RV Solar Power Basics - Why Residential Refrigerators Suck - Josh's Garage 

This is even more true as residential refrigerators have permeated the towable RV segments very heavily in recent years. Towable RVs typically lack the suspension of something like a diesel pusher and cause the residential refrigerators to experience stress for which they simply were not designed. The penalty for failure is pretty steep at times as many of these residential refrigerators are installed in slides before the slide is then installed into the RV. They're not always capable of being removed from the RV from through the door. We have had times at our facility in which we've had to dismount and move the entire kitchen island and in more than once case even had to remove a large window from the camp-side-slide as the fridge could not fit out of the door. Not every area of the country has appropriate service techs for residential refrigerators, and most residential refrigerator brands will not authorize an RV dealership to service their failed fridges. I've felt strongly for years that if the 18cu ft gas/elec RV Fridges actually designed for this business existed two years prior, then these residential refrigerators likely wouldn't have ever infected the industry.

I load my frig shore power for a day before going on the our weekend trip have 100w panel 1 12volt deepcyc 100ah battery and a 1000 w converter all just for the frig and never think about it it works for me

I tracked my Whirlpool residential refrigerator with a Kill-A-Watt and observing the BMK on from Magnum MS2012 inverter and get better numbers. The fridge would pull 3-4Ah at 12V when the compressor was not running. When the compressor was running to cool the fridge it would pull around 15Ah at 12V. Over a 12 hour period on a mild day facing away from the sun, the refrigerator took around 100Ah of juice from the battery. Overnight, I used around 60Ah as it is much cooler, and we were not opening the refrigerator while we slept. I have four 6V 220Ah batteries for a total of 440Ah at 12V (220Ah useable) so it is similar to your diagram. Technically I could last 24 hours, but there are other things running as well so we run the generator for a couple hours in the morning and a couple of hours in the evening. We are not fully charging the batteries, so this is a poor practice with regards to the health of our deep cycle lead acid batteries. I agree retailers are not fully informing RVers, but mainly on the health of their lead acid and AGM batteries. Residential refrigerators are not well matched for them as a power source when dry camping for extended periods without a good solar solution and a well-informed user.

We have been preaching this for years -- especially as resi-fridges have permeated into the towable RV industry at nearly every level. A mutual viewer shared this with me and I commend you for your work!

A Typical modern 485L fridge (16 cu ft) has an energy rating of 330kwh per under standardised tests, which are pretty agressive in Australia. They include high ambient temperatures and high loading of the fridge. This is 330kwh per year is approximately 1kwh per day. The 200AH of useable capacity (from your 12V 400Ah pack) at 12V is 2.4kwh. This will run the fridge alone, un-assisted for 2 1/2 days if it is properly installed (ie proper air circulation allowed around the body). To maintain that charge, I'd suggest at least 400W of solar, or more would be required, depending on where and when you travel. In winter, or climates away from the equator, as you showed, this might be an issue, as your 400W might peak at 100W, so you won't keep up, and might only get 300Wh per day or similar. During summer periods, your 400W will easily produce 1Kwh of electricity by lunch time, and most people with effective installations reach "float" on their batteries by midday under ideal conditions Regarding your use of units, you need to be more precise there. Amps per hour is a bad term to use. W is power, and typically we talk about Wh (watts used over time) watt hours, not watts per hour,, same with amps (amp hours is an informal way of expressing watt hours at a given voltage - as you showed by Watt's law). A good fridge, properly installed will use around 80AH (1kwh at 12V) in a day, or 1kwh per day. Your 720W (^A at 120V) is no way representative of the actual instantaneous power consumption of the fridge. The starting current is likely to be 6A at 120V, but the running power of a modern fridge is actually around 100 - 200W (buy one of those cheap AC power meters and see for yourself) Your maths is OK (ignoring nasty units - stick to W, Wh per day, or A and AH per day, not amps per hour or watts per hour), but the fundamental assumption about the fridge power consumption is incorrect. Also, your 12V super efficient DC fridge mentioned at the end is actually likely to be less efficient that the commercial refrigerator, and 5x as expensive. I can point you to references of people (real people, with real RV's running real life tests, with detailed measurements in 40C ambient temperatures) that can demonstrate the effectiveness of the domestic fridge solution, or more specifically, the use of a solar/battery system to run a compressor fridge.

