Sufficient solar system for full-time living?

[redheadkellyscamp]

Originally Posted by Alex Adams

Kelly, if I were going to set this up I would get the MPPT controller and see if my friend had a 350 watt 24 volt panel. That would probably give you the greatest efficiency as far as extracting every possible amp from your system. The MPPT controller will take the 24 volt input and convert it to 12 volt output for charging your batteries assuming they are 12 volt. That is more efficient than feeding 12 volt or even 24 volt into a PWM controller. The other question would be if the panels he has are configured to still work if partly shaded. Some panels will produce no power if part of the panel is shaded. Otherwise, you will need to be very vigilant to make sure your panel doesn't cut out.

Ah... thank you so much Alex. I think those were exactly the answers I needed.

[Jon Vermilye]

The Atwood MPD 93756 water heater runs on propane or 120V
AC, not 12V. On 120v, it uses around 1400 watts, or around 11.67 amps at 120v. If you are planning to run it on electricity, you will need at least a 2000 watt inverter wired to the batteries with at least #2 wire since the input to the inverter will draw around 120 amps. If the run is more than a couple of feet, larger wire would be necessary. I also suspect you will find that the pair of 78 amp hour batteries will not be adequate for the inverter load driving the water heater.

The furnace is also a propane/12V device. It will not produce heat without burning propane. All the 12V does is run the electronics & fan motor.

I agree with Alex that going with a MPPT inverter & 24V panel would be more efficient, but still don't believe you will be able to always produce 75 amp hours per day. A string of bad days will leave you without enough stored capacity to run the inverter to produce hot water. The pair of batteries & 300 watts of solar should work fine for the rest of the appliances, lights, etc, but you will need propane for the furnace, and more than likely, for the hot water.

[k corbin]

I have my Campster set up to run lights and my fridge on a roof top solar panel. My panel is 150watts Renogy with a 20am MPPT renogy controller. I have a 160 amp hour AGM deep cycle battery that is inside my trailer over the axle. My Campster never had a powered refrigerator so I bought a used Engel fridge that runs on 12v or 110 volts. Engels are a very reliable brand that uses less power than many 12v fridges. I have enough power to run my fridge, charge my phone and tablet and charge up some USB rechargeable LED lights. I can do this even on a cloudy day. My battery was back to 100% charge by 8:00am on sunny days this August. Even now in the Pacific NW on cloudy days it is back to 100% by about noon. My house battery is not set up to be recharged by my tow vehicle when driving as the alternator in my Honda Element is too undersized for that task. So solar is the only source of power that is charging my house battery. Which is good because I am doing longer times of camping in one spot for several weeks to several months at a time which means I am not hooked up to my tow vehicle for charging anyway. Seems like that is the goal you are stating.

Lithium batteries are of course much lighter in weight and smaller in size compared to the power you get from a lead acid battery. So if you have the money get one.

I also have a small Honda generator along but that is because sometimes I run other 110v equipment for a number of hours at a time. But for just devices, lights and my fridge I have never needed to use anything other than the solar.

So the key for you is not just solar but also getting a different fridge that will run efficiently on 12v.

I have an all new custom interior so I designed my cabinets with my fridge and battery dimensions in mind and made sure to put them both right over the axle, fridge on one side, battery on the other.

[redheadkellyscamp]

Ok. Awesome. It feels like this is the meat of it.

If I can’t run the water heater off of 12V, then I don’t even need a second battery, really. Although, nice to have probably, just in case.

I will definitely be putting the propane tank back on the trailer once it starts raining. As you say, Jon there is just no getting around it. I need propane if I want heat. And that’s the one thing I do want. Once the ground is wet again, I’ll be ok with it.

I just don’t think I’ll be comfortable having a pilot going 24/7. We’re all fire-paranoid out here these days. And we’re, just today, having red flag warnings due to hot/dry/windy fire conditions. Wind at 30-40 mi/hr last night. So the season’s not over yet. Everything will change once we get rain again, although it’s starting to feel like that might not ever happen.

