Snowbird CTC appliances. Solar vs propane and mods to order.

[rebar]

Hello people..

This is the last summer I'm willing to look for the rare used 7x16 narrow track trailer I want. I found two companies in Iowa, Jensen and Custom Classic Trailers, who will build a custom cargo trailer for me which has me a bit stressed out, because I don't want any remorseful after thoughts after spending 2X what a used trailer would cost. Hindsight's 20/20.

My question is regarding appliances and whether I should use solar or propane to run my refrigerator and water heater? I'll need a space heater once in a while so propane will be needed anyway and will use a generator to run a microwave and AC when needed. I only plan on spending a couple of weeks per year in this CTC for the next 8 years, but then will spend months at a time in it after I retire chasing nice weather. But solar innovations and better efficiency is bound to happen within 8 years, so I'm tempted to set it up for propane for now because solar cannot provide all the power.

What would you do in my position, and what custom mods regarding appliances would you ask the trailer builder to install? Maybe blind threaded inserts in the roof to mount solar panels for example? Can I install a big roof vented 3 way fridge and 5 gallon water heater without any special mods or headers on the outside wall?

Thanks!

[flboy]

No problem at all to run small fridge on solar whether you plan on an expensive DC fridge or cheaper Dorm style AC fridge. Both use very little power and a modest solar setup should do it.

On water heater, alot depends on your solar capacity and environment at any given time. They take alot of power.

I have a propane/electric and if I am plugged in or if solar is at high capacity due to good sunlight, no problem. It takes 1100W for about 20 minutes to heat 6 gallons which is plenty... but need to be able to recover batteries at some point when boondocking.

If you are going to have the generator anyhow for the Air Conditioner, then you are all set. You can recharge batteries as needed if solar is not ideal for battery recovery.

I designed my CTC with a modest 500W of solar and 425aH of batteries, but you could do much less for just a fridge.As is, the capacity I have will even run my AC for a few hours for most all scenarios and the gen is backup. Electric fridge, gas/electric water heater, propane stove, oven and heat when needed.

As for what to have the mfg. do, I'd say if it is within your skillset to do yourself, then do it yourself as it will be done better most likely and will not cost a premium. They get you for any mods.




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[rebar]

Thanks Don. I subscribed to your build thread and you've done a outstanding job, but I still need to read it all..

A "small fridge" wont be big enough for the two of us when boondocking for a week or more. Can I power a large fridge with separate freezer compartment and a water heater with solar? Will I really save money in the long run?
And is there a generic or common size of solar panel? I'm wondering what the spacing is for the mounts because I don't want any additional roof penetrations. Maybe two rows of versatile L-Track welded on the roof for whatever I want to mount?

I only camp in full service camp grounds as a last resort, or if they have a Laundromat after a couple weeks out.

[flboy]

I wouldn't say you'd save money at all with the solar over propane fridges and water heater. You may spend more for solar setup than you will save with AC appliances over the propane appliances.

For me it is about versatility and I needed AC electric anyhow for other things, so I used AC appliances driven now by a 3000W pure sine inverter.

I just like the whole solar thing and I am a person who likes to mess with technology. Certainly propane is very established, easy to understand, and it just works. Forget about using the 3 way Propane fridge on electricity unless plugged in. They are huge power drains and very inefficient.

On the roof for panels, there are many sizes. I went with 100w panels at 12v. Doing again, I may consider a larger panel at 24V just because of less wiring. The charge controller handles either 12 or 24vdc in most MPPT configurations.

Your idea of versatile brackets sound very good. You can figure out panels later based on price, needs, etc..

Good luck. Tough choices and everything is a tradeoff. Budget and your comfort with technology may be good guides.

I really ended up with a hybrid of solar/electric and propane with fridge 100% electric, hot water is gas or electric, and stove 100% gas. I do have a single induction burner I can use if wanted on generator or shore power. All other appliance such as Air Conditioner, TV, microwave, blender, etc. use AC power from solar, gen, or shore.

Solar will definitely run a larger fridge if needed. You'd be suprised at how little power they actually consume when compressor is on. Just need to do the math to see what is required and if it is worth it to you for sustaining solar capabiltiy, battery bank and inverter.



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[rebar]

I wouldn't say you'd save money at all with the solar over propane fridges and water heater. You may spend more for solar setup than you will save with AC appliances over the propane appliances.