I have been RV'ing for many years and have experimented with solar. It is great. But I would never give up my dual AC/propane fridge. Yes, I know they aren't very efficient, not even running on AC, but the missing factor in the equation is how much energy comes in 2 - 30 lb propane bottles. It's a lot and will run that fridge for weeks. I also won't give up the propane stove, same reason. I remain highly sceptical that a 12 volt fridge can be all that much more efficient than a residential fridge since the technology is essentially the same. You save the inverter loss but that's about it. I have also experimented with solid state coolers. Forget about it they aren't very efficient. Sure they only draw 50 watts but they do so 24/7 which adds up to a lot of AH. Now don't get me wrong, I love my solar panels (300 W total), and have 200 AH of battery. The system works great. But I have converted everything to LED and the TV is only 24 inches (also LED). It works good to charge devices too because 300 watts is more than you need if the sun is out. But if the furnaces is running at night I still run out of power after a few days, even though most of the energy comes from propane also. Oh and forget about air conditioning unless you are plugged in or have a whole bunch of gas cans, it just isn't doable. When my dad first took the family camping back in the day the trailer did not even have a battery. The fridge was propane/12 volt (for travel), the heater was a wall mounted propane convection job, the stove was propane, and the only light was a single mantle style propane light (which also threw off a lot of heat). No batteries at all. The water pump was manual. There was 110 V lighting but it only worked if you were plugged in. My dad got some 12 V incandescent bulbs and jerry-rigged a cord so he could clip the 110 v system onto the station wagon and run the 12 volt lights, but the car wouldn't start in the morning so he only did that once. So the ideal setup is a propane/electric fridge, propane stove, propane heater, LED everything you can, 300 watts of solar, 200 AH batteries, and a fantastic fan (tends to run when there is excess solar).

I live on a 45-foot Chris Craft, my RV is seldom used, but for whatever reason, I keep it. One of the first things I did when I got my 2015 Minnie Winnie was toss that propane firestarter of a refer out the door and replaced it with a dual voltage marine refer. I also took out the drawer under the old 3-way and made it a freezer draw refer. I have left it on for four straight days boondocking as they call it, yet there is no docking to it, with the 3,000-watt solar panels I put on the roof and had zero battery issues. Can't say that for those RVing around me.

The trouble with this is having a big frig. I have a 9 cubic foot frig 400 solar 3 batteries I run all led lights my cpac , dvd player computer and frig and never have had any trouble even on days that the sun doesn't shine it works for maybe 3 days before I have to worry. I also run a window ac for about 30 to 45 minutes at night to cool down the trailer 6X14 cargo trailer again no trouble I carry 2 weeks of food in the frig. also if the frig stops working I go buy another one for about 300 bucks I got about 6 years out of my last one and that was camping for 6 months out of the years and the frig running all year long because I use it for a shop frig ( but still in the trailer )when I am home so I don't have to run to the house for my ice tea I just walk out of the shop and into the trailer and refill my glass.

I agree, should be more views. I too have made this mistake and the cost of running this fridge on solar is not worth the money it takes nor is there enough capacity to carry the batteries, or purchase very expensive Lithium ion batts. The math doesn't lie. I have run it a 100 times, and have tried reducing usage and the batteries just won't make it. Actually 400ah of batts (200 usable) will get you about 10 hours with nothing else running, including all the parasites from tv's and such. Great video more should see.

Love you man. Everyone needs to watch this to determine the setup they need to buy ty

Thank you for the breakdown! I initially made the mistake of not converting the math from 120v to 12v and bought a 1.4A fridge I was planning on using. It later dawned on me what I had gotten wrong and fortunately I am still in the planning phase. When trying to figure out what it will take to make the fridge work, it ends up costing way more than a two way fridge does (batteries, solar, etc.) and you end up being better off just going with the two way fridge. I now have a fridge to sell, but that's much better than spending thousands on a solar system to only discover that it still won't keep up. You did an excellent job at explaining it and I wish I had came across it before I made my error in my calculations.

Great Video, thanks for the info!

Your fridge compressor runs 50% of the day? Are you kidding? Good grief, fix that leak or whatever has your fridge injured. I am an EE and yes, the compressor draws a lot of power but it also gets cold, really cold, and does so in an hour or so. It does it without an open flame while I am running down the road. LiFe batteries can help a lot here but yes, that means money.

Excellent video, right on. Hard for some to realize the difference between amps at 120v and amps at 12v, and get a grip on inverter efficiency. But watts are watts. Compare any DC boat refer with a compressor to any residential refer and you will quickly understand the difference. At home, you don't care much about energy efficiency regarding refers because your electric power supply seems to be unlimited. Boondocking is another story. Refrigerator efficiency is mega important. And PS: I think most top of the line DC refrigerators are better insulated than any residential refrigerator !

Yeap... lost me after the triangle was drawn 😅😅😅

Go 12v DC compressor fridge! There are 10 cubic ft models to replace the single door absorption models.

Woah this was very helpful, thank you!

