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Brainstorm - Solar trailer to power Off grid Gooseneck trailer/homestead.

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May 31, 2022
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My mother lives off grid. Way off the grid. She is currently using a mix of several gasoline generators to power various zones. One for the gooseneck trailer she lives in, one for her outdoor kitchen, and not sure what the third one is for. She is spending close $1000 a month on gas for generators.

She lives in a 35' or so gooseneck. Not sure the year/model. She has a couple 20 foot box trailers full of various items she calls them her workshop and her studio, but really they are primarily storage.

I am pondering suggesting she build a solar system. Place the batteries, MPPT, etc in one of the trailers, and store the panels in the same box trailer when she relocates from time to time. Ground mount them when not in use.

How inefficient would it be to run from the solar box trailer to the goosenecks power connector? I still need to find out if it is 30 amp or 50 amp.

If 50 amp and I didn't want to use a 30-amp to 50-amp adapter, would it take two MPPTs to feed the two separate 120 connectors? RV 50 amps are actually 2 120 volt connectors instead of one 240 volt.
 
My mother lives off grid. Way off the grid. She is currently using a mix of several gasoline generators to power various zones. One for the gooseneck trailer she lives in, one for her outdoor kitchen, and not sure what the third one is for. She is spending close $1000 a month on gas for generators.

She lives in a 35' or so gooseneck. Not sure the year/model. She has a couple 20 foot box trailers full of various items she calls them her workshop and her studio, but really they are primarily storage.

I am pondering suggesting she build a solar system. Place the batteries, MPPT, etc in one of the trailers, and store the panels in the same box trailer when she relocates from time to time. Ground mount them when not in use.

How inefficient would it be to run from the solar box trailer to the goosenecks power connector? I still need to find out if it is 30 amp or 50 amp.

If 50 amp and I didn't want to use a 30-amp to 50-amp adapter, would it take two MPPTs to feed the two separate 120 connectors? RV 50 amps are actually 2 120 volt connectors instead of one 240 volt.
Best to do a little more research. You should find out what her actual power consumption is and what her maximum amperage draw is. A clear picture energy consumption
Is key to designing a system that will work and to calculating the efficiency of such a system.
 
MPPT's charge DC batteries, sounds like you need a AC invertor to feed the 120, or 220 trailer power connection.

You can use "all in one", or so called "hybrid" inverters which combine the MPPT charge controller with a Invertor.
 
Place the batteries, MPPT, etc in one of the trailers, and store the panels in the same box trailer when she relocates from time to time. Ground mount them when not in use.
Just to throw the noodle out there, how old is mom and what is going to be physically involved in deploying and packing in the panels? And you mean ground mount them when IN use? A hinged mount on the roof/roofs with a hand-crank lift/drop system might be more effective in the long run. Just thinking out loud....

How inefficient would it be to run from the solar box trailer to the goosenecks power connector? I still need to find out if it is 30 amp or 50 amp.
As long as you're converting the power to AC in the trailer BEFORE you send it to the goose-neck you should be fine. You might have to use a thicker wire to compensate for voltage drop but it shouldn't be too bad.

If 50 amp and I didn't want to use a 30-amp to 50-amp adapter, would it take two MPPTs to feed the two separate 120 connectors? RV 50 amps are actually 2 120 volt connectors instead of one 240 volt.
MPPT is the charge controller between the panels and the batteries, it isn't your inverter. As for going with dual inverters, you can either go with a split-phase output inverter separate from the MPPT chargers OR many of the 5Kw+ All-In-Ones are really just 2 single units strapped together in the same box. One of the "Gotcha's" with those units is that since they put out 220v split phase power, if you want to hook up a generator it has to feed the same power going in, which requires a split-phase power generator.

There are pro's and con's to either direction.

Let me throw up my stock response to questions like this, hopefully it'll point you in the right direction on figuring out the best way to make a system that works for your mom's needs. :)
 
Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. :) Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round :) ) and help figure out which parts and pieces you're going to want to get.
 
Lots of good points already.

I've bumped into this situation several times so I can share some experience with you. It can be very overwhelming to figure out exactly what you need, sometimes it's overwhelming enough that the project dies. Assuming it moves forward it could take a while to get all the details figured out, especially if you are trying to do it right.