For me it is about versatility and I needed AC electric anyhow for other things, so I used AC appliances driven now by a 3000W pure sine inverter.

I just like the whole solar thing and I am a person who likes to mess with technology. Certainly propane is very established, easy to understand, and it just works. Forget about using the 3 way Propane fridge on electricity unless plugged in. They are huge power drains and very inefficient.

Good luck. Tough choices and everything is a tradeoff. Budget and your comfort with technology may be good guides.

Solar will definitely run a larger fridge if needed. You'd be surprised at how little power they actually consume when compressor is on. Just need to do the math to see what is required and if it is worth it to you for sustaining solar capability, battery bank and inverter.

Thanks again.. I came up with the same conclusion about solar for my home. It wont pay for itself because of the low electrical rates here in Iowa.

I guess I got caught up in the idea again when I heard Bob Wells say his 12v solar fridge would pay for itself.
https://www.youtube.com/watch?v=MBBtvkBaXXw

I realized there would never be a break-even point if I only spend two weeks a year in my CTC. But I still wonder if there would be a break-even point if I spent 8 months a year in my CTC after I retire.

[flboy]

I wouldn't say you'd save money at all with the solar over propane fridges and water heater. You may spend more for solar setup than you will save with AC appliances over the propane appliances.

For me it is about versatility and I needed AC electric anyhow for other things, so I used AC appliances driven now by a 3000W pure sine inverter.

I just like the whole solar thing and I am a person who likes to mess with technology. Certainly propane is very established, easy to understand, and it just works. Forget about using the 3 way Propane fridge on electricity unless plugged in. They are huge power drains and very inefficient.

Good luck. Tough choices and everything is a tradeoff. Budget and your comfort with technology may be good guides.

Solar will definitely run a larger fridge if needed. You'd be surprised at how little power they actually consume when compressor is on. Just need to do the math to see what is required and if it is worth it to you for sustaining solar capability, battery bank and inverter.

Thanks again.. I came up with the same conclusion about solar for my home. It wont pay for itself because of the low electrical rates here in Iowa.

I guess I got caught up in the idea again when I heard Bob Wells say his 12v solar fridge would pay for itself.
https://www.youtube.com/watch?v=MBBtvkBaXXw

I realized there would never be a break-even point if I only spend two weeks a year in my CTC. But I still wonder if there would be a break-even point if I spent 8 months a year in my CTC after I retire.

I'd have to watch his video, but could it be he is talking about cost of propane vs free solar power once you make the solar power investments? Maybe for full timers like himself, but Id say it would not for the weekend warriors.


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[Pinstriper]

I question whether there is enough surface area to generate enough electricity to drive a hot water heater from solar.

However, my monster-in-law had a solar water heater on the roof of her Arizona house. It was a black box with a manifold of smal black pipes through which water ran, and when the sun was up, yowzer she had free hot water. You may be able to fab something like this, recirculating and a tank so you have more going than just the volume of water in the tubes.

Its only hat during the day, of course. Again I don’t think you can haul or charge enough battery to drive an electric water heater. Just too much juice.

If you must have nightime hot water, plan on a generator and not a small one, or use propane.

Consider also a generator what runs on propane. Makes pre-trip provisioning simpler.



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[flboy]

Pinstriper, you never drive anything directly from the solar panels in the configuration on an RV. They are for charging batteries. Batteries supply current directly and surges to 12vdc appliances and/or inverter. I can run a 3000w inverter and run an 1100w water heater long enough to heat water in 20 minutes (6 gallon tank). The 500w of solar then recovers the batteries in a few hours. So you plan your system and qty of panels based on composite drain you anticipate all day vs what is needed in terms of power to recharge while sun is out. When there is a mismatch due to weather, usage, or etc... time to pull out Honda and make some up.

225ah is the capacity I have (50% of the 450ah roughly with 4 golf car batteries) and at 12.5 vdc running 1100w for a whole hour would only take me to ~75% charge. Obviously 20 minutes is only a fraction of that... so you see, no issue since I can run apprx. 2800watts for an hour before I would reach 50% at 12vdc. So on a sunny day, electric water heater is no problem. Of course I can use propane also, but solar is free power once you have the equipment, so I use it when I can.




