Need Advice on Adding Solar (LONG)

[DBG8492]

The paperwork accompanying my purchase of this old boat included a schematic of the DC charging system created in 2019. I've verified nearly all of it as accurate and re-created it in Visio so it's easier to visualize.

The only "battery bank" in the design is the "Inverter Bank" made up of two 8D 425 AH FLA units wired in parallel. This bank is charged directly from the Xantrex Freedom 458 2500W inverter/charger. It also supplies all of the DC voltage for the inverter when the shore power/genny is not available. This is the only bank/battery monitored by the Xantrex remote at the helm. The inverter powers the fridge primarily, but we will be adding a small chest freezer, a laptop, and a monitor (I work from the boat), and we will use a very small projector at night to stream movies/shows.

The generator start battery is a 4D FLA unit. It is isolated and when on shore power, it charges from the Xantrex through a diode isolator located in the engine room - losing .7 volts in the process. When off shore power, it charges from the genny alternator only - directly connected. It is not monitored.

The two engine start batteries are isolated 8D FLA units and double as the house batteries, supplying DC voltage to the DC Distribution Panel. They can be used individually, or paralleled through a four-position switch (off, both, 1, 2) on the panel. They are not monitored and are charged when on shore power by the Xantrex through the same diode isolator as the generator start battery, with the same .7 volt loss. The alternators for each engine run through a separate diode isolator at the helm to charge the batteries when underway, also at a .7 volt loss, but at a bulk charge voltage of 14.4 volts rather than the 13.7 float charge the Xantrex supplies, thanks to the monitor being on the Inverter bank.

The original diagram shows a link between the isolators (bottom right in the pic) - however, I don't think it exists because the isolator in the engine room is missing a wire on one of the supply terminals. The only piece I haven't visually verified is the isolator in the helm (on the right in the photo).

I want to be able to anchor out for extended periods while using the generator as little as possible, so I'd like to add solar to this while changing as little of the original setup as possible. The solar would need to charge both the inverter bank and the start/house batteries. When anchored out, our 12V will be primarily used for house lights (minimal), the vacuflush heads, the freshwater pump, and Starlink.

The initial plan was to use four 160-watt panels in a 2S 2P config, feeding a Victron 100/50 MPPT Smart controller feeding the Inverter Bank only and letting that charge the rest of the batteries through the engine room isolator. This solves everything and even allows the solar to help keep the genny battery topped off.

However, I'm wondering if this will present the same issue I have with the Xantrex now, where it only monitors the Inverter Bank and once that's fully-charged, it goes into float mode and the charge to the house batteries becomes a trickle charge of around 12.8 volts - I'm not sure that's adequate.

Anyone have any insight or should I take this to one of the Solar forums?

 

[SteveK]

-The red wire between isolators is not needed, perhaps the reason it is not present.
-Not sure why you need an isolator or the 4 way switch from the engine alternators.
-The Xantrex is charging all batteries as long as the switch is on. The way it is drawn, the inverter battery is topping up the other three batteries.
-You said the start batteries feed the house DC loads and the inverter battery only feeds the inverter when not charging.
-The three switches above three batteries are not needed per ABYC, but nice to have.
-Is the black box the MPPT from solar, can't read text.

 

[Bud]

-The red wire between isolators is not needed, perhaps the reason it is not present.
-Not sure why you need an isolator or the 4 way switch from the engine alternators.
-The Xantrex is charging all batteries as long as the switch is on. The way it is drawn, the inverter battery is topping up the other three batteries.
-You said the start batteries feed the house DC loads and the inverter battery only feeds the inverter when not charging.
-The three switches above three batteries are not needed per ABYC, but nice to have.
-Is the black box the MPPT from solar, can't read text.

I think the isolator, that all the batteries are wired to prevents the inverter batteries from discharging into the start batteries and it also prevents the inverter/charger from charging the starter batteries.
Bud

 

[ranger58sb]

The two engine start batteries are isolated 8D FLA units and double as the house batteries, supplying DC voltage to the DC Distribution Panel.

I want to be able to anchor out for extended periods while using the generator as little as possible, so I'd like to add solar to this while changing as little of the original setup as possible. The solar would need to charge both the inverter bank and the start/house batteries. When anchored out, our 12V will be primarily used for house lights (minimal), the vacuflush heads, the freshwater pump, and Starlink.

