Solar Show and Tell

[Troutboy]

I’m the opposite of Ray when it comes to solar. I have 500W on roof, 200W portable all wired into a vIctron 100/50 mppt controller. Other components: victron BMV, Victron multiplus inverter/charger and 300 amp hour of victron lithium. We do extensive boondocking off grid in Colorado. When wife comes we use microwave a lot and things like hairdryer and curling iron. System is awesome, we are NEVER energy limited. I rarely use the portable panels, only if I am parked in highly shaded area. I have done a week with no issues. Grey/black tank becomes limiting factor. I do think the prewire is undersized at 10g. I used 4 from combiner box down to mppt controller. In 10g there will be friction loss for sure. Depends on length of run. It’s definitely worth the time and effort to rewire and not worry about losses., in my opinion. Can you do it with the 10, yes, but why be limited or lose power in the wires? You want as much comming from the sun as you can get. To me it’s like taking a shower and putting on dirty underwear.

I detailed my self install on the forums, and have wiring diagrams etc if interested. Let me know.

http://www.airforums.com/forums/f382...-a-162955.html

[AirMiles]

Trout, you are incorrect about the resistance losses using 10AWG with 400W of series-parallel solar. The series-parrallel Losses are LESS than running it full parallel. My series-parallel installation only has 28' of 10-2 on the roof. A full parallel setup will have double that. So that's 1/2 less resistance due to roof-top length. There is additional resistance savings with double the voltage running through the 10-2 on a series-parallel versus a parallel setup. A wire of half the length at twice the voltage will have 1/4 the resistance.

Let's use this calculator to check the voltage losses on each configuration: https://www.wholesalesolar.com/solar...n/voltage-drop :

Here are the inputs for a series-parallel installation length=14', 10-2, copper, voltage=34, amps=6 . . . calculating . . . voltage at end of circuit 33.79 at 6 amps with 0.62% loss. A series-parallel configuration therefore has two of these 33.79V at 6A inputs into the rooftop box or 33.79V at 12A. This totals 405.48W.

Here are the inputs for a parallel installation length=14', 10-2, copper, voltage=17, amps=6 . . . calculating . . . voltage at end of circuit 16.79 at 6 amps with 1.24% loss. A parallel configuration therefore has four of these 16.79V at 6A inputs into the rooftop box or 16.79V at 24A. This totals 402.96W.

Now we know the amps and volts at the rooftop box and its nearly tied. Let's move down from the roof to the controller using the same calculator as above with a 30’ wire length.

Here are the inputs for a series-parallel installation length=30', 10-2, copper, voltage=33.79, amps=12 . . . calculating . . . voltage at end of circuit 32.69 at 12 amps with 2.63% loss. Therefore, the watts to the controller equals 32.9V times 12A, or 394.8 Watts to the controller.

Here are the inputs for a parallel installation length=30', 4AWG, copper, voltage=16.79v, amps=24 . . . calculating . . . voltage at end of circuit 16.34 at 24 amps with 2.68% loss. Therefore, the watts to the controller equals 16.34V times 24A, or 392.16 Watts to the controller.

The final results are that the 400W series-parallel configuration using the 10AWG factory pre-wire did provide slightly more power to the controller than a 400W parallel configuration using 4AWG. Let's just call it a tie and stop dissing the factory pre-wire.

[Troutboy]

I wasn’t dissing it in your case. Sorry if I wasn’t clear. For lower watts and a config like yours it works well. If you do go parallel and have as much as 600W I think it’s worth The effort to pull bigger wire.

It’s all about what works for each of us. There is not much info on running panels like you have. Most either go one way or the other.

Yours works well for you and is good guidance for others. My experience with shading when panels are in series is not good. So I wired for what worked for me and seems more fool proof or overkill. But that’s how I do things, lol.

The important thing is that we are camping, enjoying our solar power systems and they work for our situations. Thanks for starting this thread, as I am learning new things.

