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diy solar

Stuck at first-time 2000W solar setup on boat

horstenegger

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Hello everyone,

Although I would describe myself as someone with interest and affinity for all things tech, I'm quite inexperienced when it comes to electrics. Also, I'm great at languages i.e. I suck at making calculations. I also haven't participated much on forums in general thus far, so please forgive me for breaching any written or unwritten rules.

So, not being quite sure to begin, or even what to ask, I'll just jot down what comes to mind right now and do my best to keep this as compressed as possible.

I'm moving onto a sailing catamaran full time, and intend to rely on solar 99% of the time (i.e. anchoring over marinas with shorepower). The boat is equipped with 12V DC appliances / instruments and 230V AC outlets (we're in Europe). Everything after the battery bank has already been installed by a professional marine electrician. However, he ran out of time, so I'm taking care of the power generation and storage myself. Based on my guesstimates on worst case scenario power consumption, I've purchased the following:
  • 5X TrinaSolar 400W panels (41,2 Voc), of which 3 will be mounted at the stern of the boat (virtually no shade), and one on each side of the salon roof (possibly some shade from the mainsail at times on either side)
  • 56X Fortune cells (for either a 1400Ah battery bank @ 12V, or 700Ah @ 24V if that's better)
  • 14X JBD (Overkill) BMS, although I may not need them all if I end up building a 24V battery bank instead
The only things I know I still need / want to purchase, are:
  • Victron Multiplus Charger / Inverter
  • Victron BatteryProtect (although unsure which one)
  • Victron smart MPPTs, although unsure how many and which ones
  • Victron CerboGX + display + RPi with Victron's open source Venus OS in order to make compatible with our non-Victron batteries and BMS, or a full non-Victron home-brew equivalent to CerboGX on a RPi instead (which I think I prefer, but haven't delved into yet)
  • Master fuse for the battery bank (BlueSea Class-T?)
  • Solar panel wiring. Still pretty clueless on that one.
I've now come to a point where I have some questions / doubts about a couple of things, on which recommendations / opinions on various forums are all over the place, but also they apply to slightly different setups / scenarios / needs every time. Here a few:
  1. I'm reading a lot of setups include both one or more BMS and a (smart)shunt, while our electrician stated that shunts are redundant if you already have a BMS. In which cases would implementing a (smart)shunt be recommendable, and how?
  2. The boat has a 12V setup, but some experts (including Will) recommend setting up a 24V battery bank when the distance (i.e. cable length) from the solar panels to the batteries reaches a certain point and/or power consumption is relatively high. But where's that line? And does it make sense to use a 24V battery bank on a 12V boat? Obviously we would need a 24V->12V converter after the batteries, which results in decreased efficiency, but others argue that there are such efficient converters nowadays and the benefits are greater than that sacrifice.
  3. Am I right to think it's best to implement 3 MPPTs: one for the 3 panels at the stern and one for each on the salon roof? And how 'heavy' should they be?
  4. I've seen similar setups with BMS and a Cyrix-Li-charge 12/24V-120A intelligent charge relay, but haven't been able to find an explanation as to why this would be needed / recommendable. Seems a bit redundant to me but probably I'm missing something.
  5. Other questions / considerations. I'm pretty sure there's a few that I should be asking which I'm still ignorant about at this point.

What may be useful to mention in order to avoid topic deviation: Due to our relatively high solar output and easily expandable battery bank, as well as the fact that we'll be following the sun and avoiding the darker / colder seasons, charging from alternators and/or generator aren't part of the plan, at least not for now.

It would be awesome to get some of your recommendations / advice on the points above, as well as on anything I haven't thought of / mentioned yet. I'm also more than open to suggestions on other / non-Victron equipment than mentioned in my 'still to purchase' list, as long as it's relatively easily available in Europe. Many thanks in advance!

