You seem to have failed to grasp some of the major concepts about solar panels, and are then getting angry when the experts point out your lack of knowledge. The output is a constant current source with the current dependent on the amount of light falling on the panel, so the voltage measured on the output will vary, but it varies with the load.

If you connect the output from solar panels to a battery, the battery will stabilise the output voltage.

Ian0 I probably was not expressing myself well enough. I appreciat you trying to get to the bottom if it. I don't think that I am lacking knowledge, but if I do then please point it out to me.
I understand the basics of MPPT, NOCT, STC, temperature degradation and all this.

The idea is to have the "center" battery voltage matching the "center" MPP of the solar panels. (caribbean, no clouds, no seasons, no variation in temperature, ...) SPP = single power point.

I understand that if I center the panels to the batteries, that there will be a very minor inefficinecy compared to MPPT. But the purchase of a couple of extra solar panels is economically more viable than some fancy non-economical MPPT.

The BMS disconnects the battery from the bus when the voltage drops or exceeds the battery specification.

Everybody is invited to read up about LiFePo4 chemistry, voltages and safety, also about the capabilities and possibilities of the mentioned BMS's. I would encourage that.

The exact ammount of batteries has to be worked out based on temperature that the panels are subjected to.

Again, no MPPT needed. But if there are concerns about the capabilities of the BMS's disconnecting the batteries then I would like to hear about them.

By "frequency drive" do you mean a Variable frequency drive? They are for driving motors, and they normally take a single or 3-phase AC input, and would soon shut down with an error message if given a randomly varying DC input, so I'm presuming that what you have is actually a grid-tied solar inverter. You were not too specific about what this device was: probably you don't know what it does.

You are right, I wasn't specific enough. Sorry about that, I will get back with the exact type of freuqency drive, VFD, variable frequency drive and also solar panels.
i know what they do, I have to because I work with them and yes we are talking about variable frequency drives, VFD's.

How do you change yourAC's frequency? One way is to rectify it to DC with 4 diodes, smoothen the ripple with capacitors and then convert it to AC at the desired frequency using inverters.

If I am correct about what it is, then supplying it from a battery is a really bad idea, because it is an MPPT controller (you know, the thing that you refuse to use) and its job is to extract the maximum power from the source. Attempting to extract the maximum power from a battery is probably not such a good idea.

MPPT means "maximum power point". How does a frequency drive (variable) know or care where the DC is coming from?
This is the first time myself I have seen or heard about such an installation.
But somehow those frequency drives accept (direct) DC input. I guess this would be DDC then?
And they are also connected to grid AC 480V.
I haven't even looked at that part, I was just asked about how batteries could be intergrated into the system (without MPPT, PWM).
I guess the BMS's classify as PWM controller? ...

I will be back with exact solar panel specification and the type of the (variable) frequency drive which accepts 480V AC / 850V DC

 

But what is this here? 23,726 posts... I just can't geat my head around this "I post just to have more posts than someone else and very soon 1000000"-thing.
Can you please elaborate on your post?

We are monitoring this thread and your activity on the site. This being the internet I can see where (Country, City or Provence) you posted from.

For the record I posted the majority before I became a moderator, I joined because I have a passion for electronics, and had a resume as a Lead Tech for Rockwell International, Collins Radio Division for most of my career.

 

Thank you Ya’akov. I came here because I was looking for answers that I didn't expect. Those are the ones that I can learn from. But I expect from people that reply to my post to respect the basics of a conversation etiquette.
They have to do a lot of homework, I don't like to be insulted nor disrespected, do you or do you think they do?
They just came here to hijack my post with the subjects that they had in mind without proper reading the basics of my aticipated project.

Only one did.


To be entitled to a correction you should have read the subject, thought about it and have the required understanding.
I am open to ideas, additions and corrections if it is from people that have read the post, have sufficient knowledge of the subject and their correction is about the subject. Otherwise just ask me politely and I will explain it to them where they misunderstood something or are lacking fundamental knowledge.


They are more than welcome to open a post where they inform the entire audience of the forum about the dangers of electricity and point the people towards that thread.. Everyone can then descide for themself whether or not they are lacking knowledge regarding high voltage, and whether or not they want to participate in that subject that differs. I feel that it is rude to hijack someones post.
Start your own.

It is dangerous to connect a 120V AC socket. It is rude to highjack every post that talks about voltage above 12V and for them to throw that in there because that is what they have in mind.
Etiquette of a conversation is to listen and to understand each other.

Every AC socket is a minimum of 120V.
All solar installations are 1000V of 1500V these days.

Yes I can fall down the ladder aloft connecting those panels.
Yes I can fall down the stairs going down to get some tools from the truck.
Yes I can have a deadly accident in the car when I buy the cables not wearing a seatbelt.
...
Don't highjack my post please for things that are important to you but nobody else!


Those credentialed engineers have to learn to read and put some though into the task in question. If you are not capable of doing so you will never become a credentialed engineer. If you don't read the questions and don't put any thought into it but still chose to drop your off-topic subject into and engineers topic that is looking for smart advise, then you are just rude.

Don't highjack every post for the purpouse of improving your forums-ranking. I didn't dismiss the only one engineer here, that has responded so far and that has an understanding, and more important put some thought to it.
I don't respon well to rude people. And yes I initiated this post, and I can expect conversational etiquette. If you want to educate people about dangers of electricity please do so in your own post and send me an invitation to your discussion.
My post was about another subject, please join but show common conversational etiquette and respect.

I have taken your points but only can agree with you on some of them and I will work on them. I don't appreciate your threats though, I don't consider them professional nor good attitude either.


I appreciate you expressing your opinion in such a polite manner, but there is nothing wrong in my expectation to receive the basic conversational etiquette here.

Unfortunately your response reinforces the idea that you don't understand the nature of your difficulty here at all.

This is unlikely to end well, sadly.