Sufficient solar system for full-time living?

[redheadkelly]

I find myself unexpectedly needing to live in my 13’ Scamp full-time this winter with no water or power hook-ups.

I’m trying to determine the most inexpensive setup to just run the lights & DC appliances. I can live without A/C, for now.

My priorities are the refrigerator & the heater.

From what I have been able to determine, I’ll need a second battery. But then people seem to be saying that 100 watt panels would be enough.

Just to be safe, since it’s winter, in Northern California, I was also looking at 200 watt systems.

Amazon has this Renogy kit available right now.

Renogy 200 Watt 12 Volt Monocrystalline Solar Starter Kit with Wanderer https://www.amazon.com/dp/B00BCRG22A...ing=UTF8&psc=1

It seems that there are some mixed feelings about Renogy, but if their quality is usually reliable enough that it will most likely be operational when I get it, I’m willing to take a chance on them for this price.

Question is... is this everything I need? Is this a Kit I can leave set up full-time during the windy/rainy months & it will keep my battery charged so I can run my fridge & heater? Or am I going to find that I’m going to have to purchase more components to get it all working?

I like that it looks like I can add an inverter to it later, if I do want A/C, but I don’t need it now.

From what I’ve been able to teach myself rather quickly, this is sufficient, but I just want to be sure.

Thanks.

[Doug in Sacramento]

You will not be able to run a refrigerator on 12 volt DC for any significant length of time, unless you have a great deal of battery storage capacity. You will need to rely on propane for refrigeration.

[Thomas A Cronquist]

Originally Posted by redheadkelly

I find myself unexpectedly needing to live in my 13’ Scamp full-time this winter with no water or power hook-ups.

I’m trying to determine the most inexpensive setup to just run the lights & DC appliances. I can live without A/C, for now.

My priorities are the refrigerator & the heater.

From what I have been able to determine, I’ll need a second battery. But then people seem to be saying that 100 watt panels would be enough.

Just to be safe, since it’s winter, in Northern California, I was also looking at 200 watt systems.

Amazon has this Renogy kit available right now.

Renogy 200 Watt 12 Volt Monocrystalline Solar Starter Kit with Wanderer https://www.amazon.com/dp/B00BCRG22A...ing=UTF8&psc=1

It seems that there are some mixed feelings about Renogy, but if their quality is usually reliable enough that it will most likely be operational when I get it, I’m willing to take a chance on them for this price.

Question is... is this everything I need? Is this a Kit I can leave set up full-time during the windy/rainy months & it will keep my battery charged so I can run my fridge & heater? Or am I going to find that I’m going to have to purchase more components to get it all working?

I like that it looks like I can add an inverter to it later, if I do want A/C, but I don’t need it now.

From what I’ve been able to teach myself rather quickly, this is sufficient, but I just want to be sure.

Thanks.

I would buy a 12 volt cooler Iceco and use that for your refrigerator. You can put in were the refrigerator would go, and place the cooler on slide outs. Thats what I did when I had a 13' Scamp. Check out slim potato head on youTube. He has a Trillum 13" great mods. Solar panel mounted on top...He lives in Canada.

Tom C

[redheadkelly]

Originally Posted by Doug in Sacramento

You will need to rely on propane for refrigeration.

Yes. Thank you Doug. I have seen others say that propane is better for the refrigerator when boondocking.

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 again.

I used one of the solar calculators & it said I could run the the fridge if I had a second battery. It wasn’t specific about which fridge it was using for the calculations though. I just have a little Dometic 1.9. I haven’t been able to find anywhere where someone has done the math & figured out exactly how long it can run on 12V. I just need it to be good overnight & the temp outside & in the trailer will probably close to fridge temp anyway most of that time.

If the solar isn’t enough on some days, I can switch to propane temporarily, just as a backup.

[redheadkelly]

Originally Posted by Thomas A Cronquist

I would buy a 12 volt cooler Iceco and use that for your refrigerator. You can put in were the refrigerator would go, and place the cooler on slide outs.

Thanks Tom.

But I already have a perfectly good refrigerator installed in the trailer. And I don’t have it in me take make any big mods.

I barely have it in me to figure out the solar & get it running. I’m looking for the most plug & play solution available at this point.

Literally just connect something to the battery & be done with it, hopefully.

[JessieJanet]

we recently purchased an iceco chest fridge & my husband has a heated-line cpap. We have 2, 100 w solar panels, no inverter on our 19'.
The overnight draw running the fridge on Eco at 34°, & the cpap was <5%. We also charged cell phones & used lights.
We just finished a slide-in drawer system for the iceco. Still need to trim it out. Seems the list is never finished!

