Questions -- MPPT Tracking, Solar vs Legacy P&O

[Vic]

System is one of the ones listed in the Signature  --  48 V FLAs (right now,   single Classic 150 with one PV array  --  18 SW 175s at elevation of N Lat + 15 degrees,   and 12 175s at about Lat + 6 degrees).   Total PV STC power = 5.25 Kw,   strings of 3 PVs for String STC Vmp of 106 V.

Have noticed a few issues  with Tracking (or perhaps Sweep) differences between Solar and Legacy P&O (hereinafter, P&O).   Most often,   this occurs  when going to EQ Start,  from either late in Absorb,   or when in Float,  just after the Classic's transition from Absorb.

Today,   let the Classic finish its Absorb,   it went to Float,   and then Rested after two minutes.

The Mode has been Legacy P&O  for several months (due to smoke/haze/clouds),   and still was in P&O today.

Started an EQ (from the above Rest),   and  the Classic (CC) was producing about 170 watts.   Vin was about 114.8,   last Voc was 115.4  --  very lightly loaded PVs.

Re-booted CC (PVin off,  bat breaker off for 30 seconds,  and reverse sequence).

Still in P&O,   CC booted and was making about 1,750 Watts,   Vin was about 108 V.   This seemed too low production,   pushed Enter a number of times (this seems to do nothing in P&O).

SO,  switched to Solar.   Then the CC was making about 3,500 watts,  with the Vin of about 85 Volts.

Even having waited a number of minutes,  when in P&O,   it seemed that the CC was unable to get itself out of the very,   very low production,   or the one half production situation.

In the past when trying to switch twix Solar and P&O,   the CC has seemed to just want to produce very low power.  This is also when trying to EQ in the Summer,   and wanted to extract as much power as possible from the PVs,   and the result often seemed to cause very little power production in either of these two Modes after the first Mode switch.

Have long wondered about the thing with low production after switching Modes when trying to EQ,   and the situation from today has only been noticed this once,   but an additional curiosity.

EDIT:   Should have mentioned that,   YES,  the latest(non vocal) FW: 2126 & 2133.
Thanks,   Vic

[boB]

Hi Vic.  I don't understand what the problem with P&O would be ?  Usually, P&O is guaranteed to work best when other modes don't work, at the expense of being a bit slower.  How much higher is the EQ voltage than the Absorb voltage ?  Maybe something weird happens up there ?  I don't know.

Pressing ENTER "should" start a new sweep.  Remember that you can also (from main status) press the upper-left soft key to reduce the MPP input voltage.
Upper-right soft key to increase the input PV voltage.  Sometimes you have to press those buttons a couple times to get it where you want the voltage to go.

[Vic]

Hi boB,

Thanks for the reply and info.

The Absorb voltage was 59.1,  and the set EQ was 63.1,   temp comped.

The Classics have so many built-in capabilities,   that I had forgotten about using the two  Soft Keys to change the Vin.

This is not a huge deal,   but,   sometimes things seem to get a bit stuck.  Usually when doing an EQ,   am hands-on with the MNGP,   and pet the batteries during the process.

Just for you to think about,   as,   am sure that you might be running out of other things to think about with the B17,   etc.

73   Thanks,     Vic

[mike90045]

I just hook up the computer and use the LocalApp to make changes.   

I always use P&O.  I found when switching modes, I had to (in the localapp) switch Charging OFF and back ON to properly start a new charge scheme.

[WillEert]

Why would one want to adjust the MPP input voltage? I would have thought it would be where ever it made the maximum power following the last sweep.

I notice sometimes my Classics do not seem to try to increase the output to maximum usable. Sometimes I turn my stove on for few seconds to give them load and then turn it off again. Once "jump started" like this they seem to do fine. This is not all the time but once in a while.

Will

[australsolarier]

on my 12V system, i noticed following:
in p & o mode after float starts in light use, the midnite does not keep float voltage and SOC goes slowly down

in solar mode however, when in float so halfway to the absorption point, it suddenly reduces output to ca 70% of available output.

so, as a consequence the 12v system midnite is in p & o mode and i let the computer run when going to work, as otherwise SOC is down to 70% or so when i return, which in the winter is not so great for having a full battery before sunset.

when i say light use, probably so 150w or thereabouts.