Solar/Lithium system diagram and questions

[delliott00]

Good day everyone!

Trying to finalize the design for my solar/lithium setup on my FP Lucia 40. I want to integrate into the existing equipment like the Multiplus/Inverter setup (which has worked great with 800ah of AGM). So I'm planning to do a fairly straightforward setup and want to keep the engine side separate aside from the emergency bridge.

I already have the batteries, mppts, PV panels, cerbo, etc... just need to source a few more things like battery cables, busbars, fuses, switches etc.

Would appreciate any input on the following questions (see the attached diagram):

1. Is the single Victron Smartshunt enough? Or should I have one for each battery? Victron support seems to say one is fine. I think I'm limited to connections on the Cerbo and only have 3 inputs, so 3 shunts and that bank is used up.

2. I hate messy cabling so I'm thinking of doing a double busbar setup on each side (pos/neg) -- see diagram. Battery cables to busbar will be 10' or so, all the same length. Kilovault says 2/0 or 4/0 gauge. My plan has the battery cables at 2/0 and the jumper between busbars would be 4/0. Does that sound right? My old school amp tables say that's overkill, but I'm all for having cables that don't heat up.

3. Are the fuses in the right location? Any recommendations on type and where to get them? Recommendation for solar MPPT fuses? Ok to use the MC4 cable type inline solar fuses?

4. I have one battery on/off switch. Do I need another for the Multiplus and/or MPPTs? There is already one for house 12v, and I'll add one for the Mabru A/C once that is installed.

5. What size busbar posts? Any recs for a good busbar and where to buy?

6. Can the multiplus be configured for LFP charge curves using the Cerbo? Or do I need the Mk3-USB cable and the laptop app?

7. Any reason not to use the Kilovault BMS ethernet network and app to allow the batteries to talk amongst themselves? Won't be on the Cerbo display, but the Kilovault app seems to have what I need.


Thanks for any help. Sorry the diagram is a bit rough, using powerpoint so kinda limited.

BTW not a newbie... I'm very experienced with wiring both 110/220 AC and 12VDC, just want to double check everything before I start getting the last few items.

Thanks everyone. Saludos de Puerto Rico!

Dave
SV FreeLuna
Fountaine Pajot Lucia 40

[emilecantin]

Originally Posted by delliott00

Good day everyone!

Trying to finalize the design for my solar/lithium setup on my FP Lucia 40. I want to integrate into the existing equipment like the Multiplus/Inverter setup (which has worked great with 800ah of AGM). So I'm planning to do a fairly straightforward setup and want to keep the engine side separate aside from the emergency bridge.

I already have the batteries, mppts, PV panels, cerbo, etc... just need to source a few more things like battery cables, busbars, fuses, switches etc.

Would appreciate any input on the following questions (see the attached diagram):

1. Is the single Victron Smartshunt enough? Or should I have one for each battery? Victron support seems to say one is fine. I think I'm limited to connections on the Cerbo and only have 3 inputs, so 3 shunts and that bank is used up.

2. I hate messy cabling so I'm thinking of doing a double busbar setup on each side (pos/neg) -- see diagram. Battery cables to busbar will be 10' or so, all the same length. Kilovault says 2/0 or 4/0 gauge. My plan has the battery cables at 2/0 and the jumper between busbars would be 4/0. Does that sound right? My old school amp tables say that's overkill, but I'm all for having cables that don't heat up.

3. Are the fuses in the right location? Any recommendations on type and where to get them? Recommendation for solar MPPT fuses? Ok to use the MC4 cable type inline solar fuses?

4. I have one battery on/off switch. Do I need another for the Multiplus and/or MPPTs? There is already one for house 12v, and I'll add one for the Mabru A/C once that is installed.

5. What size busbar posts? Any recs for a good busbar and where to buy?

6. Can the multiplus be configured for LFP charge curves using the Cerbo? Or do I need the Mk3-USB cable and the laptop app?

7. Any reason not to use the Kilovault BMS ethernet network and app to allow the batteries to talk amongst themselves? Won't be on the Cerbo display, but the Kilovault app seems to have what I need.


Thanks for any help. Sorry the diagram is a bit rough, using powerpoint so kinda limited.

BTW not a newbie... I'm very experienced with wiring both 110/220 AC and 12VDC, just want to double check everything before I start getting the last few items.

Thanks everyone. Saludos de Puerto Rico!

Dave
SV FreeLuna
Fountaine Pajot Lucia 40

A single smartshunt should be enough, it also has a wire to monitor the starting battery's voltage (no current, though)



Regarding Bus Bars, I recently installed a Lynx Distributor, and I really like it. It's basically 2 big beefy bus bars (1000A) plus 4 fuse holders all in one nice blue box, and once you count everything it's actually cheaper than getting all these components separately. The Lynx shunt would fit neatly with them too. You could get 2 distributors; one on each side of the shunt and you'd avoid the 4/0 cable between your buses. IIRC the Lynx shunt also includes a contactor on the positive side that'd replace the switch (that might be the Lynx BMS, though)
See here for documentation: https://www.victronenergy.com/media/...0-c67f667fa47d

Fuses are there to protect the cabling. Imagine a short at any point in your system, will an appropriate-size fuse blow or will the wire just heat up? From a quick look, it looks like the wires leaving the positive "distribution" bus bar (the upper one) would need fuses. In theory solar panels come with wire big enough to support their short-circuit current, but once you parallel them they need fuses, and I'd assume the MC4 inline ones are made for this purpose and should be fine.


I don't know the answers to your other questions.

[delliott00]

Originally Posted by emilecantin

A single smartshunt should be enough, it also has a wire to monitor the starting battery's voltage (no current, though)



Regarding Bus Bars, I recently installed a Lynx Distributor, and I really like it. It's basically 2 big beefy bus bars (1000A) plus 4 fuse holders all in one nice blue box, and once you count everything it's actually cheaper than getting all these components separately.

That's a good point. I dismissed the Lynx system because I have very limited bulkhead space for mounting a long row of components, and they need to be daisy chained. But I could move a couple of things (engine strainer, and relocate the existing MPPTs) and clear out space for it. You're right, looks like the lynx power in/shunt/distributor setup isn't much different in price from the shunt/busbars/cables/fuses cost.

Will mess around with that idea and see if I can go that route. It does cut down on cabling.

Thanks for the input!

Dave

[Statistical]

Your primary DC wire (4/0) should have a fuse unless its capacity is less than or equal to the three battery fuses.

You may also wish to have a battery switch on each battery. This would make it easier to take one battery out of the system if needed.

Likewise the connections to the inverter/charger, AC, and 12V DC panel should also be fused. Not sure if they were omitted for brevity.

I would recommend the three primary battery fuses be Class-T (or whatever the European equivelent is if you are on that side of the Atlantic). The fuses from main DC busbar and "downstream" can be lower AIC rated fused (i.e. ANL).

However it largely looks good.