So probably no fridge for a while.

You’re not the first to suggest a different fridge, k Corbin. I’ve been living for years with the trailer plugged in & I love my little absorption fridge. It’s so quiet. Depending on how things go, we might have power back out here in 6 months or less. So I don’t really want to jump into switching things out if I don’t have to. If it looks like things aren’t going to work out here, though, I’ll definitely look into the fridge you suggested.

[Jon Vermilye]

If you are pushing to save amp hours, changing the 1141 incandescent lamps to warm LEDs could save you at least 5 amp hours per day (using your 4 hour figure). A bit of an initial cost, but they are far more efficient than incandescent.

[k corbin]

A pilot light is a lot more likely to blow out when it is windy than it is to start a fire. Those flames are not out in the open near combustible materials.


As you said you have been running it for years without any problems. That should tell you just how likely it is to become the problem you are worrying yourself over. It is not an "open" flame because the pilot lights are not out in the open, they are inside metal compartments meant to create a zone that is safe to have them in. Quit over reacting, think it through, they were engineered to prevent fires from happening.

[Glenn Baglo]

Originally Posted by k corbin

My Campster never had a powered refrigerator so I bought a used Engel fridge that runs on 12v or 110 volts.

How many cu. ft. is your Engel?

[k corbin]

Originally Posted by Glenn Baglo

How many cu. ft. is your Engel?

its Tiny! but not the smallest one they make. It works perfectly for me though as I am not a beer drinker or even a wine drinker except on rare occasions. I also avoid drinking sodas.

I cut food like veggies up into the size of pieces for salads or stir fry and store them in ziplocks. No wasted space in my fridge so I get about 10 days or more of stored cold food in it for one person.

But even the larger Engels are still energy efficient.

By the way, a smaller sized full fridge uses a lot less power than a big half empty fridge like the one in your photo does. The food retains the cold in it when you open the fridge a lot better than empty air space does. And as mine is a top loading fridge all the cold air does not fall out of it when I open it. I have been using it for full time living for the last 3 months and it is working just great for me, not too big and not too small.

You can see best see its relative size in this photos showing it on top of the wheel well inside my aluminum angle cabinet framing. I was just doing a check fit for overall size before I made the pullout tray for it. The cabinet is about 6"' long overall and 36" high.

[thrifty bill]

Step 1: Optimize/reduce energy use.

Step 2: Design a system to meet these reduced/optimized needs.

Everything gets smaller (batteries, solar panels) once you optimize use. 1141 light bulbs should be long gone, as LEDs use 90% LESS power. I enjoy twice as much light for 80% less consumption. Sweet.

Leaving propane out of the arsenal of power sources is foolish. Heat, hot water, and refrigeration are all handled quite well with propane. Between propane and LED lighting, you can reduce your power needs to a small fraction (and reduce the footprint and COST of such power generation and storage).

[redheadkellyscamp]

Yes. I hear what you're saying k corbin. I wasn't so much thinking that the wind was going to cause a fire, though. It was more I had had a bad night because of it & just don't want to add to the list of things that are going to keep me up at night, especially those that might have me thinking about fire. It's not so much over-thinking, at this point, as it is PTSD.

But it's fine. I can live without a fridge for a while. I'm OK with using the heater & stove with the propane because I'll be awake while it's happening. Once it starts raining & the ground is wet again, I'll get the propane hooked back up. No problem there. Then, we'll see how long it takes me to get tired of packing a bag of ice back up there every 2 days for the fridge. At that point, I might be willing to look at other options.

The most important thing is that I didn't know exactly what I could & couldn't do with solar and I feel like I have a very good handle on that now. So, now I can start making decisions accordingly.

Thanks again everyone! I feel like I really know what I'm doing now.

