Couple questions if I may for future full-timing

[Lyle]

Aloha!

So I've been reading and learning as much as I can for a few months now in preparation for going full-time (while working) in a 28' gooseneck. We intend to travel and boondock as much as possible, hopefully 90-100% of the time. Mostly western US, plus Canada and Alaska. It's overwhelming, but I think I'm beginning to understand the basics. 4-5 years traveling is the current plan.

Here is my tentative plan to give you an idea of the system I'm considering:

3850 watts of solar on the roof via 7x 550w Solarever panels. It fits, with room for a maxxair.
15.46kwh of 24v diy batteries (16x 302a 3.2v prismatic cells via solarsupplyhouse.com). I believe this will give me enough of a power reserve in case of extended bad weather. Plan to leave enough space for another 8 cells if I find the need down the road.
Victron Lynx shunt
Victron Lynx distributor
Victron 2412 70v and 12v distribution panel for 12v systems
120V distribution panel
Victron Cerbo GX and Touch 70 with sensor hookups for fresh water, grey, diesel and ?
30amp? (50?) shore power hookup
Master disconnect
Solar disconnect

We'll have a 12k 110v mini-split AC, 2 macbook pros, an imac pro with 2 monitors, w/d, a pair of isotherm 12v fridge/freezers (or similar), tv, coffee, and the regular comforts of home. 12v puck lights, 12v indirect led strips. Plus we'll have Milwaukee tools to charge sometimes (m12 and m18 systems), all my camera gear (not a big power drain), and a 3hp electric outboard battery now and then. Not sure on propane stove or induction yet. I plan on installing a diesel heater so we won't have to rely on the mini-split for heat (to save energy, I figure this will greatly extend our bad/cold weather time if we get stuck for a while). I feel like I can't really do an accurate power audit since I don't physically have much of this stuff. We want to be able to boondock for 2 weeks at a time with a good battery buffer for extended days of poor solar production.

First question is what do you suggest for wiring the solar panels? Series? Both Series AND parallel? I understand that series wiring with multiple mppt's is preferred if you will be in full sun most of the time (I could do a 250/85 on 4 panels and a 250/60 on the other 3), but perhaps I've got enough watts there that doing something like 4 panels in a 2/2 parallel and then 3 in series would make sense? Best of both worlds? Would save a bit on a smaller 150/85 mppt, but my main objective is obviously to max out my efficiency while counting on enough coming in. Feel like I have some cushion here with plenty of panel. Was thinking of keeping it to two mppt's as that's just one distributor, but wonder if going to 3 or 4 and everything in series would be the way to go. I'm happy to add a second distributor if you tell me more mppt's is an improvement. As you can see my head is spinning with the possibilities. We will not have a generator and hopefully never be on shore power. Our sun/shade/trees/weather is going to vary tremendously, and we wont be running from bad/hot/cold weather (I'm a landscape photographer, so bad weather is good for me).

Second question is what do you think for the Charger/Inverter? I'm currently leaning towards a pair of Multiplus II 24/3000 in parallel, but I'm not sure that's needed or appropriate. Could I get away with one and not worry about running too much at once? Should I get the Quattro 24/5000 instead? That would allow me to have a 30a and a 50a connection but I don't see much benefit otherwise. The shape of the new Multiplus II's definitely is more convenient for where it's going.

See any other flaws in my plan or anything I should consider? I appreciate the feedback and expertise here!

Thanks so much,

Lyle

 

[sunshine_eggo]

I feel like I can't really do an accurate power audit since I don't physically have much of this stuff. We want to be able to boondock for 2 weeks at a time with a good battery buffer for extended days of poor solar production.

You definitely can. "Accurate" is almost impossible. A good estimate is very doable. You can literally take every item you listed and find/assume a power consumption as well as the daily hourly usage. Key it into the energy audit from link #1 in my sig.

First question is what do you suggest for wiring the solar panels? Series? Both Series AND parallel? I understand that series wiring with multiple mppt's is preferred if you will be in full sun most of the time (I could do a 250/85 on 4 panels and a 250/60 on the other 3), but perhaps I've got enough watts there that doing something like 4 panels in a 2/2 parallel and then 3 in series would make sense? Best of both worlds?

Generally speaking with all the potential shading on an RV roof, more parallel is better. 2S2P on one MPPT and 3S on the other. Place the 3S panels in your best non-shaded locations.

