Questions on upgrading solar on travel trailer

[Mcstiggens]

Hello All,

I am just getting started here on the forum and with learning about upgrading my solar system. I have had some experience with hooking up a super simple system in my 4wheel Popup truck camper as well as building a DIY solar generator on wheels (from welding to wiring), all from scratch.
That said, I am going to sound like a real noob here because the scope of this project will prove to be much more advanced that what I have dealt with prior.

Here are the specs that I have to work with:

34' Grand Design Imagine 2910BH travel trailer with a 50 amp system which is "solar ready" and comes with one 165w panel and 25amp controller.

Here are my needs:

I plan to boondock and be 100% self reliant on power, using solar/battery/inverter to run my rig just as I would with shore power, preferably with little to no limitations. (Not necessarily concerned with running AC at this point though)
I will also be prepared to supplement with generator when necessary.

I mostly intend to run the furnace and 12V fridge on a regular basis as well as lights, peripherals etc.

I can fit and am planning for approx. 1650 watts worth of solar on the roof. I will not plan to achieve this all at first but it's the goal.

I plan to have 2 to 3 200 Ah LifePO4 batteries, totaling 600 Ah battery bank. (Preferably or most likely a 24V/48 system? That is where I start to get stumped.)


Here are my limitations:
Well, $$$ and time are the imitations.

I am having to move from my house and will be boondocking at my equipment yard.
So, I need to quickly set up a solar system with what I already have and what I can afford to purchase.

I don't have the time to save up for the fancy Victron MPPT controller/charger etc. that I would prefer to use and plan to purchase when I can afford it down the road.

Here is what I have purchased or already have on hand so far for the upgrade:

1-Renogy 3000W Pure sign wave inverter
2-200AH 12V LifePO4 batteries
8-185W used Solar panels totaling 1480 watts -10% give or take, since they are a few years old....lets say 1350 Watts of solar.
(these panels were purchased used and are very large so I don't plan on mounting these to the roof of the RV. I will be purchasing something more modern and lightweight/low profile or flexible down the road for the roof install. These will be mounted on top of a shipping container where I will park my trailer and tap into them until I can be totally self sufficient and off grid with the trailer mounted panels.

Here is where I need your input:

I should add here that even though I mentioned running a 24/48V system above, due to the aforementioned budget limitations, I am going to start with 12V since it seems a bit simpler and cheaper.
Also, I have read so, so ,so much on the topic that my head is about to explode and I have so much more to deal with at the same time, such as moving out of my house, shop, setting up my off-grid equipment yard/boondock spot etc.

I also do not retain knowledge very well anymore. (getting slow in my old age).
So please forgive me for bringing up some topics that are sure to have been answered many times before. I just have very little time and bandwidth to deal with any more research.

I have seen more complicate systems with buss bar, shunt and other more advanced items. I need to keep it simple for the sake of time and budget.

It appears the first thing I will need to do is figure out what solar controller to purchase and install.

I need help figuring out where to go from here. I will assume a 50amp controller would be correct for this application. Any suggestions on that?
I suppose I will need a transfer switch as well.

The trailer is "inverter ready" so all I need to do is tap into the wired loop running from the breaker box to install that.

The factory wiring that goes to roof for the solar panels is 10 GA. Is that sufficient for my needs?

Given all I have stated above, what do you think is the most basic and cost effective way for me to set this up....just to get it running. I can upgrade as needed down the road.

I'm sure I could rattle off more details but this is enough to get the conversation started.

I certainly appreciate you for reading this far and I look forward to your tips and suggestions. There will be lots more I'll need to ask about down the road here.

Thanks,
Lane O

 

[sunshine_eggo]

Most important to understand what your limitations are...

1350W of solar, Flat on roof:

Summer 1200W = 6kWh/day - how much you can use per day in summer (way too little for A/C)
Winter = 720W = 2.8kWh/day - how much you can use per day in winter

Exceed either of the above consistently, and you will eventually run your batteries completely flat.

5.12kWh of battery capacity - how much you can use before needing to recharge.

Using round numbers, if you use 7kWh/day instead of 6 in the summer, you will run your batteries flat in 5 days.

If your fridge runs on propane, you MUST run it on propane. Propane fridges run on AC power consume 5-6X the same sized residential fridge. A typical 7.6cu-ft propane fridge will consume 4-5kWh of energy daily.

Unfortunately, your choice of 12V means you need a buttload of MPPT current.