[Ray Eklund]

Originally Posted by pwlldvd

Wow! That’s 1/2 the price of the Renogy I am looking at.

How long have you had it? At that price, and with Costco warranty, seems like it should work.

******
I am going to catch TroutBoy in the mountains someday and draw his excess power into our Solar Pauper Power system...

Costco.com
Coleman 100w Solar Panel with 7amp Charge Controller ($160 less $40 member discount, $13.20 sales tax). Received $2.40 Executive Member 2% cash back.

Costco item #1150689 Coleman 100Watt Solar

Ordered 9-15-2017
"For an immediate refund (including shipping and handling), simply return your purchase to any one of our Costco warehouses..."

I used an extension cord that had a damaged plug to connect the Solar Panel to the batteries (about 20 feet). You need two male ends on the extension cord. A female plug attached near the batteries to the controller. Another female plug connecting the Solar Panel to the extension cord on the other end.

The Charge Controller has a yellow small LED when not charging and a green LED when a charge is being sent from the Solar Panel to the Batteries.

This works for us camping Off the Grid. We are tent campers and an Airstream is a convenient way to haul WAY TOO MUCH STUFF that is not necessary, including a Solar Panel. But... no complaint.

Did not need an Electrical Engineering degree from the University of Wyoming, that was connected to the Electrical Grid and no longer used candles and lanterns.

[AirMiles]

Trout, thanks for the reply which cleared up the comment. We are both right as you stated. The factory pre-wire is best for 400W. In your case, 500W or more, you must use the 4AWG because losses would be awful with the pre-wire at 500W run in parallel.

I actually believe 400W on the factory pre-wire is the sweet spot. At 400W, you get double the voltage which halves the resistance and two parallel sets to offset shading. If you put only 200W in parallel on the factory prewire, you lose the double voltage resistance loss advantage. If you put 200W in series on the factory pre-wire, you lose the second set of parallel panels for shading advantage.

Let me run the numbers quickly. Two 100W panels in parallel on factory prewire is 17V at 6A with 14' of 10-2 results in 16.9V at 12A times two equals 202.8W. Then 16.9V at 12A through 30' of 10AWG factory pre-wire is 16.01V at 12A totaling 192.12 Watts. That's 4% total loss versus 2% loss with 400W on either the factory pre-wire or 4AWG. Yup, double the loss. But let's be real, are you really going to notice 4 Watts of loss? 2% or 4% loss is just rounding error.

Again, thanks for the comment and giving me the idea to run these numbers. Bottom line, boondockers with solar on their Airstreams will likely have full batteries each day. It doesn't get any better than that! Right Ray?

[Ray Eklund]

Originally Posted by AirMiles

Again, thanks for the comment and giving me the idea to run these numbers. Bottom line, boondockers with solar on their Airstreams will likely have full batteries each day. It doesn't get any better than that! Right Ray?

******
For those of us who use their Airstream as an expensive tent... this is as good as it needs to be to make Nancy and I happy.

We also make use of 1000watt LED flashlights using D and C Cell batteries. Not Solar Charged... but the experts on this Thread may have a mini-solar panel patent on the handle surface of these flashlights in the... near future?

If I were not Electrically Challenged... It may be time for Solar Powered Flashlights coming to Airstream Owners, from someone on this interesting Thread of true experts! E=MC2 ?

[Mattirs]

Originally Posted by Ray Eklund

******

If I were not Electrically Challenged... It may be time for Solar Powered Flashlights coming to Airstream Owners, from someone on this interesting Thread of true experts! E=MC2 ?

Or we could be like the Klingons and have a nano blackhole as an energy source?? Don't know how to do the calculations to figure out how heavy of a blackhole one would need for 20 years of power on an AS. Anybody up to it?

I do have a flashlight that I charge off of the batteries charged off of solar panels.