Would save a bit on a smaller 150/85 mppt, but my main objective is obviously to max out my efficiency while counting on enough coming in.

You won't see a difference 250/85 vs. 150/85. Save the money. Unfortunately with 3S, you'll need a 250.

Feel like I have some cushion here with plenty of panel. Was thinking of keeping it to two mppt's as that's just one distributor, but wonder if going to 3 or 4 and everything in series would be the way to go.

Only if you want to spend more on very small, ~1-3% improvements.

I'm happy to add a second distributor if you tell me more mppt's is an improvement.

I'm not.

Second question is what do you think for the Charger/Inverter? I'm currently leaning towards a pair of Multiplus II 24/3000 in parallel, but I'm not sure that's needed or appropriate. Could I get away with one and not worry about running too much at once? Should I get the Quattro 24/5000 instead? That would allow me to have a 30a and a 50a connection but I don't see much benefit otherwise. The shape of the new Multiplus II's definitely is more convenient for where it's going.

Size your inverter on the basis of your maximum anticipated simultaneous loads.

If you're rig is 50A, this is the time to figure things out. You can't just switch back and forth between 30A and 50A shore, and you need to make deliberate design choices.

There is a Multiplus II 24/3kW 2x120 unit that is designed to allow intelligent switching back and forth between 30A and 50A power. There is a 24V model. These units are only 120VAC, but they intelligently handle 30A/50A shore. When on 30A shore, they short L1 to L2 and provide L1 to both sides of the RV panel. When on 50A shore, they passthru/charge on L1 and simply pass L2 directly to the RV L2 panel. They are more expensive.

 

[Lyle]

Thanks so much!

Would save a bit on a smaller 150/85 mppt, but my main objective is obviously to max out my efficiency while counting on enough coming in.

I took a stab at an energy audit, but it's tough to find more than generic power info on websites. For instance, Pioneer mini split says 700 watts, but I know in real world usage (from scouring forums) that it will probably be more like 300-350 when it's just maintaining temps. That one was easy, had less luck with real world numbers for other items. I was looking at the Dometic DMC4101 fridge, which also says 700 watts but I can't imagine it would pull that around the clock. Any resources out there to discover such things besides manufacturers websites?

Generally speaking with all the potential shading on an RV roof, more parallel is better. 2S2P on one MPPT and 3S on the other. Place the 3S panels in your best non-shaded locations.

This mirrors my thoughts too.

If you're rig is 50A, this is the time to figure things out. You can't just switch back and forth between 30A and 50A shore, and you need to make deliberate design choices.

There is a Multiplus II 24/3kW 2x120 unit that is designed to allow intelligent switching back and forth between 30A and 50A power. There is a 24V model. These units are only 120VAC, but they intelligently handle 30A/50A shore. When on 30A shore, they short L1 to L2 and provide L1 to both sides of the RV panel. When on 50A shore, they passthru/charge on L1 and simply pass L2 directly to the RV L2 panel. They are more expensive.

I need to do some learning here, I don't understand this. I feel like 30 would be sufficient, but I don't really understand what it is or WHY that is. I guess I'm thinking of it just in terms of charging power and overall load. Next subject to read up on.

Appreciate you taking the time, means a lot!

Lyle

 

[sunshine_eggo]

Thanks so much!


I took a stab at an energy audit, but it's tough to find more than generic power info on websites. For instance, Pioneer mini split says 700 watts, but I know in real world usage (from scouring forums) that it will probably be more like 300-350 when it's just maintaining temps.

You've established bounds. You can run it with 350W and 700W and see where your design falls.

That one was easy, had less luck with real world numbers for other items. I was looking at the Dometic DMC4101 fridge, which also says 700 watts but I can't imagine it would pull that around the clock. Any resources out there to discover such things besides manufacturers websites?

According to Dometic, it's 156W.

Dometic DMC4101

Dometic DMC4101 - Compressor Refrigerator 10 cu. Ft, 12VDC, sleek styling

www.dometic.com

Manual says the same:

https://epi.dometic.com/externalassets/dometic-dmc4101_9600026948_93669.pdf

Assuming this is a compressor fridge, you can count on a little less than 1kWh/day for a fridge for 10 cu-ft.

If I have the model wrong, and this is a 2-way/3way fridge that can run on propane... replace it.