You might consider completely separating the engine start/house functions, just in case there might be some advantages.

That could let you use smaller start batteries. It might let you move all the DC house loads to the same bank the inverter uses, so your monitor would maybe be in place already. It might simplify your solar charging architecture. Or you may find adding a whole 'nother bank for DC house loads could have some merit, for some reason.

Or not. Just a thought...

FWIW, we have set-up similar to yours, except for no Starlink. We have NOT bothered to mess with re-doing the start/house banks... and when we anchor out, we always have to begin recharging when the inverter bank reaches our selected SOC lower limit. We've never yet had to start the genset because of the start/house banks. I suspect, without having given it too much thought, that adding solar charging directly to our inverter bank only -- i.e. not to the other two banks -- would mean we'd only have to start the generator once every 3-4 (-5?) days.

-Chris

 

[Bmarler]

That could be a whole lot simpler. If it were mine, I’d dump the isolators in favor of charge relays. Dedicate one battery for the start bank, one for house loads, completely isolate the genset from the system except for manual connection.
Aim the solar at the inverter bank with an ACR to the house bank.
If isolators are needed on the engine alternators get a fet isolator so you eliminate the voltage drop. I would prefer a smarter regulation scheme, but I understand why some wouldn’t.

 

[DBG8492]

-The red wire between isolators is not needed, perhaps the reason it is not present.
-Not sure why you need an isolator or the 4 way switch from the engine alternators.
-The Xantrex is charging all batteries as long as the switch is on. The way it is drawn, the inverter battery is topping up the other three batteries.
-You said the start batteries feed the house DC loads and the inverter battery only feeds the inverter when not charging.
-The three switches above three batteries are not needed per ABYC, but nice to have.
-Is the black box the MPPT from solar, can't read text.

Okay, so I realized I messed up creating the Visio from the schematic.

The Guest 2304A switch between the Inverter/Charger is a two-position, three-terminal switch - one input, two outputs. In my case, the input is fed by the Inverter/Charger, and the outputs go to the Inverter Bank and the Engine Room Isolator, respectively. I changed it on the diagram to make that more apparent.

View attachment 163625
As the boat is new to me, I didn't design the system as it exists, so I don't know the "why" behind anything. However, I have tested it to determine that it works and how it works, and will try to answer your questions based on that.

The Engine Room isolator keeps the three start batteries from being parallel to each other while still allowing them to charge from the same source. I have no idea why the isolator in the helm is there, as (according to the original schematic), both alternators attach to the same terminal as the outbound wires feeding the 4-position switch in the disty panel.

The four-position switch allows you to choose which Engine Start battery feeds the house, OR you can parallel them (one, two, both).

The two Engine Start batteries definitely feed the house. If you disconnect them, the house loses DC while the Inverter Bank just sits there. This is confirmed through testing. The Inverter Bank only feeds the AC loads for the Inverter. This was also tested and confirmed by disconnecting shore power while the House/Start Batteries were disconnected. Because the Guest switch is three-pole, I'm guessing that the two outputs on it are isolated - but I'm not 100% sure. But the fact that there was no DC when the House/Start Batteries were disconnected backs up that guess.

The three switches between the alternators/batteries are OEM-installed by the builder. They don't look like the switches in the Visio doc. They're just simple on/off switches in an old box, so I used the on/off stencil in the diagram rather than try to recreate the whole box.

The black panel is the Inverter Disty Panel - I should have labeled it. Nothing having anything to do with the solar is on this diagram - I'm here asking questions because I'm not sure where I should put it, so I figured trying to place it on the diagram would cause more confusion.

I'm not asking how the system works or how to improve on how it's installed right now. I'm asking that, given how it works, where is the best place to feed solar to keep everything charged while having to run the genny as little as humanly possible?

 

[Mac2]

Yesterday was April fools day, so with that in mind…Im thinking the house bank should be charged with the solar.

 

[SteveK]

connect the solar to the inverter battery

 

[SteveK]

Yesterday was April fools day, so with that in mind…Im thinking the house bank should be charged with the solar.

except, the house bank is one of the starter batteries, but the inverter battery feeds AC power. Usually a house battery is what here is referred to as inverter battery. The house DC should come off the inverter called battery and not the start battery. IMO

 

[Mac2]

except, the house bank is one of the strater batteries, but the inverter battery feeds AC power. Usually a house battery is what here is referred to as inverter battery. The house DC should come off the inverter called battery and not the start battery. IMO

Ok. Didn’t see the small print. I considered the inverter batteries the house bank. Solar to inverter batteries.

