Non-Mounted RV Solar

idahoboondock
idahoboondock Registered Users Posts: 5
This will be my first venture into the solar world. I have done a lot of internet searching to come up with this plan. Now, I'm hoping some people with experience could add to it or tell me if I've overlooked anything.

I have a pop-up trailer which I use for non-site camping. I have done some energy calculations which show that I use about 20ah per day out of my group24 flooded deep cycle battery. I am hoping that I can extend my camping to about 2 weeks without running out of power and I do not want to disturb the peace with a generator. Given that I like to park in the shade, I do not want to mount panels on the roof. I plan on having a panel that I can move around throughout the day to face the sun and pack in the trailer when not in use. Here is my current Plan.

1 60 watt polycrystal panel, Morningstar Sunkeeper 6a controller that mounts to the panels junction box, 25 ft of 10/2 wire, inline blade fuse close to battery, alligator clips that attach to batterry.

Question 1 Do I need a fuse between the panel and the controller?
Question 2 I realize this contoller is optimized for sealed batteries, and I will probably get some loss as it travels the 25 ft extension. Would I be better off using a Sunsaver controller close to the battery? Maybe velcro it to the batt box when in use.(it would be protected from rain by bunkend).
Question 3 Any suggestions to make a better system or cheaper one for my purpose? Or did I mess up anywhere?

Thanks

Comments

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Non-Mounted RV Solar

    First thought,,, more to come surely,,, Instead of alligator clips,, which are not very "current" worthy,, consider doing a permanent install at the battery with proper lugs,,, and then use and Anderson connector to plug the system in. That way you eliminate the possibility of reverse polarity with potential damage to the system. http://store.solar-electric.com/anhicupoco.html

    Since you haven't told us what your loads are,, 12 vdc 120 ac or what,,here is a general rule of thumb to figure your solar capacity.

    If you take the name plate wattage rating of the solar panel,, multiply it by the number of hours of GOOD sun per day,, (4-6 usually) divide that number by 2 and you get a pretty quick ball park wh number of useable power out of an inverter. If you don't use an inverter and all your loads are 12vdc then that number would be a somewhat higher.

    So in you case, your 60 watt panel would be 60X6X .5+180 watt hours/day of usable power. So your 20 ah would be something like 20ampsX 12.4 vdc= 248 wh

    So you can see that you are too small right off the bat. Consider upsizing the panel to ~100 watts. Also you have not built in any reserve for days (or hours) of no sun.

    I wouldn't worry about the 25' cord,, but I would use a #14 or preferably #10 or #12 cord.

    Yes,, you do want a fuse between the battery and the controller.

    Good luck.

    Tony

    PS I would add that loads ALWAYS grow with time, and people tend to over estimate the number of hour of GOOD sun they get. Both of these have the net effect of changing the above numbers,,, for the worse.

    You are helped a bit by the fact that you can move the panels around to follow the sun so that in fact you may get more than 6 hours/day.
  • idahoboondock
    idahoboondock Registered Users Posts: 5
    Re: Non-Mounted RV Solar

    Thanks for the response. I guess I didn't give enough info. I do not run an inverter. It's all 12v with my main draw being a furnace fan which I use sparingly. I realize that the 60w panel may be a little small, but my intention is to prolong my stays rather than be self sustaining. It's for camping in the summer, mostly high mountain with lots of sun but chilly at night. If it rains for a couple of days, I'm going home. 20ah per day was a high estimate, and I will probably be switching to a group 27 or 31 in the near future. You are right though, I should probably go up to a 100w panel. Just not sure I want to deal with packing and moving a bigger panel around. Thanks for the advice on the alligator clips. Are those anderson connectors easy to install with a regular crimper or do you need to buy their specific tool? Any suggestions on fuse size?
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Non-Mounted RV Solar

    I confess that I don't have a clue what the ah rating of a group 27 or 30 battery is. That said,, you want to avoid discharging your battery more than 50% and ideally no more than 20-30%. The biggest killer of "deep cycle" batteries is leaving them below 80% for more than a day or two. This will cause irreparable damage very quickly.

    As for the fuse,, some what bigger than the Imp of the panel. If your panel has a Imp of say 6 amps,, use a 10 amp fuse,,, as long as the fuse is big enough for the wire size.

    Anderson connectors are available in a variety of sizes. They can be had with different lug sizes for different wire gauges so that you can use a big connector for a #12 wire. They can be soldered or ideally crimped. The big ones need a real crimper,,, I don't know if the smaller ones can be crimped with a simple plier type crimper.