12V: 1200W/12V = 100A

Had you gone with 24V:

24V: 1200W/24V = 50A

100A of MPPT is going to cost you a lot, and you're going to need beefy cables between the MPPT and battery.

10awg is suitable for 30A, so as long as the input to the MPPT is < 30A, then you're good.

1300W/30A = 45V, so you'll just need to ensure you get a charge controller that can run enough panels in series to keep the parallel strings from exceeding 30A.

 

[Mcstiggens]

Thanks sunshine for the reply. It looks like it was cut off at the end though.

Since it sounds like 24V makes way more sense, I guess I will need to make that more of a priority from the start.

So, I could wire the 12V batteries in series, that would solve the issue with batteries.
Beyond that, it seems that many charge controllers will support a wide spectrum of voltage requirements, then I'd just need to incorporate a stepdown converter right?

I'm not sure where the inverter would be in that sequence. Would the inverter be wired after the step down so that I could still use my 12v inverter?

I believe I could still return my inverter and get a 24v unit. No issues there. I also have yet to purchase battery cables, so no issues there either.

Yea, the 10cu. ft 12V fridge is all that was offered in my unit. I think I would have preferred propane but The RV sales guys say most brands are going the 12V route as they are more reliable anyway.

FWIW, when my unit will be parked long term and lived in, (as opposed to traveling and boondocking, which will occur at some point) the panels will be placed on top of a shipping container, aiming south at 37.5 degrees. So I should get get optimal sun in that case. On cloudy/foggy days, I can run a generator for a couple of hours to supplement with charging.

This setup will be easier for immediate priority. Running the panels on the roof of trailer will come later. In any case, it seems 1480-ish watts is about the max I can fit on the trailer.

So many details. Thanks again.

Lane O

 

[sunshine_eggo]

Thanks sunshine for the reply. It looks like it was cut off at the end though.

Fixed.

Since it sounds like 24V makes way more sense, I guess I will need to make that more of a priority from the start.

Yes.

So, I could wire the 12V batteries in series, that would solve the issue with batteries.

Yes.

Beyond that, it seems that many charge controllers will support a wide spectrum of voltage requirements,

Yes.

then I'd just need to incorporate a stepdown converter right?

For 12V DC loads, yes.

I'm not sure where the inverter would be in that sequence. Would the inverter be wired after the step down so that I could still use my 12v inverter?

Never. Replace with 24V.

I believe I could still return my inverter and get a 24v unit. No issues there. I also have yet to purchase battery cables, so no issues there either.

Good idea.

Yea, the 10cu. ft 12V fridge is all that was offered in my unit. I think I would have preferred propane but The RV sales guys say most brands are going the 12V route as they are more reliable anyway.

If it's a 12V compressor fridge, that's fine. It will likely use ABOUT 0.5kWh/day. Can you link a model/manual?

FWIW, when my unit will be parked long term and lived in, (as opposed to traveling and boondocking, which will occur at some point) the panels will be placed on top of a shipping container, aiming south at 37.5 degrees. So I should get get optimal sun in that case.

Okay, so 1350W

in summer: 6.8kWh/day
in winter: 4.1kWh/day

That's basically how we're setup:



2X 5th wheels
40' shipping container with 3kW on top - room for 6kW currently inside.

In AZ, we can generate 19kWh most days.

Check the PVWatts link in my signature line #1. You can check solar hours for your exact location.

FWIW, our trailers are completely unmodified. Container houses everything. Each trailer has a 12V battery for backup purposes kept charged up by the RV converters.

 

[Mcstiggens]

Thanks sunshine. It looks like you have a similar setup to what I'm after. AND a wealth of knowledge on it.

It's settled then! I'm going 24V then from the start!

So you are just plugging your rig directly into the solar system housed on the container. I plan to have both eventually. That way, I can travel and boondock. For now I just need it at the long term location. I plan to have the trailer outfitted with the solar system and batteries, and have the panels on the container to start. (I already have a small solar generator to light up the container/shop area) It just means I can't go out boondocking without a generator for now.


Here is a link to my fridge. It is a 12v compressor style.

Furrion Arctic® 12V RV Refrigerator - 10 cu. ft, Left Hinge, Black #FCR10DCGTA-BR

Compact and efficient, the built-in design and large capacity of the Furrion 12-volt RV refrigerator #FCR10DCGTA-BR delivers flexibility while elevating the aesthetics of your kitchen.

store.lci1.com

Lane O

 

[sunshine_eggo]

Oof! $2K? Better than running a propane fridge on AC!

