need help with wiring panels and controller

System
System Posts: 2,511 admin
hi, i have a truck camper which i have previously installed one 110 shell solar panel and a small controller. i have it pretty mickeymoused together but it works great. i ran the wires down the fridge vent, attached the controller inside the fridge compartment then just ran the wires outside and around the inside of my truckbed to my secondary battery which i have sitting in the wheel well and then conects to the primary battery inside the camper. i drilled a hole in the bottom of the camper to connect the two batteries together. i hope this is not too confusing. this mickey mouse set up has worked well for me for 2 years. i have recently aquired 3 more 55 watt panels which i want to install 2 on the roof and just use the 3rd as an auxillary i can set out in the sun if i happen to be parked in a shady spot. so my question is this, i want to conect the 2 new 55w panels together on the roof in paralel, rather than in series right, positive to neg then one pos and neg coming out of each panel to the controller, i need to use a second controler because the ones i have are not rated individually for that much wattage. so is it ok to run the wires from my 110 panel to its own controller then run the 2nd two 55 panels together to the next controller, after i have all the panels controlled can i then join the wires together so i only have to run one set of wires to the batteries???? as for the 3rd remote panel, i wont really be too concerned about overcharging if i need to use this one. but how long of wire can i run and what gauge should i use. i once again mickey moused this for a recent trip to yosemite, i was usind a 100 ft extension cord which was only 16 gauge, but i was getting a reading of 18.3 off of the panel whether i was measuring it at 100 ft, or only at 3 ft where i conected it together. is this ok or just a waste of time. my battery gauge definately showed a difference while i had the panel plugged in. thanx for reding, any help will be appreciated!!!!! one more question, do the controllers have built in diodes to prevent discharching of the batteries at night or how do i install a diode and where can i get them?

Comments

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: need help with wiring panels and controller

    Knowing the mfg & model # of the existing controller, and of all the solar panels, is needed, so that we have enough info to give some informed advice. Since you know that you need at least one new controller, you may want to consider a controller large enought to replace your old one too.

    Since panel voltages change in response to temperature, knowing where you camper would be located on cold mornings, could affect the voltage coming off the panels. After a short time, the panels heat up, and the voltage drops down to a more normal value. If used in the desert, high temps reduce voltages, and may limit full charging.
    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

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  • System2
    System2 Posts: 6,290 admin
    Re: need help with wiring panels and controller
    sharistove wrote: »
    i was using a 100 ft extension cord which was only 16 gauge, but i was getting a reading of 18.3 (volts) off of the panel whether i was measuring it at 100 ft, or only at 3 ft where i connected it together. is this ok or just a waste of time
    A waste of a good solar panel, which will never be able to push much usable energy through that cable. Yes, with no current flow, you will read the same voltage anywhere along that cable, but under load, it will be a terrible restriction on the current that would otherwise be supplied by the panel.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: need help with wiring panels and controller

    in general you could place the 2 newer pvs onto their own controller, but seeing as how you have to obtain another controller anyway then why not buy one that will handle all of your panels and also would most likely allow for any future expansions as well?
    as to the wire you should have much bigger wires and for that long of a run, as was mentioned, you are wasting good pv power in that small wire. shortening the wire run will also help and i urge you to see the sticky for the voltage drop calculator in the general solar topics area. in general it will calculate the voltage drop for a given wire size and distance for a given current draw.
  • System2
    System2 Posts: 6,290 admin
    Re: need help with wiring panels and controller

    thanks guys for your help! im sorry i didnt mention that i allready have 2 controllers, the one currently hooked up, i believe is a bz mppt 100 or 200 its hooked up currently to a shell siemans sm110, i am running 10gauge wire down the fridge vent, i have mounted the controller in the fridge copartment away from any possible moisture, i am then running the wire (10g) to the secondary battery, my second set of panels i want to instal are 2 siemans sm55s, i am going to hook them up neg to pos, then run them through a mark 15 controller that i originally puchased with 110 panel as a kit, i am also going to run the wires down the vent , install the controller in the fridge compartment then run the wires to the battery. but do i need to run another whole set of wires or can i join them togetherafter they have run through the controllers, would it make a difference. it says in the mark 15 directions to run seperate wires to the battery for alternate chargung ie, generator , convertor, car alternator, but dosnt mention any thing about a seperate solar array. i dont want to purcase a new controller cuz i allready have 2 that work fine. i was reading in the instructions that the controller should be as close to the batteries as possible, is 10-12 ft too far away running 10 g wire? also what would you suggest for runiing an aux ilary panel in case i was parked in the shade, what gage wire and how long can i go with an extra sm 55, i have a total of 3 of them. i would be just fine w the one panel (sm100)but my beau likes to watch tv or run the sterio durring the day while we are at a full charging cycle. when finished we will have 220 watts + the extra 55 we can plug in when needed, we have 2 group 27 batteries, how many hours of say around 50-60watts would we use up in a day, i guess those bats have about a 100 amp hours each. im sorry i get confused w all the formulas, we have a 30w tv and 20 watt sat recvr, run a lite now and then, and thats it. we do have an onboard propane gen as well for the big stuff when needed. once again thanx for your help. also if you know of a diagram i could look at for the proper installation of the panels that would be awesome! i am right about running the pos to neg then down to the controler from the 2 seperate panels running one wire from each????