Introduction and Solar Project

tndoug99tndoug99 Registered Users Posts: 10
Hello All,
My name is Doug and I have developed a keen interest in solar energy this past year, so much so, that I embarked on building my own (small)solar energy system. For the past 6 months or so I have learned and formulated my plan.
Now, my background is as far from anything electrical as I am from China right now, and without a mentor or two to guide me, my journey will be more difficult.

I decided to start with a small 12 volt system. I wanted it to be portable, expandable, and efficient. I wanted to use the best quality I could afford. So far, these are the components I have purchased:

Xantrex Prowatt 600 truesine inverter
Blue Sky 2000E MPPT 25 amp charge controller
Battery Charger, 12 volt SmartCharger by CTI
3x40 Watts Sopray Mono 12v solar panels... 3 smaller 2.5a panels I will make foldable into one 120 Watt,7.5 amp solar panel, charge controller should be able to handle up to 3 sets or 360 watts/22.5 amps.
One 12 volt, 105 amp hour sealed deep cycle battery. In the future I would like to replace the 12 volt battery with two 6 volt, 250 amp hour sealed batteries wired in series.
A two wheel foldable monster cart to carry it all (don't believe the 250lb limit on these carts...more like 150 max)

Also a MTM solar tracker circuit and motor. I really jumped in it with this! This is a project all in itself to be tackled after my solar project is finished or near finished. I have a design in mind for this.

Things I THINK I may also need, but not sure:
combiner box, fuse block, disconnect for solar panels, disconnect for battery.

Things I want to add:
12 volt outlet
iPod player w/speakers
12" or so LED strip light

All this (except the solar panels and battery) to be installed in a 16" tall x 16" wide x 10" deep enclosure. I think it will work.

Well Guys.... am I on the right track for a small efficient system?


  • SevenSeven Solar Expert Posts: 292 ✭✭
    Re: Introduction and Solar Project

    Not really.
    A mppt controller is overkill for your panel setup. It seems you are wiring the panels parallel, so there is no advantage to the mppt. Also I don't know if mppt does any good under 500w.
    The math shows that youmare only going to have between 6 to 7a of charge current going to a105ah battery. That is just above the minimum 5% of 5.25 and won't do much if there is any load on the battery. Going to the 250ah batteries would make it much worse, not better.
    Forget the tracker and get to the 360w of panel you mentioned.

    There is a member here, mike, that built his monolith and it is portable.
    Others will give a more detailed answer.
  • tndoug99tndoug99 Registered Users Posts: 10
    Re: Introduction and Solar Project

    So I won't add any batteries and save for 2 more sets of panels(for 360 watts total).

    Why would Blue Sky make a 25 amp charge controller and say it is MPPT, when it really doesn't add anything?

    I can't give up on the tracker...I already have the circuit board and motor... and wouldn't the solar tracker help? Is it not worth the extra effort, or should I cut my losses?

    I would be very interested in reading about Mike's Monolith. I didn't know they were called that.

    Thanks for the help. I appreciate the advice.
  • BB.BB. Super Moderators, Administrators Posts: 33,319 admin
    Re: Introduction and Solar Project

    MPPT works "better" in very cold weather... if you do not get snow on the ground, your "improvements" will be less...

    The other great place to use an MPPT controller is with Vmp-array at "high" voltage (upwards of 100 VDC or even higher with some models). Many of the smaller/older controllers are not capable of higher Vmp-array voltages (which allows you longer wire runs/use less copper between array and controller)... Really great if you have to send the power any longer distances and/or if you are only running a 12 volt battery bank (and to a lesser degree a 24 volt battery bank which use higher current/lower voltage drop tolerance).

    If your array is relatively small and close to the battery shack--Sometimes it costs less to buy more solar panels and run them on a (good quality and less expensive) PWM charge controller.

    In the end, you almost have to do several paper designs to figure out what works best for you.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • tndoug99tndoug99 Registered Users Posts: 10
    Re: Introduction and Solar Project

    I can see that I know much less than I thought.

    But, that's why I'm here, to listen to what experienced people tell me and focus on what's important and to lose what's not.

    Thanks for your input.
Sign In or Register to comment.