Adding Underwater Solar Light

joe_danielewicz@msn.com[email protected] Posts: 6Registered Users
I'd like to substitute an underwater led light (12 VAC/0.5 A) like
http://www.micostore.com/led.html

to replace a standard 500 W 110 volt fixture.

I also want to use a Motorola Iridium Solar Charger panel (3.34 F, 2.97 Amps, 9.9 Watts) charging some kind of 12 volt battery to power this LED.

1. Do I need some kind of charge controller between the solar panel and the battery to prevent overcharging?

2. I want to use the existing 12 gauge wiring to connect the LED to the battery. Will this be a problem?

Thanks,

Joe

Comments

  • BB.BB. Posts: 28,083Super Moderators, Administrators admin
    Re: Adding Underwater Solar Light

    The 500 watt fixture at 120 volts is over 4 amps... So the 0.5 amp of the LED lamps should be OK... If you put a bunch in parallel--you will have to look at the voltage drop... 3 volt drop at 120 volts is much different than 3 volt drop at 12 volt.

    Regarding the solar panel--sounds like a 3-4 volt panel... Unless you use some boost type electronic power supply to get 14-15 volts at the battery (which is not usually done)--that panel will not work for you.

    You need a panel rated for charging a 12 volt battery (typically around 17 volts Vmp (max power)).

    And, usually, you will need a solar charge controller between the solar panel and the battery. Also, it would be nice to have an automatic controller to turn the lights off when you don't need them any more.

    Morning Star has some nice solar lighting controllers made exactly for this function. Morning Star also has a very nice new model MPPT type controller (better power production for up to 200 watts of solar panels).

    In the end, the size of the solar panel and the battery depend on how much light/power you need, where you live, what season(s) you want to run the lights, and how much sun you have.

    As a real rough guide--Say you want to run 4 of your solar lights for 3 hours per night.

    4 lights * 0.5 amps * 3 hours = 6amp*hours per night...

    Roughly, you get about 2 hours worth of sun from a solar panel 6+ months of the year. So, to run this, you would need a solar panel rated at:

    6amp*hours / 2 hours of "sun" per day = 3 amp rated panel.

    A 3 amp panel in watts is:

    3 amp * 17.5 volts = 52.5 watt rated panel...

    The lead acid storage battery would typically be sized to support 3 days of no sun and 50% maximum discharge (for best battery life)

    6 amp*hour * 3 days * 1/50% = 36 amp*hour deep cycle storage battery

    None of the above is written in stone--but gives you a good idea of the basics of estimating a system's performance and cost.

    For a more exact match to your area see this link (and you can look at the month by month--or even day by day) power consumption. You can take the defaults--but use a derating factor of ~0.52 for a battery powered system. You will have to use 1kW of solar panels then divide down to your 100 watt (or whatever) panel (1kW is the minimum that this program will take).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Posts: 7,967Solar Expert ✭✭✭✭
    Re: Adding Underwater Solar Light

    ditto to what BB said.

    Creating a 12V system is the best way to go, and from there, you can get converters & batteries. 6V chargers and controllers just don't seem to exist, except maybe some proof-of-concept toys. There are also likely 12v automotive LED lights (some headlights too !) if you need really bright stuff (your 500W bulb you are replacing, would need about 50W of LED to keep the same amount of lighting)
    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 ,

  • joe_danielewicz@msn.com[email protected] Posts: 6Registered Users
    Re: Adding Underwater Solar Light

    Thanks to BB and Mike for some great advice.

    I was afraid those Iridium solar panels would be too small to power a pool light. Now I have to find another use for them.

    I can see how this forum can be really useful to the do-it-yourselfer.

    Joe
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: Adding Underwater Solar Light

    the trouble with those leds are that they are 12vac and not dc. a conversion needs done and there's no easy or efficient way to come up with 12vac. see if you can find some that are 12vdc.
  • BrockBrock Posts: 630Solar Expert ✭✭✭
    Re: Adding Underwater Solar Light

    Is this going to replace an existing pool light niche? Sounds like a typical wattage for a pool. I hate to break it to you but those LED's aren't going to do much in the way of actually lighting the pool. Some locations have minimum lighting requirements for pools which is why they often just throw 500w lamps in there. To get by in an LED version I went with these http://www.haywardnet.com/inground/products/lighting/ColorLogic_LED_Pool_Lights.cfm with all the LED's on they pull 50w max and are as bright as the 500w ones they replaced. In their dimmest mode they pull 15w (just one color on). They are pricy, but completely sealed and meant to be used in a standard pool niche, they come in either spa size or pool size and come in 12vdc or 120vac and in plastic or stainless.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • n3qikn3qik Posts: 741Solar Expert ✭✭
    Re: Adding Underwater Solar Light
    niel wrote: »
    the trouble with those leds are that they are 12vac and not dc. a conversion needs done and there's no easy or efficient way to come up with 12vac. see if you can find some that are 12vdc.

    12VAC LED will work with 12vDC, the LED assembly has a bridge and a cap in it to change to DC voltage. Nice thing about an AC LEDs is that you don't have to worry about polarity.
  • joe_danielewicz@msn.com[email protected] Posts: 6Registered Users
    Re: Adding Underwater Solar Light

    What if, instead of using a 12 volt system, I used TWO Motorola Iridium Solar Charger panels (each at 3.34 F, 2.97 Amps, 9.9 Watts) charging some kind of 6 volt battery to power this LED.

    Would this be feasible?

    My next problem will be to find a submersible 6 volt LED, since most of them are 12 volt marine systems.

    Thanks,

    Joe
  • BB.BB. Posts: 28,083Super Moderators, Administrators admin
    Re: Adding Underwater Solar Light

    Probably not... 3.34 volts x 2 = 6.68 volts -- not high enough to charge a 6 volt lead acid storage battery. If you could get three panels--then that part would be OK.

    Next problem would be how would you manage the charging control? Don't remember seeing any 6 volt solar charge controllers... You could make one--but given that it is best to have a multiple charging voltage controller with temperature compensation--it is not going to be the easiest project to do for a one-off controller.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BrockBrock Posts: 630Solar Expert ✭✭✭
    Re: Adding Underwater Solar Light

    Have you looked at any of the floating solar LED lights? Some of the newer ones are pretty bright and it's all built in. Again not a lot of light using just a couple of LED's but it's already built and waterproof.

    http://search.ebay.com/search/search.dll?from=R40&_trksid=m37&satitle=solar+pool+led&category0=
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
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