Basic assistance for PV on Boat Dock

System
System Posts: 2,511 admin
in Solar Beginners Corner #1
I am trying to put a PV system on an existing floating boat dock on Lake Travis in Texas. The dock is wired for AC complete with Breaker Box and conduit.

I am looking to power an electric boat lift motor (3 lifts per day max at weekends only, each lift last 3 minutes ), motor reads 12.0/6.0 amps.
a couple of fishing lights (4-6 hrs per night). Somewhere between 75 - 200Watts each.
A couple of general purpose lights all night for safety. (Can use fluorescent)

Quite happy to be overpowered Understand I will need a pure sine inverter for the motor. Where do I start with calcs for size of panel(s), number size of batteries and size of charger/inverter.

I have hit a lot of sites but am easily confused and my abacus is sticking.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: Basic assistance for PV on Boat Dock

    steve,
    i could break it down for you, but you will need to settle on the wattages and times needed. this depends on you if you want to list the highest wattges and the longest times running or average it. those lights are what will kill most of your power and having them incandescent does not yield any power savings, but i partially understand why due to the application. are you looking to replace all of the 120vac on the dock with pv and why?
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: Basic assistance for PV on Boat Dock

    Thanks niel,
    The dock is wired but not connected to grid so i am not replacing simply taking an alternate route. I would have to run several hundred feet of cable to connect the dock. Also the lake is not constant level and the dock moves needs to move up/down so one less thing to worry about is fine.

    I thought the motor might be the killer. I am researching more effiecient/effective fishing light but currently have 200W ready to go. So from a calc standpoint need them for 6 hours per night.

    I ran some calcs on what I thought I had learned and arrived at a need for 450a/h per day. Close you think?
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    Re: Basic assistance for PV on Boat Dock

    Fishing light - do you need a single bright light to ATTRACT fish, or do you want to illuminate a wide area so folks don't snag themselves ?

    If you need that much light, consider LED's, which will consume less of your expensive power, and needs less battery.

    LED's are also avaib encapsulated, and could be submerged, like a swimming pool light, and you will get more light into the water, rather than reflected off the top surface.

    How "critical" are your loads ? Must they be 365 days/year, or if you have bad weather, will the site be "unused" and no loads applied ? Rule of thumb is to have 3 days bad weather battery storage, but thats for a house with kids and fridges in it. If you have a cloudy day, and clear night, will it need be in use, or if batteries are low, can you skip using it that night?

    Boat lift motor, I don't understand the spec you listed
    > 12.0/6.0 amps
    12A start, 6 run ? 12A @ 12V / 6A @ 24V ? amps without voltage, is only half the needed info.

    Motors generally pull power as they are loaded, more load, more draw. Is this amp # an average, or true peak?

    Lets play with a 24V system, and consider 48V too.
    (higher voltage, less amps drawn = less loss in wires)
    200W @ 24V = 8.33A
    8.33 x 6 hr = 50AH consumed.
    50% battery drain means you need 100A size battery, so 2, group 27 size batteries in series, would run the light.
    To charge it, wintertime, only counting on 5 charging hours / day (just a wild guess, you may get better sun) you will need to harvest 60A (recharge losses) into the batteries, in 5 hours. In a 24V system, recharge voltage is near 29V .
    60A / 5 = 12A @ 29V = 348W 348 x 1.3 (PV only puts out about 70 - 80% of nameplate in real life, just like the EPA car mileage) = 452W of PV panels to run 1, 200W light for 6 hours.
    Add in the price of mounts, batteries, charge controller, timers, and you are quickly up to $5K For 1 light.
    How much does it cost to did the trench ?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
    Re: Basic assistance for PV on Boat Dock

    steve,
    just so you understand, if the 12.0/6.0a means it draws even 12a that you will only use it 9 minutes a day. i am going to assume 12v operation on it so 12v x 12a = 144w. to reference to watthours or wh we see 9min/60min(1hr)=.15 and multiply this by the 144w and that gives us 21.6wh for the lift.
    now taking 1 200w light and running it for 6hrs gives us 6hrs x 200w = 1200wh/day or 1.2kwh/day. to apply this to pv one needs to divide the total power needed by the number of full sun hours(1000w/^2) you receive per day. if that is 5 then 1200wh/5hrs=240w needed. to provide this all losses must be accounted for and that could be 25-40% more making it roughly 300-336w in pv needed to provide that power for just the one 200w light.
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #6
    Re: Basic assistance for PV on Boat Dock
    steve wrote: »
    Understand I will need a pure sine inverter for the motor.

    With that, I guess it will be 120VAC.

    Currently using a genset??

