Going solar

[turf]

lol, i was pleased with myself knowing power point was a microsoft product. learning new stuff all the time.

the conduit is finished, the wire to the roof is run. with the shorter conduit fixes, the pipe gets real close to the tail light now. there is about a 1/4" clearance between the 2. i think its ok.

im waiting on some mail to finish wiring inside the battery box. i ordered the welding cable and lug ends which should be here in a day or 2.

so,..... wiring the box, hooking up the batteries, and installing the roof panels.

maybe another month?

lolol

[AlphaHare]

Originally Posted by turf

isolated or non isolated?


hey all you experts!

im looking at 24v to 12v converters. and im confused.

right now, my house system is floating, its 12+ and 12v- hardwired, no common ground with the vehicle. what im guessing they mean by "isolated".

on top of that, im going to add another 24v isolated system, that will feed my isolated 12v system.

when im looking at the converters.....
the isolated ones have 2 inputs and 2 outputs. low amps (20 or 30a)
the non isolated ones have 1 input (hot) and 1 output (hot) and share a ground. higher amps (70a+)

so.... when shopping for a converter for 24v to 12v, with my 2 isolated systems, could they be non isolated in hooking the 2 side together? or do i stay isolated.

i think the non isolated works fine for this situation but...idk
i think that would just expand my current isolated system, i think using the isolated one would make a third floating setup.

non isolated
https://www.victronenergy.com/dc-dc-...v-24v-48v-110v

isolated
https://www.victronenergy.com/dc-dc-...rters-isolated

Ask Victron.

That said, as you've seen, 'isolated' only means that the two negatives are separate. Non-isolated means the two negatives are connected (or even just one terminal.) Non-isolated should be fine.

Neither has anything to do with grounding.

Ground your DC house system to chassis. Do this as close to the house batteries as possible (just like your starting battery). Same for the primary negative buss bar if not the same as the batteries. Minimize additional grounds to chassis as you may create ground loops (inadvertent voltages). Example is to ground your PV array negative at the bus bar, not above. Ground your PV rack to the chassis if you feel the fasteners aren't enough already.

Your AC system should be completely floating. DO NOT tie AC ground or neutral to the chassis in any way.

Victron has a great wiring book available online with an extensive grounding section.

[turf]

i'll have to investigate the ac part of my setup. it was professionally installed when they made the bus into a bookmobile, so i assume its right, and its never caused an issue. when plugged into shore, i have earth ground, but i've never checked the body or frame to see if its got continuity with neutral.

today, i got back on my wiring project, i kind of felt like richard dreyfus playing with my mash potatos, in close encounters. if you could see my desk, you see a mountain of hand drawn wiring diagrams. today i got to act it out and build it.

i ran out of cable but made progress. i got a little ferrule crimp kit, and it makes dealing with wires easy. tomorrow will start working on the battery connection.

i think all my parts have made it here except for my big crimper. so, i'll make progress, but no electrons flow until the crimper gets here.

on another note....
i just ordered 12 new clearance lights. standing on the roof, you can see they are damaged. from the ground, they look fine. hail has blasted out the plastic on 7 of 12 lights, so im replacing all of the with led.

[turf]

mixing the old and new


if you havent noticed the pictures..... the old, frayed, dangling wires on the left side and the roof of the battery box are the remnants of the old house system.

the bundle of wires on the left is the house negative bus bar, on the ceiling right is the house positive bus bar.

in looking at the pictures, i think its time to redo some of that mess.

here is a couple of pictures from 2013 when i first put it together.




now the lead acid is gone, and lifepo took its place. also... and here is my question......
i have a charger wired in to charge my old lead acid batteries. i can plug it into a 15 amp circuit or run it off my generator. its an 80A dc charger, old school, pre lithium.
so the question is .... do i still need that charger? the solar would pretty much replace the plugging in part, the benefit would be to charge off of generator if needed. but its not a lifepo charger so... do i need or want it installed again?

so to redo the mess.... i thinki'll get a couple of bus bars like the the solar system and put the breakers and maybe reinstall the charger? probably put it all into plastic boxes so it looks nicer too.

crimpers showed up after sunset today so tomorrow, im hoping to finish off the solar wiring part. will see how soon i can round up some help to get the panels on the roof. but its getting closer.

battery breaker, fuse and bus bars installed.