-Lex
 
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For your solar panel arrangement let's start with the 3 on the stern. You could put those three in series or parallel. It depends on shading. If all three are shaded together or not at all most of the time then putting them is series may be a good choice. But if one of the three will be partially shaded regularly then putting them in parallel would be best. 3 400W panels is of course 1200W. If you have a 12V system then that's 100A of charge current. You would need the Victron 150/100. If you have a 24V system then that's only 50A of charge current. If the panels are in parallel you can use the 100/50. If the panels are in series you need the 150/45. 45A of charge current at 26.5V is really close to 1200W.

For the other two panels, you can use one controller with the two panels in parallel. The Victron 100/30 would work for both panels on a 12V system if only one will ever has sun on it at a time. If both can get sun at the same time then the 150/60 would be the right choice on a 12V system. On a 24V system you could use a 75/15 if only one panel gets sun at a time or a 100/30 if both get sun together.

The lower amp controllers are cheaper than the higher amp controllers. This will be one big advantage of 24V over 12V.

The 24V battery also allows for smaller (lighter/cheaper/easier) wire than needed for the 12V battery.

Something like one of the Victron Orion DC-DC converters will allow you to convert the 24V battery to the 12V needs for the loads.

One big caveat here is the size of the 12V loads. If you have some high amp 12V load such as some kind of motor, then finding a DC-DC converter that can handle it can be an issue.

The battery protect would be between the DC loads and the battery. The size depends on the amount of DC loads you have.

If you are going to use a RPi and display with VenusOS then there is no reason to also have a GX and display unless you will have something that can't be plugged into the RPi and requires the GX.
 
Thank you for your insights @rmaddy, that's very helpful start already! You response kind of confirms my assumptions on 24V vs 12V. With that being said, please allow me to respond to a few points:

For your solar panel arrangement let's start with the 3 on the stern. You could put those three in series or parallel. It depends on shading. If all three are shaded together or not at all most of the time then putting them is series may be a good choice. But if one of the three will be partially shaded regularly then putting them in parallel would be best.
I get why it would be best to connect them parallel would be best if one/some of them get shaded regularly, but the way you phrase it, it sounds like overall it's actually better to connect them in series. Only if one of them gets shadd regularly, connecting them in parallel would be the best compromise. Am I reading that correctly? What exactly is the reason that would it be better to connect them in series if all three get the same amount of shade / sun? Is there no benefit to connecting them in parallel anyway? Is it just because then I can use cheaper MPPTs?

Something like one of the Victron Orion DC-DC converters will allow you to convert the 24V battery to the 12V needs for the loads.
One big caveat here is the size of the 12V loads. If you have some high amp 12V load such as some kind of motor, then finding a DC-DC converter that can handle it can be an issue.
Good point. We have an electric winch and electric windlass (for the non-sailors here: the thing that pulls up the anchor). I'm still getting to know this boat and the motors are quite hard to reach / inspect without dismounting them entirely, but both are 12V and probably 700~1200W each. That definitely doesn't sound like a good idea with an Orion, even the heaviest one. I could swap out the motors for 24V versions, which will probably cost me approx. €150~250 for each. I haven't done the numbers yet, but I'm guessing that at the end of the day, I'll be spending approximately the same amount of money on either higher amp MPPTs + higher gauge cables by keeping the bank at 12V vs. purchasing a DC-to-DC converter + two new 24V winch motors in order to be able to connect them to the 24V bank directly ¯\_(ツ)_/¯
Plus: time. (What was sold to us as a 4 month boat refit is already taking over a year now). So for the sake of keeping things simple, I think I'll probably stick to 12V for now.

If you are going to use a RPi and display with VenusOS then there is no reason to also have a GX and display unless you will have something that can't be plugged into the RPi and requires the GX.
Makes sense. Would you recommend that though? I'm only thinking I probably can't use the CerboGX on its own because it may not work with all non-Victron batteries/BMS. Right?


