Follow Me

[Sheldon10]

Hi, can someone advise.
Can you have two 200 Classics linked in follow me mode on the same PV Array.

[KyleM]

The simple answer is Yes ......   but I think there is more to your question.

Can you give us an example of your system and why you think you need to have 2 charge controllers running it?

-Kyle

[mike90045]

With 2 MPPT controllers running from the same array, won't they both keep fighting trying to find a true MPPT point, as the other controller moves it someplace else ?

[Vic]

Mike,

I sent   Kyle a PM  last  eve,    stating that common   belief  for  several MPPT  CCs,  trying  to work  from the  same PV  array    ...      But,     also  asked,    if   Classics in  FollowMe,   might  not  be subject  to this behavior  --  have not tested this,    yet.

In Solar  Mode,    Classics  do  not really Sweep,   to find  the MPP  voltage.    It  appears that Classics  simply shut off  the  Converter (or  similar  function),   measure  the  Voc   and use  77-ish percent of the Voc,  use this as the Vmp,   and march on.

If the  Voc  could be communicated to the Following Classic(and it  did  not try to find the Voc   on its own),    then,  perhaps all would be smooth as silk ?

Guess that is the Following Classic  could receive the Vmp from  the  lead  Classic (via FollowMe),    and the Followers  got this  communicated  to  them,   then,     in other  Modes,  like  Legacy P&O,   that  all could be swell there,    too  (??),  as long as the Follower was inhibited from trying  to find its own  Vmp  from  the common PV  array.

Dunno,    would bet  that many MN  Staff  are  at  the  Big Solar  Show (SPI?),    so  they might have limited availability,    here.

Dunno,      guessing again,    FWIW,     Vic

[FNG]

You can NOT use 2 or more classics on a single solar array the MPPT will fight with each other.

Follow me simply coordinates the stages and shares battery temp

As for Solar mode it does a full sweep from VOC to Battery and finds the maximum current it is not based on a percentage

[Vic]

Hi Ryan,

Thanks  for correcting my earlier misstatement on Solar Mode not really Sweeping.

Guess that I misunderstood what boB had mentioned a few times in the past,   believing that he has said that the Classics used the measured Voc X 77-78%,   as the Vmp used,  for Solar Mode.   Guess that he was saying that the Vmp (often) winds up in this range,   NOT that the Classic set it there   ...

Have listened to Solar Mode Sweeps,  using an HF receiver/transceiver,  on one of the Classic's converter Birdies.   It seems to only need about one second for this Sweep.  Did not know that a Sweep could be that rapid,   although there is a bit of a low frequency Buzzzz ,  during the Sweep.  That buzz must be the Vin steps of the sweep  ...

Anyway,   thanks,    and hope that you and the MN Show crew all has a great SPI.   Looks like quite a few new MidNite products are nearing the Beta/shipping dates.   Thanks again,   Vic

[boB]

Guess that I misunderstood what boB had mentioned a few times in the past,   believing that he has said that the Classics used the measured Voc X 77-78%,   as the Vmp used,  for Solar Mode. 

Have listened to Solar Mode Sweeps,  using an HF receiver/transceiver,  on one of the Classic's converter Birdies.   It seems to only need about one second for this Sweep.  Did not know that a Sweep could be that rapid,   although there is a bit of a low frequency Buzzzz ,  during the Sweep.  That buzz must be the Vin steps of the sweep  ...

U-Pick or whatever it is called does this 77% or whatever is chosen percent of Voc.  That mode has to open up to measure Voc and then drops to the Vmp %

SOLAR mode sweeps from just above battery voltage to Voc and tries to catch the Vmp on its way up to Voc.

As for when the Classic is sweeping down to just above battery voltage, it MAY be that the Low-Max is causing that buzzing noise.

I would be interested to see if you find that buzzing when you turn OFF the LowMax mode in the TWEAKS menu.

73

[Vic]

U-Pick or whatever it is called does this 77% or whatever is chosen percent of Voc.  That mode has to open up to measure Voc and then drops to the Vmp %

SOLAR mode sweeps from just above battery voltage to Voc and tries to catch the Vmp on its way up to Voc.

As for when the Classic is sweeping down to just above battery voltage, it MAY be that the Low-Max is causing that buzzing noise.

I would be interested to see if you find that buzzing when you turn OFF the LowMax mode in the TWEAKS menu.
73

OH,   "buzzing"  !!  No,   not that buzzing.   To me,   when the Classic Sweeps very close to battery voltage,   the inductors emit a fairly faint "tone".

The buzzing that I had mentioned earlier,   is the Modulation of the converter birdie, (at, say 3777 KHz,  on a receiver.   THis is below the birdie's zero beat,  by about 380 HZ,   so  the modulation is easier to hear)  when the Classic Sweeps in Solar mode.   Usually hear this in the morning during Bulk,  in Solar Mode.   THIS buzzing has two frequencies  --  higher frequency at the beginning  --  about 500 Hz (perhaps),   and the latter half of this quick Sweep  is perhaps about 200 Hz.   It does not sound like a Sine wave,   but,   rather a square-ish wave (lotsa harmonics in the buzz).

This modulation lasts a total of about one second,   every few minutes.  Believe the spec for these Sweeps is a three minute interval,  at the Default setting.

Have never needed LMX,   as our STC string Vmps are either 93,   or 106 Volts,   depending on which system ...

Anyway,   none of the above really matters.   Am surprised,   that  the Solar mode sweep is this fast.

I could probably use a scope to look at the PVIN voltage and see the process,   an may do this soon.

73 boB,   Thanks!    Am sure that MidNite had a very successful SPI show.
Vic