Refers

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Out There
Out There Solar Expert Posts: 96 ✭✭✭✭
in General Solar Power Topics #1
It's time to buy a refrigerator, folks. I'm certainly leaning toward a propane unit. It's been suggested to me that I look at Icy Ball-like set ups and I've also had 12/24 volt DC units suggested. I'm looking for experiences, suggestions, recommendations?
Brian
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
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    Re: Refers

    Welcome to the forum Brian!
    Can you spare an extra single Kwh per day? If you can, you'd be better off with one of the new high efficiency electric units. Also consider the very low price of solar panels compared to a few years ago. Balance that off against the cost of propane, the travel and cost involved with propane.
    You could also consider converting a freezer to a fridge. Freezer insulation puts fridge insulation to total shame and the energy consumption of a converted freezer also puts fridges to shame. If you have the power, or can relatively easily add to your present off grid system to get the needed power, there's no way I'd go with propane. Propane/DC/AC fridges are energy pigs. A bit more PV is far cheaper than most DC fridges, and standard fridges far cheaper to replace than most DC units.
    Others though will I'm sure, have other opinions.
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  • ramloui
    ramloui Solar Expert Posts: 109 ✭✭
    #3
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    Re: Refers

    I have 2 propane fridges at the cabin right now. They work very well but because they cool down quite slowly, I have decided to leave them on when I'm not there. Beer is cold when I arrive... As you can imagine, I'm not concerned with the propane cost at this tiem.

    However, when one or both of them go, I will replace them with Energy Star rated refrigerators. They are much cheaper to purchase than propane units. When I designed my PV system, I had that load in and purchased the components accordingly. I forget who's catch phrase it is but "loads grow over time"...

    Wayne,
    Do you have instructions on how to convert the freezer to a fridge? I would certainly like to look at what is involved and keep it as option when I cross that bridge.

    Cheers!
    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #4
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    Re: Refers
    Out There wrote: »
    It's time to buy a refrigerator, folks. I'm certainly leaning toward a propane unit. It's been suggested to me that I look at Icy Ball-like set ups and I've also had 12/24 volt DC units suggested. I'm looking for experiences, suggestions, recommendations?

    Avoid propane (I've had 4 propane fridges over the past 30 years). Now I have electric. In addition to everything else wrong about propane, don't forget to consider the issue of venting propane exhaust.

    As far as DC vs AC fridges, for the cost of many/most DC fridges you can buy an AC fridge and a larger power system (panels, inverter, etc). The only downside to AC fridges is the need for a large inverter for the startup surge.

    If your electric power system is very small, you might consider a DC fridge to avoid the inverter. If your system is large enough to have a 1500 watt pure sine wave inverter, an AC fridge makes sense.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Slappy
    Slappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    #5
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    Re: Refers

    But a DC fridge does not need an inverter. So that is one less thing to worry about. I have a DC sundanzer and like it very well
    Very quite just hear a click of the relay when its turning on/off. But either way its up to your taste and/or needs.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
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    Re: Refers

    Question: how much is this refrigerator going to be in use?

    Question: will there be an inverter available to run other things anyway?

    The longer the use time (we're there for six months of the year) the greater advantage in electric over propane. And if you've got to have inverter power anyway .... the extra cost of 'special' refrigerators can be put into a larger solar capacity and then you just buy an efficient off-the-shelf 'frige for less money.
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  • Out There
    Out There Solar Expert Posts: 96 ✭✭✭✭
    #7
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    Re: Refers

    Hmmm.... I've been researching this for a while. At the same time that I need to purchase a refer, I also have to replace my batteries (read: lots of $$$ going out), so purchasing more PV, right now, is not really an option. My inverter is over 10 years old and is not a pure sine wave (Trace 4024) - it is rated at 4000 watts, though. I've been looking at the chest-style refers and I really like the physics behind them - all the cold air doesn't spill out whenever you open them. That kind of efficiency appeals to me. I've looked at the conversions (from freezer to fridge) and I like the idea. As we all know, though, everyone in the household has to be on board. I'm fine with a chest style. My wife's very first question was "where's the freezer?" She is still freezing stuff (we live far enough from where we work that having frozen meals prepared ahead of time makes sense on those nights we arrive home late and end up in bed two hours later!). So a chest style, while it looks great, might require a separate freezer. So I'm left with uprights. Now the question arises: propane, AC or DC? I've located a 21 cu.ft. LPG monster I can have for a little over half what they sell for new (this one is never used, but 2 years old). I've got a 1000 gal LPG tank and this thing uses about a gallon every three days. The DC fridges are about as expensive as the LPG that I've looked at.
    The old fridge was propane, but it's been gone for a while, now and we've realized we really need one. Can someone (vtmaps?) please talk to me about running an AC fridge on the system I have described in my signature (below)?
    Brian
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  • Out There
    Out There Solar Expert Posts: 96 ✭✭✭✭
    #8
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    Re: Refers

