Comments on Boat Setup

SVNeko
SVNeko Registered Users Posts: 5 ✭
in Solar Beginners Corner #1
Hi all, I am a newbie here setting up a solar system on our boat. I found this forum and it is fantastic; full of great advice by experienced people. The equivalent forum for boaters is Cruisersforum.com. There are many subforums there, and the ones on electrical systems are full of posts about PV charging systems. Cruising boats are essentially small off-grid cottages that live off a large battery bank and multiple ways to restore power to them. There are some fairly knowledgeable folks there as well.

In our case, we have 2 engines with high output alternators through regulators (a catamaran, it has engines in the end of each hull), a 3.5kw generator through an 80a charger, (currently) a single 180W panel through an old PWM controller and, when we are in a marina, shore power through a 100a (when on 110/60) or 80a (when on 220/50) chargers. We have an 800ah gel cell battery bank. All this is monitored through a Mastervolt battery monitor. Running these diesel engines is not ideal and the 180w panel does not do much to restore the 200 - 250ah daily draw we put on the batteries. So I am installing a better PV system and would not mind comments from the experts here.

This will be 3 Sanyo HIT 240S panels installed on davits on the aft end of the boat. They have a Vpm of 43.7, Ipm of 5.51, Voc of 52.4. This is about 30' from the battery bank. So they will be wired in series to utilize less and smaller wiring, and a single controller. Space for installations is at a bit of a premium. I plan to install a Midnite Classic 200 near the batteries to control the output. So, with that said:

1. Comments or advice generally on the setup?

2. I am clueless about integration with the existing charging and monitoring systems. The existing monitor will tell me SOC of the batteries, current in and out, ah used, etc. But is there anything I should be thinking about in terms of integration?

3. What is the best way to "turn off" the panels when not needed? If disconnected, what happens to the current they produce? I plan to handle this with breakers. I have read that the breakers can/should be near the controller. I have always understood that it is a bad idea to have an unprotected wire run before the breakers, which would mean breakers as close to the PV output as possible. Am I wrong about this?

Cheers,
Pete
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  • mtdoc
    mtdoc Solar Expert Posts: 600 ✭✭
    #2
    Re: Comments on Boat Setup
    SVNeko wrote: »
    This will be 3 Sanyo HIT 240S panels installed on davits on the aft end of the boat. They have a Vpm of 43.7, Ipm of 5.51, Voc of 52.4. This is about 30' from the battery bank. So they will be wired in series to utilize less and smaller wiring, and a single controller. Space for installations is at a bit of a premium. I plan to install a Midnite Classic 200 near the batteries to control the output. So, with that said:

    1. Comments or advice generally on the setup?

    2. I am clueless about integration with the existing charging and monitoring systems. The existing monitor will tell me SOC of the batteries, current in and out, ah used, etc. But is there anything I should be thinking about in terms of integration?

    Good choice of CC. The Midnite Classic will give you some monitoring options- both on the CC LCD and via ethernet connection/router with software (currently via their "Local App" though this is evolving).
    3. What is the best way to "turn off" the panels when not needed? If disconnected, what happens to the current they produce? I plan to handle this with breakers. I have read that the breakers can/should be near the controller. I have always understood that it is a bad idea to have an unprotected wire run before the breakers, which would mean breakers as close to the PV output as possible. Am I wrong about this?

    No need to "turn off" the panels. When the batteries are full the CC will do it for you - no or little current will be flowing. Assuming the wiring is not exposed (and it shouldn't be) I don't think the breaker needs to be before the wire run from panel to the CC (others may feel differently). It is convenient to have a breaker for the PV input and battery input to the CC near the CC. Midnites "Baby Box" with 2 of their Din mount DC breakers works well for this in a small package. It is not designed to be exposed to the elements and would need to be inside -ideally next to the CC. With one series string - no PV combiner box is needed and the one breaker near the CC should be sufficient.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Comments on Boat Setup

    Welcome to the forum Pete.

