How Does Half-Cut Panel (Half-Cell) Technology Work?

A half-cut panel is a type of panel made by laser-cutting a standard-size solar cell in two and placing the two half cells in the module. Because the cell is halved, the current through each cell is halved too. Since resistive losses are proportional to the square of the current, heating and conduction loss at cell level drop markedly. In this article we explain half-cut panel logic, the 144-cell panel example and the shading situation on Antalya roofs from an engineering point of view.

What is a half-cut panel and how is it made?

A classic solar panel consists of full-size cells connected in series. In half-cut production, the finished cell is cut through the middle with a laser, giving two half pieces. These pieces are positioned in the module as two separate zones, top and bottom; so the panel behaves like two half panels.

That is why the half-cell count looks even. For example, a module equivalent to 72 full cells carries 144 half cells. The phrase "144-cell panel" that you see on the market usually describes this structure; that is, the panel has 144 separate power-producing cells, but each is half the size of a full cell.

• The cell count doubles and the current per cell is halved.
• The panel is divided into two parallel sub-strings, top and bottom.

Why do resistive losses fall when current is halved?

Power loss in a conductor is found with the formula P = I² × R. When current is halved, (1/2)² = 1/4, so at the same resistance the loss falls to a quarter. EnergySage's review of half-cut cells also states that the loss reduction comes from this ratio at cell level.

Let us make this concrete with an example. In the manufacturer's TT605-144TN10 datasheet the panel's short-circuit current is given as 14.48 A and its maximum power point current as 13.77 A. Since the panel consists of two parallel sub-strings, each string carries roughly half of this current, about 7.2 A (calculation). In a full-cell design with the same cell size, about 14.5 A would circulate.

This gain is not by itself a big leap at module level. Even if loss in the inter-cell ribbons falls, the module's total power also depends on cell quality, temperature coefficient, glass transmittance and the interconnection method. What percentage the gain at module level is varies from manufacturer to manufacturer, and some sources cite small single-digit percentages. This should not be read as a guaranteed value.

Shade tolerance: where is the real advantage?

A half-cut panel's advantage against shading does not come from cutting the cells. The real contribution comes from the panel being divided into two parallel sub-strings. In a classic full-cell module, three bypass diodes protect three long series strings. If one cell is shaded, the whole of that string can drop out with it.

In a half-cut design, the top and bottom halves work independently of each other. If shade covers only the lower edge, the upper half keeps producing. As a result, the panel's power loss in partial shade is more controlled. This effect is more pronounced when a low-angle sun casts shade on the panel's bottom row in the morning and evening hours.

Typical shade sources in Antalya are the following:

• Water tanks, solar water heaters and stair-head housings on apartment roofs in Kepez and Muratpaşa.
• Chimneys and skylights on tile roofs.
• Mature trees and neighbouring buildings in villa gardens in Döşemealtı, Belek and Manavgat.
• Poles, wire fences and plants near fields and greenhouses.

The distribution of these shadows can affect the bottom or top row of the panel. The real solution lies in the layout plan. On shaded roofs it is worth evaluating microinverter and power optimizer solutions separately. Also take a look at the article where we cover the effect of shade on production in detail: the effect of shading on solar panels.

A 144-cell panel example: 605 W TOPCon data

605 W TommaTech TOPCon panels are used in the Manavgat, Belek and Döşemealtı installations that Solar Nexo shared on Instagram (@solarnexotr). The datasheet of the TT605-144TN10 model in this power class shows the half-cell design, and its specifications are as follows:

This combination, that is half cells, a TOPCon cell structure and multi-busbar (16BB) interconnection, has become standard in today's top power-class panels. We covered the TOPCon side in detail in our what is a TOPCon panel article. What matters here is that the phrase half-cut panel is not by itself an indicator of quality. Two panels that use the same structure can differ from each other in cell efficiency and warranty terms.

What to look at when choosing a half-cut panel

1. Bypass diode and sub-string structure: Look in the datasheet or installation manual at how the panel is divided into two sub-strings. On a shaded roof this architecture makes a difference.
2. Power and current compatibility: In high-power panels such as 605 W, current values rise. The inverter's MPPT input current must accommodate the panel's Isc.
3. Size and weight: Large panels of around 2.6 m² call for more careful installation on roofs with limited load-bearing capacity and in places with high wind exposure.
4. Warranty: Read the product and performance warranties separately. For the TT605-144TN10 the manufacturer states a 15-year product and a 30-year performance warranty.
5. Manufacturing date: In an unlicensed generation application, the main equipment must have been manufactured within the last five years (the April 2026 amendment).

Before installation, your roof's orientation, tilt and shading must be assessed together. For a free site survey you can contact us; our team takes on-site measurements on the roof and draws up the layout plan accordingly.

Managing shade in the layout plan

Independent of panel technology, the cheapest way to reduce shade is the layout plan. The following steps are followed during the survey:

• Areas that receive shade through the day are marked hour by hour; because the longest shadows form in December and January, the winter sun is taken as the basis.
• If shade-free roof area is not enough, the panels are placed not in the shaded zone but in a cleaner area and a different array.
• Shaded and unshaded panels are not left in the same series string; they are connected to separate MPPT inputs.
• The positions of chimneys, aerials and ventilation outlets on the roof are planned relative to the edges of the panel rows.

According to PVGIS data for Antalya city centre, specific yield in December and January is only 99 kWh/kWp. In July this value rises to 168 kWh/kWp. Because the low winter sun angle lengthens shadows, the same obstacle that causes no problem in summer can noticeably reduce the array's production in winter months.

The limits of half-cut panels

Half-cell technology does not solve every problem. Most of a system's losses arise outside the panel: inverter conversion, cable losses, soiling, temperature and orientation errors. In Antalya, panel temperature can rise above 60 °C at summer midday, and temperature loss is independent of the half-cell structure. You can find the calculation of this effect in our solar panel efficiency article.

In addition, half-cell panels still lose power in full shade (for example, the shadow of a chimney covering the whole bottom row). Where problems partially shade a single panel, bypass diodes come into action; but the current of all the panels in a string is limited by the current of the weakest panel. For this reason shade needs to be factored into system design from the start.

In short, a half-cut panel is a sound choice; but the whole system matters more than the technology name on the panel's label. Remember that, according to PVGIS, the panel carries a production potential of about 1,656 kWh/kWp a year in Antalya city centre at optimum tilt (33°), and that realising it depends on a shade-free and clean roof.

Conclusion

A half-cell panel cuts resistive loss at cell level to a quarter by halving the current, and works in a more controlled way in partial shade thanks to its two parallel sub-strings. Most TOPCon panels in the 605 W class today use this structure. Even so, the size of the gain varies by model; rather than promising an official percentage, reading the datasheet, the warranty and your roof's shade map together is the safest route.

#Technology#Half Cut#Half Cell#Solar Panel#Shade#Panel Technology