Help....System right?

Started by Joey, October 11, 2012, 05:41:33 PM

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Joey

Hi....Just learning and helping friend in need of power so not lots of study time thus far. I don't seem to be getting the wattage readout I should at controller. If someone could help would be fantastic. No help about here. I'll lay out system...sorry for length.
Panels: 185 W...VOC 44....Isc...5.35....Vmp....36.72....Imp....5.04. Classic 150 controller...MNPV6 Combiner...MNDC250 Mini-Disconnect.
..Magnum 4024 Pure Sine Inverter....24 Volt Battery Bank...
Low tech manual tracker.....14 PV panels in series of 2...two of these series into MC4 box...so 3 boxes each with 2 series sets joined in parallel and one box with single series set in it...from there to Combiner holding 3 15 amp and 1 10 amp breaker. Then 60 feet through #1 gauge copper into a busbar box enabling me to step cable down to #4g cable (largest the controller accepts) into a 50 amp breaker and then PV Pos and Neg into controller. Battery Pos from controller to Mini Disconnect Panel and to 100 amp breaker...branch off this to Battery Bank and into a 250 amp breaker then into inverter. I brought Battery Neg from Controller to the lug on the Mini Disconnect Panel and joined it there with Battery Neg and Neg to inverter.
When I fire it up I don't seem to get the PV wattage readout at controller. There is a similar system on property using only 4 185 watt panels and laid out the same...using Classic 200...panels in 2 sets of 2. It's a cloudy day but as an example the 4 panel system will readout....74 volts.....311 watts...12.7 amps....Batt at 24.4....at same time and conditions the 14 panel system readout is...86.4 volts...114 watts...4 amps..Battery at 28.1.... Can someone explain? Critique the system?
                                                            Thanks for any help............Joe 

boB


Joey, the larger system (2590 watts of PV) has a voltage of 28.1 volts you said...

This sounds like the battery charger may be in either Absorb or Float stage at that time.
If so, that means that the batteries are almost full and can not take all 2590 watts of
power.  Absorb and Float (and EQualize) are voltage regulation modes and
in those charge stages will put out whatever power is necessary to just keep the
voltage at that set point.

To get more power output, try turning on some loads possibly.  If the Classic
display says MPPT, either BULK MPPT or FLOAT MPPT or EQ MPPT, it should
be sucking as much as it can from the batteries because the batteries and
DC side of the system needs the power.

Let us know if the system is NOT in one of those charge stages and doing
this with full sun and the lower power output.

What was the Voc (open circuit voltage) of that 2590 watt system on the Classic ?
You can see that number by pressing the STATUS button 2 or 3 times and Voc will
be shown in the lower left corner.  The Voc number is good to know for
sanity reasons when trying to see if the PV input operating voltage is
around the correct value when in MPPT mode.   For instance, if the Voc was
100 volts, then in an MPPT charge stage I would expect the PV input voltge
to be somewhere around 75V to 80 volts....  If in Absorb, Float or EQ, the PV
input voltage will be anywhere between 75V and 100V Voc depending on how
much current/power the battery needs to keep its voltage constant.

boB

K7IQ 🌛  He/She/Me

Joey

Thanks.boB.............. You're right about the Float readout. I haven't any load on the system as of yet but will be tying into home's AC panel tomorrow. Friend wanted the darn array 350' from his house so I built a control room in the barn and am sending AC power to the house. Ugh rocky land made me mini excavator work.... It's supposed to be sunny tomorrow so that will be a help as well. Really appreciate the help and will let you know what happens.
                                                                                           Have fun...........Joe     
                                                                                         

Joey

Hi boB.....and others......

   Everything is dandy with system. Thanks for helping. AC running to house and working great. I do have a couple questions maybe you could answer.
   The inverter we're using is a Magnum 4000 w pure sine. When a couple things are running in house ...fridge..freezer...the Magnum's remote shows 6 amps ....when the water pump kicks in the remote reads out 60 amps. And continues to read out 60 amps til pump stops.
Is that just showing a 60 amp draw from 24 volt battery bank?
   Secondly.... As I outlined in my initial text, I am using the Midnite disconnect box. I've used the lug/stud in box for my negative connections..from controller to battery and to inverter. Being that this stud is joined to box and the earth ground busbar is as well, I am wondering if I am defeating the GFP of the controller.

                                           Thanks again.......Have fun Joe.....y................

boB

If you have not tied the battery negative to ground in your main box then the ground fault in the classic should still be operational.

The Magnum inverter will show What it thinks it is drawing from the DC side from the battery based on what it's AC output is doing.  That DC current draw is calculated Based on that AC output so may not be 100 percent accurate.

The DC current would be drawn from the battery as well as the classic output.  It cannot separate the 2 unless you have a BMK battery monitor connected up to the main shunt

K7IQ 🌛  He/She/Me

Joey

Thanks a lot boB..............Have fun............