    Working backwards through the questions ....

    Panels do not produce any current if they aren't connected to a circuit. No power source can. There is no harm in just disconnecting them, nor is there any value in doing so. Let the charge controller do its job.

    What you do for circuit protection depends a lot on what the circuit is. You plan on wiring all three panels in series (they are all in the same location and not subject to shading?) so really no breaker or fuse is required: the wiring to the controller should be sufficiently sized to handle the panel Isc, and they won't produce more than that. You can put a disconnect near the charge controller if you want. Fuses/breaker protect against over-current, and it does not matter (electrically) where in the circuit they are placed. They are typically near the power source for practical reasons, one of which is to prevent there being unprotected wiring with current potential on it. This is usually not a problem with PV's. When you have more than two in parallel, however, it is important to have a fuse on each before the outputs are combined.

    If your existing monitoring system uses a shunt (probably on the negative side of the battery) then the solar would be connected on the same side of that as all other charge sources. That way the monitor will keep track of power coming from panels the same as from the alternators or shore power charger et cetera. You really need to understand the wiring you've already got to figure out where this is.

    What you've got now works except the small PV, right? You probably want to remove that as it will be quite redundant with 720 Watts of Sanyo panels up. On an MPPT controller like the Classic they should produce about 46 Amps on a 12 Volt system. For complete charging this will be low on 800 Amp hours of battery (about 5% - the minimum recommended rate) but it should do well against your daily usage.
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  • mtdoc
    mtdoc Solar Expert Posts: 600 ✭✭
    #4
    Re: Comments on Boat Setup
    Cariboocoot wrote: »

    What you do for circuit protection depends a lot on what the circuit is. You plan on wiring all three panels in series (they are all in the same location and not subject to shading?) so really no breaker or fuse is required

    Good point! No circuit protection required in this case. It is convenient though to have a way to disconnect PV power from the CC. DC breakers work well for that.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Comments on Boat Setup
    mtdoc wrote: »
    Good point! No circuit protection required in this case. It is convenient though to have a way to disconnect PV power from the CC. DC breakers work well for that.

    Yes, but it will take a good one to handle the Voltage of those three panels in series: the Voc will be over 150.
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  • mtdoc
    mtdoc Solar Expert Posts: 600 ✭✭
    #6
    Re: Comments on Boat Setup
    Cariboocoot wrote: »
    Yes, but it will take a good one to handle the Voltage of those three panels in series: the Voc will be over 150.

    Yep. The midnite MNEPV breakers come in 150V and 300V rated flavors. The 150V version would probably be ok but the 300v would be a safer bet.
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  • SVNeko
    SVNeko Registered Users Posts: 5 ✭
    #7
    Re: Comments on Boat Setup

    Thanks for the feedback, guys, and for the good recommendation for a breaker. To be sure I understand, you are saying that I don't really need a breaker because if I size the wire correctly, there cannot be an overload because the maximum PV output is known. This makes sense to me, but I think I will put one in anyway. I understood that the controller will cease putting power through if there is no load, it just struck me as a little odd that I would have this system capable of putting out so much power and not have a way to manually shut it down. Also, was thinking about how to take one panel out of service, or the like, if need be. I think the breakers will do the trick.

    About integration, yes my monitor has a shunt as the first thing off the negative terminals, and I will wire the controller in after it as well, so it will monitor the controller's activities as well. What I don't understand so much is whether the various charging sources will play well with each other when engaged.

    Cariboocoot, you mentioned something about shading in series wiring. I was under the impression that with blocking and bypass diodes, partial shading of one panel would not affect other panels wired in series. Am I wrong about this? Testing done by sailors on the site I mentioned showed little difference between series and parallel with controlled shading, at least so much so to let them argue for pages and pages about the data.

    Finally, a sniff test for you. Does 8WG wiring for this array in series running 30 feet from the panels to the controller sound about right? I am having difficulty getting precise with the various calculators out there.

