diy solar

diy solar

Cinergi's 28 kWh / 4 kW Solar / 10 kW inverter RV build

I've completed the last revision the battery before I head to Kanas next week (in theory) to pick up the new RV and install this (at their facility with their assistance WRT any welding or physical work beyond my capabilities).

The previous revision had a few spots that were +40F under 120 amps of load, so I thought about it and figured out a better way to do the bus bars at the ends of the strings. I previously had 3/4" x 1/8" everywhere ... because I can't fit 1" wide bar through the hall effect current sensor. But for some reason (I've been at this for too long) it didn't occur to me to use 3/4" only for the current sensor, and 1" everywhere else. And that I could still terminate everything with 1" if I build a "bridge" with 2 3/4" pieces sandwiching the 1" pieces on either end:

IMG_9285.JPG

I just ran 9000 watts through the system and observed a +15F maximum temperature rise. Woot!

I also decided to create a dedicated standoff system for the BMS and Breaker boards which would move with the cells as they expand and contract. Having them screwed down to the black threaded rod meant that there were considerable stresses on these bus bars and I saw the contactor ripping away from the plywood.

So this version has heat shrink on the bus bars at the ends of the cells (I don't have enough to do the cell bus bars and man I'm tired of working on this thing lol). I also got all the wires in split loom and secured with strain reliefs.

BMS board with contactor, SSR, and Ethernet for CANBUS:
IMG_9284.JPG

Other side of that board:
IMG_9283.JPG

Looking down the cells from that board:
IMG_9286.JPG

Breaker board:
IMG_9281.JPG

Other side of breaker board:
IMG_9282.JPG

Entire set:
IMG_9287.JPG

Back of the set (this is 1 gauge wire temporarily, will be 3/0 in the RV):
IMG_9288.JPG

That wire, BTW, supported the 9000 watt load with a +25F temp increase.
 
I've completed the last revision the battery before I head to Kanas next week (in theory) to pick up the new RV and install this (at their facility with their assistance WRT any welding or physical work beyond my capabilities).

The previous revision had a few spots that were +40F under 120 amps of load, so I thought about it and figured out a better way to do the bus bars at the ends of the strings. I previously had 3/4" x 1/8" everywhere ... because I can't fit 1" wide bar through the hall effect current sensor. But for some reason (I've been at this for too long) it didn't occur to me to use 3/4" only for the current sensor, and 1" everywhere else. And that I could still terminate everything with 1" if I build a "bridge" with 2 3/4" pieces sandwiching the 1" pieces on either end:

View attachment 41936

I just ran 9000 watts through the system and observed a +15F maximum temperature rise. Woot!

I also decided to create a dedicated standoff system for the BMS and Breaker boards which would move with the cells as they expand and contract. Having them screwed down to the black threaded rod meant that there were considerable stresses on these bus bars and I saw the contactor ripping away from the plywood.

So this version has heat shrink on the bus bars at the ends of the cells (I don't have enough to do the cell bus bars and man I'm tired of working on this thing lol). I also got all the wires in split loom and secured with strain reliefs.

BMS board with contactor, SSR, and Ethernet for CANBUS:
View attachment 41937

Other side of that board:
View attachment 41938

Looking down the cells from that board:
View attachment 41935

Breaker board:
View attachment 41940

Other side of breaker board:
View attachment 41939

Entire set:
View attachment 41933

Back of the set (this is 1 gauge wire temporarily, will be 3/0 in the RV):
View attachment 41934

That wire, BTW, supported the 9000 watt load with a +25F temp increase.
WOW, what a system! You have done a great job putting this together. One observation; the end terminals and bus bars in your last photo look like they are pretty close to the end bracing channels. Are you considering shielding/insulating those exposed terminals a little more?

Once again, great job! I've learned a lot watching your build here.
 
WOW, what a system! You have done a great job putting this together. One observation; the end terminals and bus bars in your last photo look like they are pretty close to the end bracing channels. Are you considering shielding/insulating those exposed terminals a little more?

Once again, great job! I've learned a lot watching your build here.

Thanks! The heat shrink goes down as far as I can go without it interfering with the 3/0 lug that will be there. But given that it's connected to a terminal post, it's pretty well braced from movement. From a cosmetic perspective, it would be cool if I could cover those square tubes with something non-electrical but I don't believe it's needed from a safety perspective.

I would, in general, like some coverings over all my connection points ... but this is going in a dedicated, walled-off area of the RV basement that will have nothing else in it so I didn't optimize for overall physical safety.
 
WOW, what a system! You have done a great job putting this together. One observation; the end terminals and bus bars in your last photo look like they are pretty close to the end bracing channels. Are you considering shielding/insulating those exposed terminals a little more?

Once again, great job! I've learned a lot watching your build here.

The heat shrink goes past the bar and I can get a finger in between so... feels ok to me.
92306F92-F79C-4B06-A279-0D9F6DDA9C7C.jpeg
 
If just for looks , get some large heat shrink for the square tube

Yeah -- back of my mind wonders how well that will hold up under the pressure between the square tube and the plywood. If I ever build a 12v version I might try that. Maybe I can just paint it (back of my head is also thinking about fire-retardant paint for the plywood).
 
Welp, the RV is confirmed to be mine on Tuesday, so I disconnected everything today :eek: gotta pack the truck tomorrow.
With any luck, my system will be live in the RV, powered by solar, next week. I can't wait!!! ?
 
@FilterGuy I have a grounding question or three for you :)

In my diagram, I'm now leaning towards not merging the grounds on the AC output sides of the inverters because it seems to me that would cause a ground loop (grounds are also effectively merged at the AC input sides). That makes for a weird situation in the electrical panel on the output side since normally all grounds are merged ... I'm not even sure I have two separate busses in the electrical panel to pull that off ... anyway, I wanted to see what you thought about this.

