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Solar kit for boat

  • 04-05-2020 3:21pm
    #1
    Registered Users Posts: 196 ✭✭ daveville30


    Hi I have a boat and want to install a solar panel to keep the batterys topped up.ive 2 12v batterys linked together to give 24v to the starter.ive seen a few kits on e bay with a charge controller what size kit and would it need to be a 24v solar panel?


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Comments

  • Posts: 0 [Deleted User]


    ~300W domestic panel 60Cell far better value for money than weekend warrior little panels.

    Morningstar PWM charge controller will out run any other MPPT with a 60 cell (~32Vmp) to 24v configuration.

    Here's one I made earlier (well that's MPPT because it was a good deal)

    SZI7bUr.jpg


  • Registered Users Posts: 196 ✭✭ daveville30


    ~300W domestic panel 60Cell far better value for money than weekend warrior little panels.

    Morningstar PWM charge controller will out run any other MPPT with a 60 cell (~32Voc) to 24v configuration.

    Here's one I made earlier (well that's MPPT because it was a good deal)

    SZI7bUr.jpg
    I'm not hoping to run things just keep them topped up.i dont really understand what my requirements would be. the solar panels are in watts and the charge controllers are in amps.would a 50 watt panel and 30 amp controller be ok for 24v batteries?


  • Posts: 0 [Deleted User]


    Sure but a 50W, "12 volt" panel is almost €100 and not very efficient (cell to battery voltage mismatch link).

    A 300W panel for a house is perfect for 24V is ~€120.

    Pictured system doesn't run anything either. It's just for maintenance/storage.


  • Registered Users Posts: 1,097 ✭✭✭ freddyuk


    As the batteries will be fully charged when you leave the boat all you need is a trickle charge. I use a 30watt panel which sits nicely on the radar arch and is unobtrusive. 2 of these would give you 24v. No point in a whopping great 300w panel for this purpose.?? A decent PWM controller rated at 5 or 10 amps is more than enough and easy to come by.


  • Posts: 0 [Deleted User]


    If it costs pretty much the same why not have 10x the power?

    If you click on the link you're advising to invest in a panel that's 17% redundant or 2 x 30W = 50W PWM.
    1 x 60 cell at 24v PWM = all usable cells with just enough overhead for installation losses.

    Shore power is expensive and diesel is worse outtov port.

    There is only one genuine manufacturer of solar charge controllers. Specific gravity is quite the teller.


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  • Registered Users Posts: 196 ✭✭ daveville30


    freddyuk wrote: »
    As the batteries will be fully charged when you leave the boat all you need is a trickle charge. I use a 30watt panel which sits nicely on the radar arch and is unobtrusive. 2 of these would give you 24v. No point in a whopping great 300w panel for this purpose.?? A decent PWM controller rated at 5 or 10 amps is more than enough and easy to come by.
    I'd rather 1 panel or could I hook up to one battery that should charge the other one?I'm thinking of a 50 or 70 watt panel


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,818 CMod ✭✭✭✭ unkel


    I'm with Sir Liamalot on this. If you have the space and you don't mind a fixed (non flexible) panel, get a full size 300W panel. Far, far cheaper per watt than anything else and you could even just connect it via a €10 controller to your two 12V batteries in series for a very cheap system. Full size panels also hold their value well if you buy it cheaply, so if you decide to sell it on at a later date, you will have lost very little

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 196 ✭✭ daveville30


    unkel wrote: »
    I'm with Sir Liamalot on this. If you have the space and you don't mind a fixed (non flexible) panel, get a full size 300W panel. Far, far cheaper per watt than anything else and you could even just connect it via a €10 controller to your two 12V batteries in series for a very cheap system. Full size panels also hold their value well if you buy it cheaply, so if you decide to sell it on at a later date, you will have lost very little
    If I'm only trickle charging the batterys would a 300w not be to much where would the extra power go to.im not to clued up on solar


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,818 CMod ✭✭✭✭ unkel


    The "extra power" would go nowhere. The charge controller will not let the battery go over a certain voltage. The good thing with a big panel too, is that you can double your batteries to 4 of them. Even 8 of them. And the big panel will easily keep them topped up all year, even in winter.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Posts: 0 [Deleted User]


    Doesn't have to be 300Wp that's just where the market is at.
    60cell panel ~32Vmp is ideal.
    I have a 240Wp flavours...bit old now


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  • Registered Users Posts: 1,097 ✭✭✭ freddyuk


    I'm going to ask what size boat are we talking about? Does it have the space for a 300w panel?


  • Posts: 0 [Deleted User]


    Arah sher they work outboard or even hinged off the hull. Oil rigs put them vertically to keep the bird poo off them and they capture photons reflected off the water.
    If it was 300 watt one could lose 50% efficiency and still get better watt per € than 2 x 80w "12 volt" jobbers

    a 60cell 250W has the equivalent power of 2 x 150Ws 36 cells on PWM in a ~20% smaller package


  • Registered Users Posts: 196 ✭✭ daveville30


    28 ft boat I could put a panel on top of the wheelhouse but I dont want to take all the space up the mast is there aswell


  • Posts: 0 [Deleted User]


    Avoid shadows.

    When I'm fitting sailboats and the client needs 300Wp I fit 600Wp; 2 x 300Wp, one either side of the prevailing shade on individual controllers.


  • Registered Users Posts: 8,287 ✭✭✭ n97 mini


    In the depths of winter (when you're not using your boat) don't forget the output from a solar panel will be severely limited. i.e. get the 300w panel!