    Might be best to do lights on solar and leave the lift on the genset.
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  • System2
    System2 Posts: 6,290 admin
    #7
    Re: Basic assistance for PV on Boat Dock

    Gents,
    Thanks for the input. Lights on solar lift on genset sounds like the plan. Genset is already in use but NOT MUCH FUN WHEN TRYING TO FISH AT NIGHT WHEN ITS PEACEFUL.
    Thanks again.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
    Re: Basic assistance for PV on Boat Dock

    And, you can hook a charger to the genset, so that when it is running, you can give the batteries a boost. At least 1x a month you need to equalize the batteries, easy in the summer, with long days, but winters with clouds, the genset will be handy to charge with.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #9
    Re: Basic assistance for PV on Boat Dock
    steve wrote: »
    Gents,
    Thanks for the input. Lights on solar lift on genset sounds like the plan. Genset is already in use but NOT MUCH FUN WHEN TRYING TO FISH AT NIGHT WHEN ITS PEACEFUL.
    Thanks again.


    steve,
    please do not get upset with anybody here as we try to help and he only asked of a possible genset and does not know your exact circumstances or needs. he certainly was the only one to innocently mention a genset so your unwarranted YELLING AT US GENTS WON"T GET YOU ANYWHERE.
    you're welcome
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  • System2
    System2 Posts: 6,290 admin
    #10
    Re: Basic assistance for PV on Boat Dock

    Sorry if any offense taken, the shouting was meant as a joke fellas. Shouting over the genset is a family joke as we lower the boat into the water.
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  • System2
    System2 Posts: 6,290 admin
    #11
    Re: Basic assistance for PV on Boat Dock

    Thanks for all the input.
    Genset for lift, PV for lights it is.

    Is there a plug and play option? A ready made set that I can purchase and install myself either over the internet (batteries local). I do not mind lighting to the extent that the PV package will provide.
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #12
    Re: Basic assistance for PV on Boat Dock

    niel

    I took steve's post as a joke, so no harm, as I suspected he was using a genset to power the lights at night.

    Now onto the lights.
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  • Dannyo
    Dannyo Registered Users Posts: 10 ✭
    #13
    Re: Basic assistance for PV on Boat Dock

    A couple of months ago, I hooked up a small solar system on my boat dock, but I'm not a solar expert by any stretch of the imagination. I only use it 1-2 times a month, and I have a storage room to keep everything dry (the batteries, controller, inverter, etc.). Right or wrong, this is my system.

    one 125 amp hour deep cycle marine battery from Walmart
    one 65 watt Kyocera panel
    Xantrex c12 charge controller
    Vector 3,000 watt modified sine inverter
    I built my own mounting bracket for the panel. I used punched L brackets purchased at Home Depot.

    I purchased the first three items from NAWS.

    I have an electric boat lift (A.O. Smith 115 volt at 10.8 amps). Initially, I tried the Vector 1500 watt inverter, but for some reason it did not work. The 3000 watt inverter easily handles the initial surge of power. After the surge it only draws 300-400 watts. It only takes 1-2 minutes to raise or lower the lift, so it didn't require as much power as I thought. fyi- I didn't need a "pure" sine inverter.

    I installed one 72 green LED underwater light from Ocean Mist ($65.95 each). It uses very little power. The light is advertised for ponds, but it works fine. I made my own brackets and mounted the light to a piling. Ideally, I would like to have 3-4 fishing lights, but I'm still experimenting with it. The minnows really like the green light. Honestly, I don't expect to attract huge fish with it, but it is like a natural "aquarium". It's quite relaxing to watch them.

    I also hooked up a few lights for the dock.

    Lastly, I ran a ground wire to the shore. Not sure if it was necessary, but I did it anyway. The ground wire is a 10,000 volt wire that I purchased at Tractor Supply. It was left over from an electric fence project.

    Let me know if you want to see some pics. I'm not sure how to post them on here, but I could email them.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #14
    Re: Basic assistance for PV on Boat Dock

    dannyo,
    ok on your system and although the pv is low on the charge percentages, it will work alright when the battery is only pressed into service a few times a month. i suspect the battery capacity to be too low to handle high power draws of the boat lift even though the inverter can handle it. the total battery capacity in watts is 12v x 125a = 1,500 watts total power. the correct answer is in watthours as the 125a is actually amphours. the power drawn from the boat lift is 115v x 10.8a = 1242w and due to other losses, it is at or exceeding the capacity of the battery. most just aren't meant to discharge all of their power in an hour, especially wally world types. the savings grace here is that the voltage will dip very low under heavy load dropping out of the range of opperation for the inverter thus stopping your battery from total discharge or possible damage. the wally world type of batteries are somewhat high maintenance batteries with relatively short lifespans so practices of heavy draws or discharges that take the dod very far will lessen the lifespan even further, but it's better to learn and make mistakes on a cheaper battery.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #15
    Re: Basic assistance for PV on Boat Dock

    Battery note: when it's time for a replacement, look into a pair of 6V golf cart batteries, still pretty cheap, easily wired into series, and will double your battery capacity. If your loads don't change, you panel will still be able to just "keep up", but if you use the lift more, you will need more recharging power.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

    · Share on Twitter

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