Question RE: Solar Powered Light

Texas Wellman
Texas Wellman Solar Expert Posts: 153 ✭✭
in Solar Beginners Corner #1
I'm looking to install a light in a remote area for recreational purposes. I'm looking at several models, but for this instance let's just go with a 30 watt LED model that I am looking at.

If I want to use the light 3-4 hours typically or maybe even 5-6 hours (non-typical) about 2-3 days a week what kind of set-up do I need to be looking for?

Do I need a charge controller? I was looking at buying a "12V" panel and a deep-cycle 12V battery and just letting the panel trickle charge the battery. I have good sun in this location. I do not need to use the light every day so if it took 2-3 days to recharge that would probably be OK.

30 watt light /12V = 2.5 amps x 5 hours = 12.5 amp-hours. Considering that a cheap 12V marine-type deep cycle battery has about 100 amp hours I was thinking of coupling it to a smallish (50-100 watts) solar panel to keep it trickle charged. In winter we get about 3-5 hours of sunlight daily here in S. Texas.

Some of the 12V panels I looked at had a rated voltage of 17V. I figured that is probably with no load. If I connected the panel directly to the battery and then had the light come on every night would I over-charge the battery?

I'm not really worried about killing the battery. At approx. $100 and 3-6 months per year use I can replace it yearly if need be.

Thanks for your responses.
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Comments

  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #2
    Re: Question RE: Solar Powered Light

    Why even go thru all that hassle and extra cost?

    There are plenty of "all in one" solar lights that you could install for less than $50 that recharge each day and turn on at night. Just look for solar landscaping lights online.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
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  • Texas Wellman
    Texas Wellman Solar Expert Posts: 153 ✭✭
    #3
    Re: Question RE: Solar Powered Light

    Thanks for your reply. Most of the landscape lights I have seen are not quite what I am looking for. I have seen some solar powered area flood lights but they seemed kind of dim.

    I realize that with 30 watt I'm not getting a lot of light to start with but with LED's it seems like that would go a long ways. I might test the single light out and then add one or two more if it seems to be keeping the battery charged.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #4
    Re: Question RE: Solar Powered Light

    Trickle charging is (roughly) when the current is less than ~1% of the battery capacity (20 hour rate). Any more charging current than that, you should really get a charge controller.

    30 watts is a lot more than energy than most of the "inexpensive" LED battery based lamps--So you will probably have to build your own.

    For 30 watts at 5 hours per night, you will need roughly:
    • 30 watts * 5 hours * 1/0.61 DC end to end system eff * 1/3 hours of sun = 500 watt of solar array
    Of course, that is for a daily use system--If you only need to run it two days in a row, you could go with the battery bank to recharge the lights with a minimum 5% rate of charge...
    • 30 watts * 5 hours * 1/12 volt battery * 2 days of storage * 1/0.50 maximum discharge = 50 AH @ 12 volt battery bank minimum
    And minimum charge rate would be:
    • 50 AH * 14.5 volts charging * 1/0.77 panel+controller deratings * 0.05 rate of charge = 94 Watt minimum array
    And if you use a 100 AH 12 volt battery bank--The minimum operational panel should be >~188 watts for proper battery charging.

    To just float a battery over the winter, you could probably use:
    • 100 AH * 14.5 volts charging * 0.01 float charge rate = 14.5 watt "12 volt" panel for "floating"
    In any case, I would suggest a simple/low cost battery charger for $30 to prevent over charging and reduce water usage even when floating.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Texas Wellman
    Texas Wellman Solar Expert Posts: 153 ✭✭
    #5
    Re: Question RE: Solar Powered Light

    9830 Spot Current Draw: 1.4A@12V

    There is one specific light I really want to run. The current draw is listed up above. It's rated for 27W.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #6
    Re: Question RE: Solar Powered Light

    TWM Link?

    (n#%$*& Not 15 characters)
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Texas Wellman
    Texas Wellman Solar Expert Posts: 153 ✭✭
    #7
    Re: Question RE: Solar Powered Light

    The link to the lights?

    Here http://www.plashlights.com/Driving---Work-Lights.html
    westbranch wrote: »
    TWM Link?

    (n#%$*& Not 15 characters)
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #8
    Re: Question RE: Solar Powered Light

    wow those are tough and BRIGHT! They seem to justify the price... but hard to find much lumens info
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Shockah
    Shockah Registered Users Posts: 13 ✭
    #9
    Re: Question RE: Solar Powered Light
    Texas Wellman wrote: »
    I'm looking to install a light in a remote area for recreational purposes. I'm looking at several models, but for this instance let's just go with a 30 watt LED model that I am looking at.

    If I want to use the light 3-4 hours typically or maybe even 5-6 hours (non-typical) about 2-3 days a week what kind of set-up do I need to be looking for?

    Do I need a charge controller? I was looking at buying a "12V" panel and a deep-cycle 12V battery and just letting the panel trickle charge the battery. I have good sun in this location. I do not need to use the light every day so if it took 2-3 days to recharge that would probably be OK.

    30 watt light /12V = 2.5 amps x 5 hours = 12.5 amp-hours. Considering that a cheap 12V marine-type deep cycle battery has about 100 amp hours I was thinking of coupling it to a smallish (50-100 watts) solar panel to keep it trickle charged. In winter we get about 3-5 hours of sunlight daily here in S. Texas.

    Some of the 12V panels I looked at had a rated voltage of 17V. I figured that is probably with no load. If I connected the panel directly to the battery and then had the light come on every night would I over-charge the battery?

    I'm not really worried about killing the battery. At approx. $100 and 3-6 months per year use I can replace it yearly if need be.

    Thanks for your responses.

    What type of recreation do you need the light for?

    Click on my avatar... then click on my home page.

    4W to 100w, I can point you to a Solar Light for any need...
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  • ILFE
    ILFE Solar Expert Posts: 364 ✭✭
    #10
    Re: Question RE: Solar Powered Light

    I have a couple of these (10 watts flood lamps) on order. Them, along with a MorningStar SunLight (SL-10L-12v) controller I Just bought, will keep an outside area of our farm house lit up at night. They may not be much. But, I think they will get the job done.
    Paul
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  • Shockah
    Shockah Registered Users Posts: 13 ✭
    #11
    Re: Question RE: Solar Powered Light
    ILFE wrote: »
    I have a couple of these (10 watts flood lamps) on order. Them, along with a MorningStar SunLight (SL-10L-12v) controller I Just bought, will keep an outside area of our farm house lit up at night. They may not be much. But, I think they will get the job done.

    I doubt those meet the advertised 800Lumens, but they get the job done.
    What is the AH rating on your battery, ILFE?

    I just completed a solar lamp assembly with one of those flood-lights, except this one is built as a motion sensor security light... The assembly has a 1W night-light.

    Attachment not found.

    I am currently building 7 other assemblies with the same floodlight dusk-to-dawn.
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  • ILFE
    ILFE Solar Expert Posts: 364 ✭✭
    #12
    Re: Question RE: Solar Powered Light
    Shockah wrote: »
    I doubt those meet the advertised 800Lumens, but they get the job done.
    What is the AH rating on your battery, ILFE?

    I agree. That's why I figured I would buy two of them and see how well they illuminate the area in question, prior to buying any more of them.

    The battery I have for them at the moment, is 50ah. I have a 100ah battery I can use if I like them well enough and want to expand the system. (I see no need to go to 50% DOD for outside lighting, by going with a smaller battery.)

    I also have a spare 100watts panel. So, I will have a completely independent outside lighting system that I just need to look after once per month.
    Paul
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