I need to do some learning here, I don't understand this. I feel like 30 would be sufficient, but I don't really understand what it is or WHY that is. I guess I'm thinking of it just in terms of charging power and overall load. Next subject to read up on.

The energy audit also helps with this. It forces you to list all your power requirements and allows you to see what has the potential to be running at the same time.

Is your rig 30A or 50A power?

 

[HRTKD]

going full-time (while working) in a 28' gooseneck

Is this an RV or an enclosed utility trailer? If it's the latter, how well are you insulating the walls, floor and roof?

If you'll be primarily boondocking then a 30 amp shore power connection will be sufficient. You have enough PV to power a lot of stuff and quickly charge the battery. If you are going with 50 amp shore power then I would use the Multiplus II since it's oriented for a 50 amp RV.

My RV is three season and I have 640 watts of PV on the roof with a 560 Ah 12 volt DIY battery bank. I rarely have to fire up my generator.

 

[Lyle]

The energy audit also helps with this. It forces you to list all your power requirements and allows you to see what has the potential to be running at the same time.

Working on your version today

Is your rig 30A or 50A power?

Is this an RV or an enclosed utility trailer? If it's the latter, how well are you insulating the walls, floor and roof?

This will be a from scratch build of an enclosed cargo trailer. It will be well insulated, spray foam all the way around. 3" in the walls and ceiling. It will have a second 'floor' in it, with 18" of storage running the length underneath. Current plan is to spray foam both floors from underneath with 3" (versus 3" of foam sheet under the interior floor to keep the total height down as much as possible). Spray foam in the rear door, and it will have a second wall 18" in from that with 3" or so.

Thanks!

Lyle

 

[Lyle]

According to Dometic, it's 156W

Assuming this is a compressor fridge, you can count on a little less than 1kWh/day for a fridge for 10 cu-ft.

Entered this into the calculator with 24 hr/day and it says 3.7 kwh. Thinking about it, I'm assuming this means the fridge cycles on and off and is going to be on more like 6-8 hours a day? This reduces my battery bank needs for emergency storage quite a bit lol.

Ok, with some calculating and best-guessing on 'typical', 'max', 'low power use stuck in storm' scenarios, I have these conclusions:

1) Max usage on a day where we needed to go wild, we could go over 5000 watts of inverter, so looks like 2x 3000 inverters. Typically right under 3000 watts.

2) In a situation where we say got stuck in a snow storm, going 'low power usage' mode and assuming some solar power is still coming in we should have a minimum of 3 days battery cushion with my 15.56kwh battery bank. Adding another 8 cells would get us to the 5 days I'd ideally like to have. I think it makes sense to start with the 15.56kwh and see how it goes in real world use.

Now to dig into reading up on the 30amp vs 50amp. Sounds/seems like 30 is the way, but I still don't understand why.

Can I ask a follow up question...how does one decide to set up the various circuits out of the 120v distribution? Looks like I could have 8x 20 amp breakers, so something like this makes sense to me?

1) Washer/Dryer (1330w)
2) Bedroom, Office, Bathroom, Living Room outlets - 10 outlets (Computers, TV, Apple TV)
3) Fireplace (1500 W on high which we may never use the heat on)
4) Kitchen - 2 outlets (to have hungry appliances on their own)
5) Storage areas/Outdoor - 5 outlets (Separated in case of power tool usage or something unknown)
6) Air Conditioner (1000k)
7) Samsung fridge *edited in
8) Open

 

[sunshine_eggo]

Entered this into the calculator with 24 hr/day and it says 3.7 kwh. Thinking about it, I'm assuming this means the fridge cycles on and off and is going to be on more like 6-8 hours a day? This reduces my battery bank needs for emergency storage quite a bit lol.

Yes. It will cycle on and off. If the fridge is reasonably efficient, it will not use more than 1kWh/day.

You can refer to the energy guide of similarly sized units. Here's a 120VAC 10.1 cu-ft Magic chef:

Magic Chef 10.1 cu. ft. Top Freezer Refrigerator in Black HMDR1000BE - The Home Depot

The Magic Chef 10.1 cu. ft. Top Freezer Refrigerator is the perfect in-between cooling machine more spacious than a mini but more compact than a regular household unit. It is a suitable appliance for smaller kitchens, break rooms, office kitchenettes or anywhere with space constraints. It...

www.homedepot.com

297kwh/year is 297/365 = 0.81kWh/day. Rounding up to 1kwh/day makes it a conservative value.