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[Pinstriper]

Pinstriper, you never drive anything directly from the solar panels in the configuration on an RV. They are for charging batteries. Batteries supply current directly and surges to 12vdc appliances and/or inverter. I can run a 3000w inverter and run an 1100w water heater long enough to heat water in 20 minutes (6 gallon tank). The 500w of solar then recovers the batteries in a few hours. So you plan your system and qty of panels based on composite drain you anticipate all day vs what is needed in terms of power to recharge while sun is out. When there is a mismatch due to weather, usage, or etc... time to pull out Honda and make some up.

225ah is the capacity I have (50% of the 450ah roughly with 4 golf car batteries) and at 12.5 vdc running 1100w for a whole hour would only take me to ~75% charge. Obviously 20 minutes is only a fraction of that... so you see, no issue since I can run apprx. 2800watts for an hour before I would reach 50% at 12vdc. So on a sunny day, electric water heater is no problem. Of course I can use propane also, but solar is free power once you have the equipment, so I use it when I can.




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I understand all that. I am just saying having batteries that big, and 500w is a big solar system, too, why, all that for 6 gallons of hot water ... you are better off running the propane for 10 minutes, which you do do many many many times from a tank.


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[flboy]

I understand all that. I am just saying having batteries that big, and 500w is a big solar system, too, why, all that for 6 gallons of hot water ... you are better off running the propane for 10 minutes, which you do do many many many times from a tank.

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I see. You confused me when you said "I question whether there is enough surface area to generate enough electricity to drive a hot water heater from solar."

In my case, all the solar is not just for the Hotwater, it is for many things to include the refrigerator and Air Conditioner for a few hours at a time if needed. I just use the solar power when I have the excess instead of using propane.

I agree.. propane does the job very nicely and I do use it at times.... but if I have a full charge and plenty of sunlight... why not.. costs no more to use it and saves the propane. I would not have installed solar just for an electric hot water heater... that would be a waste.

[GTS225]

Pinstriper may be onto something with the mention of his MIL's passive hot water system. What if one had such an arrangement ahead of the electric water heater? Would this not cut electrical usage by a large percentage? I suggest arranging a valve or two such that one could drop a garden hose outside the camper, attached to fittings in the side, in the supply side plumbing to the heater. Lying out in the sun, even on the ground, would pre-heat any water before it got to the heater, thus saving quite a bit in power or fuel consumption.
Just a thought on passive systems.

Roger

[hankaye]

GTS225, Howdy;

Pinstriper may be onto something with the mention of his MIL's passive hot water system. What if one had such an arrangement ahead of the electric water heater? Would this not cut electrical usage by a large percentage? I suggest arranging a valve or two such that one could drop a garden hose outside the camper, attached to fittings in the side, in the supply side plumbing to the heater. Lying out in the sun, even on the ground, would pre-heat any water before it got to the heater, thus saving quite a bit in power or fuel consumption.
Just a thought on passive systems.

Roger

Good thoughts there. I live in my RV, in Southern NM, Past week it's been triple digit heat.
This Park was built using the minimum as the Standard. Main water lines are "maybe" 30"
deep and mostly under a thin asphalt surface. All that to say the water temp. in Summer is
on the warmish side. My propane fired hot water heater still takes 12 to 15 minutes from
click ON to Click OFF.
Now if you want some HOT water get some Black PVC pipe and some fittings of you choosing
and using the following chart http://www.torrentee.com/pdf/Pipe_Volum ... Jun-02.pdf
1 foot of 6" ID will contain 1.5 gallons. So, ... figure out you gal. needed multiply and there's your answer.

hank

[flboy]

A hundred ft of coiled up black hose would do the teick for thermal solar heating. Very portable.

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[tony.latham]

I understand all that. I am just saying having batteries that big, and 500w is a big solar system, too, why, all that for 6 gallons of hot water ... you are better off running the propane for 10 minutes, which you do do many many many times from a tank.

Exactly.

DC voltage (especially with an AC inverter) is a bad choice for producing heat.

T

[flboy]

I understand all that. I am just saying having batteries that big, and 500w is a big solar system, too, why, all that for 6 gallons of hot water ... you are better off running the propane for 10 minutes, which you do do many many many times from a tank.

Exactly.

DC voltage (especially with an AC inverter) is a bad choice for producing heat.

T

This is true. It is certainly not the most efficient way, but it is a way , and if the solar charges the batteries for free and you already have the system in place for other reasons, then it is actually more effiecient ,in terms of not spending any additional resources , to use it. That's is the point. Certainly no point in setting all that up just to heat water.

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