If there's anyone who can fill us in on some of the other points in my little list(s), that would be awesome. Free boat ride and lunch for bringers of useful insights whenever we're in the neighbourhood! (which is guaranteed to happen sooner or later, at least as long as you're not too far from the coast, as we're going to cover the entire globe)
 
I get why it would be best to connect them parallel would be best if one/some of them get shaded regularly, but the way you phrase it, it sounds like overall it's actually better to connect them in series. Only if one of them gets shadd regularly, connecting them in parallel would be the best compromise. Am I reading that correctly? What exactly is the reason that would it be better to connect them in series if all three get the same amount of shade / sun? Is there no benefit to connecting them in parallel anyway? Is it just because then I can use cheaper MPPTs?
With the higher voltage of 3 panels in series you tend to get slightly better performance at lower light conditions (early/late day, clouds, etc). That's the primary benefit of putting them in series. It's also a lot simpler to wire them in series. No extra wires, connectors, or fuses needed. And the low amps allows smaller wire.

Parallel will of course handle partial shading better assuming the partial shading is one panel at a time and not part of all three at once. 3 in parallel requires fusing each panel in a combiner box and you need bigger wire to handle the higher amps. Parallel does also allow for a lower voltage MPPT which can make it a little cheaper there.

both are 12V and probably 700~1200W each. That definitely doesn't sound like a good idea with an Orion, even the heaviest one.
The 100A Orion should handle 1200W. You can use more than one in your system (one per winch, for example). And I think you can also wire two in parallel to support twice the amperage. In the end you can do the math on the cost of a 12V system vs a 24V system taking into account all of the cascading effects on hardware choices, wiring, fuses, etc.

Makes sense. Would you recommend that though? I'm only thinking I probably can't use the CerboGX on its own because it may not work with all non-Victron batteries/BMS. Right?
I'm using a RPi and VenusOS. It works great. But I didn't have to make it work with a BMS. I'm not 100% sure on that detail but I think whatever you can do to make the BMS talk to the RPi you can also do to the GX. Both devices run the same VenusOS and both can be modified the same. And the connections on the GX should be a superset of those on a RPi. To me, use the GX if you want a pure Victron setup. Use a RPi if you want to save a few hundred dollars and maybe a bit more effort mounting it.
 
If you install bypass diodes (they may already be installed in each panel) then connecting the panels in series provides more power during partial shading.
 
With the higher voltage of 3 panels in series you tend to get slightly better performance at lower light conditions (early/late day, clouds, etc). That's the primary benefit of putting them in series. It's also a lot simpler to wire them in series. No extra wires, connectors, or fuses needed.
Interesting, I didn’t know that, thanks!

The 100A Orion should handle 1200W. You can use more than one in your system (one per winch, for example). And I think you can also wire two in parallel to support twice the amperage.
Didn’t know that either, sweet! With that being said, the electric winch and windlass won’t be used at the same time, and always during relatively short bursts only (<30 seconds).

To me, use the GX if you want a pure Victron setup.
Naaah, not necessarily…

Use a RPi if you want to save a few hundred dollars and maybe a bit more effort mounting it.
Absolutely!

If you install bypass diodes (they may already be installed in each panel) then connecting the panels in series provides more power during partial shading.
Also interesting! Will definitely look into that. Hopefully TrinaSolar integrates those in their panels. We’ll see.

So now, in contrary to my previous post, I’m now more inclined again to go for a 24V house bank. On another note - I just realized that the 14 BMS units I purchased are 4S ?‍♂️
I guess I have 14 Overkill 12V BMS for sale now ¯\_(ツ)_/¯
 
The windlass: as it is, it's powered from the engine starter battery, right? I would leave it just like that, you don't pull the anchor up without at least one engine running, do you?

The electric (sheet) winches: Catamarans aren't usually big on jibs, are they? So it's not as if you'd be trimming a huge genoa for racing all the time, is it? They shouldn't be much of an issue at all, you have plenty of batteries for that.