 

[Delta Riverat]

If it was me, I'd isolate the starter batts to just engine starting. Then combine the generator battery to the inverter bank and call that the house bank. Use the solar to charge the house bank.

Your drawing shows the port alternator charging the starboard batt and likewise.

Not to mention we have the same boats -

I'm doing the solar thing too and I'm wiring the solar to the house bank.

 

[Diep]

I'm not asking how the system works or how to improve on how it's installed right now. I'm asking that, given how it works, where is the best place to feed solar to keep everything charged while having to run the genny as little as humanly possible?

To answer this question we need to know which item forces you to fire the gen first? Inverter bank gets too low and needs charge? Or 12V start banks get too low and need charge?

Strictly speaking that would be your answer. I believe it would be easy to feed an MPPT to the inverter bank. For the starter batteries I don't know if or how that would work but anything is possible.

I get not wanting to make other changes. I don't like house loads coming off the starts and I'm in the process of planning an electrical revamp. Its like an onion once you start reconfiguring things. On the other hand if we need new batteries anyway, its worth it to us to modernize the system.

 

[Mac2]

To answer this question we need to know which item forces you to fire the gen first? Inverter bank gets too low and needs charge? Or 12V start banks get too low and need charge?

Strictly speaking that would be your answer. I believe it would be easy to feed an MPPT to the inverter bank. For the starter batteries I don't know if or how that would work but anything is possible.

I get not wanting to make other changes. I don't like house loads coming off the starts and I'm in the process of planning an electrical revamp. Its like an onion once you start reconfiguring things. On the other hand if we need new batteries anyway, its worth it to us to modernize the system.

The only addition I would add to your comment is that if there is an issue with a starting battery going low, you can add a dc to dc charger from the inverter batteries (hooked to solar) to the start battery(s).

 

[SteveK]

I get not wanting to make other changes. I don't like house loads coming off the starts and I'm in the process of planning an electrical revamp.

I thought more about these two sentences. The first post I made proceded to give opinion, I ignored the title.
IMO, if you should need it, I would start both engines from one 8D and connect the 8D that feeds house with the inverter batts. Make house & inverter bank 3-8D's. Leave one engine ALT charging directly to the 3-8D without isolator.

 

[DBG8492]

except, the house bank is one of the strater batteries, but the inverter battery feeds AC power. Usually a house battery is what here is referred to as inverter battery. The house DC should come off the inverter called battery and not the start battery. IMO

I don't mind the house power coming off the start batteries - it saves space and keeps me from carrying dead lead. The genny battery is independent, and provided it's charged, you can always run the genny to power the charger. You can also jump start from the genny battery. In a real pinch, you could jump from the Inverter bank.

 

[DBG8492]

And for what it's worth, we initially considered self-installing an upgrade to LiFePO4 batteries in a combined House/Inverter config, but our insurance company went off the rails about that. They will only cover the boat if a certified installer does the planning, installation, and certification of the system. Once they said that, we decided to spend the money elsewhere as we plan to leave to start the loop in mid-May, and dealing with that nonsense in that short of a time period simply wasn't in the cards. So all that cash went into a new anchor, chain, bilge pumps, water pump, dinghy, and outboard.

That's why we're not trying to introduce too many changes. The system installed today worked for many years for the previous owner, so no reason to shake things up at this point. If I can add solar, I will be satisfied until we're done with the loop and ready to start making other changes.

 

[Bmarler]

Solid reasoning. Live with it for a while and see where the deficiencies might be.
I find the inverter to be the biggest drain, so it makes the most sense to aim the solar at that bank. It makes a huge difference on genset time. I haven’t needed my genset ar all since adding solar, but I also have a very large house bank and a robust charging system on the main engine.

 

[Iggy]

I don't like the fact that you can not charge the house bank off the engines. You must start the genset. Maybe I am wrong?

There are some good AC load, fridge, freezer.....

They do make some isolators with no voltage drops.

 

[DBG8492]

I don't like the fact that you can not charge the house bank off the engines. You must start the genset. Maybe I am wrong?

There are some good AC load, fridge, freezer.....

They do make some isolators with no voltage drops.