[desrtdog]

Originally Posted by turf

mixing the old and new


if you havent noticed the pictures..... the old, frayed, dangling wires on the left side and the roof of the battery box are the remnants of the old house system.

the bundle of wires on the left is the house negative bus bar, on the ceiling right is the house positive bus bar.

in looking at the pictures, i think its time to redo some of that mess.

here is a couple of pictures from 2013 when i first put it together.




now the lead acid is gone, and lifepo took its place. also... and here is my question......
i have a charger wired in to charge my old lead acid batteries. i can plug it into a 15 amp circuit or run it off my generator. its an 80A dc charger, old school, pre lithium.
so the question is .... do i still need that charger? the solar would pretty much replace the plugging in part, the benefit would be to charge off of generator if needed. but its not a lifepo charger so... do i need or want it installed again?

so to redo the mess.... i thinki'll get a couple of bus bars like the the solar system and put the breakers and maybe reinstall the charger? probably put it all into plastic boxes so it looks nicer too.

crimpers showed up after sunset today so tomorrow, im hoping to finish off the solar wiring part. will see how soon i can round up some help to get the panels on the roof. but its getting closer.

battery breaker, fuse and bus bars installed.

If the charger is not meant for (or programmable for) LiFePO4 batteries, I would not use it…LiFePO4 batteries have different charge profiles than lead acid, and using a charger that is not set for those profiles could damage the batteries. Check the documentation/specs for your particular batteries, but recommend that you scrap the existing charger and go with something newer…

[turf]

yea, i dont disagree.

it would only be back up charging. so probably low use. just trying to figure out if i want to move it into the battery box here, or scrap it and pull the wires that are coming thru.

it may work fine for the vehicle side charging problem i have.

well, the wiring is done. i need to clean up a few connections, shorten a few wires, but for the most part i'm done.

the solar panels need to be mounted and connected.

the "house" electrical system is temporary wired with an inadequate wire, i will change to correct wire after i redo the house bus bars and breaker.

in the pics below, the battery leads are hanging out the middle. they run to a 300a fuse(+) and shunt(-), then to a breaker (125a), and then to the bus bars.
junction boxes on the roof are wired to the fuses(15a), breaker (30a) then the charge controllers, and bus bars.

just add panels, batteries

weather is turning shitty again, probably a week before i make more progress.

[turf]

Originally Posted by AlphaHare

Ask Victron.

Your AC system should be completely floating. DO NOT tie AC ground or neutral to the chassis in any way.

Victron has a great wiring book available online with an extensive grounding section.

i kind of glanced over this comment earlier but i dont understand it.

to my best knowledge, my frame is bonded to AC ground. it changes when im on shore, then it is also bonded to neutral and a real earth ground.

my ground moves with the source. on generator, its a floating ground of the chasis, on shore, its the pedestal.

[AlphaHare]

https://www.victronenergy.com/upload...ted-pdf-en.pdf

I think what you describe was my intent - don't tie ground and neutral when off shore power (e.g. isolated on rubber wheels.

I'm going to stop giving electrical advice on the internet. ;>)

I do have a copy of the NEC and the RVIA interpretation of the NEC. I've done a lot of low-voltage wiring (<600V). But I am not a PE or licensed electrician - obtain your own professional advice.

That said, where I was coming from....

Grounding is going to be 100% specific to the exact electrical system and components. This is mine:

My use and interpretation is based on a Victron MultiPlus 3000 Inverter Charger (that's important) and no AC loads supplied by anything other than the Victron Inverter Charger (also important). E.G. I won't have an AC panel directly connected to shore power in any way.