    This is our full-time home, Coot. See my reply to vtmaps for some of the other conditions affecting this decision-making process.... I really welcome all of your input.
    Brian
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #9
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    Re: Refers
    ramloui wrote: »
    Wayne,
    Do you have instructions on how to convert the freezer to a fridge? I would certainly like to look at what is involved and keep it as option when I cross that bridge.

    Cheers!
    Well I used home heating/cooling thermostats to control a relay, which them controlled the compressor. Of course I had to modify the thermostats to operate at the lower temps, and through experience with moisture problems, now mount the actual thermostat outside the "fridge" and extend the sensor on a longer wire, through a small hole in the top of the fridge and mount the sensor in a sealed protective container. This has been working awesome for me. BUT, I understand there are commercially available conversion thermostats designed for this job. I've also read that some folks have just modified the existing thermostat on the freezer to operate at fridge temperatures. I haven't tried that - - yet.
    Something else - - there is a huge difference in moisture levels inside a normal fridge, which drains moisture outside to evaporate in your room air, and a converted freezer which does not do this. Especially in Summer, moisture can build up inside, requiring a small hole drilled in the bottom to drain into a an placed under the freezer, from where it evaporates into the room same as a normal fridge. There is a negative side, in that during times of high Summer humidity, there can be excess moisture in the converted "fridge", but on a definite + side, vegies can last for months without wilting. They stay firm and fresh, totally unlike in a regular fridge. Also, you can set the temp to just barely above freezing without excess power draw, and things that normally go bad after a few days in a normal fridge, will instead stay good for weeks. For me, putting up with the moisture is a small price to pay for the advantages, and I can't see myself ever going back to a normal fridge for that reason alone, not even thinking about the huge energy savings. But to each his own.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #10
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    Re: Refers

    Just to echo what 'coot says. If you are going to be there full time or near full time bight the bullet and go with a good conventional now. Weekends, occasional holiday weeks, consider propane. Also consider your propane coat and what is involved in getting it.

    A full size Dometic fridge will burn ~1500 BTUS/hour, with a duty cycle of ~50%. (there are ~80,000 BTUs in a gallon of Propane)

    Intial cost of propane is higher, but if you shop the RV wrecking hard you can get them cheap. They are, for the most part, with proper understanding unite reliable. As I have said here often, being full time, if I had to do it over again, I would have gone with more PV more battery, bigger inverter and a good conventional fridge. At the time, we had always used LP and PV was $10/watt!

    Tony
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #11
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    Re: Refers

    Out There;

    You are "up against it".

    Chest freezer conversion is probably not going to go over well with the other person. They are not very convenient to use.

    So now you have to do some number crunching.

    How much would it cost to upgrade the PV system including new batteries (which you must have anyway), new inverter (ouch!), and more PV (possibly controller change as well) to get that extra 1kW hour per day for a conventional 'frige? Then add the cost of the refrigerator. How marginal is your available power now? Could you get away with bigger batteries and a run of the generator from time to time?

    Then price out what the new propane 'frige would cost, and don't forget to add the on-going cost of propane for about the same time as the batteries would last (say 5 years). One of the good points on Option #1 is that once the money is spent you shouldn't have to spend any more.

    Do the same for the DC 'frige, remembering that its power consumption would need to be included in a power system upgrade.

    Somehow you will have to work out the size inequity between the refrigerators as they aren't all going to be a convenient 16 cubic feet.

    For long-term the standard electric will be the best bet, but is likely to be the biggest capital investment. I tossed everything from our old system when I put in the electric 'frige. It was a major expense ($8,000 then), but it also allowed us to run all sorts of other things without any worry - including conventional water pump.

