As bus ribbon makes its way around the corners of a solar panel, it must divert current at right angles. These 90° ribbons are produced from a single straight ribbon which is cut and formed prior to use, or it is formed by automated equipment during application. Most automated bussing equipment uses a folding procedure to create a 90° angle at each corner, just before it is soldered in place. This is called "folded" ribbon and is seen in the right side of this image. Some assembly processes simply solder two bus ribbons together at right angles as well. The sections that are made ahead of time can be folded or carefully bent, and go by a few different names: L-Tabs, J-Tabs, and L-Bus. This is called "bent" ribbon and is seen in the left side of this image. Although either method may be used to form the bus ribbon, there are some subtle differences in how these products function. Here are some pros and cons of how bent ribbons differ from folded bus ribbons.
Pros (of bent ribbon):
- Bent ribbon has a smoother electron path, no kinks. I have been told by some customers and equipment vendors that this benefit is significant.
- Bent ribbon has a lower profile, as folded ribbon must be at least 2x as thick in the folded section.
- Folded ribbon is easier to form, hence the popularity with most automated equipment.
- Improperly bent ribbon will not retain a uniform cross section, or may exhibit rippling of the inner radius.
Indium Corporation has decided to produce bent bus ribbon due to feedback from customers and industry partners, but we also provide straight bus ribbon for those who prefer to fold the ribbon themselves. We've found out it's tricky to bend a ribbon, but as you can see from the picture above - we've found a way to make a beautiful 90° bend!