We discussed about the solar cells in our last article,today we will talk about other two important raw materials,EVA and Back sheet.
We all know that EVA is similar as the glue between the cells,glass and back sheet. If you get the solar panel,but with low quality EVA,what will happen? Let's see the following photo:
This is called delaminating of EVA,this can be caused by many reasons,if the temperature of the lamination is not correct,it also can cause it.But it is hardly happened during production,because most of the production lines are full automatic now.So this phenomenon was caused by the quality of the EVA，which factors will cause the problem of the EVA? We listed some points as follow:
The chemical formulation
The time of storage and the temperature of storage. When supplier get the new EVA,they need to keep it in the warehouse with constant temperature below 30 degree and use it in 6 months quickly.If they keep it for long time and temperature is higher than 30 degree,it will cause some changes inside of the EVA.
The reclaimed EVA.Some suppliers are also using this reclaimed EVA for their solar panels,because it can save much cost for them.
There are still other points too and we will not list here one by one.So as you can see how important of the EVA for the solar panel!
Next,let's talk about the back sheet,another important material for solar panel.In the market there are different back sheet,such as PET,TPT.etc..So which one will be the best? Let's see the structure of TPT:
TPT is with the double-side fluorocarbon structure(PVF//PET//PVF) with the integration of Tedlar(DuPont). It has excellent UV resistance and aging resistance and good electrical insulation and breakdown.Most of the best quality solar panels are using TPT as back sheet.
But some suppliers are using PET as back sheet only,it is just one layer ,when you get the panel with this kind of back sheet,you will see the back sheet of the solar panel turn to yellow after some years,even some back sheets were broken into pieces:
So if you find your solar panels with yellow back sheet after some years,you should be more careful about these panels.It will also cause the power of the panel decreased quickly in the future.
One of our solar project in Japan is still with white back sheet after 10 years,we are using the TPT as back sheet for our solar panels all the time:
Next time we will discuss about the last two materials: Frame and Junction box,we will also tell you some tips about how to get more output from the solar panel when you make the arrays.