It's dramatically cheaper, so you might want to evaluate if a 12V fridge is worth the premium.

 

[HRTKD]

The issue of going with an AC or DC refrigerator got me to thinking. If I did DC I would need to run new cabling since the existing DC cable is to run the circuit board. There is already an AC outlet in the refrigerator compartment. Going with an AC refrigerator (in my case) would be the closest thing to plug and play.

In a from-scratch build the answer it a bit more involved. If the refrigerator isn't located too far from the battery bank then the cost of DC cables wouldn't be too bad. AC cables would still be less expensive. If the inverter is going to be running 24 hours a day, you might as well make use of it with an AC refrigerator. The selection of AC refrigerators is much better than DC refrigerators.

 

[richard cabesa]

Your plan sounds like it will make a great rig. Well beyond mine but please keep us informed. We all learn from other builds. My only input here would be use multiple smaller mppt’s. Cheaper and redundant. I have 4 and a BtoB and it seems to be working great

 

[Lyle]

You can refer to the energy guide

My God, I didn't even think of looking at these. Geeeeeez. Thanks for that!

I've been really set on a dc fridge, primarily because I'm worried about that "shit we're stuck in a storm" scenario and the power usage of an ac fridge. It would be nice to have a larger fridge though, we eat mostly fresh stuff. The Isotherm and similar fridges are epic, but they're just way too expensive to justify.

Your plan sounds like it will make a great rig. Well beyond mine but please keep us informed. We all learn from other builds. My only input here would be use multiple smaller mppt’s. Cheaper and redundant. I have 4 and a BtoB and it seems to be working great

Thanks, I will! I've spent hundreds of hours planning already, can't wait to get started...waiting until our daughter graduated high school here on Maui, then we'll move to the mainland and complete the build. Would cost double to build it here with the shipping, but I'm going stir crazy not moving forward haha. Hopefully solar and battery costs continue to come down, at least! What's 'BtoB'?

 

[Lyle]

Well, it's not as drastic as I expected. Samsung 15.6cf stainless at Lowe's for $699 ($1000 less and quite a bit bigger) uses 345kwh/yr, so say .94kwh. That definitely seems worth doing, we have the room.

 

[richard cabesa]

What's 'BtoB'?

Battery to battery charger . Chassis to House charging going down the road. A little harder for you with having to run large wire to trailer but doable

 

[RvNaut]

With that much solar and 15kw of battery you should/could be looking at a 48 volt system.

 

[rustythorn]

Yes. It will cycle on and off. If the fridge is reasonably efficient, it will not use more than 1kWh/day.

You can refer to the energy guide of similarly sized units. Here's a 120VAC 10.1 cu-ft Magic chef:

Magic Chef 10.1 cu. ft. Top Freezer Refrigerator in Black HMDR1000BE - The Home Depot

The Magic Chef 10.1 cu. ft. Top Freezer Refrigerator is the perfect in-between cooling machine more spacious than a mini but more compact than a regular household unit. It is a suitable appliance for smaller kitchens, break rooms, office kitchenettes or anywhere with space constraints. It...

www.homedepot.com

View attachment 149501

297kwh/year is 297/365 = 0.81kWh/day. Rounding up to 1kwh/day makes it a conservative value.

It's dramatically cheaper, so you might want to evaluate if a 12V fridge is worth the premium.

i could not find any official info on power use for the Dometic dmc4101 but unofficially it seems to be around 250-300 kwh/yr. first though, the Dometic is 12 VDC, is there a 24 VDC option to match your batteries?

as sunshine eggo points out there are cheaper residential fridges as good but there are a bunch of residential fridges of the same size that are even better [around 263 kwh/yr], however, it seems to be hard to find where to buy these?

 

[sunshine_eggo]

Yes. It will cycle on and off. If the fridge is reasonably efficient, it will not use more than 1kWh/day.