    This is one of the handier tools I ever bought: http://store.solar-electric.com/hacrtoforlal.html

    Nowdays,, a 100 watt panel isn't really very big relative to an older 60 watt. http://sunelec.com/index.php?main_page=product_info&cPath=5&products_id=231

    Tony
  • PhilS
    PhilS Solar Expert Posts: 370 ✭✭✭
    Re: Non-Mounted RV Solar

    I've done what you are proposing and you are on track, especially with Tony's suggestions. I used a 65W panel, because I had an extra one. I also have a 100 Watt panel mounted to the roof of our RV but since we prefer to park in the shade it never really did very much. Heck, the 25' cord I have attached to the 65W panel often isn't long enough to keep the panel in the sun long as long as I'd like. I may make a 25' extension before our next trip.

    I mounted my C30 controller next to my battery box and have a short pigtail that I can then plug the main cable into.

    I made a hole in the panel frame that I can loop a bicycle lock through... just to keep it from walking off on it's own.

    The extra panel doesn't supply all of our power but when I can catch sun, it saves hours of run-time on our little Honda eu1000i generator.

    Yes, use the lugs instead of the alligator clips. You can find polarized plugs other places, I used a 25ft 4-wire trailer harness, combining the wires into 2 (two for +, two for neg) that included male and female plugs.

    I also bought another small controller and when we aren't "camping" I put the solar panel on the garage roof and it charges the truck that I pull the RV with, since that doesn't get driven for long periods. (Just NOT enough time to go camping!)
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Non-Mounted RV Solar

    ok, he's probably in and about a 100ah battery. a 60w pv will probably give about 3.5a for a charge % of about 3.5% so you are low this way too as you should be in the range of about 5% to 13%. with a 100w pv this will be around a 5.7% charge rate and if given 4hrs of full sun should be around your needs, but going even to a higher wattage pv would allow for even shorter charge times and help with cloudy or rainy days.
    as to the fuse multiply the imp of the pv x 1.5 and round up to the nearest commercially available value. for remote pvs you should use stranded wire to allow for more flexing and strength. you also don't want to undersize the wire in its legnth or its thickness so run by us the final length and size or figure it out yourself from the voltage drop calculator in the sticky in the general solar topics area.
  • idahoboondock
    idahoboondock Registered Users Posts: 5
    Re: Non-Mounted RV Solar

    Thanks for all of the info. You have convinced me that I need more power. I think I was set on not spending so much as my wife is a bit skeptical on this idea to begin with.:cry:

    I think I am going to go for a 100 or 120 watt panel. Just have to find a good deal on one. Will be using 25 feet of cable. I figured 10 gauge would be the way to go. And I figure a 10 amp fuse should work. I do have another question....some of the cheaper panels I have looked at don't state that they have a blocking diode, but the morningstar charge controllers say they have reverse (night time) protection. Will that do the same thing as a diode in the panel?

    Thanks again
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Non-Mounted RV Solar

    Yes, a good solar charge controller will not need a blocking diode on the panel (or battery) either. Adding a diode would just waste power (and can cause other issues too).

    Remember the panels are (typically) thin, tempered glass. You need a place you can put them safely when traveling, and make sure they don't get damaged by the wind if they are out on cords. The panels are pretty impact resistant (1" or smaller hail stones should not break a panel)--But, they are glass, and once broken are pretty much scrap (cannot repair).

    And, higher wattage panels are not small; check the dimensions, a 175 watt panel is near 35 lbs--you might be better off with two 60 watt panels instead of one 120 watt panel (although the single 120 watt panel may end up being cheaper--check the $$$/watt pricing between your various choices).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Non-Mounted RV Solar

    Also, rig up some sort of reminder, to not drive while panels are deployed. Clip your ignition key to a note, or tape a note to the steering wheel, work out a scheme to remind you not to drive off....
    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 ,

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Non-Mounted RV Solar

    Better yet,, tape the ignition key to the solar panel!

    T
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Non-Mounted RV Solar

    the 10a fuse may be ok for a 100w pv, but if you were to go to a 135w pv like the kd135 from kyocera you will need a 15a fuse.
    your 25ft of #10 wire will result in a vdrop % of 3.19% if going with a pv like the kd135 with 7.63a and is generally too high of a drop for most. 2 or 3 % is generally said to be a good goal depending on cc manufacturer referenced. the voltage drop should be held to .24v for 2% and .36v for 3% and the lower it is the better. for 1 pv and a non mppt controller, this may be somewhat overkill or moot to get to that goal, but just to let you know, 23.5ft will give a 3% vdrop %.
    if you get a 100w pv, this does lower the current present making the 25ft run of #10 quite acceptable if your goal is 3% or less. note that wmp/vmp=imp. if you have a 100w pv with a vmp of 17.5v this would be 5.714a imp and would be about 2.25%.