Solar system for enterance sign

wildduk
wildduk Registered Users Posts: 1 ✭
in Solar Beginners Corner #1

Hello,  

I was wondering if someone could lead me in the right direction to buy a solar system for a neighborhood entrance sign.  We don't need much, but want to get a quality system that will last.   I've seen a few custom setups around town that have what we need but not sure where to start.  

A solar panel,  waterproof battery enclosure, and a few small LED lights is what were looking for.  We will be doing the install ourselves.

I really don't want to go with what I can get at Lowes/HD as I don't think it will last.   I also don't mind spending a few bucks to build a good system. 

Thanks

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #2
    With solar, you want to start with  the loads. LEDs with efficient electronics are going to be the place to start. Keep your power needs low, then the solar+battery capacity can be kept low too.

    http://www.ledsupply.com/blog/the-search-for-a-battery-powered-led-strip/ (I don't know anything about product or website)

    So--Just to take the above as an example. AA batteries contain ~1 Watt*Hour of energy. 8x AA batteries lasting 15 hours (over night) in their example.

    If you want to run the sign for 3 days  of no sun (assuming you use a controller that shuts down during day time) that would be:
    • 8 Watt*Hours per night * 3 nights = 24 Watt*Hours of storage
    For most battery systems, discharging to 50% state of charge gives you longer battery life:
    • 24 WH * 1/0.50 max discharge = 48 Watt*Hours of storage
    • 48 Watt*Hours / 12 volt nominal battery = 4 AH storage @ 12 volts (relatively small battery bank)
    Assuming you use 8 WH per night--And live near Atlanta Georgia:
    http://www.solarelectricityhandbook.com/solar-irradiance.html

    Atlanta
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 56° angle from vertical:
    (For best year-round performance)
    Jan Feb Mar Apr May Jun
    3.55
              		3.96
              		4.86
              		5.24
              		5.36
              		5.00
     
    Jul Aug Sep Oct Nov Dec
    5.18
              		5.01
              		4.82
              		4.92
              		3.96
              		3.52
     
    Assume a minimum of 3.0 hours of sun (on average for "bad" December):
    • 8 WH per night * 1/0.61 solar panel+controller+battery eff derating * 1/3 hours of sun = 4.4 Watt solar panel
    That is a pretty small system--You can get a smallish Lead Acid Battery (agm/deep cycle), plus a solar lighting/charge controller:

    https://www.solar-electric.com/sunsolligcon.html

    All of this really depends on the amount of energy consumed overnight (a 10 amp lighting controller + Lead Acid battery would be "overkill" for a very small/low power LED sign)... Picking the right components does depend on the overall size of the electrical system.

    There are more choices/decisions to be made--But this is a start to sizing such a system.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #3
    Our host sells generally well regarded products. You'll need to be a bit more specific on the application though. For example, do you have specific lights in mind, and if so do you know their power draw, number needed, etc.?

    LED lights often run off 120vac transformed down to 12v. Some can be used directly with 12v systems (can handle voltage ranges from around 10.5 to 16v or so). Others need the voltage more tightly regulated. Being able to use 12v directly will simplify things in this application.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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