    Cheers,
    Pete
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
    Re: Comments on Boat Setup

    Multiple charge sources usually don't create much of a problem, other than disagreeing on what the actual battery Voltage is and what the correct set points will be. As a rule the one with the highest Voltage "wins". In this case the MidNite can be programmed to "play well with others" so it isn't going to be much of an issue.

    Blocking diodes: there shouldn't be any. Pretty rare when you need any in fact.

    Bypass diodes do help with shading issues, but .... shading is a highly variable thing. Knocking out part of a panel and dropping its Voltage isn't an issue, knocking out a whole panel and dropping its current can be. In that respect panels in parallel will have less issues with current differences due to shading than panels in series. Not all panels are the same, either. On a boat the shading will not be consistent as it is with a fixed install, so trying to plan around it may be utterly futile. If the panels are in about the same location (all together) they should function fairly well. The odd dark line from rigging will be a momentary thing and won't affect the over-all daily performance much.

    Quick check of the wire sizing. Your Voltage is high, your current is low: the V-drop shouldn't be an issue. Imp is about 6, Voltage near 120, distance 30 feet, wire size 8 AWG: V-drop about 0.2 Volts, 0.2 %. You could go down to 20 AWG and be just over 3%. Me, I'd go with 10 AWG - same as the panel leads. That would still be like 0.3% drop. Can't ask for better.
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  • SVNeko
    SVNeko Registered Users Posts: 5 ✭
    #9
    Re: Comments on Boat Setup

    Thanks. This is all a big help. I am close to completing the system design, but would appreciate a little more help. I am planning to include breakers between the panels and the CC and between the CC and the batteries. Based on the parameters in the above posts, does this make sense? 15A/150V DC breaker (http://www.solar-electric.com/mnepv.html) after panels. 80A/48V breaker (http://www.solar-electric.com/mr60ampdccib.html) after CC?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Comments on Boat Setup

    The breaker on the PV will be acting only as a disconnect because there will be such a small amount of current there. There will, however, be a fairly large Voltage potential. What's worse is that potential will be at its maximum when you try to connect/disconnect (Voc). Should you risk a 150 Volt rated 'switch' on 150+ Volts Voc? How good are you at remembering to cover at least one panel before turning it on or off?

    The breaker for the charge controller will work fine, unless it is a 48 Volt system. "48 Volts" is its maximum recommended operating Voltage, and a 48 Volt system will easily run 12 Volts higher than that. Should be fine of 24 or 12 Volt system.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #11
    Re: Comments on Boat Setup
    SVNeko wrote: »
    In our case, we have 2 engines with high output alternators through regulators (a catamaran, it has engines in the end of each hull), a 3.5kw generator through an 80a charger, (currently) a single 180W panel through an old PWM controller and, when we are in a marina, shore power through a 100a (when on 110/60) or 80a (when on 220/50) chargers. We have an 800ah gel cell battery bank. All this is monitored through a Mastervolt battery monitor. Running these diesel engines is not ideal and the 180w panel does not do much to restore the 200 - 250ah daily draw we put on the batteries.

    Is your boat all totally DC? All the electrical systems in our boat, except for starting and monitoring systems for the propulsion engines and generator, are 120/240V AC. Our battery bank is 24V but all it runs is the inverter. We put 1.5 kW (six 250W panels) on our boat so we don't have to run the generator constantly if we're anchored off-shore.

    But I was wondering if this is for an inverter system or if the boat is all DC? It's hard to imagine a live-aboard boat will all DC power, especially 12V, but I suppose it's possible.