The panels series/parallel... I would be slightly more worried about high voltages in a rough saltwater environment than marginal solar performance gains.
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On the 12/24V question... thinking about it (not for too long, obviously ;·)... I would probably stay on 12.
Most of my boats were on 24, my house is on 24, I don't draw much so I don't need 48...
Now, if you're used to living at sea - on batteries - you understand energy conservation/management. So you probably won't draw that much either.
You boat is wired for 12V. Which means that the cables are (hopefully) correctly sized for that.
The DC converter, you'd want to carry a spare, just with the cost of that you can afford thick enough cables for any add-ons.
So personally, I really think I would just stay on 12 and save me the hassle :·)
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Hi all, first off - thank you so much for all these insights and suggestions, and sorry for the long downtime. Life happened. But we're back to picking up this subject as of tomorrow as we need to order supplies in order to receive and install them in time before we're hauled back into the water on March 15th. The pressure's on.

The windlass: as it is, it's powered from the engine starter battery, right? I would leave it just like that, you don't pull the anchor up without at least one engine running, do you?
It actually isn't (connected to the starter battery). But it would make sense to do so I guess.

The electric (sheet) winches: Catamarans aren't usually big on jibs, are they? So it's not as if you'd be trimming a huge genoa for racing all the time, is it?
Well...we typically use >100% gennakers, i.e. the bigger ones that surpass the mast. They can get quite big and require quite some power to trim!

As for panel configuration - One panel panel of both groups of panels will most likely be shaded regularly by the sail or boom, so we'll be connecting all the panels in parallel. Although I feel I would prefer to build a 24V setup, I think I'll stick to 12V for now, mainly because I have purchased 14 4S BMS units. It's too much of a hassle to sell them all and order new ones (and receive them in time from China). We may run into a wall with the wiring though, due to the mounting holes of the hardtop bimini supporting tubes connected to the hulls (thru which the wires will run) being too small. I'm still trying to figure out how thick a wire we'll be needing, but if it does indeed turn out that the required gauge for 12V won't fit thru them, we'll probably have no choice but to go 24V so we can use smaller solar panel wires, but then convert to 12V before it reaches the batteries so we can keep the 4S BMS units that we already have. Would that be a good idea, or a not so good one?

Furthermore, a couple of questions remain unanswered:

  1. I'm reading a lot of setups include both one or more BMS and a (smart)shunt, while our electrician stated that shunts are redundant if you already have a BMS. In which cases would implementing a (smart)shunt be recommendable, and how?
  2. I've seen similar setups with BMS and a Cyrix-Li-charge 12/24V-120A intelligent charge relay, but haven't been able to find an explanation as to why this would be needed / recommendable. Seems a bit redundant to me but probably I'm missing something.
  3. Is it necessary / recommended or an overkill to integrate a Victron BatteryProtect into the setup?
Thanks again guys, can't wait to share the final setup and its results once done.
 
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The wire size for the panels, whether the batteries are 12, 24 or whatever is irrelevant.
You could have them all in series - probably not the best in a salty, rough environment, very high voltage - or some in series and then paralleled.
Which is a bit hard to do with five, but solutions can be found. Just use an appropriate charge controller.

As for monitoring, if your BMS(s) can do that, you wouldn't need anything more, and protection they should definitely afford.
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To answer a few questions (from my perspective RV MotorHome):

1. I would use the Smartshunt. It easily connects to the Cerbo and will deal with all your batteries as one LARGE battery. The shunts are way more accurate than bms’s are. One item you will have to watch it to make sure your 14 batteries are charging and discharging at the same rate. Be sure and use busbars and equal length of cables.
2. Can’t help you here.
3. Battery Protects definitely have their place. I use 2 of them. My reasoning is In a low voltage situation- I want my inverter to shut down first, then the nonessential loads, then the essential loads, then the bms goes critical. This way I can more easily get the bms restarted. I would not be in my rig, (otherwise I would fix the issue). I have them for a line of defense for when I am not in the rig.
4. Earlier you said you didn’t want any generator or dc-dc charging off the motors. If your alternator can handle it I would install a DC-Dc charger - Victron Orion Tr Smart non-isolated charger. A single one will draw 30 amps from your motors alternator. You may find those amps useful… but the main reason is if you have a problem and no solar, by running your boat motor you can keep the absolute essentials on - radio, charts, nav lights, and lights to fix the problem.
 
