Forum Discussion

azrving's avatar
azrving
Explorer
Apr 25, 2015

Solar plan

i read all of the posts of the solar installs and try to read everything that comes through. I didn't buy a trimetric or anything else to measure my use but some suggest matching it to the battery amp hours. I have 4 gc 2 Sams club batteries so about 400 ah. One online calculator said I was around 55 amp hours a day so it would seem that I could go 4 days but that's not true. It's more like 2 days and obviously depends on several factors.

Factors like how cold is it, how much water I pump from a 6 gallon jug on the ground and through my winterizing valve into the fresh tank, number of hours of 40 inch led tv which draws 6.7 amps. I have looked at the other heating options and could only really go with the cat platinum vented but have nowhere to mount it. I like my furnace as it does a great job, it just sucks 5 amps.

I understand how to cut down on energy use in several areas but I dont want to conserve, I dont want a wool hat in bed, I dont want extra bedding, I want to be just as comfortable in the RV as I am at home. The main reason I leave the north is to escape the cold, not to go camping or compromise on comfort. Not sounding snobbish just saying that everyone does it differently. I have wondered why I see people walking around inside big rigs with a flashlight only????

So far I have done it with 4 cheap batteries, an PD 4655, a Quick Charge brand battery charger 50 amp and a mega watt 30A 15.5 v power supply. I have had extremely short generator run times. probably because of hitting them with 105 amps and doing 15 volt top charges.

So right now I made it through the winter and I'm in the process of watching the batteries. I'm not worried about them but I am amazed at what they have done for me. I figure they should last 4 years for $350.00 so if they only last a year and a half that's fine. That's a $225 penalty for what I put them through. No big deal or I wouldn't have spent $3,000 on diesel fuel.

One thing you guys had mentioned is the generator noise out in the desert. I have never been out there and always pretty much woods camped so far. My Honda is in an insulated cabinet in back of my truck and is very quiet but when I visited west Texas I found out what you mean about the noise. It's a whole different game out in the wide open areas.

So it's time for solar. I dont plan on inverting to the heavy stuff. I always start any measurements with one question and that is do you EVER want to run the AC? I do, so I'm going to have the Honda 3000 with me. I will just push the remote start button for the Honda to run the the micro, hair dryer or toaster.

I'm thinking about 3 160 watt panels or 4 120 watt, a Morningstar PWM 45 Tristar. I would like to do this one time and do it right. I think I would be around $1,500 or so. On top of that price I may go to Trojan's or Crowns if my turds are shaky after running them this summer.

What am I messing up on? I like the idea of connecting straight to the panel box instead of those mc type connectors?? I have a crimp tool for all the connections. I also have a bit of 6 gauge on hand and will buy whatever is needed. I think I can make a combiner box and go thought the frig vent with Home D components. The controller will be within a few feet of the batteries. I have blue seas switches that let me separate banks for equalizing and charge either or both banks from either charger.

I dont want to have to go up there to tilt but I will make them tilt-able just in case.








Less chance of shadows?


If I use 4 panels they would probably be more like 22 inches wide I believe.


Thanks for your help and all the excellent reading you have provided. I made it through the winter because of you guys.
  • westend's avatar
    westend
    Explorer
    Apr 25, 2015
    rjxj wrote:
    Westend, Thanks, I have never worked with MC4. I had this impression of light weight quirkiness or funny ends. I did notice a forum comment about people voiding their warr by cutting the mc4 on the panel.
    Most of the issues with ditching the stock MC4 connectors and using straight wire probably has to due with the way the box on the module is built. Some are glued together and some have plastic bits that don't like to release and be put back together. The MC4 connection terminals are weatherproof and easy to use. They are built with (+) and (-) phase differently so phase connection is hard to mess up. They also have a UV resistant jacket, as mentioned.

    I would definitely weigh the differences between 24V and 12V modules. There are pluses and minuses for both. FWIW, I chose to use a single 24V module because it has greater power density, is easy to install (rather than 2 x 12V), and price/watt. I may add an additional module in the future so I wired everything with that in mind. I use a Morningstar MPPT-15 controller, at present, and may just purchase another if I upgrade. I've found that the Morningstar is a good product, plenty of functionality and does everything well.
  • azrving's avatar
    azrving
    Explorer
    Apr 25, 2015
    I should add to my comment about my gc2's being turds. I'm just joking around and would possibly buy them again. They have done well for us. In fact I have commented on here in the past about a set of 4 group 27's that I run in series in a 48 volt electric pontoon boat. Those are also considered cheap batteries but I have charged them with a Lester 48 volt industrial charger that regularly hits 61 volts. They were purchased in the summer of 2008 and I just put them back in the boat after leaving them on a battery tender for 7 months. One of them died last fall and I put a like size gp 27 from 2012 in the mix. so 3 are from 2008. That little tender kept up all 4 in parallel with a sg of 1.280.
  • time2roll's avatar
    time2roll
    Nomad
    Apr 25, 2015
    Call for accurate shipping but I recommend finding a supplier to pick up in person.