I would offer that getting a decent inverter charger and modest battery bank installed ASAP will likely cut the monthly fuel costs by 75% or more. Now you're running the gennie at nearly full load for few hours every other day then coasting on the energy stored in batteries the rest of the time. Big time fuel savings. Just guessing but I suspect the gennie's are currently spending most of thier time with almost no load on them.

Then you can finish designing and acquiring the rest of the system while saving a lot of money on gas and the hassle of getting it to the site.
 
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Where? She is on the east slope of a ridge in Northern California. I know that limits evening sun and a factor in planning this. For simplicity I was thinking one of the all-in-off grid units like one of the EG4.
 
Lots of good points already.

I've bumped into this situation several times so I can share some experience with you. It can be very overwhelming to figure out exactly what you need, sometimes it's overwhelming enough that the project dies. Assuming it moves forward it could take a while to get all the details figured out, especially if you are trying to do it right.

I would offer that getting a decent inverter charger and modest battery bank installed ASAP will likely cut the monthly fuel costs by 75% or more. Now you're running the gennie at nearly full load for few hours every other day then coasting on the energy stored in batteries the rest of the time. Big time fuel savings. Just guessing but I suspect the gennie's are currently spending most of thier time with almost no load on them.

Then you can finish designing and acquiring the rest of the system while saving a lot of money on gas and the hassle of getting it to the site.
Worse, she is running generators as needed at 3 different locations around the site. Almost no battery storage at all. Want to charge her phone - power up a generator. Her trailer might have some battery but she has said she relies on flashlights for light because it doesn't seem to last through the night.

Revision on this - I am going to build myself a small milk crate like solar "generator" with a few panels, and take it with me the next time I visit. Show her how simple it is, and discuss ways to improve what she does. He is in her mid-70's and a bit eccentric.

Somebody offered to sell her their DIY power/solar trailer for $25,000.00 and it seemed pretty high for a 5 year old system and probably not lithium batteries. Not sure its full specs, but it had at most 4 ~400 watt panels. That is judging from grainy pictures and limited knowledge. Person selling it had used it to power small construction sites (think hauling out to the build site for cabins / 1-3 bedroom shacks) to run power tools and lights.
 
Worse, she is running generators as needed at 3 different locations around the site. Almost no battery storage at all. Want to charge her phone - power up a generator. Her trailer might have some battery but she has said she relies on flashlights for light because it doesn't seem to last through the night.

Revision on this - I am going to build myself a small milk crate like solar "generator" with a few panels, and take it with me the next time I visit. Show her how simple it is, and discuss ways to improve what she does. He is in her mid-70's and a bit eccentric.

Somebody offered to sell her their DIY power/solar trailer for $25,000.00 and it seemed pretty high for a 5 year old system and probably not lithium batteries. Not sure its full specs, but it had at most 4 ~400 watt panels. That is judging from grainy pictures and limited knowledge. Person selling it had used it to power small construction sites (think hauling out to the build site for cabins / 1-3 bedroom shacks) to run power tools and lights.
That trailer did not sound like a bargain. I'd steer clear of that. There's often a solar trailer on eBay for $12k or so. They have ~2500 watts of solar. Thousands of them were made by a company that went bankrupt.

You might even skip the home brew milk crate for now. One or more of these portable power stations and one solar module per station will be life changing for her. That link is just meant to get you started on the road of a product, not a specific size or brand recommendation.
 
@CaliforniaCurmudgeon, your mom sounds a bit like my dad who is living in a 1970's motorhome. I sure hope they never meet. I shake my head every time I talk to my dad. He's got some crazy ideas. The two of them together could really get in trouble.

No, the $25k solar trailer doesn't sound like a good deal.

Look up threads by forum member FireTodd. He put together a "milk crate" system that his fifth wheel plugs into. His thread at the very least will show you that it can be done. He did install solar permanently on the roof of the RV.

Most fifth wheel trailers are 50 amp. If all you're doing is providing an outlet that the trailer's shore power cord plugs into, it may be a bit more simple that way than if you're trying to directly wire an inverter into the trailer's system.
 
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