Lesson 1: The perfect Size of Your Solar Module Production Line

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You can make an automatization mainly for two reasons:

1. Because of quality advantages
2. Because of cost savings

Below we will make some examples for this two reasons.

It makes a lot of sense to make automation in all the parts where it is critical for the quality. You can automate not only the production process it self (stringing, layup and so on) but also in the quality check there are a lot of quality systems that
help you to check the quality automatically.

There is no security that an automated process in all parts over your production will lead to a much better quality result in the product!

Of course even with 100% manual made panels you will be able to produce a very good solar module with a very good quality.

But: The work of a human is not stabile all the time! Some days he will be better and some days he will make failures.

A machine will make all the time the same quality: If you adjust the machine well it will make perfect solar modules and one will be as good as the other. So it is much easier to improofe your quality if you have a highly automated solar module production line!

This is the reason why you can say that in a long term, a higher automated production will make panels with a higher quality than a production line that is based on a hand made process.

If we go through the process of a solar module production, than there are some parts where it is very critical for the quality if a solar module and some parts where it is less important to have an automated process. Below we will list some critical parts of the production:

Cell soldering:

Solar cells are very thin and can break very easy! If the solar cell is broken in the micro structure (you can not see it with your eyes) than the power of the solar module will go down over the time much faster than with a perfect soldered cell.

This is why it makes sense to automate this part first with an automated stringer!

This part you should think about before thinking about any other automatization.

We recommend to make stringing fully automated even with the smallest line!

Lay
up of the strings:

Next part in the production is to take the strings of solders cells onto the glass.

Also this is very critical to make it by hand because you can crack cells by touching them or if you take a manual gripper and moving too fast there can be damages as well!

The automated solution is a layup station with automated grippers or robots that are placing the strings very soft on the panel. Addition to the technical advantage of this station you will get a much better result in the “optical quality”. This means that all the strings will be 100% placed the same (space in between, complete parallel). This will make a better impression by your customers. If your line is about 20 MW or bigger, you definitely should make it fully automated!

Soldering of the sides (busing):

After placing the strings on the panel they have to be connected together to be able to produce power and transport it to the junction box. It is very important that the soldering connection is 100% perfect to avoid hot spots and to avoid losses.

Of course the safest way to make the soldering of the sides is a fully automated soldering process, but on the other hand this systems are very expensive. Because of the costs we do not recommend an automated soldering system for the sides for lines below 100 MW. In all other lines you should make it by hand.

Lamination process:

The lamination process it self always is automated, you can not make it by hand. But there are differences in the way you load and unload the laminator.

Especially the loading of the panels is very critical, because: 

• ​every solar module have to make the same process. If one solar panel is heated a bit longer and another a bit shorter, than the quality will not be the same!
• ​when you l​oad the panel, than it is not a package it is all separated. Every touch can damage the panel and the cells.

With loading the laminates fully automated you will be able to make sure that every lamination is the same quality. We recommend to make the laminator fully automated, at least if you have 20 MW or more!

Of course there are many other parts where it makes sense to make automation but this four steps are the most important processes where you really should think about an automation.

Of course you can make most of the quality checks (not all!) manually! But you have to think about the long term reliability of a quality check:

A human can be very very good in the quality check, but sometimes when he is tired or a bit ill, he will be less efficient and sometimes he will be 100% accurate.

The result will be a quality check that is not the same all the time and so the quality of your product will be not the same all the time. However the goal for every production should be to have a stabile quality all over the process and at any time.

This is why it makes sense to think about automated quality check systems, for example:

Optical cell tester in the stringer: Make sure that there will be no damaged cells in the strings
String tester: Make sure every soldered string will produce enough power
EL-Tester: Will show if there are (hidden) micro cracks in the cells that will make problems in the future
Hi-Pot Tester: To find out if there are any leakage currents in the panel isolation
Flasher: Making sure the panel has the power you are claiming! The flasher is one of the most critical parts in the production where you really should think about a very accurate one

There is another point in quality: The optical appearance!

Even when a panel will be 100% electrical OK you might have problems to sell it for the normal price if the appearance is like:

Strings not parallel
Cells distances are variating
Frame is not 100% 90°
Frame is bending
Label is not always at the same place

And so on! This has nothing to do with the electrical quality but optical.

Animation can lead to a higher quality or it can replace workers and therefor saving costs. Unding out if it makes sense to make an automation for cot reasons it is simple: You can easily calculate how many workers can be saved with a robot or an automation. Than you take the salary of the worker(s) and the costs for the automation. With dividing them you will find out how long it takes to get this money back.

Of course it depends a lot of the salary that the workers get. This is why an automation in a country with low salaries makes less sense than in a high salary country.

Now we will make some examples for automation to replace human workers.

Example 1: Cell soldering:

Cell soldering can be done manually but you need a lot of workers to make it. To give you some idea: A new stringer can make about 1.200 cells / h wich is about 40 MW. To operate this stringer you need 1 operator per shift, so 3 person in 3 shifts.

To make the same amount of cells with manual operators you will need 12 people per shift, so 36 in 3 shifts.

So if you will make 40 MW automated stringing instead of manual stringing you will safe about 30-33 people. This is a lot and one of the reasons why even in low developed countries with low labour costs, the stringing will be done automatically at a size of 20-40 MW latest.

However it might make sense if you want to make only some MW like 2/3/4/5.

Summary: Cell soldering makes sense for automation not only for quality matter but also for cost savings.

Example 2: Trim/tape:

Trimming and taping can be done manually and fully automated. There is no advantage in quality of an automation but of course you can save some workers and therefor costs.

One worker can make trim and tape for about 50 MW. To make it with a robot you can also do both steps with one robot and you would have a capacity of 100 MW maximum.

So lets compare the solutions:

100 MW manual trim / tape -> Two workers per shift, 6 workers in 3 shifts

100 MW robot -> one robot

If you want to have the return on invest in 3 years you can calculate:

6 workers + 25% (for example for holiday) = 7,5

So in 3 years you have to pay 22,5 “year salarie
s”.

The robot will cost minimum 100.000 € more than the manual solution.

Result:

If the monthly salary of one worker will be 370 Euro or more AND if you can assure hat in the first 3 years you will always be 100% operation, than it might make sense.

Summary:

In my opinion even with 100 MW it makes no sense to make the trim / tape by a robot. You are loosing cash and you are loosing flexibility. Also the risk is high if anythink changes in your production that you will have to invest again in the robot. So trim / tape is not a part in the production where I would spend any Euro / Dollar in automation.

This calculation can be done in any other step of the production line in the same way as I did above.

Lesson 3: The Investment Needed

LESSON3