Please Recommend a Charge Controller for my Application

PlantGuyPlantGuy Registered Users Posts: 4
I need a charge controller that I can set to only power the load during daylight hours.  All of the ones I've seen (even the ones with "timer capability") are designed to mainly power the load at night or all of the time.  For my application, I don't need the load powered at night.  To keep the aesthetic footprint to a minimum I'm only using a 10W panel and a 7AH battery.  This is a 12V system.  The battery will power the load most of the night, but the next day the panel has to charge it for about 4 hours before the load side is active again, and that is the primary time when I really need the system to be working. 

Can anyone recommend a charge controller that could be set to only power the load side during daylight hours? Thanks.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 28,141 admin
    I am a little confused... Will the 10 Watt panel also be charging the 7 AH battery during the daytime?

    Do you need the charge controller (or daylight switch) to specifically turn the load "on and off" during daylight hours?

    It sounds like you really want to run the load 24 hours per day, and the solar charger to both "run the load" and charge the battery (at the same time) during the day.

    If the second is true, any solar charge controller will do that just fine. Assuming your load energy (amp*hours per day) is capable of being powered by a 10 watt panel--Or roughly 9 months of the year in a sunny climate:
    • 10 watts / 17.5 volts Vmp = ~0.57 Amp Imp
    • 0.57 Amps * 0.80 battery efficiency * 4.0 hours of average sun minimum per day = ~1.8 Amp*Hours per day maximum load
    Really need to know more about your load (average current, hours per day running, etc.) and where the system will be (nearest big city), and if run seasonally or all year long.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PlantGuyPlantGuy Registered Users Posts: 4
    I only need power to my device during the day.  I'd like to have the load either automatically switch off at the end of the day, or be able to set up a window of time during the day when it would be on.  7:00 am till  7:00 pm for example.  Yes the panel will be charging the battery during the daytime.  I am located in Wichita Falls in north central Texas near the Oklahoma border.  The load being powered only consumes about 200 mW, so the 10W panel has no problem in both powering it and charging the battery during the day.  The problem is that without a way to automatically turn off the load at dark, the battery gets drained during the night.  This system needs to run year round.  The most important time frame to have power is from 7:00 am to 4:00 pm. I am currently using one of the inexpensive CMTP02-10A charge controllers. Thanks for your help.
  • PlantGuyPlantGuy Registered Users Posts: 4
    Correction.  I meant to say that the load only consumes 200 mA.
  • BB.BB. Super Moderators, Administrators Posts: 28,141 admin
    This is not a cheap solution, but it is a battery backed timer with ability to run AC or DC circuits:

    http://www.solar-electric.com/fldctico.html

    You can probably find something cheaper on EBay or other import site. Amazon has (it appears) a bunch:

    https://www.amazon.com/MISOL-Controller-display-program-programmable/dp/B0090MTLFO

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PlantGuyPlantGuy Registered Users Posts: 4
    Great idea!  I had considered using a timer, but I'd always assumed that it would consume as much current as the load.  This looks very promising.  I'm going to order a couple of these:

    https://www.amazon.com/DBPOWER-CN101-Digital-Programmable-17-times/dp/B00H4XP7QS/ref=pd_sim_60_3?ie=UTF8&dpID=411jYI6LX9L&dpSrc=sims&preST=_AC_UL160_SR160,160_&psc=1&refRID=N5B58G7NRBFPV964H8D7

    I'll let you know how it works out.  Thanks for your help.

    -Benny

  • BB.BB. Super Moderators, Administrators Posts: 28,141 admin
    You are very welcome... By the way, watch the energy usage/battery state of charge:
    • 0.2 amps * 12 hours per day = 2.4 Amp*Hours per day
    At 4 hours of sun per day, you are looking at ~1.8 Amp*Hours per day of energy. You are running right on the margin of enough power with a 10 watt panel--Let alone what happens in winter (if you run it all year round).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MangasMangas Solar Expert Posts: 547 ✭✭✭✭
    I just installed a new generation Intermatic electronic timer on a water pressure tank  air pump.

    They make several comprehensive digital timer models.


    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
  • 2manytoyz2manytoyz Solar Expert Posts: 370 ✭✭✭
    One of the solar controllers I'm using is a MorningStar Sunlight-10.  Regulates up to 10 Amps  (120 Watts).  It has a built-in 10A relay to control lights, with adjustable settings.  What I've done is added an external 40A relay.  I can then use this to turn on lights dusk to dawn, and turn off loads during that period.  When the sun comes up, the relay drops out, turning off the lights, and operating the daytime loads.

    Never need to adjust for time of year, no clocks to set.  It constantly measures the output of the solar panel, and adds a 10 minute dwell time, it knows when it's daytime or nighttime.  Very slick.


  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Old thread, but what about a simple photo cell, to turn off the load when there is no light?

    Tony
  • BB.BB. Super Moderators, Administrators Posts: 28,141 admin
    Photo cells pass current where there is light--So you need a relay (or electronics) to reverse the polarity ('on' when dark).

    Could also get a small solar cell and a relay (relay or transistor/fet/etc. holds open when sun is up, closes when sun sets)....

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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