[czunc]

AirMiles, Thanks for your input! I appreciate the information that you and TroutBoy gave. I really like the simplicity of using the factory solar prewires and 4 panels but I'm still torn on running new wires. Its easy to read all of these post and start to "over engineer" my system only to really need a basic system. I think the the factory wiring will be sufficient for my needs. We are really just concerned about heat all night and lighting. I'm not sure how much these really use but I'm guessing somewhere around 100ah a night? Someone mentioned portable solar panels but we are out and about in the daytime and I dont plan on babysitting a set of panels. I currently have 100ah suitcase panel that we usually just lay flat because we leave before dark and come home to dark.

[AirMiles]

I like my panels that are permanently mounted on the Airstream. This way solar is always charging my batteries whether camping, in storage, or on the road. With my setup, I can really forget about the batteries, use all my Airstream power features except the microwave and A/C, and the know the batteries will be fully recharged the next day. The only thing I need to do is not park under a complete canopy of tree shade. With a full canopy of shade, I may need to limit that stay to three days or boost charge with a generator. A generator is also needed to run the A/C and microwave.

My AM Solar setup cost $2,000 including four 100W solar panels, a Victron 100/30, a Victron BatterySmart, mounting hardware and wiring. My batteries are a pair of $100 Duracell EGC2 golf cart batteries placed inside the original battery box with a total 230AH. For $2,200, this system can run your furnace all night, run your fantastic fans all day, take showers with water heated with propane, charge your cellphones and laptops, run the refrigerator on propane and use the lights as needed. You do need to somewhat limit TV usage to about three hours per day (I watch the NASCAR races on weekends). This is what I did all summer long and never "needed" anything but the solar to maintain my batteries. I actually disconnected my 120V battery charger inside my Airstream so my batteries only get solar charging even when I run the generator or plug into shore power. I boost charged my batteries one time with the 120V battery charger at a campsite where there was a complete canopy of trees on the third day, probably more as a test of 120V charger than actual need. Does this system sound like it would meet your needs?

If you think you may want to go with over 400W in the future, I would recommend getting the Victron 100/50 up front instead of the Victron 100/30. That way you will not have any wasted equipment if you decide to add more solar later. You could also start with the two golf cart batteries now and upgrade to lithium in the future.

The other "nice" feature of my setup is that I installed it myself in three half days in my driveway on a ladder/scaffold. It took about two hours the first day to install the Victron 100/30 and connect all the wiring inside the Airstream. About five hours on the second day to mount the panels on the roof. And about five hours on the third day to wire the panels on the roof. Twelve hours total for a first-time solar installation while taking my time and being extremely careful. I know I could do it a second time in eight to ten hours. But I would still split the job over three days because it is hard on the back and feet!

[Troutboy]

The furnace will use 9amps while running. It cycles on and off depending on how cold. Two weekends ago low temp was 35F and we set inside temp at 66F. Can’t remember how many times it cycled but battery drained 10% or for me around 30 amp hours. With my 500W it was back at 100% by 10 am next day.

The cost is really driven. By lithium. For my equipment cost was $3700 and I have the 100/50. In addition I purchase the multiplus 3000 which is $1600.

The lithium bank I bought was just under $4000. I had the money so went lithium because of weight. But my first design was going to be wet cell or agm. The system air miles has will do most everything . As I said mine is a bit overkill but it gives me a sense of security, and allows me to maintain full charge even when cloudy etc fit a few days. Also as I said, if you use microwave or hairdryer you need a bigger inverter. The microwave uses 130amp per minute so that can kill you. When my wife comes, we need the inverter. When she doesn’t come and it’s me and the kids, we don’t even turn inverter on and batteries never drop below 90%.

In even drained a pretty robust system for total cost of $1500-$2000 using trimetric charger and monitor with new batteries. There are many ways to skin this cat and it depends on your use cases (as others mention here).

Like Ray, we usually use the AS for a big aluminum tent with heat. I think I could easily live on just my 200w portable panels and be fine.

