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Old 03-07-2016, 03:07 PM   #11
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As others have indirectly pointed out, your residential fridge is your real issue. CPAPs are a drain, but are manageable with a decent battery bank.

Given the cost of a large solar array (and the associated wiring), I would seriously consider replacing your residential fridge with a propane/AC model. When boondocking or dry camping, put the fridge on propane. Then you can likely do well with 200W of solar panels, and never run your generator (unless you get multiple consecutive cloudy days). With the fridge running on propane and the CPAP running on 12V, there would be very little need for your inverter.

This assumes your hot water heater and furnace can also run on propane.

just my thoughts
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Old 03-07-2016, 04:09 PM   #12
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Originally Posted by Anders View Post

For you I think you should run the fridge on solar during the day and on propane at night, add a package like The Solar Extreme 480 watts and it comes with a 3000 watt inverter.
That would be a nice option, but the OP has a residential fridge and they do not run on propane.


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Old 03-07-2016, 05:03 PM   #13
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Look...unless you KNOW how much energy you use on average... then double it you don't know how much battery power you need OR how much panel wattage you need.
Get a true battery monitor and figure this out (Victron or Trimetric) then build your system.
If you use 100 amp hours a need 200 amp hours of batteries . And you need 400 watts of solar panels to reasonably supply 100amp hours a day in sunny climates. You can figure out the ratios but it all starts with knowing what you use.
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Old 03-07-2016, 05:33 PM   #14
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Originally Posted by TonyD View Post
At a 10 cm water pressure setting a CPAP which draws 2.5 amps would need 20 amp-hours in 8 hours.
At a 20 cm water pressure setting a CPAP which draws 4.5 amps would need 36 amp-hours in 8 hours.

Fridges do not use a lot of 12v power except some have a heat strip that is used to defrost the refrigerator and can kill a battery quick. Heat strips can be easily disconnected.

You should run a fridge on propane to reduce electricity load. It isn't practical to use solar to run a fridge on a/c power.

I personally feel if you are going to go solar you should go large. I would not go smaller than a 400 watt system and 400 amp-hours of battery capacity.

Four 6 volt golf cart batteries from Sams Club for 85/each will provide 400 amp hours of capacity for a reasonable price.

With 400 amp of battery you actually have about 200 amp-hours usable. You do not want to go below 50% battery capacity because it will shorten battery lifepsan cycles a lot if you do.

I recommend a Renogy system and amazon has good prices on them.

You'll want to install an auto transfer switch so that inverter power from batteries does not power the converter that recharges the batteries. You also want to isolate the ac fridge power line for the same reason so it is only hooked up to generator power to prevent accidental usage of inverter a/c power to run the fridge.

Running a fridge on propane for my fridge uses about 1.5 lbs of propane a day on high. I usually run the fridge on high cool when generator is running and then switch to a warmer setting overnight.
A residential fridge ain't got no propane LOL
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Old 03-07-2016, 05:53 PM   #15
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I just bought a 200W Solar Powered Folding Portable Solar Panel for Caravan Trailer Camping RV on ebay from echoworthy for $336. Max current is about 11amps. Comes with bilt on 15 amp controller. Hooked it up on an overcast day and hooked to low battery. Clamp on amp meter showed an 8 amp chargr to battery. The folding legs are real flimsy ( I added L brackets and it firmed up much better.)and wire is to short and awg is small. I'm only charging one 120 ah battery so it works. Replaced wire leads with 25 ft of 8awg and I am upgrading to a Trimetric TM2030 monitor and a sc2030 programmable charge controller. Still keeping it mobile.
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Old 03-07-2016, 11:22 PM   #16
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Originally Posted by mdstudey View Post
I am looking at buying a 200 Renogy set up because we are going to be boondocking at Big Bend. I have a Resmed cpap and just looked at batteries for it. I saw costs from 300+ to 700+. I could can get the 200w to start our solar system than I can for the battery. I would still need some type of power to recharge the battery. Thanks for the heads up for turning off the humidifier. I will have to ask my DME if they have a loaner battery.
OK. Cpap. Get one that runs 12 v. I have had three different ones all had an external power supply and the output was rated 12 -14 v and 3 or 4 amps with humidifier that probably accounts for half the amperage. Otherwise we are all led and have frig with switch that turns off the door frame warmer. All of my machines had factory cig lighter plug cords available and operation was no different than off 120v power supply.

200 watts solar meets our needs with three 70-80 amp group 24 batteries. We run small 12v TV for hours daily and 200 watt HF cheapy inverter for direct TV box with a manual Sat dish.

For the new TH on order now it comes with 200 watts solar and we will start with two interstate GC2 6 v batts from Costco at $85 each.

That will be for starters. More may come.

My solar dealer is Renogy might be a tad better output if you believe YouTube but it is a tad more expensive at the same time. The new TH has
A GoPower controller that looks good according to the specs I have found. Better be good. Mya buddy had that done as an after production factory add on at. $1500 for 160 watts. He charges two huge AGM oversized $350 6v batts and is very happy.
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Old 03-07-2016, 11:38 PM   #17
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We have 600 watts of panels into a 60 amp solar controller and about 600 amp hrs of batteries. Also a 5,000/10,000 watt surge inverter.
All of my solar equipment except for the just installed Outback MPPT controller, came from Renogy. Really good company to do business with. Great customer service.
I used a 40 amp Renogy controller for over a year, but 600 watts was pushing it too far. Still have two new 100 watt panels in the garage that I haven't had time to install now that I've installed the larger controller.
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