Victron MultiPlus Inverter/Chargers disconnect the AC input ground from the AC output ground when not energized by shore power. When disconnected, the AC ground and Neutral are not tied together (that's only out on the pedestal), and the Victron case is isolated from AC Ground.

The enclosures of electrical equipment should be bonded to chassis. That's the inverter, DC/DC converters, etc. According to Victron, any GFCI will only work if the MultiPlus case is grounded. That ground is not a current carrying conductor to the best of my knowledge.

Note in the pictures, the genset diagram is equivalent to my shore power in. I don't have a genset. My AC 'loads' are going to be minimal - a few AC (4-6) outlets.

[turf]

keep up the electrical advise, alpha, thats how we (i) learn.

the victron book was a good read. i think in their grounding chapter, they misuse the word "ground" a lot, when they mean "bond".

imo, you should be "grounded" to your source. when on inverter, ground to inverter, when on gen, ground to gen, when on shore, ground to shore.

switching sources gets real confusing.

i have a transfer switch that changes the location of the neutral/ground bond. it changes between having the neutral/ground bonded at the generator or being bonded at the shore pedestal. i see the victron inverter has its own relay that can detect whether the ground/neutral bond exists, then can bypass it and and switch it to itself.

i think....


i always wondered how a floating ground works, today i stared to figure it out. i guess gfci's are your friend.

[Rucker]

Originally Posted by AlphaHare

Ask Victron.

That said, as you've seen, 'isolated' only means that the two negatives are separate. Non-isolated means the two negatives are connected (or even just one terminal.) Non-isolated should be fine.

Neither has anything to do with grounding.

Ground your DC house system to chassis. Do this as close to the house batteries as possible (just like your starting battery). Same for the primary negative buss bar if not the same as the batteries. Minimize additional grounds to chassis as you may create ground loops (inadvertent voltages). Example is to ground your PV array negative at the bus bar, not above. Ground your PV rack to the chassis if you feel the fasteners aren't enough already.

Your AC system should be completely floating. DO NOT tie AC ground or neutral to the chassis in any way.

Victron has a great wiring book available online with an extensive grounding section.

Ahhhhh....

This is not the first time this topic has come up. Normally I'd just say 'use the search feature to find other threads on the word bonding' but because this topic is potentially a hot one, I particularly recommend the following thread:
https://www.skoolie.net/forums/f13/n...ing-39510.html

In it you'd find the back and forth dialogue about whether or not to ground the AC system to the bus chassis.

It's important to get this one right.

My two cents:
-On your DC circuits everything can be grounded to the chassis, and all devices should have a negative or return wire direct to the negative bus bar connected to the negative pole of the house batteries. There is little dispute about this recommendation.

-On your AC devices and branch circuits ALL ground wires (NOT the neutral or white wire--just the bare copper ground wires and all metal device enclosures) should be grounded to the bus chassis. This includes the ground wire from shore power that is feeding the house AC branch circuits.

Bonding on the other hand is a different thing, and a quite specific term meaning connecting the house AC circuit neutral to the ground wire. This should happen only at the source of the power, so as others have discussed the only place where the white wire (or neutral) should be connected to the ground is at the generator, when the generator is in use; or when shore power is being used, at the source of shore power, which is waaay back at the main panel in the residence where the ground rods are. Sub panels, campsite power pedestals and any other source of AC power outside the bus should similarly NOT have their white wire/neutral connected to the ground wire.

The thread at the above link has a more detailed discussion of bonding/grounding.

[AlphaHare]

Rucker and Turf - I appreciate that you grasp the nuance here. And yes, bonding vs grounding and that having shore power/generator/battery inputs makes it tricky.

Again, speaking only in my application (as designed) - the MultiPlusII 3000KV 120AC has an internal relay that connects AC output neutral to the MultiPlusII case ground when no shore power is available.

It disconnects the same when shore power is available. Case ground is minimum 8AWG (per the NEC) or better, the same size as the AC maximum, 6AWG.