The wire size for the panels, whether the batteries are 12, 24 or whatever is irrelevant.
But...wait..24V needs less thick wires than 12V (right?), so if the bundled 12V wires won't fit through the bimini support tubes' mounting hole, 24V wires should/might/could (right?).

1. I would use the Smartshunt. It easily connects to the Cerbo and will deal with all your batteries as one LARGE battery. The shunts are way more accurate than bms’s are. One item you will have to watch it to make sure your 14 batteries are charging and discharging at the same rate. Be sure and use busbars and equal length of cables.
Thanks Rocky. I assume you mean I should have the batteries managed individually by BMS and as one large batter by the SmartShunt? I still have no clue as to what the added benefit of that brings to the table. From what I understand, a benefit could be to provide the BMS with more accurate readings, but if I understand correctly, that would mean that I will need 14 SmartShunts, as I have a 4S14P setup (i.e. one between every BMS and its designated battery pack). Anyhow, that does not seem to be the purpose you are referring to, since you're mentioning the 'one LARGE battery' bit. So, what exactly is the benefit of adding a SmartShunt before/after the entire bank?
As for connecting a smartShunt to Cerbo - I highly prefer going the RPi + Venus route. From what I've read, it's quite complex and a bit flimsy to hookup a SmartShunt to an RPi (will need USB converters etc), which would mean I would be forced to purchase the Cerbo GX, which I don't really want or need for anything other than being able to simply/efficiently integrate a SmartShunt. Is adding the SmartShunt for the purpose you're suggesting by itself worth purchasing a Cerbo GX instead?
EDIT: Nevermind, just found out that the SmartShunt also has BlueTooth and therefore doesn't necessarily needs to be connected to a Cerbo.

3. Battery Protects definitely have their place. I use 2 of them. My reasoning is In a low voltage situation- I want my inverter to shut down first, then the nonessential loads, then the essential loads, then the bms goes critical. This way I can more easily get the bms restarted. I would not be in my rig, (otherwise I would fix the issue). I have them for a line of defense for when I am not in the rig.
I had to read this 3 times but yes, that does indeed make sense. Will do, thanks!

4. Earlier you said you didn’t want any generator or dc-dc charging off the motors.
Generator definitely not. This is a relatively light, performance-first boat. Weight is my biggest enemy. DC-to-DC is more like 'not yet'. After weight, time is my biggest enemy, so it's mainly a case of first thing's first. But eventually I do want to incorporate some sort of backup, be it charging the housebank from alternators and/or being able to fallback to starter batteries (we have 2 engines so 2 starter batteries) in case housebank fails.
If your alternator can handle it I would install a DC-Dc charger - Victron Orion Tr Smart non-isolated charger. A single one will draw 30 amps from your motors alternator. You may find those amps useful… but the main reason is if you have a problem and no solar, by running your boat motor you can keep the absolute essentials on - radio, charts, nav lights, and lights to fix the problem.
Yep, totally useful. I can't access the engine bay right now but I believe my alternators are 130 115 amp Mitsubishis. Should be fine, right?
 
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But...wait..24V needs less thick wires than 12V (right?)

Yes. And 200V even less :·)
If you have an MPPT charge controller that will take 200V+, you could wire all five panels in series, if they make 40V each...
But then you would have 200VDC running through your wires, which on a boat could be... dodgy.

In any case, from panels to controller you have a lot more than 12V even if you keep them in parallel.
If they're rated 41.2 open circuit, you'll probably get over 35 from them under load.
So size your wires to 35, not 12. After the controller you'll probably have some 14V, but it's a much shorter run, right?