The inverter bank is the one that can't be charged off the engines - and yes, that's odd considering it runs the fridge, freezer, and other stuff that's important, LOL

But like I said, I didn't design it, and I don't think the point of the design was accounting for more than a couple of days on the hook.

And yes, they do - the Argofet from Victron has very little voltage drop, and I'm considering switching them up when I add solar because that's what I am going to use there.

 

[DBG8492]

This is the plan for solar:

It will be totally separate from the rest of the charging system and dedicated to the inverter bank. Once that reaches a certain voltage (TBD), the Orion will kick in and charge the start/house batteries.

Again, the idea isn't to NEVER have to run the generator, it's to limit how often I need to run it if I want to be on the hook for more than a day or two.

It keeps the start/house batteries completely isolated, and it adds full monitoring for every battery used by the house - which is something I don't currently have. The only battery not in the mix is the genny start - I don't see a reason to add it.

Also, this system can easily be added to or changed when I'm ready to redo the charging system.

 

[SteveK]

You sure do up nice layouts easy to read with the Visio.
Did you change batteries from 2-425A FLA to 2-200A LFP

 

[DBG8492]

Yes - I changed it - I can't believe I made that error. But I own it - I screwed up. The TOTAL bank is somewhere around 400 Ah.

And thank you - being a network engineer for most of my adult life has paid a few dividends. At least here I don't have to do them in crayon like I used to for the C-Level meetings.

 

[Diep]

Looking good. Is it possible to stack another Orion on the system? Depending on your alternator capability you could tune them and get some more amps out of the mains. Might not be needed with the solar.

 

[Mac2]

Hard to tell distances in the drawing. Consider a on/off switch between battery and inverter and a breaker before the mppt (not sure how quick you can disconnect your solar).

 

[DBG8492]

There's about 3 feet of cable between the Inverter Bank and the inverter - it's protected by a 300A fuse, and there's a Guest on/off switch between the Inverter and ALL of the batteries.

And yes, I should probably add a switch between the panels and the MPPT. Good call.

 

[DBG8492]

Looking good. Is it possible to stack another Orion on the system? Depending on your alternator capability you could tune them and get some more amps out of the mains. Might not be needed with the solar.

Also a good idea - but I am going to start here and see what develops.

The first thing I'm likely to change is the current diode isolators for Argofets, depending on the real-world performance of the one I'm adding for solar. Everything I've read says they're better, but I'm a "see for myself" type.

 

[dutch-barge]

the Xantrax. (Hope you have good nerves keeping it ) only charges when on shore power and will charge at the same time the solar panels also charge

The Victron 100/50 MPPT Smart controller will charge just as the Victron inverters do , bulk, float etc. IF you had a Victron inverter/charger. You can program the onverter/charger to ONLY charge is the SOC is below a set % and have the solar panels do the charging for free

 

[Flatswing]

Okay, so I realized I messed up creating the Visio from the schematic.

The Guest 2304A switch between the Inverter/Charger is a two-position, three-terminal switch - one input, two outputs. In my case, the input is fed by the Inverter/Charger, and the outputs go to the Inverter Bank and the Engine Room Isolator, respectively. I changed it on the diagram to make that more apparent.

View attachment 163625
As the boat is new to me, I didn't design the system as it exists, so I don't know the "why" behind anything. However, I have tested it to determine that it works and how it works, and will try to answer your questions based on that.

The Engine Room isolator keeps the three start batteries from being parallel to each other while still allowing them to charge from the same source. I have no idea why the isolator in the helm is there, as (according to the original schematic), both alternators attach to the same terminal as the outbound wires feeding the 4-position switch in the disty panel.

The four-position switch allows you to choose which Engine Start battery feeds the house, OR you can parallel them (one, two, both).

The two Engine Start batteries definitely feed the house. If you disconnect them, the house loses DC while the Inverter Bank just sits there. This is confirmed through testing. The Inverter Bank only feeds the AC loads for the Inverter. This was also tested and confirmed by disconnecting shore power while the House/Start Batteries were disconnected. Because the Guest switch is three-pole, I'm guessing that the two outputs on it are isolated - but I'm not 100% sure. But the fact that there was no DC when the House/Start Batteries were disconnected backs up that guess.

The three switches between the alternators/batteries are OEM-installed by the builder. They don't look like the switches in the Visio doc. They're just simple on/off switches in an old box, so I used the on/off stencil in the diagram rather than try to recreate the whole box.