All AC branch circuits, all three conductors, are 'isolated' to the output of the inverter. There may or may not be ground and neutral bus bars in the circuit breaker box, but they are not bonded to each other, and not connected to school bus chassis ground except through the MultiPlusII.

The AC shore power input, all three conductors, are also isolated to the MultiPlusII input terminals. The ground is made through the pedestal and back to the RV park panel and earth bonded there. When AC powered, the school bus chassis is disconnected from MultiPlusII case ground (and not bonded to neutral) and there can be no 'hot skin' condition.

I have no directly shore-powered AC circuits - everything comes after the inverter. It would be different if I had this and the grounding more like you describe.

All of that is what I intended when I said 'don't tie AC ground or neutral to chassis'. Like my girlfriend says to me sometimes - "are there more words with that?" ;>)

Apologies for any confusion - this is all very component/design specific and I shouldn't make sweeping generalizations.

[turf]

haha, rucker, i sure am a dick online....
good old thread!

alpha, in your setup....

no ac input.... only battery/inverter?

you are bonded at the inverter then and voltage needs to return there.

yes, i would wire 3 wires to each junction, and ground as usual at each junction and gfci outlets.

neutral is the straight way back, ground is everyway back..... your gfci's should detect the leaking voltage to ground if its grounded.

i think that victron book is a bit misleading. i could look closer but....

i think the distribution descriptions were good, but what did that mean?

imo, a rv electrical set up is the TT setup in their victron manual. i think you are considering yourself an IT setup, and thats not the case with your big inverter.
if you had a battery and small inverter with built in outlets, you'd be the IT setup, no real need for a ground.

[AlphaHare]

I think it's "TT" for both.

I'll have an AC shore power option, but the AC will go through the Victron first, and all the grounds are then connected through the pedestal back to the park electrical panel.

When disconnected from AC shore power, the Victron uses the internal relay to attach AC neutral output to Victron case ground, and there is a ground wire from case ground to school bus chassis.

In both cases an RCD should work.

My only lingering question is if I should connect the shore power inlet ground to the bus chassis. The bus chassis then would be disconnected from the Victron AC input (if not plugged in), and would be connected to earth when plugged in.

And yes, there seems to be some conflicting or ambiguous information in the documents. I'm going to be calling tech support for sure...

[AlphaHare]

duplicate - sorry

[turf]

howdy folks!

spent a bit of time the last couple of days working on the bus solar. yesterday didnt make it out of the 30's, so not too much time for me outside. 30 degrees and 30 mph winds.... no fun outside.

today was better and i got some stuff done.
the wires got their shrink wrap and i cleaned up, shortened, and hung more hose clamps to secure the wiring.

and....

the first panel went up!!!

woot woot!!!! and it worked!!! woot woot!!!!

im going to have to find a helper for the rest. it was a feat to manage that big panel up to the roof without breaking it. probably this weekend i can finish these panels...

on another note.... my diesel heater is not working. did some troubleshooting with it and just ordered a new fuel pump for it. hope that gets it fixed up.

and

i used up a tube of jb weld fixing up my brand new dometic broken air conditioner. hoping now it wont fall apart as i drive down the road.

[Rucker]

Originally Posted by turf

haha, rucker, i sure am a dick online....
good old thread!

alpha, in your setup....

no ac input.... only battery/inverter?

you are bonded at the inverter then and voltage needs to return there.

yes, i would wire 3 wires to each junction, and ground as usual at each junction and gfci outlets.

neutral is the straight way back, ground is everyway back..... your gfci's should detect the leaking voltage to ground if its grounded.

i think that victron book is a bit misleading. i could look closer but....

i think the distribution descriptions were good, but what did that mean?

imo, a rv electrical set up is the TT setup in their victron manual. i think you are considering yourself an IT setup, and thats not the case with your big inverter.
if you had a battery and small inverter with built in outlets, you'd be the IT setup, no real need for a ground.

No worries! And yes, those manuals are not always precise. I'm going to reply to Alpha with more detail on this point.

