Reading 14.2v input on resting with PV breaker off

Started by carmelo, November 23, 2017, 08:30:57 PM

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carmelo

Hi everyone.

I am new to Midnite and jsut finished my installation with the following:

2 strings of 4 Solarword 240w PVs with the following specs:
Voc: 37.2
Vmpp 30.2
Isc 8.44
Impp 7.96

So a total of 1,920w / 148.8v
Going into a combiner box with 15amp breaker for each string.

Charging a 5 strings in 24v of RA12-105 batteries with the following specs:
105ah
12v
Connected in parallel to a common busbar using 1/0 wire with 24" in length.
For a total of 525ah at 24v
(I know that more than 2 strings in parallel are not recommended, but I had no other option and took as many precautions as possible)

My problem is that I am seeing 14v of input on the MNGP even with the PVs breaker off and at night time. To confirm this reading, I measured the voltage using a voltmeter at the PV+ and PV- on the classic and they were showing the same.

If I turn off the Battery output breaker, the Classic 150 obviously turns off and the voltmeter show 0v when reading directly.

What could be causing volts from Battery crossing to the PVs and showing as input voltage?

I am attaching the readings as of 11/23/2017 9:30pm with PV breaker off.




Matrix

Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Westbranch

you will see that idiosyncrasy as long as you own the Classic. 

there is a reason it holding onto ~ 1/2 of the last incoming voltage but I don't remember it right now.

hth
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 Cisco WRT54GL i/c DD-WRT Rtr, NetGr DS104Hub
Cotek ST1500 Inv  want a 24V  ROSIE Inverter
OmniCharge3024  Eu1/2/3000iGens
West Chilcotin 1680+W to come

ClassicCrazy

normal to see that voltage at night or with no PV 

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

mike90045

that "stray" voltage from the batteries lights up the SPD on my pv array at night
http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

carmelo

Quote from: Matrix on November 23, 2017, 09:06:17 PM
Same issue when I first started using the Local App

http://midniteftp.com/forum/index.php?topic=3865.msg37620#msg37620

Thanks Matrix and all the other.

I was kind of worried that some current was crossing back to the PVs. Have a good and sunny day!!!

CDN-VT

Canadian Solar 350W 37.6 VOC  30.6 VMP 8.22 ISC 7.87 IMP ,-15 c +30c max  4 strings in 2 in Series for 24v Classic 150 -1020 Ah  Freezers & fridges ~~~ Second Array same panels of 3sx3 parallel for 24 V Classic 150 -440 Ah Outback Barns & out blds.
48Vdc almost done,11Strings up of 3s11P same panels