    Three panels is easier in series to stay under the max controller voltage. MC4 was plug and play for me. No crimps, No combiner box. Just a straight pull down to the controller.
  • azrving's avatar
    azrving
    Explorer
    Apr 25, 2015
    smkettner wrote:
    Call for accurate shipping but I recommend finding a supplier to pick up in person.

    Three panels is easier in series to stay under the max controller voltage. MC4 was plug and play for me. No crimps, No combiner box. Just a straight pull down to the controller.


    I just logged in at solar blvd and it keeps saying 10 panels at 448 pounds with a shipping charge of over $400. If I want them overnight it's $3,600. I will email them. So does it mean I could use a MS mppt 45 Tristar or mppt 60? So my only risk if running series is I'm more susceptible to shadows or shade?
  • NinerBikes's avatar
    NinerBikes
    Explorer
    Apr 25, 2015
    Golden_HVAC wrote:
    I like the bottom picture with 4 panels. I have a total of 415 rated watts, and my Tri-Metric would read -120 AH in the morning in January, and I could fill the batteries by sundown.

    My RV used 35 Ah daily to run just the CO, propane detectors and refrigerator. The water pump is insignificant, as it can pump 2 GPM for a hour and empty a 120 gallon tank with 7 amp hours.

    I liked watching a bunch of TV, and had a direct TV receiver, and ran a 19" tube set. Now I have a flat screen, both used about 80 watts.

    I agree that the microwave should be run from a generator, as mine went bad because I ran it on my Trace 1500 watt MSW inverter for about 5 minutes, it never cooked as well on shore power again!

    While possible to run the A/C from a 2KW pure sine inverter, it would take about 800 watts of solar to do it! I do not have that much free area on the roof.

    SunElec.com they sell aluminum frame solar panels in the $1 - $2 per rated watt price range. Make sure that you are getting panels with a frame, or you will have noplace to mount them.

    I cut 6" long 2" angle aluminum (Home Depot) with 3 holes 3/16" for #10 screws into the roof (with rubber roof sealant that helps hold it down, even if the screws where to be removed) and a 5/16" hole for a 1/4-20 bolt into the solar panel frame. A Nylon locknut will discourage any would be theft.

    Home Depot also sells grey Romex rated for direct burial, and exposure to sunlight. #10 wire can handle about 12 amps, so if you are running 7 amp panels, I have two on one run, but it would offer less voltage loss to have one panel per wire run. I ran the wires down my refrigerator vent to the controller.

    Some MPPT controllers can handle 48 volts (or more) input, so you might be able to string up 4 panels in a row, and the controller can take in 75 - 100 VDC and put out 12 VDC to the battery at much higher amperage. Then one run of #10 wire will handle more than enough amperage.

    I would recommend a pair of 20 amp controllers PWM (they are only about $25 - $35 each) and #10 wire connection for each pair of 100 - 150 watt panels). That would probably be a lot less expensive to install than a MPPT controller and less expensive wiring. The money saved could pay for one of those 150 watt panels at a place like SunElec.com

    I debated a lot about installing the Trimetric. I ended up buying it because the wife said so. For the cost back in 1997, $375, I would have been able to purchase another 75 watt solar panel. But the wife said so. The Trimetric does not add more amp hours to the battery, just monitors it very accurately. It was nice to know how full the battery actually was. Back in 1999, the 120 watt panels where $429, now it is much less.

    So the MPPT controllers are to expensive to be worth the extra 10% in power that they claim to put into the battery. The Trimetric is also a expensive accessory that is not going to add any amp hours.

    Good luck!

    Fred.


    I think the two PWM controllers and 4 150W panels, laid flat, no sun chasing, should about do it. About 16-17 amps per pair of panels, run parallel to each controller. Run each controller to a pair of 6V batteries. Extra wattage is in use for laying panels flat, they won't pick up quite as much juice in the winter, unless you chase the sun aiming them, pretty hard to do with roof mount. Not hard to do if you have a gimbal mount or the panels are portable.

    But Fred pretty much nailed it.
  • JiminDenver's avatar
    JiminDenver
    Explorer II
    Apr 25, 2015
    I don't believe in sacrificing either after roughing it for 20 years. That doesn't mean I can't save power with LEDs, lower power TV, fans, etc. The batteries will have shallower cycles normally and last longer in the not so wonderful times.