[Rucker]

Originally Posted by AlphaHare

I think it's "TT" for both.

I'll have an AC shore power option, but the AC will go through the Victron first, and all the grounds are then connected through the pedestal back to the park electrical panel.

That works. My inverter (Renogy 2K) doesn't have an option to toggle shore/battery inputs. I found it helpful to have a branch circuit that is ONLY fed by shore power-for the AC, the battery charger, and maybe something else I forget what.

When disconnected from AC shore power, the Victron uses the internal relay to attach AC neutral output to Victron case ground, and there is a ground wire from case ground to school bus chassis.

A year or two ago there was a discussion around whether the automatic toggling of the bond actually worked as advertised-I can't remember which brand inverters though. Turns out the vendor replied to someone's email saying 'yeah we're still working on that feature, so even if it is documented as such it may not be true'. So there's that.

A simple check would be to confirm an open circuit between the white/neutral and the ground wires on the output of the inverter when on shore power, and a closed circuit between the two when on battery power. Might be something worth checking.

In both cases an RCD should work.

My only lingering question is if I should connect the shore power inlet ground to the bus chassis.

My opinion: yes, ground everything you can to everything you can.

The bus chassis then would be disconnected from the Victron AC input (if not plugged in), and would be connected to earth when plugged in.

In the above scenarios, with no shore power the chassis and all wiring from your shore power inlet to the Victron would still be connected to the inverter ground-through your inverter's ground to chassis. And if the Victron works as advertised, and the neutral bonds to ground at the inverter as it should, there will be no conductors anywhere in your bus that may get energized and not quickly trip a branch circuit breaker.

And yes, there seems to be some conflicting or ambiguous information in the documents. I'm going to be calling tech support for sure...

Keep us posted!

[turf]

ok,ok.... been thinking, and that usually means trouble.


the bus has 2 starter batteries, group 30, in the battery tray.
the bus has a third group 30 battery in the battery tray, and that is the starter battery for my big generator.

these 2 systems are tied together, but switched and separate.
they have a common ground. but they also have a solenoid, that separates them so they dont drain each other. i believe when the gen has power, they are combined, when no power, they are separate.

so.......to continue
my bus house system is floating dc 12v(+) and 12v(-)
independent of the bus batteries.
the house battery is a big lifepo. this powers my heater, fridge, water pump.... etc

and now the solar chargers on top of the floating system.


everything is bonded to my ground plane (the bus) but the house 12v(-) is not.

i've been considering tieing them together. i think i could do a simple battery negative to frame jumper and call it good.
but then i started thinking....
how does this affect my starter battery? i thought batteries tied together, died together. why do i want to hook up my battery to the one that dies? would the starter rob the house battery? do i need to isolate it like the generator battery?

i have no desire to charge the house from the bus alternator. right now the generator chargers the house battery from a plug in charger.

once i switch to 24v, does it all change again?


what is the proper connection between multiple vehicle batteries and a house battery, and a different voltage?

[turf]

after writing it down, i think i have it figured out......

start battery 1 (-) connects to start battery 2 (-) connects to house battery 3 (-)

start battery 1 (+) connects to start battery 2 (+)sometimes via the solenoid, then house battery 3 (+) never connects to starter 1(+) or 2(+)

the solenoid was throwing me off until i wrote it down.......

[Albatross]

If the positives are never in contact with each other, then there is no completed circuit, and you would never really have a drain on your house battery.



What could happen in theory is that if/when either the motor or the generator is in operation, then some kind of level change between the absolute ground (earth) and the negative plane could happen which would shift your house voltages up or down a little bit--because you're changing the relative differential between the house positive and the house negative. It is possible that this could cause some kind of jitter or noise in your household circuits, from lights flickering to some minor noise coming out of speakers. If everything is connected properly, this shouldn't be much of an issue, but if something on the automotive DC side were to fail and induce some kind of significant shift in the level, such as a voltage regulator or something like that, then you might experience some unwanted side effects.