Daklein
Posts: 79
Joined: Fri Sep 06, 2019 7:58 pm
Delivery Date: 02 Sep 2019
Location: Hartland, MI

DC Solar trailer system

Wed Feb 12, 2020 9:13 pm

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. https://photos.app.goo.gl/qbVKkST35cJAB9Zc9

The inverters will allow me to run pretty much the whole house, just not particular things all at same time. Like the AC that we really never use, that load will stay on a grid only panel. Will leave the EVSE in the garage on the grid, but also be able to run it from the inverters. The main panel in the basement will be fed from the inverters output. When I want (weekend days off-peak, little value in sending power out to grid), I'll also be able to AC our existing 4.7kw system enphase inverters to feed back into the battery or house loads.

It has 2650 watts of 10 panels, two strings of 5 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. Now the trailer is all disassembled. Today I took the rack off the trailer and moved it to the garden, I think I've settled on ground mounting with the existing frame racks in a line along the garden fence. Only have to buy 150 of wire and conduit, and it's semi-portable, vs hassle and materials to mount on roof which will need reshingling in 5-10yrs anyway. I'll mount the inverters in the garage tomorrow I hope, then start building a box around the batteries.

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.
2014 Leaf S Plus :o (12/2019 62kWh swap!)

LeftieBiker
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Re: DC Solar trailer system

Wed Feb 12, 2020 9:52 pm

It doesn't sound like you'll have a huge power surplus, but in cases where you do are you going to use it to charge the EV(s)?
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2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
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Daklein
Posts: 79
Joined: Fri Sep 06, 2019 7:58 pm
Delivery Date: 02 Sep 2019
Location: Hartland, MI

Re: DC Solar trailer system

Thu Feb 13, 2020 6:17 am

Yes, we'll charge the car from it some. This will not cover all of the leaf energy, but it's a start. Our electric use has increased with the leaf, and we also have a heat pump water heater on a separate meter that I could offset. If I add about another 10 panels beyond these, then we would be back to supplying all our own electric, net over the year at least.

They may be changing us away from net metering, to a tariff that values outflow to the grid at about half (7.5c) the regular retail rate (15c).

With a battery system, I can switch to a time of day rate, and send all of the existing grid tied solar out during weekday peak rate for credit, still 16 cent, vs 23 to buy on peak. Run the house on the battery and extra solar during peak weekdays, don't buy any 23c electric!! On weekend days, which is off peak, use all solar to charge house and car batteries fully and run the house. Sending out is only worth 5c, so not worth it on weekends.
Any shortfall I may need to buy back off peak is 12c, likely mid week in winter will need to.

I won't really come out much ahead with 16 vs 12 and battery charging losses, especially with flooded batteries. But I get all this additional complexity, grid independent backup power for the couple times a year the grid is down, and more toys to play with. :)
2014 Leaf S Plus :o (12/2019 62kWh swap!)

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