[RogerDat]

A very basic output calculation is to figure for 4 hours a day one gets full amperage output from panel, and for another 4 one gets 1/2 output.

Ignores a lot of variables but does come up with a reasonable number for "typical" amp output for number of hours. One might be able to reposition the panel periodically throughout the day to aim toward the sun better, or it could be mounted flat on the roof. Latitude and time of year influences number of hours of daylight. Some parts of the country experience pretty regular rain which cuts into those charging hours. But as a general "rule of thumb" it works ok. Runs into trouble when one isn't planning for a generous margin of reserve.

So a panel that puts out 5 amps would give you 4 hours at that 5 amps and 4 at 2.5 amps due to the sun being at a steeper angle in the morning and evening, thus reducing output. I would short hand that to 6 hours at full panel output on a sunny day.

I don't recall many if any fires started by camper propane systems. They are nearly as safe as home if checked and maintained on a regular basis, if not more so in seismically active areas. When was the last time one went through the house with soapy water checking the house gas fittings?

In some areas fire restrictions won't allow any external fires in stoves or lanterns, others will have restrictions that the stove or lantern must have an "off" knob, lever, or switch. Some areas have banned liquid fuel stoves, restricting one to propane or butane. I assume to mitigate the potential that someone spills liquid fuel or tries to fill a hot device and fuel ignites.

The "flame" on a propane fridge is about the size of a fat candle flame. You could cover it with your thumb. A routine checkup should confirm that if the flame goes out the gas shut off is activated. Or that furnace shut off remains off if furnace doesn't light.

You have a smoke and CO detector which should be tested and are in much closer proximity to any problem. They should go off well before any situation has time to grow. There is a reason current code requires smoke detectors in basement. Fire in basement doesn't have time to get going before alarm alerts occupants upstairs.

I can on one hand be sympathetic to ones feelings after personally seeing a tragic fire, but logically there is no more risk today than there was this time a year ago. Cars use flammable fuel. Even electrics have a potential for a battery fire.

Charging battery will give off hydrogen gas, one spark can set it off. This is why RV batteries are outside or well ventilated. With jumper cables the negative cable is supposed to be to the metal of the car not at the battery. Avoids having the battery charging for a bit building up hydrogen then if cable is moved it sparks. Know a couple of people who forgot that. Shattered battery case from explosion and acid make for some nasty slow to heal wounds.

I can totally see if possible not running the heater in a 13 ft. Scamp while sleeping. I can use a good sleeping bag and fire up the heat in the morning to take the chill off. I wouldn't worry very much about the fridge personally.

You will want a good battery status monitor. With a high draw load it would be easy to have the batteries go below 50% charge and that does damage them to some extent. Shortens their life expectancy and ability to store power.

[RogerDat]

A member here made plastic "curtains" that hung from tension rods used to secure fridge contents while traveling.

By hanging a clear plastic curtain down in front of each shelf they helped reduce the amount of cold air that flowed out when the door was opened. No data on how much it reduced cold flowing out and warm flowing in but it looked like it should help. Commercial use plastic curtains in opening of walk-in and drive-in refrigeration units so one can assume they have enough impact on reducing energy consumption to be worthwhile.

[k corbin]

You seem to be confusing the pilot light on trailer fridges with the open flames on camping stoves and lanterns. Those camping stoves and lanterns are only rated for use out of doors. The pilot light on a trailer fridge is contained inside of the trailer's structure. It is a flame but it is not an "open" flame.


Of course you do want to inspect your propane system for leaks and such but that is just part of the normal annual inspection you would want to do anyway.

[gordon2]

Originally Posted by k corbin

..The pilot light on a trailer fridge is contained inside of the trailer's structure. It is a flame but it is not an "open" flame.
...

Its also not a "pilot" light.

pi·lot light, noun
1. a small gas burner kept continuously burning to light a larger burner when needed, especially on a gas stove or water heater.

There is no larger burner ignited by the small flame on an absorption fridge. The little flame is the burner.. the entire burner - the sole heat source, and it is not started by a smaller flame.