[redheadkelly]

Originally Posted by JessieJanet

we recently purchased an iceco chest fridge & my husband has a heated-line cpap. We have 2, 100 w solar panels, no inverter on our 19'.
The overnight draw running the fridge on Eco at 34°, & the cpap was <5%. We also charged cell phones & used lights.
We just finished a slide-in drawer system for the iceco. Still need to trim it out. Seems the list is never finished!

Right? Now that I’m making myself wrap my head around solar, I keep thinking of all the things I can do.

So your chest fridge doesn’t seem to draw a lot. I wonder how that compares to a tiny Dometic fridge. I’m having a hard time finding exact numbers.

And how do you charge phones with no inverter? Do you have some sort of 12V outlet in the trailer? I don’t have one of those, but I would love to figure out how to charge a phone somehow.

Which panels did you get? Did they come with a controller? I realize now that the ones on Amazon that I linked to have a 20A controller & I’m pretty sure that won’t work.

Thanks!

[Alex Adams]

Kelly, you need to find out what model fridge you have. Then you can find out how many amps are used when running in 12 volt mode. Then you need to find what model heater you have and do the same. Then you will need to estimate what is used by the lights by determining what kind of lights they are: LED, incandescent. Once you have that, then you can estimate your usage by multiplying the number of amps by the amount of time the different draws are actually on. For example, since it is colder, your fridge will run less often. Remember, you are estimating so it is not going to be 100%. Now, figure out how many hours of daylight you have by figuring the time between 1 hour after dawn and an hour before sunrise. That would be the period you will be able to get electricity from your panels. The panels in the kit you are looking at looks like they would supply about 11.44 amps under perfect conditions. Since it is fall/winter in northern California I personally would divide the rated output of the panels in half meaning you will probably get 5.72 amps. Now multiply that by the amount of time you determined you would have sunlight. That would be the number of amp hours you would be able to get from the panels. If that number is less than your combined loads, you will not be able to run everything. Quite frankly, if your fridge is a 3-way absorption fridge I doubt the solar setup you are looking at would handle the load with it running on 12 volt power. If you ran it on propane, then the system you linked to should be able to run everything. Just remember your total amp hours supplied by the solar system has to be greater or equal to your total draw to make sure you don't run out of power extra batteries or not. In addition, should you be unlucky and have an inordinate number of cloudy days in a row, you still may run out of power. If it isn't already, get your tow vehicle configured to charge the batteries via the 7-pin connector for your trailer and find out the amp output of the alternator. Worst case, you can plug the trailer in and run the vehicle to charge the batteries.

[steve dunham]

We had a 2013 , 17 ft Casita SD with a 5 cu ft refrigerator, one 27F wet cell lead acid battery , one 100 watt Renogy portable solar panel and LED lights
Only once did our battery approach 50% and that was after 4 days of cloudy , rainy , cool weather
Run your refrigerator on propane, skip the inverter, and be conservative with your use of electricity
If you wish to run your A/C , use 120VAC appliances and run your refrigerator on something besides propane , my suggestion would be to plan on camping with hookups

[redheadkelly]

Originally Posted by Alex Adams

Once you have that, then you can estimate your usage by multiplying the number of amps by the amount of time the different draws are actually on.

Ah yes, Alex. Math! Thank you. I studied this years ago, but it's all long forgotten now.

I was having a hard time finding amperage values for my specific appliances. And the panels are rated in watts, so my brain was not figuring how to line those two up.

Most people here are probably already old pros at this, but just for the next guy who comes along who isn't ...

DOMETIC RM 2193 refrigerator	10 Amps		24 hours	240 amp hours
Suburban NT-16SE heater		2.8 Amps	1 hour		2.8 amp hours
1141 light bulbs		1.6 Amps	4 hours		6.4 amp hours
								----------
								249.2 amp hours

Avg winter daylight 	9.8 hours - 1 hr morning - 1 hr evening = 7.8 hours
								 * 11.44 amps from panels
								  ----------
								 89.4 amp hours per day

Oh geez. I'm so glad I did this. I used the solar calculator that Scamp recommended & it suggested a 200 watt system with a 2nd battery. I guess it was way off. In fact, from what I remember, it doesn't line up with my numbers at all.

I really, really don't want to run my fridge on propane. The last thing I did before the fire came through was take the propane tank off the trailer. And now I'm a little shell shocked about putting it back on. There have been so many close fires over the last few years & we've been so nervous about fire for so long, I'm just not ready to have a flame going all the time.

