+800W and 25% efficiency solar panels?

When visiting a solar fair, one of the things that catches your eye is the race to announce the most powerful panel. The evolution of commercial panel power has been spectacular: in just over three years, we have gone from 400W panels to the current+ 700W panels.

But what is behind this increase in power? Is it all due to improved efficiency or are there other factors at play? In this article, we will try to explain the main factors that are enabling this rapid evolution and what we can expect in the coming years.

 

Power vs. Efficiency: What do they mean and how are they related?

Let’s start by understanding the differences between power and efficiency.

• Power: This is the maximum amount of electricity that a panel can deliver under standard conditions (STC: irradiance of 1,000 W/m² and 25°C). It is measured in watts (W) and is the value indicated on the panel’s technical data sheet (e.g. 410W, 540W).
• Efficiency: This is the percentage of solar energy received that the panel converts into electricity. For example, an efficiency of 22% means that for every 100W of sunlight, the panel converts 22W into usable electrical energy^[1] .

It is important to understand that a more efficient panel generates more electricity while occupying less surface area, but a more powerful panel (with more watts) is not necessarily more efficient: it may simply be larger or have more cells.

 

Cell and panel efficiency: why are they not the same?

Another aspect that is often confusing is cell and panel efficiency

• Cell efficiency: This is the performance of an individual cell under ideal conditions. Laboratories often report high figures that show the maximum potential of each technology.
• Panel (or module) efficiency: This reflects the actual performance of the assembled set of cells, taking into account losses due to space between cells, cables, frames and encapsulation materials. It is always lower than that of the individual cell .

 

There is usually a loss of 1-2% between the cell and the module, although this may vary depending on the technology. The following Fraunhofer chart shows the latest data on cell and module efficiency by technology:

 

 

Factors influencing the power growth of panels

1. Efficiency

It is obvious that with more efficient cells, the power per unit area will be higher. Efficiency varies greatly depending on the technology used. The famous NREL graph is the bible for understanding the evolution of efficiencies by technology.

 

 

This famous infographic from NREL (National Renewable Energy Laboratory) compiles world records for laboratory efficiency for each solar technology. It is important to note that these are laboratory results, which are values that indicate the commercial potential of each technology, values that may not be achieved if their manufacture is not industrially viable.

Another interesting aspect that can be seen in the NREL infographic is the technologies whose evolution has stagnated. For example, organic cells have not improved their efficiency since 2023, a sign that their development has stalled. However, we can see the rapid improvement of technologies such as perovskite and HJT, which are in full swing. Other mature technologies such as thin film have seen very little improvement in recent years, indicating that they have reached their theoretical maximum.

Among current commercial technologies, back contact cells are the most promising. They are based primarily on moving all connections between cells to the rear, thereby using more surface area for the cells and improving their efficiency.

Below is a comparative table published in PV Magazine summarising the differences between technologies:

 

 

The market share by technology has been changing rapidly, with PERC technology replacing the old BSF (Back Surface Field) in the early 2020s, while TOPCon (passivated contact) is now the majority technology.

 

 

2. Size

One of the main factors explaining the growth in panel power is their larger size. In recent years, we have seen two clear trends:

• Increase in cell size: from 156 mm (or M0) to 210 mm (or M12).
• Greater number of cells per panel: from the old 60 cells per panel to the current 72 cells (or 144 half-cells).

 

 

Even using 72 cells per module, the growth of the cells has led to much larger panel sizes, increasing in power but also in surface area and overall size. In fact, panels currently measure between 2.5 and 3 m2, but they are expected to continue growing beyond 3 m2 in the future.

 

 

Current ranking of the most powerful modules on the market

There are rankings of the most powerful products on the market available online, such as at this link

 

 

Will we ever see 1000 W modules?   

In terms of efficiency, it does not seem that we will see any major changes. With new Back Contact-based technologies, improvements over current technologies will be approximately 1%, meaning that commercial products will not see any major differences in power.

 

 

However, perovskite/tandem technologies promise higher efficiencies, although they are far from being commercially viable solutions.

 

In terms of size, it is unlikely that we will see cell sizes larger than the current M12 in the short term, as each increase in size involves changes throughout the entire manufacturing chain. In addition, logistics are key in this industry, as millions of panels are moved each year and even the slightest change in dimensions can result in significant additional transport and assembly costs.

 

In the coming years, we will see 800 W panels, but it is likely that the growth in power will slow down and it will take longer to overcome this new barrier. In fact, Trina Solar has already announced the manufacture of the first +800W panel, with tandem-perovskite technology, M12 cells and a total surface area of 3.1 m2, although it is far from being a series product.

 

Conclusion

 

In the coming years, we will see the 800W power and 25% efficiency per module barrier broken thanks to tandem perovskite technology, but commercial products based on TOPCon and Back Contact technology are likely to remain at the current average of 700W.

The 1000W barrier will take time to reach and will probably involve some growth in cell size. In addition, the low prices of modules do not encourage the search for higher efficiencies, as minimum LCoE values are already being achieved with mainstream technology panels.