[redheadkellyscamp]

Thank you RogerDat for your reply. It was helpful to hear someone else think through what I've been thinking.

I did eventually think to get someone out there to have the whole thing inspected. That definitely seems to be the next step. But the ONE guy in town is booked till December. It's starting to look like it won't be too cold before then, though.

I'll be the first to admit that some of what is happening here is irrational. Or some sort of overblown concern based on recent extreme circumstances. But it is what it is at this point. It might take some time, and another rainy season, before that calms down.

Part of it is just caution. I've lived here for 50 years & we've always had long, hot, dry summers. But we never used to have dry lightening igniting fires everywhere. That's new. The extreme dryness has been palpable the last few years in a way it never has before.

And I lived much closer to Paradise when that happened.

No one wants to be Mrs. O'Leary's cow, or the guys that burnt down 1/2 of southern California trying to have a gender-reveal party. Especially if fires are taking out whole towns now. And it just feels like anything remotely related to fire could make the whole thing go up these days. Someone started a fire down the road from us just from a shell, or a spark, or something, during target practice.

So... until it starts raining again. No fire anywhere. I hear what you're saying k corbin about it not being an open flame. Or apparently not even technically a pilot-light. I have run the fridge with the propane before, when the power got shut off due to heavy winds. But, as you said before, the winds blew it out.

It's fine. Right now I don't have electric or propane out there. If the weather was never going to change, I'd actually be fine with that.

I am getting a 300-350 watt solar panel from my friend who works at the residential solar company. I just bought a duplicate of the battery I have & everything to get the two connected. Now I just need to the find the right charge controller.

I think once the cold does finally get here, I'll have what I need to run the heater, and then some.

I wasn't aware of the hydrogen issue with batteries, RogerDat, but I have wondered if there was anything I need to be careful of with the solar. The battery I have now is just in the standard plastic battery box that came with the Scamp. Is there enough air-flow in something like that to make sure there's not a build-up of gas? Seems like there would be.

Thanks again everybody!! I definitely have a much better handle on what I need than I did when I first asked. Definitely an education.

[gordon2]

Originally Posted by redheadkellyscamp

... The battery I have now is just in the standard plastic battery box that came with the Scamp. Is there enough air-flow in something like that to make sure there's not a build-up of gas? ...

If its on the tongue (or outside) and the little vents on the box have not been sealed, then its fine. The gas generation is not a lot, and really only a concern when under heaving charging. Even then, there has to be a spark to cause an explosion. So with a battery box on the tongue with vents it is no concern.

[gordon2]

Originally Posted by gordon2

...when under heaving charging....

Urgg... I hate when people make typos and don't correct them.. and when I do it, it's 100% worse.

Of course I meant HEAVY charging.

[thrifty bill]

Originally Posted by redheadkelly

But the reason I’m in this situation is that we just had one of the big fires come through & literally burn down the house I was living next to.

I’m afraid I’m a little fire-phobic now & I just don’t think I’m going to be able to sleep knowing there’s a flame burning 3 ft from my head. As it is, I don’t think I’m even going to be able to turn on the propane until it starts raining .

It would be interesting to see data on RV fires: propane versus electrical. I would not be surprised to see electrical fires are more common. But I could be wrong.

Certainly many of the recent CA fires were started by electric failures.

[Glenn Baglo]

Originally Posted by thrifty bill

Certainly many of the recent CA fires were started by electric failures.

Pacific Gas & Electric Co. power lines have caused more than 1,500 California wildfires in the past six years, including the deadliest blaze in the state's history.

[Alex Adams]

Glenn, that's like saying more house fires are caused by electric lights than Kerosene lights. While true, it means nothing since there are far fewer Kerosene lamps compared to electric lamps. Same with Power lines versus gas lines. You would need to calculate the number of fires started per mile of line to see which truly causes the most fires.