We bought a 10.1cu-ft Magic Chef 120VAC powered unit (apartment size) for $400 from Home Depot. For $1600, I'll take the 10% efficiency loss! The cooling unit on our 12cu-ft absorption fridge went out. Repair for $2k? Nope. Even though 2 cu-ft less, this fridge feels infinitely more usable than the double door unit. Having the 6" of extra depth the cooling unit occupies really helps.

Since everything is in the container, and it's eventually planned to power a dwelling, it's 48V and 10kW. I would recommend a similar approach... leave the trailer untouched with its onboard 12V system intact and available for limited backup if the AC power goes down. There's an efficiency penalty of about 10%, but IMHO, it's more than worth it.

 

[Mcstiggens]

Yea is pretty spensive. If I had to replace the fridge I would probably go the 120VAC route as well. Your right about the depth in absorption fridge. I had one before. No Bueno.


Can you please clarify on the following:

"There's an efficiency penalty of about 10%"

I think you mean running the distance from the system to the 5th wheel right?

I like your idea on keeping separate from trailer for now.

I do want to expand to at least 200ah LifePO and another 2 panels which could be stand-alone mounted on the ground in an ideal location, out of shade when boondocking out somewhere. That way, I may get by with just running my lights and fridge while boondocking for a couple days and hopefully get by okay since I could also run a generator when necessary.

 

[sunshine_eggo]

Yea is pretty spensive. If I had to replace the fridge I would probably go the 120VAC route as well. Your right about the depth in absorption fridge. I have them before. No Bueno.


Can you please elaborate on the following:

"There's an efficiency penalty of about 10%"

I like your idea on keeping separate from trailer for now.

I do want to expand to at least 200ah LifePO and another 2 panels which could be stand-alone mounted on the ground in an ideal location, out of shade when boondocking out somewhere. That way, I may get by with just running my lights and fridge while boondocking for a couple days and hopefully get by okay since I could also run a generator when necessary.

24VDC to 120VAC to 12VDC is about 75% efficient.
24VDC to 12VDC is about 85% efficient.

 

[Mcstiggens]

24VDC to 120VAC to 12VDC is about 75% efficient.
24VDC to 12VDC is about 85% efficient.

Copy that.

So with what we discussed so far, if... lets just say, money was no object, or I sold some BTC before it's time, would this be a good pick for my particular needs?

MultiPlus 2000VA - Victron Energy

The MultiPlus, as the name suggests, is a combined inverter and charger in one elegant package. Its many features include a true sine wave inverter,...

www.victronenergy.com

I worry about trying to skimp now but paying more in the long run for my skimping mistakes


Or I could go this route but still would need transfer switch and controller but at least it could still be done for nearly half the cost of the Victron:

https://www.amazon.com/gp/product/B0BRDB54B2/ref=sw_img_1?smid=AV81IYWDGNYH4&th=1

It would certainly be nice to have a unit that incorporates Inverter/charge controller/transfer all in one.

 

[sunshine_eggo]

I have two Victron Quattro 48/5000 units, and a MPPT 250/100, so I'm the wrong guy to ask if you're on a budget.

I have a complete 24V/2000W inverter, 215Ah 24V batt, with 60A MPPT and battery monitor "spare" system. That's about $800 I spent that I had to re-spend as I learned.

If you're really looking at Victron, I would go with something scalable:

https://www.victronenergy.com/upload/documents/Datasheet-MultiPlus-II-120V-EN.pdf

Available in 24/3000, 48/3000 and 48/5000.

Yes. They're expensive, but they're awesome.

Given that you're budget sensitive, an all-in-one might be your fastest/cheapest option. This has a 3kW inverter/charger and 80A MPPT built in:

Growatt 24V 3kW Stackable 120V 2kW MPPT 80A – Off-Grid Inverter SPF 3000TL LVM-24P – Watts247 Wholesale

watts247.com

If one isn't enough, you could go two in parallel either 6000W 120VAC or 6000W 120/240VAC split phase like your 50A unit likes.

Three downsides:

1. will consume about 40-50W each on top of whatever your loads are.
2. they really like clean generator power and may not charge particularly well when charging from generator, and AC charging is ON/OFF based on voltage - no absorption or float.
3. One unit would be unlikely able to start an RV A/C unless you put a micro-air soft start on the A/C unit.