If sizing wires for 35V fits your needs, you're OK. In any case, the battery voltage is irrelevant.
So I would keep them in parallel. What you gain in conductor diameter you'd probably lose on insulation thickness anyway.
You could also have separate controllers for the bow panels and the side ones. Adds redundancy too :·)

So the only advantage of having 24V would be the sheet winches. But then those are already wired for 12V, right?
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UPDATE: Found out that my TrinaSolar panels actually in fact have bypass diodes integrated into their junction boxes! Which would make the concept of connecting them in series more appealing, despite possible partial shading, right? Apart from the salt water environment thing of course... But I believe that risk should be ale to be mitigated sufficiently with adequate fuses etc.

EDIT:

Yes. And 200V even less :·)
If you have an MPPT charge controller that will take 200V+, you could wire all five panels in series, if they make 40V each...
But then you would have 200VDC running through your wires, which on a boat could be... dodgy.
Of course. I was more thinking about 3 on one MPPT and 2 on the other?
 
In any case, from panels to controller you have a lot more than 12V even if you keep them in parallel.
If they're rated 41.2 open circuit, you'll probably get over 35 from them under load.
So size your wires to 35, not 12. After the controller you'll probably have some 14V, but it's a much shorter run, right?
Doh. Because you place the MPPTs as close to the batteries as possible. Silly me.

If sizing wires for 35V fits your needs, you're OK. In any case, the battery voltage is irrelevant.
So I would keep them in parallel. What you gain in conductor diameter you'd probably lose on insulation thickness anyway.
You could also have separate controllers for the bow panels and the side ones. Adds redundancy too :·)

So the only advantage of having 24V would be the sheet winches. But then those are already wired for 12V, right?
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Yeah no I will indeed keep the batteries 12V. Just wanted to keep the run from panels to my battery compartment (where all the other power management stuff is located as well) as simply and light as possible. And the possible issue with the holes being too small for larger gauge wires. So I may be simply forced to put the 3 stern panels into series and the 2 on the coach roof as well because the wires will otherwise be too big to feed through the tube/hole that leads them into the starboard hull (where our batteries etc. are).
 
Wiring from solar Panels to mppt’s: these wires do not depend on the battery- they depend on the mppt voltage - and really they depend on how you are wiring them up - serial vs parallel.
(I couldn’t find the exact specs - so these numbers are a guess Voc 41.2 - amps about 8)
With three in series you will have Voc of 124v and 8amps) 10 or 12 gauge solar wire will be fine for the run to the mppt’s (this size is also fine for your two single panels. If parallel you will need to fuse each panel and have about 24 amps - 10 gauge wire minimum- probably better with 8. (Another option is a 100/30 mppt for each panel- even the three on the back - so five100/30 mppt’s) You probably want your two single panels on their own mppt because of shading issues.

Before you make too many more decisions you should get your lithium battery figured out. (This will be a big one). (Those fortune cells are great cells). You need to decide on 12 vs 24v. Then you need to decide on how many separate batteries - for example- your initial post suggested fourteen 4s batteries in a 1p4s14p arraignment (one cell hook in parallel, then 4 in series to create 12v, then fourteen of these 12v batteries in parallel). To connect these batteries you will need a buss bar (look at the Victron power in) and all the cables to the batteries will need to be the exact same length.
Fourteen will probably be problematic. You can also go with seven batteries of 2p4s7p. Or two big batteries of 7s4p2p. You need to figure out your space to assemble them. Your high amps needs will also factor into how many separate batteries you need. What size of mppt are you getting?

Edit: I just remembered you are in Europe so you use mm2 (millimeter squared for wire size - sorry I use awg.
 
