Had to put my plans on hold. Now ready to go. Help me design my system please?

minisolar Solar Expert Posts: 158 ✭✭
Hey everyone, I own a piece of land that I would like to park a travel trailer on. I still haven't bought a travel trailer. My plan is to use the travel trailer as a cabin for the next 3-4 years while slowly finishing up my cabin next door. Then I will transfer my system there - while possible keeping the panels in the same location. We will probably go up every weekend or so and stay for 2-3 nights at most but likely just 2 nights. 

I am hoping I can get some forum help with designing and installing my system. I think I know what big components I need but I do not know the exact other parts and also about how to connect it all together. Maybe first I will list what I think I will buy so far (obviously feel free letting me know if I should get something different) 
All the other important stuff, cables, shunts, disconnect switches, combiner box and so on - I hope I can get help with to build a diagram so I can build this. And obviously notes on what I chose so far are greatly appreciated. 

Design notes:
  1. I own a honda generator 2000. Which I will use to boost my system if need be. I also own IOTA Engineering DLS30 
  2. I want a dedicated wall plug of 5v usb to charge phones and such. 
  3. I need a dedicated 12v charger for my dewalt batteries. I saw they sell one that plugs into the car lighter? can I incorporate that one in my system? 
  4. Run power to the fan in the outhouse. a 12v dc fan that is unless easier to run ac? 

General questions
  1. I am assuming that whatever trailer I will buy I will be able to wire my system to feed the 12v from my batteries directly and my ac from my inverter directly to camper's ac system without too much complications? is that true? 
  2. I want to have a few dedicated usb wall ports with 5v and 2.1 amp (or similar) that will run directly from my batteries to charge our phones and tablets. Is that something worth doing for the power savings? I will charge two phones and two tablets each night. 
  3. My place is in upstate NY. Not 100% sure I will go up to the cabin in winter but if I am. Should I always bring my generator to charge the batteries when I get there then before leave so they stay in fairly charged mode? 


  • 706jim
    706jim Solar Expert Posts: 514 ✭✭✭✭
    You can charge phones and tablets from 12 volts as they don't take that much power. Otherwise, you're better off running from your inverter through 120 volt wiring and using transformers. Don't waste a lot of effort ton 12 volt wiring. Too much line loss and no decent standard connectors IMO.
    Island cottage solar system with 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 30th year.
  • Wheelman55
    Wheelman55 Registered Users Posts: 236 ✭✭✭
    edited May 2020 #3
    Suggest that you think small for now. I’ve done the same as you and lived happily with a 180 watt folding solar panel/pwm charge controller combo. This easily powers my 220 ah 12v battery. 

    We run two ARB fridges, two iPhones, 2 tablets, a Caframo 12v fan and two headlamps with this rig. 

    I built up a battery station with both USB and 12 v marine cig plugs to power things. I’ve got a 3 stage charger for the battery for just in case it’s cloudy. Also run two Honda eu2000i’s. 

    Something this simple could power your needs. 

    A neighbor brought in a small camper trailer and borrowed two 200 watt panels. They ran his trailer just fine. Fans, fridge, lights, devices. So maybe buy a trailer set up for solar and only buy panels. 

    I have a 12 v charger for my Makita batteries. It takes forever to charge a battery. Suggest you use the Honda to charge the batts with AC power. 

    Then when it’s time to power up the cabin you can buy the right gear. I’m betting that your need for power will change between now and then. 

    Off-Grid in Terlingua, TX
    5,000 watt array - 14 CS 370 watt modules. HZLA horizontal tracker. Schneider: XW6048NA+, Mini PDP, MPPT 80-600, SCP. 390ah LiFeP04 battery bank - 3 Discover AES 42-48-6650 48 volt 130ah LiFePO4 batteries
  • softdown
    softdown Solar Expert Posts: 3,822 ✭✭✭✭
    edited May 2020 #4
    Use a small fan in the outhouse. I'd use none at all and use natural ventilation to keep odors reasonable. Small loads add up. I have a medium large solar system - it was still worth it to replace the 50" tv with a 40" tv. Now I consider replacing the fridge with an inverter fridge.