This was the trailer right after the fire. And the view from my front door now 2 months later. The fire came over those hills at the end of the valley & burned everything in view except my trailer & the garage. The house was so hot when it was burning, it melting the siding on the garage. I feel so lucky that my little trailer survived. I hate to temp fate with more fire.

Guess I'll have to come up with some other solution to store food. Maybe I'll dig a root cellar. Or just eat out of cans all winter.

[Huck]

I had 2 100w solar panels and they only ran my refrigerator until about 2 am. I have 2 batteries but right now I don't remember the AH.

[redheadkelly]

Originally Posted by Alex Adams

The panels in the kit you are looking at looks like they would supply about 11.44 amps under perfect conditions. Since it is fall/winter in northern California I personally would divide the rated output of the panels in half meaning you will probably get 5.72 amps.

One more thing, if you don't mind, Alex.

Just to do my due diligence, I was trying to find where you got the 11.44 amps value for the solar panels I linked to.

If 'amp = watt / volt', right?

And they're 200 watt panels.

Then 200W / 12V = 16.66 amps, right?

I'm guessing there's more to it than this. Just trying to learn something so I won't have to ask as many questions next time.

Thanks.

[redheadkelly]

Originally Posted by Huck

I had 2 100w solar panels and they only ran my refrigerator until about 2 am. I have 2 batteries but right now I don't remember the AH.

Unfortunately, Huck, I'm learning that that would probably be the case.

[Alex Adams]

Kelly, the solar system you linked to is 200 total watts not 200 watts per panel. I looked up the Renogy 100 watt panels and got the amps from the tech specs. I think you are underestimating the heater usage and overestimating the fridge usage. I don't believe the fridge will run continously so you are over on that usage especially since the weather is colder now. On the other hand, the Scamp is not insulated very much so I think you will be running the heater longer than 1 hour per day. I also think you are overestimating how much power you will get from the solar panels. I think you will be more likely to get 6 amps not 11.44 unless you live in an area in Northern California that is sunnier than I remember this Time of year.


I sympathize with your apprehension in using the propane but how are you going to cook? You must be using a propane or white gas stove so you already have some sort of flammable fuels. If the trailer isn't going to move, you could see if the tank can hook up without being bolted down in case you need to remove it quickly. You're root cellar idea is a great one. It worked for the pioneers. Just make sure you research how to do it properly.

[redbarron55]

If you are trying to run a three way refrigerator (any absorption fridge that draws 10 amps DC) solar is a losing proposition.
If you are running a high efficiency compressor refrigerator, however, with it drawing 4 amps for 50% of the time the numbers work out differently.
But anyway the best choice would be the propane operation, but the compressor would give you a better chance than the 10 amps for the DC heater.

[JessieJanet]

My husband thinks the panels are Renogy. We have 2 6v batteries, linked (? I think this gives more storage?). We do have 12v plugs we installed, our rig is an '84. Our young techie-friend & Carl replaced wiring & re-plumbed w/ pex, as well. We also built a dry toilet ('composting') which serves us well.
Would love to put the wool insulation in, put so far, not willing to spring for the costs involved!

[Jon Vermilye]

Originally Posted by redheadkelly

One more thing, if you don't mind, Alex.

Just to do my due diligence, I was trying to find where you got the 11.44 amps value for the solar panels I linked to.

If 'amp = watt / volt', right?

And they're 200 watt panels.

Then 200W / 12V = 16.66 amps, right?

I'm guessing there's more to it than this. Just trying to learn something so I won't have to ask as many questions next time.

Thanks.

The wattage rating of solar panels is under ideal, not real conditions. The most you can expect from a 100 watt panel is around 30 - 40 amp hours per day on the good days and far less under clouds.

To show a real world example, here is a graph of the output of 480 watts of panels (2 rooftop 160 watt panels tilted to the proper angle for January at Quartzsite and a 160 watt portable) in the Arizona Desert (Quartzsite) during December. Ignore the first week - that was with electrical hookups. The graph is in watt hours, and since I'm using lithium batteries, to convert it to amp hours, divide by 13.6. The highest was 110 amp hours, lowest on cloudy days was just a couple of amp hours. For more details, here is a link to my journal page where I posted the information.

If you really can't be comfortable with running the refrigerator on propane, the suggestion of switching to a efficient 12V compressor refrigerator is the only practical solution. It will take far more than 200 watts of solar and a pair of 12V batteries to successfully produce & store the 240 amp hours per day your absorption refrigerator requires running on 12V.

