Will a 30w solar panel be enough to charge 20ah battery?

Nano
Nano Registered Users Posts: 7 ✭✭
in Solar Beginners Corner #1
hi guys im new to this solar system thingie i already got most of the things expect solar panel...
i have a 20ah 12v battery and i want to use it to charge 2 phones and 2 tablets at the same time which is around 30w of power using 12v to 5v adapter after the sun goes down.. and also i wanted to ask what can i run off modified sine wave inverter?
· Share on Twitter

Comments

  • Nano
    Nano Registered Users Posts: 7 ✭✭
    #2
    anyone?
    · Share on Twitter
  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    edited September 2016 #3
    Hi Nano,
    It looks like the load (charging phones and tablets) would be about 3 to 4 amp hours out of the 20AH battery, which is about what want for that size battery. If you don't already have one, you will need a PWM charge controller to properly charge the battery. Here is a link to a good one at a good price. https://www.solar-electric.com/sg-4.html

    The 30 watt panel will provide about 1.5 amps for charging. That's about an 8% charge rate, which is a little low but it will work.
    You will need 2 to 3 hours of good sun to recharge the battery. Be careful not to over discharge the battery due to poor charging conditions like a couple days of bad weather.

    Modified sine wave inverters do not play well with anything that has a transformer or a motor. Think refrigerator, florescent lights, fans. These loads may work, but the wave form causes the production of heat in the windings, which is a loss in efficiency and can stress equipment, sometimes to failure, although that is rare.

    Good luck with your project  
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
    · Share on Twitter
  • pdh
    pdh Registered Users Posts: 31 ✭✭
    #4
    > You will need 2 to 3 hours of good sun to recharge the battery

    I think you'll need more than that. If the battery is 50% discharged (which is as far as you should take a lead-acid battery), you'd need at least 10 AH to fully recharge it. That's 6.67 hours at 1.5 amps. In real life you'll probably need somewhat more than that, since the recharge process isn't 100% efficient.

    I use the charge controller that Raj recommends, in a small setup about the same size as yours (50 watt panel and 22 amp-hour battery) and I'm very happy with it.

    Don't forget to put a fuse between the battery and the controller. I use a 5 amp automotive fuse (ATM type).
    · Share on Twitter
  • Johann
    Johann Solar Expert Posts: 245 ✭✭✭
    edited September 2016 #5
    Most likely you have an AGM battery and that will require a different charge and/or controller. Anything else could shorten the life of the battery. Make sure that your equipment is designed to charge your battery properly to avoid problems.
    · Share on Twitter
  • Nano
    Nano Registered Users Posts: 7 ✭✭
    #6
    hi and thank you for response :) so i will be better of getting a 50w panel?
    i know that i should not go below 50% and for pwm im planning to go with EPEVER VS1024A because it has a nice screen so i can monitor stuff :)
    · Share on Twitter
  • Nano
    Nano Registered Users Posts: 7 ✭✭
    #7
    i have sealed lead acid battery and i will go with glass fuses if its not a problem or should use ATM ones?
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #8
    Glass fuses are fine... I suggest you size the fuse(s) (and your wiring) to (at least) 1.25, round up to next standard wire/fuse size). Whichever current (your charging or loads) is greater.

    Say you have have 5 amps charging and 10 amps max continuous loads--Then 10 amps * 1.25 = 12.5 amp ~ 15 amp fuse (and wiring).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • Nano
    Nano Registered Users Posts: 7 ✭✭
    #9
    i know i know :) thanks for response
    · Share on Twitter

Categories