    It takes a lot of power to charge the better lithium tool batteries. Why not charge the phone with your cars 12 volt outlet? Keep the solar system simple though you sound like you know what you are doing.

    Upstate NY in winter with no usage? I might disconnect the batteries for three months at a time. Self discharge is slow when cold.

    Building a cabin eh? It will take longer and cost more than planned in all likelihood. Best be prepared for the unexpected. We will likely experience a recession due to shutting down the economy. Cheap labor may become eagerly available.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • MichaelK
    MichaelK Registered Users Posts: 234 ✭✭✭
    I can see a couple of decisions already that I would question?  First, I would discourage anyone from designing a 12V system for anything that's not on wheels.  In the long run, you'll be much better off starting out with at least a 24V system.  Especially if you're planning on running any power-tools off the system.  I just built a workshop some distance away from my 48V cabin, and designed a 24V standalone system for it that I'm very pleased with.  It runs my tools effortlessly.

    The second problem I see is the purchase of expensive 12V panels, and wiring them in parallel. You're going to spend 320$ (plus tax) for 400W of panels.  You'll get much more bang for your buck buying grid-tie panels.  Just two months ago I bought four 240W grid-ties for 220$.  I'm getting more than double the watts for just 2/3's of what you will be paying.  Since you're buying a MPPT controller, you'll get less voltage drop wiring panels in series, rather than parallel.  Even if you've already purchased the 12V panels, wire them in at least a 2S2P configuration. You could wire the grid-tie panels exactly the same way.

    I'm actually helping a neighbor do it that way right now.  Since I got such a good deal on my panels, he wanted some.  I however got him the 40A Renogy controller instead if the Epever, though their specs are almost the same.  Actually, the Renogy might actually be made by Epever.  His system is four Trojan L-16 batteries wired in series for 24V, four 240W grid-tie panels, and a Renogy 40A MPPT charge controller.  For the 380$ he spent on just the panels and controller, you couldn't buy even 5 of those 100W panels.

    System 1) 15 Renogy 300w + 4 250W Astronergy panels,  Midnight 200 CC, 8 Trojan L16 bat., Schneider XW6848 NA inverter, AC-Delco 6000w gen.
    System 2) 8 YingLi 250W panels, Midnight 200CC, three 8V Rolls batteries, Schneider Conext 4024 inverter (workshop)
  • minisolar
    minisolar Solar Expert Posts: 158 ✭✭
    Thanks fro the input. 

    Michaelk - I would love to buy cheaper panels but so far I have not been able to find any online that are cheaper... Maybe you can steer me to the right direction? 

    Can you please elaborate on why I should go 24 vs 12? btw I cannot go grid tie. I don't have power on my land. If it just to run tool then I am not sure if that is worth it for me. Only tool I use continuously which is wired is my miter saw which I can always power with my generator if I need to for that once in a blue moon usage. This is a weekend cabin. 

    Also, I have read that unlike lead acid, AGM are maintenance free and require no equalization. Even read that they are better for seasonal cabins because of that. I was looking at the sam's club gc 215ah 6v batteries. which at $90 a pop are a great deal but I am willing to pay more for that ease. Any recommendation on where to get inexpensive agm's? 

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Here's my simple suggestion for a starting 24V system
    Four Golf Cart 6V 200ah batteries.  24V 200ah bank.
      your 400w of panels can provide 13A of charging, a bit on the lightweight side, but 2 more panels, for a 3S2P solar array with a decent 30A controller, will give a fairly simple but effective system
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • minisolar
    minisolar Solar Expert Posts: 158 ✭✭
    I just posted my diagram. Can you please look it over and tell me what I am doing wrong, missing, and how you would have done it differently? https://forum.solar-electric.com/discussion/355740/please-critique-my-plan-diagram/p1?new=1
  • Thom
    Thom Solar Expert Posts: 196 ✭✭✭
    2000w inverter I would go with 24v system. 2000W @12v it would draw 166 A . 
    Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator . Added 2@ 100w panel with a midnight brat