Module making is becoming increasingly interesting. Unlike in the past, when module manufacturers were solely relying on innovations at the cell level in order to improve performance, they are now very active employing innovative approaches to improve PV panel output power independent from cell efficiency. It is not only about power output, module makers are commercializing concepts that improve reliability and durability.
Launched at the REI India trade show, the TaiyangNews Advanced Solar Module Technology Report provides an overview on solar module technology with an emphasis on developments in the field of advanced technologies.
Module efficiencies and power ratings continue to go up with PV manufacturers working on several advanced module concepts of which 5 are basically on everyone’s radar:
Glass glass modules – with a fundamental difference of replacing the backsheet with glass – is one of the up and coming module concepts. This concept not only results in more durable product, it also enables the adoption of another important technology – bifacial modules.
Bifacial technology uncovers the rear side of the PV module for sunlight absorption. The gain varies between 5 and 30%, depending on various aspects, such as device design, site albedo, mounting conditions.
Half cut cells is a simple but effective way to improve the module power. By cutting a fully processed cell into two pieces, resistance losses can be reduced, providing a power boost of about 5 to 6 W. Today, a 60 cell equivalent module reaches a power rating of around 330 W with 120 half cells.
Shingle modules are also based on cell slicing – not into two pieces but several strips. The process completely changes cell interconnection by eliminating ribbon. Here, cell strips are connected in as shingle manner, similar to roof tiles. On the heels of two US pioneers, several companies have recently launched shingled modules as well. A shingled module with 19.1% efficiency and a very high power rating of 405 W, equivalent to a 72 cell module in size, is available in the market.
One of the simplest ways to reduce resistance losses is to increase the number of busbars. While 4 busbars are today’s standard and 5-busbar products are increasingly launched, the first companies are introducing 6-busbar cell panels. More sophisticated is multi busbars technology, which is built on the same template as ‘more busbars’ and with the same goal of reducing resistance losses in fingers. But the magnitude is higher – it employs at least a dozen thin wires instead of flat ribbons and needs different equipment. Multi busbar technology, which also saves on silver paste, has a product in the market that comes with a 400 W power rating.
The very good thing about these advanced module technologies is that they can be implemented separately but mostly also together, thus offering the possibility to add up the different benefits. For example, half cut bifacial cells interconnected in multi busbar fashion in dual glass configuration is possible.
The TaiyangNews Advanced Solar Module Technology Report 2017, which is published with support from the Asian PV Industry Association (APVIA), is for download free of charge here.