 full solar cells, they have 120 or 144 half-sized ones, while module design and dimensions are similar to that of conventional ones. Half cell modules have several advantages compared to regular full cell modules. They show better shading tolerance and reduced risk for hot spots. But most importantly, half-cut solar cells offer increased efficiency. Let’s have a closer look and find out how this works.
Standard full cell module
Half cell module
Half cell modules show a much better efficiency than full cell modules. The reason is the halved area of the cells.
Basically, it can be said that the higher the current, the higher the electrical losses. Cutting the solar cells in half also halves the current per cell. Since the power loss is proportional to the square of the current, the total power loss is reduced by 75% compared to a full cell. This effect increases the overall efficiency of the half cell module significantly.
Current in full cell
Current in half cell
Improved shade tolerance
Half cell modules are more resistant to the effects of shade than traditional solar modules.
This is not due to the cells being cut in half, but rather a result of the wiring methods used to connect half cells in a module. In solar modules, the cells are wired together in series in so called “strings”. In standard modules, there are 3 of them. If only one cell of a string is shaded, the entire string of cells will stop producing power. This would mean a loss of 33.3% of the module’s power production.
Half cells are also wired in series, but in a different way. The overall number of cells is separated in two twin sections, one in the top half and one in the bottom half of the module. In principle, these two sections can be regarded as two separate modules which are connected in parallel. This way, a half cell module has 6 strings of cells instead of only 3. If one cell in a string is shaded now, only 16.7% of the module’s power production is lost, not 33.3%.
33.3% power loss with full cell module
16.6% power loss with half cell module
In case one section of the half cell module is shaded, the other section will still produce at full power. Thus, the module output is still 50%. In case of a standard module, the power loss would be 100%. This is particularly of advantage if snow slips down the module and covers the lower part.
100% power loss with full cell module
50% power loss with half cell module
Reduced risk for hot spots
When one solar cell in a module cell string is shaded, all the preceding unshaded cells will dump the energy they produce into the shaded cell as heat.
This creates a hot spot that can potentially damage the solar module if it lasts for a long time. Twice as many module cell strings means only half as much heat. In case of half cell modules, the lower heat production reduces the risk of hot spot damage to the module.
The reasons explained above make a half cell module a good choice. Due to the higher efficiency, half cell modules have the potential for quicker payback periods as compared to any traditional counterparts. Particularly for sites where shadow casting and limited area are the main constraining elements, the installation is even more worth the upfront cost. The bottom line is that half cell modules are a cost-effective solution where you do not have to compromise on neither quality nor output.