If the problem are the tubes you want to run the wires in, consider
What you gain in conductor diameter you'd probably lose on insulation thickness

Me personally, I would be slightly more worried about having 120+VDC with saltwater splashing all over the place than a minimal voltage drop from panels to SCC.
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Wiring from solar Panels to mppt’s: these wires do not depend on the battery- they depend on the mppt panel voltage - and really they depend on how you are wiring them up - serial vs parallel.
That's becoming the million dollar question. The tricky thing is that the hardtop bimini's support tubes are being re-made and aren't currently mounted onto the boat yet, so I don't know exactly how much / little room I'll have to feed the cable thru. However, I need to order and install the whole lot including the wiring before bimini structure gets mounted. Since all these aspects (series/parallel, wiring, MPPTs) are so intertwined with each other, I feel like I'm in a bit of a chicken vs. egg situation.

(I couldn’t find the exact specs - so these numbers are a guess Voc 41.2 - amps about 8)
Here they are: https://static.trinasolar.com/sites/default/files/EN_Datasheet_Vertex_DE09.pdf
It's the 400W model so indeed 41.2 VOC but more amps if I'm reading it correctly (11.7?)

With three in series you will have Voc of 124v and 8amps) 10 or 12 gauge solar wire will be fine for the run to the mppt’s (this size is also fine for your two single panels. If parallel you will need to fuse each panel and have about 24 amps - 10 gauge wire minimum- probably better with 8. (Another option is a 100/30 mppt for each panel- even the three on the back - so five100/30 mppt’s)
So let me recapitulate this: I can either install a ~24A fuse between each panel (sounds more waterproof in the figurative sense of the word, but less so in the literal sense), or a 100/30 MPPT between each panel (and of course after the last one)? The latter idea sounds more expensive, but also more appealing for some reason. Although not sure why. Gut feeling.

You probably want your two single panels on their own mppt because of shading issues.
Well, that's the question, now that I know that my panels have bypass diodes, I guess connecting them in series and hook them up to one MPPT sounds pretty viable, no?

Before you make too many more decisions you should get your lithium battery figured out. (This will be a big one). (Those fortune cells are great cells). You need to decide on 12 vs 24v.
Nooo, please no. I just got off that rollercoaster and decided on staying on 12V. Please don't tempt me to go back to that drawing board haha.

Then you need to decide on how many separate batteries - for example- your initial post suggested fourteen 4s batteries in a 1p4s14p arraignment (one cell hook in parallel, then 4 in series to create 12v, then fourteen of these 12v batteries in parallel). To connect these batteries you will need a buss bar (look at the Victron power in) and all the cables to the batteries will need to be the exact same length.
I'm not quite sure what you mean by 'cell hook', but yes indeed [4 cells in series] X 14 in parallel. The Fortune cells came with their own busbars. Roger on the exact same cable length. Despite my limited knowledge, that I knew (and probably would have done by myself anyway).

Fourteen will probably be problematic.
Why? In terms of dangerously high current? Or in terms of space? Because I have plenty of space. The batteries are already in the compartment and I still have enough space to double the size of the bank (which probably at some point I will, if/when our engines die out and we switch to electric propulsion).

You can also go with seven batteries of 2p4s7p. Or two big batteries of 7s4p2p. You need to figure out your space to assemble them. Your high amps needs will also factor into how many separate batteries you need. What size of mppt are you getting?
Well that depends on whether I'm connecting the panels in series (thanks to bypass diode) or parallel, which brings us back to full circle.
My head is about to explode ?

Edit: I just remembered you are in Europe so you use mm2 (millimeter squared for wire size - sorry I use awg.
No worries, this really is the least I can stress about at the moment ?

If the problem are the tubes you want to run the wires in, consider


Me personally, I would be slightly more worried about having 120+VDC with saltwater splashing all over the place than a minimal voltage drop from panels to SCC.
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I'm not quite sure what you mean by SCC, but a minimal voltage drop is indeed not something I'm too worried about. I'm more worried about solar cables not fitting through all the nooks and crannies of the boat (it's 8~10 meters / 24~30ft from the panels to the MPPTs) because they're too thick and /or too stiff. And weight. Performance focused catamarans hate weight. Every kg counts.
 
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