[uncle_bob]

Originally Posted by czunc

AirMiles, Thanks for your input! I appreciate the information that you and TroutBoy gave. I really like the simplicity of using the factory solar prewires and 4 panels but I'm still torn on running new wires. Its easy to read all of these post and start to "over engineer" my system only to really need a basic system. I think the the factory wiring will be sufficient for my needs. We are really just concerned about heat all night and lighting. I'm not sure how much these really use but I'm guessing somewhere around 100ah a night? Someone mentioned portable solar panels but we are out and about in the daytime and I dont plan on babysitting a set of panels. I currently have 100ah suitcase panel that we usually just lay flat because we leave before dark and come home to dark.

Hi

100AH = capacity of a battery or use of power over some period of time

100W = power out of a solar panel

Unfortunately the two are not the same thing.

A 100W panel will give you around 5A into your batteries. If it does that for 8 hours, you get 40AH. In a lot of cases, you will get way less than that, in a few cases you might get a little bit more.

====

If you do a series parallel connect of your four panels on the roof, there is no good reason to change out the wires. Hook that into a good controller ( like a Victron ) and it will work very well.

Bob

[Fair_Enough]

What my small system looks like:

Three (3)-100W Renogy Eclipse mono panels. Technical information below. Panels mounted flat without screws into the roof.

Goal for me is to keep a below 2% voltage drop. In low or diminishing light, keeping voltage as high as possible is of the utmost importance.

Total project cost $1,177 with no consideration for my labor

I can add a 4th 100W Eclipse panel ($181 now) and stay below my VD goal, but would require a smaller OTR antenna or ?? since that space is the only logical place to put another panel.

Reason for parallel is performance in partial shade.
Reason for Trimetric equipment is because I know and trust it.
I also now have two GC-2 East Penn (Duracell) 230 Ah 6 volt batteries, same reason I know what I have and how to make them last.

While wiring, I also upgraded battery cables to #4/0, where #2/0 would suffice, from batteries to bus' to future 2000W Inverter/charger. I re-purposed the cables from another job. And, modified factory wiring arrangement to truly cut off loads.

I also installed a small 300W Samlex PSW inverter and dedicated outlet (with USBs) that can power a table top fan, TV, a small blender, and coffee grinder; even a hair dryer on low heat / low fan. Probably will need to be much more robust in the future.

On a resent 3 week trip, the converter was never turned on and the lowest SOC observed was 80% this was with little furnace use, lights used conservatively, water pump and 2 to 3 hours of TV viewing and the previous day was rainy, dark and dreary.

WW

Tech info: 100W panels are Renogy Eclipse; purchased from Amazon - 17.7V Vmp - 5.7A Imp; 40.8" x 20.7" x 1.4" in a parallel arrangement with 18' of 6 AWG from SCC to combiner - producing 1.37% voltage drop, or 0.24 volts... then from combiner to each panel from 6' to 12' long 10AWG "Solar" cables via Female and Male MC4. The 6 footers = 0.39% voltage drop or 0.068 volts - The 12' = 0.17% voltage drop or 0.14 volts.

Other items: Trimetric SC 2030 and TM 2030 RV, 500A Shunt, temp sensor, homebuilt combiner, 10 AWG solar wire, 6 AWG wire, crimp wire lugs, gland nuts, bus bars, 30 amp DC Breakers (2), Renogy curved Z and straight brkts, double sided tape, and sealant. Trimetric equipment purchased from the AltE Store.

[AirMiles]

Wolfwhistle, Thanks for sharing your system with the details needed to copy your installation. Its a great example that others may want to copy. I have a few questions so we can all learn from your installation.

You designed to maximize voltage. Is there something you've experienced with voltage loss? What's the best wattage you've seen from your solar and best amps you've seen to your batteries? You have a lot of confidence in Trimetric, can you explain why? You seem very knowledgeable about electrical systems, did you work in that industry?