  • Registered Users Posts: 196 ✭✭ daveville30


    I'll still be doing the same routine in the winter go down every couple of days start her up to charge the batterys.id like to be able to leave her a week though and have full charge on them


  • Registered Users Posts: 1,097 ✭✭✭ freddyuk


    So there you go..... a 300wp panel is nuts for you. I have a 8m boat now (but cannot get to it) and have fitted a 150wp panel onto the "house" battery as I am a solar nut and it was available. It takes up roof space which is supposed to be for sunbathing (ha, ha) but is more than enough. It clips on the roof rails so can be easily removed for cleaning etc. The engine battery is sitting there quite happy for some weeks but can be charged from the mains if required. Good batteries will not die after a few weeks if there is no load on them. In fact to keep Lead Acid batteries long term they need a mains charge regularly but solar can never do this so its a compromise.
    At home, then the more solar panels the better as the loads are far higher and surplus is rare but not on a boat it is wasted and intrusive. Space is at a premium so design a system that works for your boat not slap on the biggest solar panel possible based on the home based system as you will not be able to store the power. If you are living aboard then more the merrier.... the fridge will need 100w + alone.


  • Posts: 0 [Deleted User]


    freddyuk wrote: »
    In fact to keep Lead Acid batteries long term they need a mains charge regularly but solar can never do this so its a compromise.


    How odd. Living full time in a vehicle for a decade I've found the inverse to be true.
    If defining fully charged as 1.275 SG


    I guess I must be doing it wrong.



    I wouldn't advise abandoning batteries to their own devices without input.


    It's not about panel size, it's about not getting ripped off.
    Last time I checked a 150W panel was €200 and a 300W panel was €120.


    Why pay more for less?


  • Registered Users Posts: 1,097 ✭✭✭ freddyuk


    I have lots of time for you but a boat is different. Space is a premium. If you just go out and do some fishing for the day then you will not be using much battery power and when you get back the battery/ies are fully charged so just need a trickle until next time you go out. A van roof is dead space but a boat roof is possibly multi use so having it taken up with a solar panel which will be in "potential" for much of the time is not great efficiency. A house roof is 100% dead space so fill your boots there as it will not matter.I feel the OP is looking for a solution that does not need overkill.
    But yes as regards solar in general get as much as you can .... I totally agree.


  • Posts: 0 [Deleted User]


    Same goes Freddy. And I you.

    Merlin Smartbank £20 best split charge relay driver you can get. It'll add years your engine battery life through your already fitted solar.

    Domestic panels are dominating 2 x 12volters...price and performance. hang 'em off the stern, ballast to the deck when ashore...I just don't understand why pay a premium for a small output. Plenty of power to feed efficiency losses put them in the hold when underway if they're fouling the rigging.

    09.webp

    solara-power-m-ez-mount-mark-gilg-sv-tarok-4.jpg

    solara-power-m-ez-mount-folded.jpg

    solara-power-m-ez-mount-undershot.jpg

    If you need the power; double up, you can't have the same shadow both sides of the vessel.


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  • Posts: 0 [Deleted User]


    And yes I know they're all 12 volt panels in photos :o
    That's what I mean by outboard...mechanical principles are transferable.


  • Registered Users Posts: 196 ✭✭ daveville30


    I'm still none the wiser I cant have a big panel I need something for on top of wheelhouse.if I buy a 50 or 70 watt panel would it need to be 24volt or are they all 12v panels


  • Registered Users Posts: 196 ✭✭ daveville30


    I'm still none the wiser I cant have a big panel I need something for on top of wheelhouse.if I buy a 50 or 70 watt panel would it need to be 24volt or are they all 12v panels


  • Registered Users Posts: 6,376 ✭✭✭ Alkers


    Same goes Freddy. And I you.

    Merlin Smartbank £20 best split charge relay driver you can get. It'll add years your engine battery life through your already fitted solar.

    Domestic panels are dominating 2 x 12volters...price and performance. hang 'em off the stern, ballast to the deck when ashore...I just don't understand why pay a premium for a small output. Plenty of power to feed efficiency losses put them in the hold when underway if they're fouling the rigging.

    09.webp

    solara-power-m-ez-mount-mark-gilg-sv-tarok-4.jpg

    solara-power-m-ez-mount-folded.jpg

    solara-power-m-ez-mount-undershot.jpg

    If you need the power; double up, you can't have the same shadow both sides of the vessel.


    That's all well and good for a cruiser or sheltered sailing but that panel is going to take a battering offshore and cause some serious windage if racing.

    Maybe a thin or flexible panel would fit without getting in the way, admittedly will be higher price per W but you only need as much as you need ! Can you post a pic op?


  • Registered Users Posts: 196 ✭✭ daveville30


    Same boat and mast set up as mine. Only I have liferings epirb ect


  • Posts: 0 [Deleted User]


    Flexible panels aren't UV stable...mad isn't it. 3-7 year lifespan depending on brand. Twice the cost.


  • Posts: 0 [Deleted User]


    I need something for on top of wheelhouse.if I buy a 50 or 70 watt panel would it need to be 24volt or are they all 12v panels


    You need at least 60 series solar cells to charge 24v.


    The small ones are usually 36 cell. These are called 12v but they're more suitable for 16v.


  • Registered Users Posts: 196 ✭✭ daveville30


    60 cells per panel?


  • Posts: 0 [Deleted User]


    It doesn't matter if it's one or two panels as long as there's 60 or more cells.


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  • Registered Users Posts: 196 ✭✭ daveville30


    Thanks.them charge controllers come in different amps 10 20 ect what would you recommend for 24v


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