The black panel is the Inverter Disty Panel - I should have labeled it. Nothing having anything to do with the solar is on this diagram - I'm here asking questions because I'm not sure where I should put it, so I figured trying to place it on the diagram would cause more confusion.

I'm not asking how the system works or how to improve on how it's installed right now. I'm asking that, given how it works, where is the best place to feed solar to keep everything charged while having to run the genny as little as humanly possible?

I get why no one wants to run the generator. Noise cost etc. My feeling on that was most generators die from lack of use & maintenance. So despite having a 1200 Ahr combined, house/inverter bank, I happily ran the generator for a short while (30-40minutes) daily On the hook in the Bahamas-cooled the boat with AC, helped bulk charge the FLA house/inverter bank at the end of the day via inverter charger (small solar, couldn’t meet all demands on the hook).
I dedicated one start battery to starting - charged by Pt alternator, combined the other engine start with the house/inverter bank-charged by STBD engines alternator. Manual combiner switch as well as an ACR between start & house/inverter, no isolators since start battery is usually fully charged within 1/2hr of running and both alternators seem to work together fine without a centerfielder.
I preferred to wire the genset battery so it was not connected to house/start/inverter batteries in any way. Carried jumper cables in case of unexpected emergencies.
Being cheap, this allowed use of inexpensive FLA high CCA start batteries for main & genset start, with FLA GC2/L16 scrubber batteries for house/inverter. Each battery is then optimized for the needed function. $200 for a watering system. Inexpensive redundancy & reliability allows anchoring in isolated places.

 

[DBG8492]

I get why no one wants to run the generator. Noise cost etc. My feeling on that was most generators die from lack of use & maintenance. So despite having a 1200 Ahr combined, house/inverter bank, I happily ran the generator for a short while (30-40minutes) daily On the hook in the Bahamas-cooled the boat with AC, helped bulk charge the FLA house/inverter bank at the end of the day via inverter charger (small solar, couldn’t meet all demands on the hook).
I dedicated one start battery to starting - charged by Pt alternator, combined the other engine start with the house/inverter bank-charged by STBD engines alternator. Manual combiner switch as well as an ACR between start & house/inverter, no isolators since start battery is usually fully charged within 1/2hr of running and both alternators seem to work together fine without a centerfielder.
I preferred to wire the genset battery so it was not connected to house/start/inverter batteries in any way. Carried jumper cables in case of unexpected emergencies.
Being cheap, this allowed use of inexpensive FLA high CCA start batteries for main & genset start, with FLA GC2/L16 scrubber batteries for house/inverter. Each battery is then optimized for the needed function. $200 for a watering system. Inexpensive redundancy & reliability allows anchoring in isolated places.

It's not me who doesn't want to run the genny - it's the Admiral. I'm perfectly happy running it as much as possible, as I want to be comfortable. The Admiral is worried about disturbing folks in anchorages.

I get that - and I'm not going to pull up and drop anchor right next to someone and crank it up, but if I'm a reasonable distance away, and the night calls for AC when sleeping, then I'm running the genny. I didn't buy a boat with AC to act like it's not there.

 

[Mambo42]

I had the same reasons for changing to solar, but for me there was also the reason I don't want to sleep with a running generator. Some people don't care and have the generator running while they sleep, for me that is a no no.
The set up I have is a house bank of 1400 Ah of LiFePO4 which can be charged via the generator, the alternators, shore power or via solar.
The start batteries are being charged via their own alternators or via the Victron charger which gets its power from the house bank through the inverter.
The solar panels run through MPPT controllers into a bus bar and then via the Victron Quattro to the batteries.
During the summer and even already now during sunny days I don't need the generator at all. The solar panels are more than enough to bring the batteries back to 100 % every day. Just to keep the generator alive I run it every 2 or 3 weeks for about half an hour. That is more than enough to keep it healthy.
As for the AC. I can run the AC through the night off the house bank without a problem. I don't have a central AC system, I have 3 separate AC's, which use about 40 Amps each, so at night I only have the one in the room where we sleep. Per hour that comes down to about 15 - 20 Amps and over 8 hours that is just 160 Amps, which I have without a problem. If I would have a central AC throughout the whole boat it would become a different story, I guess it would be impossible to run the AC all night off the batteries.