I'm still debating on whether I bond the 48vdc negative bus to the chassis ground (along with the AC ground and 12vdc ground). Right now the 48vdc system is isolated (the DC-DC converter is isolated), but I'm a little worried about static buildup since this is a 5th wheel trailer that's sometimes connected to a truck's electrical system. And while the 48vdc system is pretty physically contained to the battery compartment (nothing in the RV is 48v), grounding it would provide better protection against 48v shorts to chassis.

(Note: not pictured here, it looks like the SCC chassis have case grounds that I need to connect to the grounding bus, too. And I don't plan to ground the panels since it's a mobile system. Comments welcome)

It's a large system and New Horizons RV is highly interested in my build, so I also want to build this safely so I don't give them any bad ideas.

Thanks!
 
In my diagram, I'm now leaning towards not merging the grounds on the AC output sides of the inverters because it seems to me that would cause a ground loop (grounds are also effectively merged at the AC input sides). That makes for a weird situation in the electrical panel on the output side since normally all grounds are merged ... I'm not even sure I have two separate busses in the electrical panel to pull that off ... anyway, I wanted to see what you thought about this.
The Victron Inverters have all of the AC-in and AC-out and case grounds tied together internally. Consequently, all of the lime green wires below are electrically tied together.

1616816765944.png

That presents an interesting challenge to properly ground the inverters and not create a ground loop.

I'm still debating on whether I bond the 48vdc negative bus to the chassis ground (along with the AC ground and 12vdc ground). Right now the 48vdc system is isolated (the DC-DC converter is isolated), but I'm a little worried about static buildup since this is a 5th wheel trailer that's sometimes connected to a truck's electrical system. And while the 48vdc system is pretty physically contained to the battery compartment (nothing in the RV is 48v), grounding it would provide better protection against 48v shorts to chassis.

Perhaps the first discussion should be about grounding the AC. You have 240V AC wondering around the RV and if one of the hots touches metal that is not tied to the AC ground it presents a dangerous situation because the fault won't be cleared by the breaker blowing. Consequently, the AC ground should definitely be tied to chassis. (If you have not reviewed my AC/Household grounding paper you should. It describes how the grounding clears the fault)

Now lets talk about where that leaves you on the 48V circuit. Since the inverter ties AC ground to it's case, in order to keep the DC isolated from chassis, you would have to remove the two wires running from DC ground to the inverter. In addition, NEC considers 48V nominal as dangerous and requires it be grounded.

Personally, I would tie the 48V dc to Chassis.

Before I go too far in any further recommendation....

1) what is the 'EMS' and the little brown box next to it?
2) will you tie 48V neg to chassis?
 
The Victron Inverters have all of the AC-in and AC-out and case grounds tied together internally. Consequently, all of the lime green wires below are electrically tied together.

View attachment 42700

That presents an interesting challenge to properly ground the inverters and not create a ground loop.

I'm still debating on whether I bond the 48vdc negative bus to the chassis ground (along with the AC ground and 12vdc ground). Right now the 48vdc system is isolated (the DC-DC converter is isolated), but I'm a little worried about static buildup since this is a 5th wheel trailer that's sometimes connected to a truck's electrical system. And while the 48vdc system is pretty physically contained to the battery compartment (nothing in the RV is 48v), grounding it would provide better protection against 48v shorts to chassis.

Perhaps the first discussion should be about grounding the AC. You have 240V AC wondering around the RV and if one of the hots touches metal that is not tied to the AC ground it presents a dangerous situation because the fault won't be cleared by the breaker blowing. Consequently, the AC ground should definitely be tied to chassis. (If you have not reviewed my AC/Household grounding paper you should. It describes how the grounding clears the fault)

Now lets talk about where that leaves you on the 48V circuit. Since the inverter ties AC ground to it's case, in order to keep the DC isolated from chassis, you would have to remove the two wires running from DC ground to the inverter. In addition, NEC considers 48V nominal as dangerous and requires it be grounded.

Personally, I would tie the 48V dc to Chassis.

Before I go too far in any further recommendation....

1) what is the 'EMS' and the little brown box next to it?
2) will you tie 48V neg to chassis?

I guess I could merge the two AC out grounds as close as possible to the inverters and take a single run back to the breaker panel?

Yeah all AC ground will be tied to chassis.

It's interesting because in some of the Victron diagrams, case ground is tied to DC negative. In others, it's not. It makes sense to tie case ground to the AC ground so that kind of fault can be cleared... and from what I remember, the DC inputs of the quattro's are isolated ... I was trying to protect from an internal DC fault but ... as long as I'm safe on the AC side and safe from static buildup ...

1) EMS is the incoming energy management system (just a fancy surge protector) from the shore connection
2) That's what I'm debating; my decision will come down to whether I need to do that so I can prevent differences in potential between the now-floating 48v system and the rest, or fi that's even necessary.
 
Since the Quatros tie case and AC grounds together, I would go with this

1616868949025.png

Notice that I daisy chain the AC ground and the Case grounds. This avoids ground loops.
Also note that I tie the neg bus bar to ground. This grounds both the 48V and 120V to chassis
 
Since the Quatros tie case and AC grounds together, I would go with this

View attachment 42766

Notice that I daisy chain the AC ground and the Case grounds. This avoids ground loops.
Also note that I tie the neg bus bar to ground. This grounds both the 48V and 120V to chassis

oh! Daisy chain. Why didn’t I think of that? Haha thank you!
 
Thinking aircraft engine fire system would be "cooler". Just fill up the bay with foam. :)
Or the proteng systems. FM200 filled tube that releases fire suppression gas under heat. Cool and somewhat expensive, but in a fire, I’ll spend the money.
 
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