No announcement yet.

DC Solar auction trailer, installing at home

  • Filter
  • Time
  • Show
Clear All
new posts

  • DC Solar auction trailer, installing at home

    Hello all, first time posting here. I have a travel trailer with a medium size solar setup on it, and a grid-tie system on the house with enphase inverters.

    I recently drug home a nice DC Solar trailer. Vegas to Michigan. A little bit crazy, but entertaining so far. I'm figuring out details of how I'd like to set up the components in the garage as a grid interactive / battery backup system.

    It has 2650 watts of 10 panels, which is a good match for the Midnite Classic 250 (CP model). The panels will go on the garage roof, or ground mount outside, with the CC inside with the 2 SMA inverters.

    It has 2 forklift batteries on it. They are 24 cell, 48v, 540Ah rated, and 1900 pounds each. They will go in the garage because that's as far as I'll be lucky to move them, with a vented battery box around them. They were on this solar trailer since mid 2018 based on an inspection tag I found on the trailer, and I think just maintained by the Midnite CC some of that time. The CC shows 700 kwh lifetime, which would be an average of 2.5 kwh per day. The CC was turned off and the pack OCV was about 51 when I got it, and they needed some water added, the level was a little below the top of the plates. We'll see how they work out. So far they seem normal for the ambient temperatures and limited solar here, I charged the car a little from it a couple times.

    One initial question is how to best use the two packs in parallel. On the trailer, there are just anderson connectors into a 2/00 Y cable to the SMA input, no fusing or breakers beyond the input breaker on the SMA. I would like to have a mid string fuse or breaker on the end of each battery to protect from operator error near the main 48v bus. I wonder about laddering between the cells in the two packs to prevent imbalance. Any opinions or experience with using two large packs together? Fusing, breakers? Add to this topic over here?

    Another interesting point I noticed, the output of the CC was run out to the battery on it's own with a nice large #4 or so size cable and tapped onto the positive of one of the two batteries. Good that the CC sees a good voltage signal of the battery, compared to connectign to the + bus at the front of the trailer with other items taking some current from there. But bad that the second battery has a longer length of cable and 2 anderson connectors extra resistance. So I would guess that second battery might be not as good condition as the first one.


  • #2
    Nice purchase Dale, I see they are having another auction the end of February. 60 more trailer units. Did you bid online or make the trip down? Any info would be appreciated. Would you know the weight of trailer and trailer hitch size?


    • #3
      Originally posted by Andy Muzik View Post
      Would you know the weight of trailer and trailer hitch size?
      There is/was only online bidding as far as I know. They had pickup the following day thursday through at least the following monday. The plain solar trailer I estimate was 6-7000 pounds; 4000# batteries, 1000# trailer, 500-1000 pounds in the box on the front, and 1000 for the solar panels and the frame they're mounted on. The trailers have a pintle hitch lunette ring on them, can see in the pictures. I unbolted that and bolted on a 2 5/16 ball coupler, (curt 25330, picked up from an Amazon locker once I got to Vegas), and used a hitch with load distribution bars from my camper.


      • #4
        Dale, how is yours working out so far? Especially the batteries. I just picked up one of the trailers at auction. Hoping the batteries are not shot.


        • #5
          Was there another auction? I didn't see.

          There's a FB group with the most discussion I've seen so far about the trailers. 'DC Solar Auctioned Trailer Discovery'

          My battery seems to be ok. Others are fine also, but at least one or two had some overdischarged or dead cells.


          • #6
            Since I live in Las Vegas, I've been tracking the Global Auction sales locally. They have one scheduled for the second week of June. Another auction I frequent in Phoenix, called Cunningham auctions, just had 3 of them.


            • #7
              Neat! Since you're local, go inspect them and check them out. The SMAs have a stored histogram of percent time spent at SOC, at least while the SMAs were turned on. Between that, and looking at pack voltage as you find them, and what the Midnite says for generation kwh, it should be easy to see if a particular one is good.

              Is there a listing for the June auction, how many more will they be selling? I don't see anything yet at,


              • #8
                There are still hundreds of units parked at the Las Vegas Motor Speedway. I know some folks that might let me in there, but I have no idea which are coming up for auction. I could never inspect all of them. When I know the auction details, I can go take a look at them


                • #9
                  A couple more for auction in Phoenix tomorrow.