    There is a certain assurance in having all standard, plug-in 120 VAC equipment available anywhere and only having the "technically tricky" part be the power supply itself. And when that is conventional 120 VAC it can be supplemented or replaced by the generator until repairs can be made.
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  • Out There
    Out There Solar Expert Posts: 96 ✭✭✭✭
    #12
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    Re: Refers

    I have the option (and the likelihood) of running the generator (it's a new 8kw Generac). I understand where you're going with this. It's a case of hearing it from others - especially others who have 'been there & done that'. I was going to invest in a micro hydro generator this next year. Mayhaps I'll be putting that money (plus some more) into upgrades on the system. Right now, we're not electricity hogs. Biggest usage is the well pump (240v), but I've got over 400 gallons of captive air tank capacity, so the pump doesn't run very frequently. We also use a washing machine and some kitchen gadgets on an irregular basis. So our biggest usage is lighting. We might be able to squeeze enough out of the system to run an efficient (small) refer and expect the generator to run a little more frequently, at first. Maybe next year install more PV instead of the micro hydro :p
    Brian
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
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    Re: Refers

    Keep in mind I manage to run everything with 232 Amp hours @ 24 Volts and 700 Watts of panel.

    You have eight L16's so that's already more battery capacity than I have: around 640 Amp hours @ 24 Volts. Your eight 80 Watt panels @ 640 Watts is inadequate for that much battery. I'd ignore the wind turbine for now, as they are notoriously over-rated.

    I would bet you could probably reduce your battery bank, increase the solar array, and come out ahead. You need to pick up a Kill-A-Watt and start measuring things so you have a fairly accurate daily Watt hour consumption number to work with.

    Running the water pump as-needed from the generator would be a big help, and the same with the washing machine. That 8kW Generac is probably overkill, but you aren't likely to want and invest in a Honda inverter-generator along with all the other expenses at this point.

    Really, with 640 Amp hours @ 24 Volts you should have about 2kW of array and an MPPT charge controller as well.
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  • Out There
    Out There Solar Expert Posts: 96 ✭✭✭✭
    #14
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    Re: Refers

    Ah-Ha! THIS is precisely the kind of feedback I was hoping for when I joined this forum! Thanks, Coot!
    Brian
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #15
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    Re: Refers

    Out There,

    The large Propane fridges that I have seen (about 18 du ft) were US$ 2500 - 3000. They had no internal light bulb, and were manual defrost. They did not have very uniform coolness, and in hot weather did not cool very well. A neighbor bought one such LP fridge and it lasted 4.5 years. He went with an upright 120 VAC efficient fridge and was much happier.

    An EnergyStar upright often uses very little more, or no more power than does a small one.

    Have been running a 120 VAC 18 cu ft fridge for seven years off-grid and would never go back to LP.

    Just my opinions. Good Luck, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Out There
    Out There Solar Expert Posts: 96 ✭✭✭✭
    #16
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    Re: Refers

    That's good to know, Vic. The one I was looking at (LPG) was a 21 cu ft monster! It used 3 D cell batts for the internal light (so they've figured that one out, I guess). I think we could get by with an even smaller unit than what you've got. Maybe add some insulation to the sides and top (it will be in an alcove) and provide good under and over ventilation for the tubes.
    Brian
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #17
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    Re: Refers
    Out There wrote: »
    Can someone (vtmaps?) please talk to me about running an AC fridge on the system I have described in my signature (below)?

    regarding your batteries: Sure you can run a fridge. I run a fridge in my house, and a fridge and a freezer in my garage with only four L-16 batteries. It costs very little power to run the garage units in the winter (when I have the least solar resources) because I keep my garage slightly above freezing for most of the winter.

    regarding your inverter: That may be a problem. AC refrigerators really like pure sine wave. Even if a particular fridge works on modified sine wave, the motor will run hotter and less efficiently and may vibrate and clatter.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • westend
    westend Solar Expert Posts: 46 ✭
    #18
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    Re: Refers

    I was up against the same decision, recently--LP vs AC or DC refrigeration. This was for my travel trailer so situations are different but the physics and issues remain the same. I did not choose LP for a few reasons--they are not good chillers in the summer (there is a limit below ambient they will run), they exhaust hot combustion gas, they are unreliable (the domestic refers, Dometic and Norcold have numerous recalls and safety alerts because of leaking and fire), they are expensive, the coolant is ammonia (if a pipe or fitting leaks, you will have ammonia gas inside the structure).
    I chose to use a smaller 120v fridge and inverter. The 12v DC fridges are better in terms of efficiency but 10 times the cost. My little dorm fridge draws 80 W and has a duty cycle of about 1/4 in the summer. A new Samsung 10 cu. ft. freezer/fridge draws about the same, I'm told. If you need more capacity, the larger models will draw more than the 1//2 KW. If you don't want to pour a lot of money into a new 4000w pure sine inverter, you could always get a Xantrex Prowatt Pure Sine 1000w to run the fridge and maybe some of your entertainment devices. Xantrex Prowatt invertersThey are very inexpensive for what you get. Good luck with the fridge.
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