    I didn't even install a charge controller for the solar panels. I just put in a 6 breaker combiner. I got ~30 Vmp panels and they barely make 28 volts when they're hot. The charge spec for our batteries (Interstate UL16's, 6V) is 28.8 bulk, 31.0 absorb. So the solar is basically a 1,100 watt battery maintainer. When the boat is moored in its slip we don't hook up to shore power. I flip off five breakers and leave one panel operating, which basically keeps the battery bank charged, but never quite gets it to float voltage.
    --
    Chris
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  • SVNeko
    SVNeko Registered Users Posts: 5 ✭
    #12
    Re: Comments on Boat Setup

    Hi Chris, this boat is mostly DC. Most boats that I am aware of, at least sailboats, run a lot of 12V appliances and items - for us lighting, refrigeration, pumps, etc. are all 12Vdc. We do have 220/50 and 110/60 AC generation and distribution, but that is pretty much limited to battery charging, washer/dryer, water heater and pass-through to cabin outlets. We plug a few AC things in, but most installed items are DC.
    Pete
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #13
    Re: Comments on Boat Setup

    Cool. I had though most larger boats over 50 feet had pretty much gone to all AC. The DC system in our boat is very limited and just about everything is AC except for nav/docking lights, one small 24V bilge pump (the big one is 240V), and one light in the head and one in each stateroom. And, of course, 24VDC power to the pilothouse from the house batteries.

    I should mention that we don't take our boat out very much at this point because it's got two old run-out 6-71 Detroits in it that don't have enough power to even get it out of the hole. The last time we had it out the blower shaft busted on the port engine and it quit. I got a pair of brand new 3406 Cats sitting in my shop on skids and those are going in it this next winter. We've been gradually updating and upgrading stuff in it because one of these years, when we get it done, we're sailing it down to the Caribbean for the winter. We bought the boat really cheap. But buying it was the cheapest thing we've done to it so far :cry:
    --
    Chris
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  • Panamretiree
    Panamretiree Solar Expert Posts: 278 ✭✭
    #14
    Re: Comments on Boat Setup
    ChrisOlson wrote: »
    We've been gradually updating and upgrading stuff in it because one of these years, when we get it done, we're sailing it down to the Caribbean for the winter. We bought the boat really cheap. But buying it was the cheapest thing we've done to it so far :cry:
    --
    Chris

    Chris

    Had some friends that did the Great Loop a few years back. His few comments on the trip besides that it was great was that he would have a pilot house style boat, big diesels (his 38 foot Bayliner had the small Hino diesels), and he would install/have bow and stern thrusters. This last point was that thrusters in tight quarters and with wind are cheap insurance, especially if you have a fairly good sail area. Arlene and I talked about this as well and considering she did most of the dock work, we would have installed them if we had kept the boat, makes it easier on her when leaving and coming back in. Twin engines are great, but don't always make leaving and coming in that easy. Sidepower has a new set of bolt on thrusters that look quite good.

    JMHO.

    Cheers

    Ernest
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #15
    Re: Comments on Boat Setup

    Our boat is a 58 foot motor yacht. The pilot house is fully enclosed with both heat and air conditioning. We just gone done installing a new Ray Marine electronics package in it with autopilot, radar, new radios, nav gear and satellite. We will be putting in bow and stern thrusters when we install the new Cat diesels this coming winter. We were told that slips in the Caribbean are pretty tight and without the thrusters it's almost impossible to dock a boat our size.

    The old Detroits in it are 238's and they'll only push it at about 8 knots. The Cats are six and a quarter 3406's, so going from 450hp to 1,200hp will make a big difference. The boat originally had 450 Crusaders in it and is supposed to cruise on plane at 12 knots. But nobody can afford the fuel bill on those old big block gas V-8's anymore so the Detroits were put in it about 10 years before we bought it.
    --
    Chris
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  • Panamretiree
    Panamretiree Solar Expert Posts: 278 ✭✭
    #16
    Re: Comments on Boat Setup

    Used the integrated navigation package last year on the 50 ft Maple Leaf, great piece of kit, makes voyaging more civilized. Also had the AIS receiver as well. Lots of fish boats use it as do smaller boats, great addition as well and reasonably priced. Smallest boat we picked up was a 30 foot sailboat off the Oregon coast as we pulled into the Juan de Fuca Straight, we were curious why such a small boat had an AIS transceiver, but probably came with the nav package.

    Cheers

    Ernest
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