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Fifth Wheel 1200W Solar, Growatt 24V/3000W Inverter, Four SOK 12.8V/206AH 2S2P Design/Build

Hagrid

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Jul 19, 2021
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I've spent the last two months designing and building a solar power system for my Grand Design Reflection 5th Wheel. I put it in the front storage compartment - the one that faces the pickup's tailgate.

I've put 6 200W panels on the roof connected 3S2P to a Growatt 24V all-in-one solar charge controller/ATS/3000W inverter. 24V and 12V connections are through a Victron Lynx Fuse block/buss, and I'm powering my 12V house system via a Victron Orion 24-to-12V converter and Rex buss bars, which replace the old house batteries and are wired directly to the house DC panel.

The battery bank consists of four SOK 12.8V 206 AH (2636WH) batteries wired 2S2P to provide a total of 824 AH at 12.8V (412AH of 24V power) for a total of over 10,000 Watt Hours.

Only one hot leg of the shore power/generator connection is wired directly to the AC-in side of the Growatt. The 3000W inverter output is wired directly to my house AC panel and I've jumpered it to both sides of my former 50Amp service, so that I have 25Amps of 120VAC available when the inverter is turned on. The batteries will charge from either or both at once of 1) solar panels, 2) shore power/generator.

My goal was to have a practical system for long-term boondocking, so I've been willing to give up the 50Amp service for a more modest 25Amp AC service. I also have a Micro-Air Easy Start for my air-conditioner, which I have not wired in yet. I look forward to seeing if I can actually run my A/C unit on solar/battery power out in the desert this summer.

UPDATE: We took the rig out to the Oregon Coast for a four day weekend, and never hooked up to shore power. We used the AC outlets to our hearts' content (microwave, fireplace/heater, boil kettle, phone chargers, hair dryer, etc.) and the batteries held up amazingly well -- we had nice blue skies and warm temperatures at the Brookings Harbor RV Park, and even with the low January sun angle, our batteries stayed nearly full for the entire four days. Couldn't be happier. I'm now looking at ways to install a manual switch that will allow me to use 50A shore power if/when available.
 

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I've done similar to my Keystone 35ft (30A) trailer. Used 6/210w panels into a Growatt 24v/3000 (mounted on televator) w 2/170AH bigbatteries.com batteries, that is then plugged directly into the stock trailer wiring (via a male plug in the floor).

***** One key thing I would recommend to all is to rig up incoming shore power connection with a by pass switch to be able to plug/unplug from the Growatt/solar system. This way if there is ever an issue (like batteries drained to low and system shuts down and you can't start it up right away) you can just switch/unplug the solar system form the power loop and go back to stock set up -- to direct shore power or generator. *****

I set this up as a UPS system - autoswitching. Programmed to use shore power first, batteries/solar second. Plug and unplug from shore power, travel, doesn't matter, trailer stays 100% powered. 120v/12v...the freedom and convenience is awesome.

As a side note, I did not use a A/B bypass switch for incoming shore power, I just mounted a male connector into the floor (were the stock wiring originally led into from the side wall), and added the corresponding female plug on the shore power cable. I also added a female plug to the Growatt AC output (and a male plug to the incoming AV charger). So I can plug in shore power 1) directly into trailer and bypass the solar setup or 2) into the Growatt, that then outputs to the male connector in the floor to the trailer.

The neat thing about this is (I didn't plan this), I can reverse the shore power cable (which is just stuck through a wall grommet in the wall in mine), and export my power externally (see pic). If the trailer is by our house for instance, and the grid power goes down...I can power my house items like fridge/freezers/heaters/lights etc. and be recharging batteries via solar. It's the best of both worlds.
 

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