my first post

Stu Piddly
Stu Piddly Registered Users Posts: 11
I have been lurking here for over a year now,planning my system,It will be 12 volt,mounted on a 6x10 cargo trailer,main load will be an Engel fridge/freezer 35liter cap. and charging laptop,cell phone,cfl ,maybe a small 12volt TV,the Engel uses 18 to 42 amphours per day I'm told,depends on temp setting,-10 runs 70%,40f runs 30% of the time,so,my expected load will be 50-60 ah per day (guessing).I was thinking 2 or 3 kyocera 135w panels and two 6v golf cart batterys (220ah sams club). I was at the MREA fair this last week,and made my first purchase,four 135w kyoceras for $2 per watt,no shipping,cash and carry ,full warranty,I remember reading here that it is hard to grow a system,should be sized correctly right away,might be hard to buy a matching panel later,and you always need more panel than you think you do. I have 550w of panel,13% of 220ah is 28.6amps,about what these panels will produce. I noticed some of you run four golf car batts with less panel than I have(icarus),how do I decide on 2 or 4 batterys? I was thinking my next purchase would be a tri metric meter and do some actual testing of the stuff I will be powering. Is this a good plan?

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: my first post

    Welcome to the forum.

    Yours will be an all DC system? No inverter for 120VAC?

    Let's take a look at what you've got.
    50-60 Amp hours a day is easily done, if accurate.
    The golf cart batteries will make up to 110 Amp hours available with just one set (50% DOD).
    Four Kyocera 135's is 540 Watt hours. Using the typical 77% efficiency factor they will provide:
    28 Amps peak potential charging current @ 14.8 Volts, or 12.7% of the batteries capacity;
    About 1.6 kW hours harvest per day based on 4 hours of good sun.

    So far, so good.

    You may want an MPPT charge controller to go with that. It would provide some charge advantage and would simplify wiring of the panels (higher Voltage array).

    You could run two sets of those batteries with this, but the charge rate would be a bit minimal.
    Do you think you need that extra capacity?

    The more accurate you can get your load numbers the better your planning will be. I haven't heard of anyone using a Trimetric in place of a Kill-A-Watt (which only works on 120 VAC) but it should be fairly accurate for measuring actual loads.
  • Stu Piddly
    Stu Piddly Registered Users Posts: 11
    Re: my first post
    Welcome to the forum.

    Yours will be an all DC system? No inverter for 120VAC?

    Let's take a look at what you've got.
    50-60 Amp hours a day is easily done, if accurate.
    The golf cart batteries will make up to 110 Amp hours available with just one set (50% DOD).
    Four Kyocera 135's is 540 Watt hours. Using the typical 77% efficiency factor they will provide:
    28 Amps peak potential charging current @ 14.8 Volts, or 12.7% of the batteries capacity;
    About 1.6 kW hours harvest per day based on 4 hours of good sun.

    So far, so good.

    You may want an MPPT charge controller to go with that. It would provide some charge advantage and would simplify wiring of the panels (higher Voltage array).

    You could run two sets of those batteries with this, but the charge rate would be a bit minimal.
    Do you think you need that extra capacity?

    The more accurate you can get your load numbers the better your planning will be. I haven't heard of anyone using a Trimetric in place of a Kill-A-Watt (which only works on 120 VAC) but it should be fairly accurate for measuring actual loads.

    I have a kill-a-watt my laptop is pulling 28 watts on it right now,and I just checked my cell phone charger,pulls 6 watts for about 1/2 hour per day,I can buy 12volt chargers for these,and then I would not need an inverter. I dont know what would be cheaper,I suppose there are other things I could plug into a small inverter that I have not thought of. I thought a trimetric meter would be very usefull after the system is up and running to monitor the batterys,and I could use it to check power use of my 12 volt stuff before I buy batterys.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: my first post

    do definitely recheck your load requirements and if accurate then go ahead with your plans as you've already laid them out here. as coot said, consider an mppt cc and by the size of things you'll need at least a 45a mppt cc as a 30a mppt cc would leave little to no margin for any current gains.
  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    Re: my first post

    I'm kicking myself for not going to the MREA fair now!! I didn't know what to expect and fathers day/weather.. I need a few more KD135's! :cry::cry::cry:
  • Stu Piddly
    Stu Piddly Registered Users Posts: 11
    Re: my first post
    I'm kicking myself for not going to the MREA fair now!! I didn't know what to expect and fathers day/weather.. I need a few more KD135's! :cry::cry::cry:

    attendance was down a little,rained some,this was the third year I volunterred to help set up,I went to many workshops,I really enjoyed the "convert your motorcycle to electric workshop"
  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    Re: my first post

    I wish there were these kinds of fairs around san antonio. :cry:
  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    Re: my first post

    Very cool. However, is it always over fathers day weekend? kinda stinks :-) Sounds like a cool thing to check out and.. buy things! hehe. About a 4 hour drive but well worth it! See ya next year! :D