A few questions on the inverter. You are preparing to move up to 2000W. Are you going to expand your battery bank for that increase? A 2000W inverter could draw 180A which would be a huge draw against a 230AH battery bank. My 230A battery bank stresses with my 1000W inverter.

Again, thanks for sharing your system with us!

[JMynes]

You don’t have to break the bank to add solar.
I have $750 in my 200 watt system. 2 Renogy panels, TM2030, SC2030, and associated wiring, connectors, hardware, VHB tape, Sikaflex, circuit breakers, etc.
Factory prewire.
No charge for my labor. ��
My batteries don’t discharge just sitting there any more.
I’ve seen 10 amps of charging with both FanTastic fans running. One fan can run 24/7 and the batteries recharge by 10AM in bright sun.
In the future if I need more I can add a third panel for a modest expense. I feel that keeping some roof space open for maintenance access is also an important consideration.
200W isn’t going to allow me to boondock indefinitely, but it will stretch my power to equal my tank dumping interval.

[AirMiles]

Thanks Jmynes for sharing your system configuration, cost and results. It is amazing what you can get for seven hundred dollars nowadays. Its also very easy to self-install a small solar system on a 2017 and up Airstream with the Zamp rooftop box. Stick up to three solar panels on the roof with some 3M 4950 VHB Tape and SikaFlex. Run a wire between each solar panel and the 3-input Zamp rooftop box. Connect a controller between the green and yellow solar pre-wires and the positive and negative buss bars with a fuse on the positive wire. And you get nearly unlimited battery power! Even with only 200W or 300W, I wouldn't need to boost charge my batteries very often.

[Fair_Enough]

Originally Posted by AirMiles

Wolfwhistle, Thanks for sharing your system with the details needed to copy your installation. Its a great example that others may want to copy. I have a few questions so we can all learn from your installation.

You designed to maximize voltage. Is there something you've experienced with voltage loss? What's the best wattage you've seen from your solar and best amps you've seen to your batteries? You have a lot of confidence in Trimetric, can you explain why? You seem very knowledgeable about electrical systems, did you work in that industry?

A few questions on the inverter. You are preparing to move up to 2000W. Are you going to expand your battery bank for that increase? A 2000W inverter could draw 180A which would be a huge draw against a 230AH battery bank. My 230A battery bank stresses with my 1000W inverter.

Again, thanks for sharing your system with us!

AM,

Will try to answer your questions. My background is 46 years in telecom / datacom - installer to Application Engineer. My mantra was "I might not be able to fix it, but I can make it so no one else can."

Charger to battery voltage drop should never be more than a 3% across the conductor (one way). My 300w array is capable of 17.1 amps at Vmp of 17.7 volts. I have seen 18 amps initially which drops rather quickly / naturally as voltage rises to Absorb. Less than perfect sun I've seen 15 amps as current drops and voltage rises over a few hours. "Full" is displayed when 2% of Ah is reached at the same time voltage is at the absorb set point.

Inverter to battery should be no more than 1% voltage drop and that at the peak it can produce. My old 2000W Magnum peak was 3200W and the main breaker was 250 amp. Catastrophic fused at 300A. Cabling all #4/0 to the inverter. Even with 460 Ah bank, it wouldn't take long to deplete the batteries. Of course, drawing much higher than C20 gives you far less than the rated Ah, the ole Peukert effect will get you every time.

To me its about voltage and less about amps. So if in less than ideal light condition the current will certainly be lower than ideal, but if voltage levels are also lower than ideal you simply will have a less than full battery and it takes longer. If this is a common occurrence that would be telling you to add more panels if possible. Making 14.6v from 17v from the panel is easy but if low light only nets 14.6v you would end up with 14.2v with a 3% drop or 14.3% at 2% or even much less. An analogy is trying to fill a tire to 80 psi with a 81 psi source. Voltage is the pressure and the volume in the tire is the amps. Its about voltage. But a battery that is charged too slowly never reaches true 100% either.

