Charging problems with schneider XW+ and Schneider mppt 60A CC

Windsolar

Hello all,

We are a small company doing off-grid installations and usually we like schnider's equipment as it is rubust and high quality,
how ever it seems in 2 installations where we put the schnider charge controller instead of the morningstar we usually install therehave been charging issues and our clients need to use there GEN's fairly early.

systems spec. as follows:

1. 625A 48V lead-acid deep cycle batteries
2 Xw 60a mppt chargers (schneider/xantrax)
XW+ 8548 schneider inverter
16 pv panels - hanwah 255W /Voc 35.2V/ Vmpp 27.9V / 6.67A
array assembly - 2 X3panels(series) in 1st CC  (105V - 13A)

                           5 X2panels(series) in 2nd CC (55V - 33.35A)

client's consumption is fairly low

the batteries do'nt reach over 50V where as other systems reach as high as 56V
we have tried changing configuration from 2 stage to 3 stage - has'nt helped.

has anyone had this issue before? any suggestions?
thanks

Dave Angelini

No, I never had this issue before but if you want advice you are going to have to list the settings on the chargers.
Your second array is too low of a VMP for a 48V nominal.
You also need to list where the system is, all the facts that might help. 
It sounds like you have not done many of these as changing from 2 stage to  3 stage  charging is a giveaway to me.

--Dave  You can contact me below .....

BB.

You need to have a minimum Vmp of ~70 vdc. Otherwise you will see low charging current/low battery charging voltage.

In warm to very hot weather, you will see upwards of 20% Vmp voltage drop.

-Bill

new2PV

Like Bill said, you need more volts in.  The schneider conext designer tool would have shown that the 2 panels would not have enough volts to work properly.  You need 3 panels in the string to make this work. 

vtmaps

Windsolar said:

16 pv panels - hanwah 255W /Voc 35.2V/ Vmpp 27.9V / 6.67A
array assembly - 2 X3panels(series) in 1st CC  (105V - 13A)

                           5 X2panels(series) in 2nd CC (55V - 33.35A)

In your two arrays, you show the string voltages, but in the 2x3 you used Voc and in the 5x2 you used Vmp.
Using Vmp, it should look like this:
2 X3panels(series) in 1st CC  (84V - 13A)
5 X2panels(series) in 2nd CC (56V - 33.35A)

As Dave, Bill, and new2PV mentioned, the string voltage is too low on the 10 panel array.

You need to use only 9 panels in a 3x3 configuration.

By the way, the concept of using two arrays, one of which has marginal voltage, can work well.  Panels with Vmp=30 are quite common.  I have seen them used in a 60 volt configuration.  Normally, that is not high enough for a 48 volt battery, but with a PWM controller (less voltage drop than MPPT), they contribute to bulk charging (that's when you need the most power).  There was also a second array with higher voltage and an MPPT controller.  On hot days, the higher voltage array would have to do all the absorb charging, but absorb requires less power than bulk.  I would not consider the system optimal, but it worked.

In your case, with a Vmp=27.9 and most of your panels in the low voltage array, I think you would be best just use 9 of the 10 panels.  Do not try to use all 16 panels in a 4x4 array... I think that is too high a voltage for the controllers.

--vtMaps

new2PV

Here is a snapshot of 3 hanwha panels in mppt0 255's with canadian solar  260s as mppt1

YehoshuaAgapao

150V MPPT charge controllers favor series sets of 3 60-cell panels.

72-cell and 80-cell panels don't fit well - two panels can sometimes be too low and 3 panels can sometimes be too high (derate, shutdown, possibly breakdown/burnup).

You can sometimes buy 96-cell panels which will do well in series-sets of 2, but I've only seen them on ebay.

new2PV

I bet lifting those 96 panels would not be fun.

Dave Angelini

He is referring to the Sun Power 96 cell panels and because they are so efficient, they are not that heavy. Certainly quite a but lighter when compared to other 327 watt 72 and 60 cell solar panels.

new2PV

Those are nice panels, I do know the other 72 cell panels are a pig! If he configures his strings with 3 panels per string he will be ok.  He just has to make sure the absorb time or amps is set to get a full charge in.