Looking for advice

Storm Registered Users Posts: 2
Hello all, 
new to posting to the forum, but I have been reading many of your posts for quite some time. I have been considering building a solar generator on a trailer that we could take out to our job sites that would essentially run items at night, generator during the day for the batteries can recharge. We would like the trailer to run tool chargers, lights, radio, refrigerator (small), and an small air conditioner. In my various searches I have found I have found this item,


This seems perfect for what we need and from what I can tell a pretty damn good price. And I do not have to put it together. Being a novice to all this, I am looking for the advice and opinions of those with much more knowledge on the subject. 
So please let me know what you think of this trailer. Do you agree it is a good price for the equipment? Do you agree that it should run what we would like without issues. Can we add batteries to it to create more stored power or are the panels to small for that?

Thank you all in advance for your input.

Storm J


  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Welcome to the forum,

    It looks like a well balanced system.   The batteries are a significant part of the expense... make sure they are fairly new and are being properly maintained. 

    As for whether the system can meet your needs... that I can't answer... depends upon the energy consumption of the fridge and the air conditioner.   Also depends on your location and insolation.   If you have a generator at the site, you may need to run it occasionally.

    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    something strange there, those 2 black boxes, in the additional pictures, beside the XW look like 2 MidNite KID CC's...?? Enlarged the pic and Yes they are KIDs....  why not a full Classic 150, the kids top out at 30 Amps..? so that is about 1400W, effectively, per kid, so under 3000W total max.

    they only have 1780W...
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • BB.
    BB. Super Moderators, Administrators Posts: 33,468 admin
    Actually, the pictures are of two different trailers, or there was a modification to what was used... The 2nd to last photo is 2x Midnite Kids, and the last picture appears to be 2x Schneider/Xantrex MPPT controllers. Either is fine, but the pictures are not consistent.

    The installation looks like it was done very well... But it does come down to the question of how much power you need/expect from the system.
    • 1,710 Watts of solar panels * 0.52 off grid system eff * 4.0 hours (reasonably sunny ~9 months per year) = 3,557 Watt*Hours per day minimum nominal output ~9 months per year....
    If you are around Norwich CT, average hours of sun per day:

    MonthSolar Radiation
    ( kWh / m2 / day )

    3.6 kWH per day of electric power is not bad... It can run a full size Energy Star Refrigerator, lights, well pump, and probably some battery/tool chargers... The A/C, it is possible, but would need to know more about the A/C unit and your needs.


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Storm
    Storm Registered Users Posts: 2
    Thank you for input and advice thus far gentlemen. I will ask about the discrepancy in the posts and the age of he batteries. I plan on using this in Central Texas Bill, sorry I failed to mention that. Would adding batteries to the unit be feasible? 
  • BB.
    BB. Super Moderators, Administrators Posts: 33,468 admin
    edited July 2016 #6
    From a design rule of thumb point of view (conservative), 5% rate of charge (weekend/seasonal usage), to 10-13% rate of charge (full time off grid, >9 months off grid):
    • 1,710 Watt Array * 0.77 panel+controller derating * 1/48 volt battery bank * 1/0.05 rate of charge = 549 AH @ 48 volt bank maximum
    • 1,710 Watt Array * 0.77 panel+controller derating * 1/48 volt battery bank * 1/0.10 rate of charge = 274 AH @ 48 volt bank nominal
    • 1,710 Watt Array * 0.77 panel+controller derating * 1/48 volt battery bank * 1/0.13 rate of charge = 211 AH @ 48 volt bank minimum
    So, I would not really add more batteries unless you add more solar (or use more genset/plug-in grid recharging). 380 AH @ 48 volts is "comfortable" -- 760 AH @ 48 volt would be way to large of bank for the present array...

    If you want to run more solar, on the present battery bank, you could very nicely justify a ~3,800 Watt array (1 kW per 100 AH @ 48 AH battery bank)... And if you doubled the bank to 760 AH, then you could justify a (rough) maximum to 7.6 kWH of solar array--But that makes the a very large array (and mechanical mounts) for that trailer (~4.4x larger solar array than presently on the trailer).

    Again, the above numbers are weighted to using lots of solar and little genset/plug-in recharging power...


    For Fort Worth Tx:

    Fort Worth
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 57° angle from vertical:
    (For best year-round performance)
    Jan Feb Mar Apr May Jun
    Jul Aug Sep Oct Nov Dec

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