[redheadkellyscamp]

Thank you so much everyone.

I definitely have a better understanding of what I'm up against now.

The original solar calculator that I used must've been using numbers for a compressor fridge & mine is definitely an absorption fridge. That's what initially lead me down the wrong road.

Alex, from what I've read, the absorption fridge runs all the time. It definitely doesn't have a thermostat & it doesn't cycle on & off, from what I can tell. It just has a high-low dial on the controls outside so that you can adjust it according to season.

Dometic's website says:
Input voltage (AC) 110 V
Input voltage (DC) 12 V
Rated input current (AC) 1,05 A
Rated input current (DC) 10 A
Rated input power (AC) 115 W
Rated input power (DC) 115 W

That's where I got the 10 amps * 24 hours a day. I'd be happy if that wasn't the case. redbarron55 got the same numbers that I did here, so I'm afraid it might be true.

I got the numbers for the heater from a parts & accessories website. For some crazy reason, this information isn't in the Users Manuals for any of these appliances. The site says '12VDC 2.8 amp draw'. In the past, I have only used the heater to heat up the trailer right before I go to bed, so it usually isn't on for even an hour.

As far as calculating the amps of the solar panels go, I used 200 watts for the 2 panels as a whole & then divided by 12 V. That's correct, right?

200W / 12V = 16.66 amps

I understand that this is not a real-world number. Like you said, it won't be operating under perfect conditions. Just want to make sure I'm using the correct equation.

And I just used your 11.44 number in my math as a starting point and, even then, it clearly wasn't enough. So it's definitely not going to be enough if we consider winter weather conditions.

At this point, I think I'll just give up on the fridge & only worry about having heat. Maybe I can find the money in my budget to go into town & have a nice hot meal every day.

Thanks redbarron55 & Jon. I think I have a much better understanding of what I'm doing now. I've been living in this spot for the last 2 years & now just trying to find a way to make it work without the utilities connected yet. Maybe it's just time to consider a move. Curious how Quartzsite might be this time of year. I need quiet.

JessieJanet, the ones I was looking at were Renogy, too. But now I think I have to rethink my entire plan. I love the idea of a 12V outlet/charger in the trailer, though. That's a good one.

My pictures didn't post the first time, so I'm trying again. I've spent the last 2 years here plugged into water & power. The fire took out almost everything on the property except my tiny trailer & the garage that had just been rebuilt after a previous fire.

Just sharing because, in my mind, this is a Scamp miracle.

You can see the valley that is the view from my front door as it is now. The fire came over those hills & burned the whole valley and then some.

[redheadkellyscamp]

OK... I think I'm really getting this now, so I'm gonna come at it a different way.

I went to the place where I bought my battery & the guy said that it holds a total of 78 amp hours of charge.

So, if letting it fall below 50% decreases my voltage below 12, then I have about 39 amp hours per day, well, really per night, to use as I please. Except, obviously, for the refrigerator.

Luckily, I ran into a friend last night that works for a residential solar company. She said she could go grab me a panel out of the dented pile for next to nothing. She said they typically run about 300-350 watts.

It looks like some residential solar panels come in 12V, some don't. So, I can request that she find me a 12V & get a PWM charge controller or I can get a MPPT charge controller to make whatever she gets me work with the 12V system in my trailer, correct?

At 300 watts, I would get a max of 25 amps, but considering winter conditions, lets say half that. So, that would give me a potential of almost 98 amp hours of charging per day. That's plenty to charge 2 batteries.

With 2 batteries, I still wouldn't be able to run the fridge, but it would give me room to run the heater & the lights and also the water heater & water pump.

Here's how the math works out in my head...

panel watts		300	
system volts		12	
			-----
panel amps		25	

> imperfect conditions	12.5 amps	


Avg winter daylight 	9.8 hrs - 1 hr morn - 1 hr ev = 7.8 hours
							12.5 panel amps
							-------
							97.7	amp hours per day charging

Enough to charge:

battery #1		78	amp hours full charge	39	amp hours to 50%
matching battery #2	78	amp hours full charge	39	amp hours to 50%
							--------
							78	amp hours a day

Enough to run:

Suburban NT-16SE heater		2.8 amps 	3 hours		8.4 amp hours
1141 light bulbs		1.6 amps	4 hours		6.4 amp hours
Atwood MPD 93756 water heater	116.7 amps	0.5 hours	58.3 amp hours
SHURflo 2088-554-144 water Pump	4.5 amps	0.5 hours	2.25 amp hours
								-------									
								75.4 amp hours per day

[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.