Here's what's so cool. The SC2030 can placed anywhere along the route from panels to battery without a problem.

For me it is about having a full battery at the start of the evening, than it is worrying about long life. But, fulling charging every time, plays hand in hand with long life.

I haven't decided on the inverter size yet. I will not be running a microwave, so 1500W or even 1000W will probably be enough. You are right about matching to the bank. 230Ah and 1000W is a good match for short duration use. If in this small trailer if a microwave was a necessity, I think to get the Ah I would need considering the logistics (weight primarily) I might enter the LiFePo4 arena, kicking and screaming all the way. But guess what the Trimetric pair is ready for them. So, no microwave, but I might find myself accommodating the DWs curling iron / hair dryer. I like to overbuild in case I might need a 2000W at some point. It is possible to under fuse the circuit to limit the DC load. Such as installing a 2000W inverter but using a 175A breaker.

So, why I like the SC2030 is its size, simplicity and cost. I have had 4 packages / systems with not a single issues. Bogart support is very responsive when I have needed them. SC2030 is $119 and the TM2030 is $160. A required shunt is about $24

Their charger is rated for 30 amps; it can reduce current to 31 amps when higher amps are being delivered without harm. Its silent. It can work autonomously, but with the TM2030 is when you get the most out of it. You can also have the TM-2030 by itself.

The TM2030 RV model is the smaller faced one that I like.

The docs that Bogart provides are a lesson plan unto itself. Someone wanting to get into this, could get a TM2030 and with the documents pretty much learn all they need to do it. You can start out with generic settings and go deeper into it as you want to. History functions are very nice IMO

IMO this setup is good for these small systems with 36 cell panels in parallel. I can see the advantage of MPPT in grid tie (required) or in larger systems. When using higher voltage panels or several in series with small gauge cabling or when you have long wire runs ... makes sense.

What I don't buy into is all the hype and companies selling something with an agenda. Great marketing and not so great products and industries in bed with other industries that are out for a profit without your interest in mind. Getting the latest thing can be more bleeding edge than cutting edge.

Clint

[LuvsPossums]

Originally Posted by AirMiles

Ray, Thank you for sharing your solar setup on the "Solar Show & Tell" thread. Yes, adding solar can be as easy as Ray describes. Buy a solar panel, connect it to a small controller, and connect the controller outputs to your battery. Its as easy as hooking up a battery charger and YES it will work.

Ray's setup probably outputs about 5A. With the ability to keep this portable 100W panel pointed directly at the sun, that 5A could be achieved for 10 to 12 hours per day. Therefore, Ray could be getting 50 to 60 Amp Hours on a good day. I could get by on this much solar with a little conservation.

That's a lot of juice for just over $100!

Wondering if you or Ray could walk me through this?
I once had a Bambi, but had to sell (really miss my Sport!) and now have a Eurovan that I bought to boondock in (much more user friendly for disable to not deal with towing.) Having a Eurovan, I have a popup-top that is at an angle that I can capitalize on if able to angle the van.

The challenge I have is being disabled, so I am limited with what I can put on the roof and an install of anything needs to be handled with great care to not crack my roof. I plan to travel when. the weather is perfect to avoid having to use ac, so my energy needs should be easily filled, & I'm really hoping 1 panel can do the trick, but if not, I can at least adapt and know if nothing else, my electronic devices can operate, even if it's only my smart phone.

The EVC (Eurovan Camper) comes equipped with a 3 way fridge and propane burner, so those are covered (although I'd love to run the fridge on battery if possible.) Ultimately I want clean energy to power AC, but waiting on advanced tech to come to the USA (IF we ever decide to catch up to the rest of the civilized world).

[AirMiles]

Wondering if you or Ray could walk me through this?