While I lean towards buy-once, cry-once, I would consider something like this for simplicity and speed.

 

[Rocketman]

The Victron Multiplus inverters are great! I have the 12/3000 in my MotorHome. One thing to be aware is Victron is realistic in the spec sheet - the 3000 will do 2400w of induction power - I believe the 2000 does 1600w.

With only 1600w you need to be very careful what you power.

My 3000 will power 1 large item -microwave (convection microwave), hair dryer, even the A/C with an ez start). But if I have one high item going and we add a medium item - toaster, etc. we overload. (When you overload- everything 120v goes out - then comes back on in 1 minute or so - it’s the inverters way of saying - hey dummy - you did it again - let’s try not to do that again… at least that’s how I interpret it).

We run the small items without thinking about them - computers, Starlink, chargers, residential fridge, etc.

My concern with the 2000 is it would be too small for my wife and I.

 

[Mcstiggens]

Interesting. Thanks for the input Rocketman Yes, I plan to stick with 3000w minimum.

Once I got to looking at the link you sent sunshine_eggo, I found this option, which looks even more appealing, better price and with better reviews; I'm definitely feeling good about spending 1/2 the price of the Multi-plus ll right now.

3000W 24V Solar Inverter Charger

Hightlight: ★ All-in-one solar charge inverter: 3000 Watts Pure Sine Wave Inverter Combined with 60A MPPT solar Charging and 40A AC battery charging ,you can enjoy the stable power from the sun and the utility grid to keep you powered under any circumstances. ★ Four charging modes: AC Priority...

sungoldpower.com

 

[sunshine_eggo]

I've had personal experience with that Growatt, and that seller provides excellent support - he really knows the products he sells.

My personal impression on Sungold is that support is hit and miss. However, the two units appear to be nearly identical in features/specifications except the Sungold has a much higher voltage MPPT. It is very important that you provide it with well above the minimum MPPT voltage of 120V, i.e., make certain your series Vmp is at least 120V and preferably higher.

It will have the same 3 limitations of the Growatt.

@Rocketman is making a confusing distinction. ALL INVERTERS are rated in VA. Dig into the specifications of something like a Magnum MS4024PAE or similar Tier 1 inverter, and you will see they're actually rated at 4000VA when all the marketing materials say 4000W.

Victron confuses things by being honest and making a distinction between VA and W. VA = W when the power factor = 1.0. Certain devices like electric motors have a power factor < 1.0.

 

[Mcstiggens]

Well I am really big on supporting folks who stand behind and their products AND provide great support after the purchase. I will definitely give the Growatt serious consideration since support is everything.


This one looks very appealing as well but no idea about support:

3000W 110Vac 24Vdc All In One Inverter Charger

PowMr 3000Watt All In One Inverter Charger 120Vac 24Vdc with 60A MPPT Solar Charge Controller PV 100V for lithium/lifepo4 Battery And Lead Acid Battery.

powmr.com

 

[sunshine_eggo]

That unit looks just like the Sungold. PowMr is in the "inconsistent" support category for me... but for that price, I'm tempted too...

If you go with the SunGold or PowMr, make sure they ship from the U.S. and any returns go to a U.S. address. Sometimes dealing with the Chinese manufacturer direct is a pain.

 

[sunshine_eggo]

Cheaper on prime...

https://www.amazon.com/PowMr-Inverter-Off-Grid-Controller-Lead-Acid/dp/B0B9ZMZ2YY

I have no need for this stupid thing, but I'm having a hard time not buying it...

 

[sunshine_eggo]

... trying to see what I can power in the house... Hmmm... mebbe my office needs to be totally off grid....

 

[Mcstiggens]

That's the spirit. I'm a big fan of redundancies. 2 is 1, one is none right?

 

[sunshine_eggo]

That's the spirit. I'm a big fan of redundancies. 2 is 1, one is none right?

Two inverters in split phase. If either fail, can run the other in 120V mode.
24V/2000W backup system w/separate batteries.
1 propane generator in one of the 5th wheels and 2 portable generators on site.

Thinking about running all my Internet and network gear and a couple of servers off it...

damn you!

 

[Mcstiggens]

PowMr is in the "inconsistent" support category for me... but for that price, I'm tempted too...

Yes, I just might risk it and buy the 3 yr assurion protection with for like $60 extra. For that price, and free prime shipping it's worth the gamble. Then if I wanna upgrade later with the Victron, I can keep with the redundancy program.