Assistance with system

[Bluedog225]

I’m doing something wrong and I’d appreciate some help.

I’ve got my four 48 volt SOK server rack batteries hooked together feeding a Victron lynx distributor (aka bus bar).

I have also attached a victron 150/35MPPT to the distributor.

My solar panels are three 300 watt panels in series at about 70 V and 9 A. The panels are covered with a thick cotton tarp but still reading 70 volts.

The Quattro is connected to the distributor but not turned on.

I inadvertently hooked up the panels before the batteries. The mppt gave me a battery over voltage fault.

I disconnected the battery (with a temporary blade fuse) and disconnected the solar by pulling the wire. [edit-the blade fuse feeds battery to the mppt]

When I tried to insert the 30 amp blade fuse, it gave quite a pop. I haven’t found the fuse to see if it is blown. It went flying (chuckle). The wires on the battery lines to the mppt and distributor bus bar are all about 52 volts.

What’s the correct procedure at this point?

I’m thinking I should:
-power down the batteries
- insert the 30 amp inline fuse
-power up the batteries so the mppt can adjust to 48 volt
-attach the wire from the panels to the mppt
-uncover the panels

I don’t know why there would’ve been an in rush current to the MPPT in my previous set up.

Any thoughts appreciated.

 

[Hedges]

Fuse on battery side or PV side?

Precharge resistor for battery side. Maybe "power up batteries" does that; it is possible they have soft turn-on of FETs.

Covering panels will reduce current, but not voltage very much.
Avoid connecting MC connectors or wires when (full) current can flow. But fine to close a switch once connected.

 

[sunshine_eggo]

My solar panels are three 300 watt panels in series at about 70 V and 9 A. The panels are covered with a thick cotton tarp but still reading 70 volts.

This doesn't sound right. What are panel specs?

I inadvertently hooked up the panels before the batteries. The mppt gave me a battery over voltage fault.

MPPT was probably assuming 12V since the battery voltage wasn't set. This shouldn't be a big deal at all once you reprogram the MPPT for 48V.

I disconnected the battery (with a temporary blade fuse) and disconnected the solar by pulling the wire. [edit-the blade fuse feeds battery to the mppt]

When I tried to insert the 30 amp blade fuse, it gave quite a pop. I haven’t found the fuse to see if it is blown. It went flying (chuckle). The wires on the battery lines to the mppt and distributor bus bar are all about 52 volts.

I don't recall seeing a spark when connecting my battery to MPPT. I assume you being startled is what sent it flying?

What’s the correct procedure at this point?

I’m thinking I should:
-power down the batteries
- insert the 30 amp inline fuse
-power up the batteries so the mppt can adjust to 48 volt

Sounds right. IIRC, you will need to manually set it to 48V.

 

[Bluedog225]

Something does seem up with a panel voltage. I’ll know more when I have sun again.

Yes, it startled me pretty good. I’ve been out of my depth hooking up this stuff.

The fuse is on the battery side.

I have shut off the batteries and inserted a 15 amp fuse without incident after using a pencil sharpened at both ends to dissipate any charge.

Do I need to manually reprogram the MPPT? It was previously used on a 12 V system. I was under the impression when I turned the batteries back on that the MPPT will sense the 48 V and reprogram itself.

Thank you for your help. Photos below.

 

[Bluedog225]

One more question. The cerbo is hooked up and functioning. But I’ve got a little baggie, full of termination plugs, and the manual is fairly indecipherable about which ones need to be inserted to make the thing operate correctly.

Does anyone have a photo that would help. Or an ver simple explanation? The cerbo manual is in fact rocket science.

I may know more once I’m brave enough to turn on the Quattro and see what happens

 

[Bluedog225]

Update. The good news is I think I got it working.

I turned the batteries on and got into the settings via Bluetooth and changed the mppt to 48 V manually. It seems happy. I’ll know more when the sun comes up tomorrow.

I also flipped the switch on the Quattro, and to my surprise my single hundred watt lightbulb turned on. Pending successful solar charging tomorrow, I think my system has been placed into service.

Lots of cleanup to do but it seems like there aren’t any major mistakes.

Thanks all.

 

[sunshine_eggo]

Something does seem up with a panel voltage. I’ll know more when I have sun again.

37V * 3 is workable. Those are 250W panels, not the 300W you indicated.

Yes, it startled me pretty good. I’ve been out of my depth hooking up this stuff.

Fair. I've tossed a few things out of fright.

The fuse is on the battery side.

Good.

I have shut off the batteries and inserted a 15 amp fuse without incident after using a pencil sharpened at both ends to dissipate any charge. View attachment 185366

Worth noting that while those cables are not horrible, they are not what one would call fine strand like Victron typically recommends for MPPT connections. Consult the Wiring unlimited link #6 in my signature.

Do I need to manually reprogram the MPPT? It was previously used on a 12 V system. I was under the impression when I turned the batteries back on that the MPPT will sense the 48 V and reprogram itself.

Yes, you need to reprogram it. The only time it auto-senses is the first time you connect the MPPT to battery, i.e., when you first connected it to the 12V system. Now it must be manually set to be a 48V system.

One more question. The cerbo is hooked up and functioning. But I’ve got a little baggie, full of termination plugs, and the manual is fairly indecipherable about which ones need to be inserted to make the thing operate correctly.

The termination plugs are only used on the VE.Can and BMS-CAN ports if you're using them.

 

[Pi Curio]

I would recommend swapping the 10AWG inline fuse holder for something else. I've bought the same thing but after reading many reviews about the fuse holder melting at over 10A it's sitting collecting dust.

It may have something to do with having the fuse fully sealed by the housing, but unless the one I have, looking exactly like yours, is some kind of knock-off or not, I wouldn't risk it. Especially having it that close to that nice SCC with probably a 40A + fuse.

Just my 2 cents.

 

[Bluedog225]

Agreed on the inline fuse holder. I’ve got a 150 volt 30 amp old fashioned lever disconnect to hook up. I just couldn’t get comfortable with no way to shut it down.

Too bad about the wiring. But I see your point.

For some reason, the cerbo isn’t showing much data. I’ll give my connections a review.

Thanks all.

 

[Steve_S]

OK, a quick linear install review...
Solar Array -->Breaker/Fuse -- to SCC Solar-In.
SCC Solar-Out ---> Breaker/Fuse ---> To Batt Input Point.

Powerup Process for ALL OFF
- Batteries ON
- SCC to Batt Breaker ON (Scc must register Batt Voltage to setup)
- SCC ON, followed by Panel Breaker ON
Then Inverter ON.
-- Inverse to power off safely.

By turning on the Solar 1st without the SCC knowing Batt voltage, you can fry the SCC ! You got Lucky !!
Automotive Fuses are dubious at best, for solar they are a Huge NO-NO ! I would never ever trust any other than genuine Bussman motive fuses.

A small solar array can easily be fused with an Inline MC4 Fuse, they work quite well and with little hassle, just make sure you can get at it.

 

[Bluedog225]

Mistakes were made. I think I bought some grace by covering the panels.

 

[Steve_S]

Mistakes were made. I think I bought some grace by covering the panels.

Panels can & will show some voltage even when covered but without more than a couple of Watts at best and zero amps (the most important part).

 

[rodrick]

Mistakes were made. I think I bought some grace by covering the panels.

When I hooked up my victron 100/30 scc’s the first sparked quite impressive so on the other 3 I used a pre-charge resistor and that was with no pv whatsoever