I'm not sure what the question is? If you have a fiberglass roof that pops up, you can mount panels to it with the same procedure as on an aluminum Airstream.

1) Clean the surface with isopropyl alcohol, let it dry for several minutes, and then attach the mounting brackets with 3M 4950 VHB tape. After 24 hours, seal the taped area of the mounting brackets with SikaFlex 221.

2) Then you need to get the 10 gauge wires into the van and connected to the inputs of a solar controller placed as close to the battery as possible. I'm not an expert here so I would suggest to call AM Solar. Here are pictures of many of the AM Solar installations which may give you some ideas: https://amsolar.com/solar-panels-for-rv/?

3) Then you need to connect the outputs from the solar controller to the battery with at least 6 gauge wire with a fuse or circuit breaker on the positive wire.

Again, look at the pictures on the AM Solar site for ideas. Look at the equipment sold at AM Solar and call them to discuss your needs. If you buy your equipment from AM Solar, they will be available to assist you with the installation either over the phone or by installing it at their facility.

I know I'm sounding like an AM Solar salesman. That is not my intent. They are just extremely knowledgeable and helpful. Their prices are probably slightly higher than some of the other do-it-yourself resellers, such as Renogy, because of the level of service they provide. I also found Renogy was very helpful when I was shopping for my system. I chose AM Solar because they would have completed my installation in their shop, at a fair hourly rate, if I got in over my head. This backup option gave me the confidence to attempt this project. This may be the level of support you are looking for.

[uncle_bob]

Originally Posted by LuvsPossums

Wondering if you or Ray could walk me through this?
I once had a Bambi, but had to sell (really miss my Sport!) and now have a Eurovan that I bought to boondock in (much more user friendly for disable to not deal with towing.) Having a Eurovan, I have a popup-top that is at an angle that I can capitalize on if able to angle the van.

The challenge I have is being disabled, so I am limited with what I can put on the roof and an install of anything needs to be handled with great care to not crack my roof. I plan to travel when. the weather is perfect to avoid having to use ac, so my energy needs should be easily filled, & I'm really hoping 1 panel can do the trick, but if not, I can at least adapt and know if nothing else, my electronic devices can operate, even if it's only my smart phone.

The EVC (Eurovan Camper) comes equipped with a 3 way fridge and propane burner, so those are covered (although I'd love to run the fridge on battery if possible.) Ultimately I want clean energy to power AC, but waiting on advanced tech to come to the USA (IF we ever decide to catch up to the rest of the civilized world).

Hi

One panel will put out a maximum of 100W in full sun. It will do that at about 16V from a normal panel. 100W at 16V is 6.25A. The solar converter will turn that into 12 to 13V on the output. At 12V 100W is 8.3A. Both on the input and output of the device, 10 gauge wire is plenty big enough to handle the current. It's also large enough for any run inside a van at insignificant voltage drop.

If you get full output from the panel for 8 hours, that's doing very well. If your converter runs at 90% efficiency, that's also doing well. Net result would be a bit over 50AH on a perfect day. On a normal day, something in the 30 to 40AH range is a pretty good bet.

A normal fridge running on propane pulls about 1A to run the control board and other "stuff". That gets you to 24AH a day. Parasitic loads / miscellaneous stuff likely run another 10AH or so each day.

So with a lot of care you *might* just squeak by using virtually nothing on the trailer but a fridge on propane. If the fridge decides to run on 12V, that's a lot more current and you likely are in trouble. Things like a furnace or a fantastic fan overnight also will take you way outside your budget, even on a perfect day.

If you can arrange a way to get three panels up on the roof (and there's a place to fit them) that's a much more reasonable solution to the problem. You still need care and management of your power use. At least you aren't running out on a daily basis.

Bob

[Fair_Enough]

Your “let’s say” would be 5 amps from the inverter and 50 amps from the batteries.

Just saying Edit: replied to #13 but tried to delete. WW