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Discussion Starter · #1 ·
Hello
I'm here to educate myself, this is my first post , I am not an engineer, and I usually speak French.....
Before posting, I did some Forum research and the post that came up ( tesla charging) was one of 2015 which ended with name calling between "Dimitri" and "Jack".....
I don't have the knowledge to say who is right and who is wrong.

Now to my question, in a EVTV video there was this picture: which I know has no relation to vehicle.....but..
Circuit component Font Rectangle Parallel Technology

So the "Battery controller" is closing and opening to let the solar panel do their stuff, ie: charging the pack.
Why use 480 volts of solar and not 403 v ???
thank you
Jean-Pierre
 

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480 (or 500) is what's called "open circuit voltage" - voltage without a load connected. Once you start drawing power from the solar array, voltage will drop.
 

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Cricketo has the right answer, but also, about 400 V (actually 208 V) is a standard voltage for three-phase (delta) power from electrical utility companies in Europe and is available in some locations in North America (with 240 V being the corresponding wye connection voltage), but is not a standard for solar panels, batteries, or other DC sources.

In the diagram the solar array is labelled as 500 V, but the output is labelled as 480 V. That probably means that the open-circuit voltage is 500 V under ideal full-sun conditions, the voltage for maximum power output under the same conditions is 480 V, and the voltage under real sun exposure conditions will often be substantially lower. The components and settings are chosen so that in minimal sun the solar array can still effectively deliver power to the DC bus (which in this case is intended to run at 400 V), and the DC bus voltage is high enough that the battery charger can always charge the battery (even when the battery is nearly fully charged and so at its highest internal voltage).

It appears that there is no controller (just a contactor) between the solar array and the DC bus, so the DC bus voltage may actually go well above 400 V under some conditions... which is okay as long as the battery charger's allowed input voltage is not exceeded.
 

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Discussion Starter · #4 ·
Thank you both,

In this set-up, as I understand, the battery controller opens the contactor ( at the output of the solar panels) , when the cells are at 3.9v ( or whatever voltage the user choose ) and closes when the cells are at 4.2v ( or whatever...).
So what is the "tolerance" concerning the 400v, what happen if it was...450v ? I know the controller would shut the contactor when the cells reach 4.2v, but what happens when you charge a 3.6v cell at .... 5 - 6 volts ?

Choosing solar panel is a trial and error thing ?? in this particular set-up


JP
 

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but what happens when you charge a 3.6v cell at .... 5 - 6 volts
I think that's actually where the current draw will be so large, output voltage from the solar array will drop dramatically. The biggest concern in that setup is the fact solar output will be fluctuating, which may confuse the BMS. Perhaps the diagram is simplified, and there is a charge controller too ?
 

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Perhaps the diagram is simplified, and there is a charge controller too ?
I think the diagram is very poor without supporting documentation, because the functionality of the "battery controller" is not evident and there's a mystery dead-end box beside it. There's zero chance I'm wading through one of the EVTV videos to extract the technical information.

But yes, just switching a contactor on and off would be a horrible way to control battery charging. That's what you get with the junk controller that is tossed in with the panel and some junk wiring as part of basic solar power package.
 

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Discussion Starter · #7 ·
Here is the 2 hours long video of EVTV........the good stuff starts at 1:39:40. The arduino computer controls everything.

JP
 

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Here is the 2 hours long video of EVTV........the good stuff starts at 1:39:40. The arduino computer controls everything.
The time reference would be good... if a specific video were linked. But anyway, I'm sure that the controller sitting on the CAN bus tells the other components what to do, and that's described somewhere.

The voltage supplied by the solar array and seen by the battery will depend on the load (current), and should be actively controlled by a regulator, not just switched on and off; however, anyone can post anything they want in a YouTube video, whether it makes sense or is a good idea or not.
 

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The voltage supplied by the solar array and seen by the battery will depend on the load (current), and should be actively controlled by a regulator, not just switched on and off
That's another good point. That battery pack can suck a lot of current if allowed, and PVs also have their maximum current ratings, in addition to the array wiring.
 

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Discussion Starter · #12 ·
The time reference would be good... if a specific video were linked. But anyway, I'm sure that the controller sitting on the CAN bus tells the other components what to do, and that's described somewhere.

The voltage supplied by the solar array and seen by the battery will depend on the load (current), and should be actively controlled by a regulator, not just switched on and off; however, anyone can post anything they want in a YouTube video, whether it makes sense or is a good idea or not.
ha, the link has disappeared
search for : . Octobre 2017
Tesla Model S Battery Pack Solar Energy Storage
JP
 

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Man, that's painful to watch. The guy seems to know what he is talking about, but the style isn't for everybody :D
I gave up on EVTV long ago. That was before someone pointed out that YouTube can run at up to twice normal speed, but I'm not sure that the random chatter style would work for me even for half the time.
 

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Discussion Starter · #17 ·
Either way, he was talking about MPPT there, so it's likely not a PV array straight to the DC bus connection.

He did say somewhere in the video that he was presently by-passing the MPPT and going straight to the DC bus bar, just like the drawing.


JP
 
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