Besides what the others are saying...you give an example of a HUGE home fridge. Most older RV's use a 9cu ft maximum. Not only that, if your fridge is running its compressor...even in 110 degree weather...half the time...Houston, YOU HAVE A PROBLEM! I wish, just one time, people would not grossly stretch the figures to make their point. Your math on the watts is great...too bad you could not have been accurate in other areas.

good work bro

How does this not have more views!? Thanks for making this video, i'm tired of telling people this hahaha Ill just link them to your video now ;)

Love this next Video can run 12v ferg on 1. 100w solar panel ?

Use a inverter. Not all campgrounds are squishy either. Not only that I would have had to spend 2 thousand dollars to buy a new RV fridge because my RV is 40 years old and can’t get parts for it the only saloution replace. So which would I rather spend? 2 Gs or 3 hundred to have it removed and use a smaller res fridge my friends gave me and get inverter eventually. Doesn’t bother me to spend time in private camp grounds either in fact it’s better the people are nice and if U need anything there’s someone to talk to about it plus U get to meet great people and isn’t that part of the camping experience????? As well.

Josh did you think do this video with lithium iron phosphate Lifepoa 100 amp/hr 12 volt and on safe side drain it at 80% 4 battery. 4 - 320 solar panels. I'm think that fit 2- 320 solar panels in a same area as 4- 100 panels

Has any residential refrigerator caught fire.

Josh we are in the looking stage for our first RV. It will probably be a Class C which they typically use a 8 cubic ft fridge. The two and three way fridges scare the hell out of me with their safety record. I will replace it with a compressor driven fridge. I have found the brand Nova Kool which has primarily been a marine use fridge but they are starting to go for the RV market with a 9 cf fridge which will slip in perfectly where the 8 CF fridge was. They are pricey but seem to be built for heavy usage. Do you have any other suggestions for a efficient smaller fridge? Thanks!

Dog my residential fridge draws 102 running watts on my killawatt, idk what monster fridge you're working with haha

Excellent video! you might want to rename your video or have different tags to get more hits. you might want to do a final cost comparison as long term for an RV refrigerator "off the grid" would make more sense.For example most propane refrigerators average about 1000 btu's per hour of propane. There are 96,000 btu's in 1 gallon of propane. Therefore you can run an average refrigerator for 4 days on 1 gallon of propane.

But the inverter pulls power to to create 110v

Luckily. 400 watts of solar and a 6 (not a 16cu) AC/DC refrigerator/frezzer is no problem. By the way, I don't open the fridge every hour to check if my chow is still there. An efficient 6cu AC/DC fridge plus solar equals no problem. Josh, please get rid of that gigantic AC only fridge and yes ... your ice cream is still frozen. Stop opening the door and letting the cold out!!

Cold food sucks?

Your calcs are way off. An 18 CF residential frig uses akes 600 KW in a year (check the yellow sticker), or 1650 watts per day, or .57 AC amps per hour on average. This translates into 6.3 amps of DC battery drain per hour via an inverter, or about 150 amps in 24 hours. So if you've got 200 AH of usable batteries to work with then it would run for 32 hours. 150 DC amps x 12 V = 1800 watts per 24 hours needed. 100 watt solar panel x 10 hours (very generous, but your assumption) = 1000 watts so 2 panels would do it. Now to get that 100 watts per hour you'd need a mppt charge controller to convert 18.9 volts down to 14.4 volts yields 7 amps of charge the batteries, otherwise 30% of your panel production is wasted using a pwm controller. Obviously nobody is going to get 1000 watts a day from each 100 watt panel, but those were the assumptions you elected to use to make your case.

Actually there are 12v fridges. Truck stops sell them. Yet there are small.

What's wrong with Conway Twitty???

Wow your perspective is so incredibly wrong. The amount of energy a residential uses is way below your estimates. The only thing you have stated here that is correct is understanding ohms law and that the only acceptable equations that are useable here are watt hours not amp hours from there you go off on assumptions and some really bad math. Granted you have to know what you are doing to make all of this work and an RV salesmen or dealer isn’t going to have a clue how to make that happen!

Buy 500 lbs. of ice. That should work. no power needed. so simple. 😁😂👄

You need a math lesson. Most of the class a mh,s have at least 4 6 volt batteries. Mine has 8. I can go 20 hours without running the genset. But no matter what fridge you have a modern decent class a has lots of loads that can deplete your batteries Lights, water pump,2 TV,s,DVD,satellite system,toutets and chargers for phones and tablets. So pne needs to run the genset about 1.5 hours every day. Your double door propane fridge aldo draws 12 volts Withe a house fridge uour total is about 3 hours a day. Ask people that have house fridges. They would never go back to one of those fire starters with soft ice cream. Every house fridge comes with a label that tells you how many AH it draws. Do the math with that data. Your video is all bs. Flawed