    So I'm covering the roof and filling the battery bay. I'll make the panels tiltable if I have to but I hope to avoid it. I think I'd rather put out a portable than climb the roof.

    With as much solar as you have planned you will find out as I have that it will act like a micro generator. We don't have any huge loads over night so the batteries hit float early and stay there unless we run a big load. Those are short so what isn't covered by the solar is replaced quickly. My system was designed to be able to run a small air conditioner directly and have the batteries stay in float.

    I too have done the cardboard thing, have the panels and controller. Am still working out the batteries and wiring but hope to mount it all soon.
  • time2roll's avatar
    time2roll
    Nomad
    Apr 25, 2015
    rjxj wrote:
    I just logged in at solar blvd and it keeps saying 10 panels at 448 pounds with a shipping charge of over $400. If I want them overnight it's $3,600. I will email them. So does it mean I could use a MS mppt 45 Tristar or mppt 60? So my only risk if running series is I'm more susceptible to shadows or shade?
    The trouble is these big panels need to go truck freight not UPS/FedEx so not very cost effective unless shipping 10+ panels.

    Is there a city/state that we can recommend a supplier?
    I like SolarBLVD because it is an easy drive for me to Norco CA.

    Three panels in series the 45 should be fine. I go the 60 for 675 watts and it is probably bigger than needed. Worst case the 45 would limit amps to 45 for a short period. The controller will limit amps and protect itself so you can overdrive it a bit. The 60 may have a few more features so no regrets to upgrade.

    If you go four panels you will need to go 2 series 2 parallel to stay under the controller 150 maximum voltage rating.

    ALL solar panels drop power quickly with shade issues. These panels have bypass diodes to allow current to go around shaded portions. IIRC most are split into three sections with the diodes so you lose 33%, 66% or 100% of the panel depending on conditions. I have camped plenty in the shade and the battery still gets charged. Much debate on this and I think it is mostly a wash with certain shade conditions better for parallel and others better for series.
  • azrving's avatar
    azrving
    Explorer
    Apr 26, 2015
    smkettner wrote:
    rjxj wrote:
    I just logged in at solar blvd and it keeps saying 10 panels at 448 pounds with a shipping charge of over $400. If I want them overnight it's $3,600. I will email them. So does it mean I could use a MS mppt 45 Tristar or mppt 60? So my only risk if running series is I'm more susceptible to shadows or shade?
    The trouble is these big panels need to go truck freight not UPS/FedEx so not very cost effective unless shipping 10+ panels.

    Is there a city/state that we can recommend a supplier?
    I like SolarBLVD because it is an easy drive for me to Norco CA.

    Three panels in series the 45 should be fine. I go the 60 for 675 watts and it is probably bigger than needed. Worst case the 45 would limit amps to 45 for a short period. The controller will limit amps and protect itself so you can overdrive it a bit. The 60 may have a few more features so no regrets to upgrade.

    If you go four panels you will need to go 2 series 2 parallel to stay under the controller 150 maximum voltage rating.

    ALL solar panels drop power quickly with shade issues. These panels have bypass diodes to allow current to go around shaded portions. IIRC most are split into three sections with the diodes so you lose 33%, 66% or 100% of the panel depending on conditions. I have camped plenty in the shade and the battery still gets charged. Much debate on this and I think it is mostly a wash with certain shade conditions better for parallel and others better for series.


    I'm wondering if that large of a panel will be a negative if I get a newer rig some day. I mean at 65x40 is not like some of the huge square ones but not as nimble as a 60x26. Do people usually leave them or move them?

    I'll call them and get a shipping price. High shipping costs may not be the thing to worry about if it offsets the other costs.

    Would this large of a panel still be tilted even when mounted vertical? Would it be an added wind damage risk over mounting horizontal?

    I do like the idea of going to almost 700 watts. Like an engine, there's no replacement for displacement. Going by Handybob and others I could probably do pretty good with 2 of those at 460 watts and a mppt 45 Tristar. BUT for a little more I can have a mppt 60 and have extra capacity. BUT going down in size, I can just go pwm. I need to start writing it all down. Tomorrow.


    Thank you everyone
  • NinerBikes's avatar
    NinerBikes
    Explorer
    Apr 26, 2015
    I kind of see roof mounted solar panels as fixtures. Once they are affixed to your RV, they become part of the real estate, a permanent fixture. Don't want holes in your roof if you remove them. Considered a permanent Home Improvement.

    Now portable goes with the owner, upon the sale

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,188 PostsLatest Activity: Jan 17, 2025