You can refer to the energy guide of similarly sized units. Here's a 120VAC 10.1 cu-ft Magic chef:

Magic Chef 10.1 cu. ft. Top Freezer Refrigerator in Black HMDR1000BE - The Home Depot

The Magic Chef 10.1 cu. ft. Top Freezer Refrigerator is the perfect in-between cooling machine more spacious than a mini but more compact than a regular household unit. It is a suitable appliance for smaller kitchens, break rooms, office kitchenettes or anywhere with space constraints. It...

www.homedepot.com

View attachment 149501

297kwh/year is 297/365 = 0.81kWh/day. Rounding up to 1kwh/day makes it a conservative value.

It's dramatically cheaper, so you might want to evaluate if a 12V fridge is worth the premium.

FWIW, I just replaced my Norcold 1218 with the above fridge. Here's what my smart plug says:



.47kWh the day of install - heavily used and cooled a small amount of food
.84kWh the first full day following install - typical use until about 2pm + cooling a 24 pack of soda
.28kWh today so far - not opened once (we're not there)

I can see it cycling on and off:



It burns < 60W, and it looks like VRM caught a surge?


Here's the data from the Norcold:


Note August... The highest day was 9.2kWh for the absorption fridge... It varied quite a bit as I would occasionally switch to propane. Most days were > 7kWh and most days the fridge was not opened even once.

here's what the absorption looked like... in FEBRUARY!!!



Low of 18°F, high of 50°F.

 

[HRTKD]

I have a Dometic RM2852 absorption refrigerator in my camper now. Here's the specifications for it.
59-15/16″ (H) x 23-11/16″ (W) x 24″ (D)
250 lbs
8 Cu Ft

That Magic Chef would light my trailer by 133 lbs!!!! That would balance out the added weight from my solar panels and inverter. The Magic Chef has by slightly more than 2 cu ft internal capacity. More beer!!! The only issue is that the Magic Chef is 1.2" deeper than mine. I don't think that's a huge problem. I might be able to make more room in the back and allow it to stick out a bit in the front.

EDIT: the specification sheet says the depth is 26.2, not the 25.2 that the main webpage in the link says. I don't know that I can "fix" a difference of 2.2"

 

[sunshine_eggo]

I have a Dometic RM2852 absorption refrigerator in my camper now. Here's the specifications for it.
59-15/16″ (H) x 23-11/16″ (W) x 24″ (D)
250 lbs
8 Cu Ft

That Magic Chef would light my trailer by 133 lbs!!!! That would balance out the added weight from my solar panels and inverter. The Magic Chef has by slightly more than 2 cu ft internal capacity. More beer!!! The only issue is that the Magic Chef is 1.2" deeper than mine. I don't think that's a huge problem. I might be able to make more room in the back and allow it to stick out a bit in the front.

We had 3" on the top and 8" on the right spare but ours is in a slide, and it barely fits depth-wise... It does stick out about an inch more, but I don't care. We lost 1.9 cu-ft, but with the added depth to the fridge (from lack of a cooling unit taking up space), it feels way more usable.

Doubt you'll be able to make any more room at the back, and you'll likely need to move the AC plug.

Is the RM2852 really that heavy? I'm pretty sure that's what was in my other trailer, and I bought a second magic chef for that one as well (haven't installed it yet). There's no way the 7.6 cu-ft absorption weighed that much unless there's 100# of ammonia, and it all leaked out. I mean I lifted it out of the hole by myself, and I'm not abnormally strong. Could that be a "gross weight" fully loaded?

 

[sunshine_eggo]

I have a Dometic RM2852 absorption refrigerator in my camper now. Here's the specifications for it.
59-15/16″ (H) x 23-11/16″ (W) x 24″ (D)
250 lbs
8 Cu Ft

That Magic Chef would light my trailer by 133 lbs!!!! That would balance out the added weight from my solar panels and inverter. The Magic Chef has by slightly more than 2 cu ft internal capacity. More beer!!! The only issue is that the Magic Chef is 1.2" deeper than mine. I don't think that's a huge problem. I might be able to make more room in the back and allow it to stick out a bit in the front.

EDIT: the specification sheet says the depth is 26.2, not the 25.2 that the main webpage in the link says. I don't know that I can "fix" a difference of 2.2"

I noticed that too. It's 25.2"

 

[HRTKD]

I noticed that too. It's 25.2"

Ah good. I dug some more on the dimensions of my refrigerator and it's the recess that is 24", not the refrigerator itself.



I'm not sure where pulled that 250 lbs weight from. I found a weight of 124 lbs. Dang. I would have upgraded just for the weight savings.