Photovoltaic modules with high efficiency and performance

Photovoltaic modules with high efficiency and performance are increasingly taking centre stage in technical developments. While many suppliers are concentrating on standard solutions, competition is shifting more towards efficiency, power density and behaviour under real conditions.

Photovoltaic modules are increasingly developing in the direction of higher efficiency and more stable performance under real conditions. The combination of cell technology, module design and electrical layout determines how much energy is actually generated. Factors such as temperature behaviour, shading and contacting play a greater role than in previous generations.

Aiko photovoltaic modules with rear contact cell

Aiko was founded in 2009 and initially operated exclusively as a manufacturer of solar cells. Production was aimed at other module manufacturers who further processed the cells. The strategic direction only changed with the development of its own back-surface contact cell in 2021. This cell technology shifts all electrical contacts to the rear side. This leaves the front of the cell completely free of conductive structures such as busbars. This results in a larger active area that can absorb sunlight. Aiko is now using this technology for its own modules in order to realise the benefits directly in the product. The step from cell supplier to module manufacturer is a logical consequence of the company's desire to fully control technical performance.

Neostar 2 Generation for rooftop applications

With the Neostar 2 generation, Aiko is specifically targeting the private rooftop sector. The modules combine technical properties with a design approach that is increasingly in demand in this segment. The rear contact cell creates a homogeneous surface without visible conductor tracks. In combination with a black backsheet, this results in a consistently dark appearance. This so-called full-black look is often favoured for residential buildings in particular. Technically, the module achieves an output of 470 watts with an efficiency of 23.5 per cent. These values place it in the upper range of current rooftop solutions. The decisive factor here is not only the maximum output, but also the stability of this output under changing conditions.

Temperature coefficient as a factor for real performance

One point that is often underestimated is the behaviour at rising temperatures. Photovoltaic modules lose power as they heat up. The so-called temperature coefficient indicates how strong this effect is. At Aiko, this value is minus 0.26 per cent per degree Celsius. Many conventional modules tend to be in the range of minus 0.29 to minus 0.3. The difference appears small at first glance, but adds up over the entire system. This effect can be measurable, especially in larger installations or in sunny regions. A lower power loss per degree means that more energy is generated throughout the day.

Shading optimisation through cell architecture

A central problem with classic modules is shading. If shade falls on individual cells, this can impair the performance of entire cell strings. In conventional systems, affected areas are often switched off via bypass diodes. Aiko takes a different approach. The rear contact cells operate at lower voltages and enable finer control within the module. If a cell is shaded, it can be specifically bypassed without the entire string failing. The technical background lies in the shorter distances that electrons have to travel within the cell. While conventional cells have to cover a distance of around 130 micrometres, this distance is reduced to around 30 micrometres. As a result, the current flow remains more stable even in partial shading.

Comparison with conventional modules in operation

The difference becomes particularly clear in a direct comparison. Demonstrations show that the output of conventional modules can drop sharply when shadows move. As soon as a central area is affected, energy production drops significantly or stops completely. In contrast, the output of modules with rear contact cells remains comparatively constant. Individual shaded areas have less of an effect on the overall system. This leads to more even energy production over the course of the day. The most important technical advantages can be summarised:

• free cell surface without front contacts
• Lower power loss as the temperature rises
• more stable energy production with partial shading
• higher efficiency thanks to optimised cell structure
• homogeneous optics for the rooftop area

Development from cell technology to module

The development shows how much the focus in photovoltaics has shifted. Whereas installed output used to be the main focus, today the actual energy yield is becoming more important. Aiko utilises its experience in cell production to transfer this approach to complete modules. Control over the entire value chain makes it possible to optimise technical details in a targeted manner. At the same time, it is becoming clear that progress is not only achieved through larger surface areas or higher nominal outputs. The physical properties of the cells and their behaviour under real conditions are decisive. Photovoltaic modules are thus evolving from standardised products to technologically differentiated systems. Efficiency, temperature behaviour and resistance to shading are becoming key criteria - and it is precisely here that it is decided how much energy a system actually delivers.