Solar Refrigerator

Holling
Holling Registered Users Posts: 7
Hi all,
I'm a total noob looking for some advise. My daughter is an insulin dependent diabetic. Insulin needs to be stored in a refrigerator or it will go bad due to warm temperatures. A loss of electricity for a few days in the summer (Phoenix) would be deadly for her. I want to put up a solar system to run a small refrigerator but I do not know where to start.
I'm looking for an efficient refrigerator along with what ever it will take to run it.
Thank you for your input.
Holling
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solar Refrigerator

    If there will be somebody at home for somebody to "light up" the propane fridge and a place to store a couple 20lb tanks--You might look at a propane powered refrigerator (wrecked RV, or there are even some portable 2/3 way powered ones).

    Otherwise, a small chest freezer converted with a refrigerator temp controller would be a good option. About 1/2 to 1/4 the Watt*Hours per day as any other "Upright" refrigerator.

    Once you figure out your loads (a Kill-a-Watt meter is great for AC loads around the home)--then we can get into the details to design the off-grid system.

    For an "emergency" power supply--a solar PV system + charge controller + battery bank + inverter + backup genset (for bad weather/winter time) is usually not a cheap solution for a 1 week outage. (Remember the batteries will need to be replaced every 4-8 years or so).

    The propane powered fridge or even a small backup genset + fridge may be a better option.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Solar Refrigerator

    Small propane/2 or 3 way from dometic would be just the ticket. They make a very small cooler sized portable but it is fairly expensive. Just FYI a full size RV sized Dometic will burn ~ 1500 btu/hr, with a duty cycle of ~50%. (There are ~79,000 btu in a gallon, 20# is about 5 gallons.

    Tony
  • monoloco
    monoloco Solar Expert Posts: 103 ✭✭
    Re: Solar Refrigerator

    Check out Engel refrigerators, they make very efficient refrigerators in a variety of sizes.
  • cfcw
    cfcw Solar Expert Posts: 25
    Re: Solar Refrigerator

    Well, these guys have forgotten more about solar than I will ever know, but I will try to fill in some blanks for you.

    For a small solar system you need just a few components:
    • A method to generate electricity- the solar panels
    • A method to regulate the energy going into the battery- a charge controller
    • A method to store the energy- the battery (or batteries)
    • The hardware to connect it all together, a little wire, a fuse, etc.


    Depending upon your selection of refrigerator, you may also need to convert the stored energy from DC back to AC, which is what most consumer refrigerators use. To avoid this step, you can buy a DC-powered refrigerator.
    I've got an Engel that works off AC or DC. They're expensive but they are also very portable so they can be used for car camping or tailgating. There is another company that makes a similar unit that is several hundred less. There are some very inexpensive coolers but I believe they use a peltier (sp?) effect and are only effective to reduce ambient temps about 40 degrees. They also use lots of energy for what they do. My Engel pulls about 40 watts when it's running. In the heat it will run most of the time during the day. I'll try to run a test with my watts up meter and see what happens over 24 hours or so.
  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    Re: Solar Refrigerator
    want to put up a solar system to run a small refrigerator but I do not know where to start
    Take a look at this
    http://www.compactappliance.com/FP430-Compact-EdgeStar-Portable-Refrigerator-Freezer/FP430,default,pd.html?cgid=Outdoor_Living-Travel_Coolers-Portable Freezers

    Can be used as a refrigerator or freezer, works on 120 AC or 12/24 volts DC. This unit draws 4 amps at 12 volts when running. I don't know about it efficiency but assuming it runs 40% of the time or about 10 hours a day, that would equal 480 watt hours each day. A couple of L16 420 amp hour batteries can supply 2520 watts to 50% DOD so it could run about 6 days before it would be necessary to recharge the battery which could be done with a generator and battery charger. If the power comes back on within that period, you could recharge the battery from the grid power using the same battery charger. If you need longer coverage, you could double the battery bank or add solar panels and charge controller. In any case the batteries will require periodic maintenance. Adding solar panels will be an expensive option.
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Solar Refrigerator
    cfcw wrote: »
    Well, these guys have forgotten more about solar than I will ever know, but I will try to fill in some blanks for you.

    For a small solar system you need just a few components:
    • A method to generate electricity- the solar panels
    • A method to regulate the energy going into the battery- a charge controller
    • A method to store the energy- the battery (or batteries)
    • The hardware to connect it all together, a little wire, a fuse, etc.

    And inverter if you need 120VAC
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • monoloco
    monoloco Solar Expert Posts: 103 ✭✭
    Re: Solar Refrigerator
    mikeo wrote: »
    Take a look at this
    http://www.compactappliance.com/FP430-Compact-EdgeStar-Portable-Refrigerator-Freezer/FP430,default,pd.html?cgid=Outdoor_Living-Travel_Coolers-Portable Freezers

    Can be used as a refrigerator or freezer, works on 120 AC or 12/24 volts DC. This unit draws 4 amps at 12 volts when running. I don't know about it efficiency but assuming it runs 40% of the time or about 10 hours a day, that would equal 480 watt hours each day. A couple of L16 420 amp hour batteries can supply 2520 watts to 50% DOD so it could run about 6 days before it would be necessary to recharge the battery which could be done with a generator and battery charger. If the power comes back on within that period, you could recharge the battery from the grid power using the same battery charger. If you need longer coverage, you could double the battery bank or add solar panels and charge controller. In any case the batteries will require periodic maintenance. Adding solar panels will be an expensive option.
    The EdgeStar looks nice and is priced right, but draws more current than the Engel. I have a 44 quart Engel which draws max 2.5 amps at 12V. I used mine all last winter as a fish freezer in Baja with 3-55 watt solar panels and 1 Costco marine battery. Turning it all the way down in the morning and then turning it up slightly at night I was able to minimize the draw down of the battery while keeping everything frozen very solid. The other nice thing about Engel is that they have a 20+ year record of being very reliable.
  • mikeo
    mikeo Solar Expert Posts: 386 ✭✭✭
    Re: Solar Refrigerator
    I have a 44 quart Engel which draws max 2.5

    Is it like this one?
    http://www.compactappliance.com/MT45FU1-Rugged-Compact-Engel-Portable-Refrigerator-Freezer/MT45F-U1,default,pd.html

    from the same supplier? Nearly twice the price at nearly half the amps, certainly worth considering. To store a few drugs, these may be way overkill in size.
  • monoloco
    monoloco Solar Expert Posts: 103 ✭✭
    Re: Solar Refrigerator

    Yes, that is the model that I have, but I paid a bit less for it from a different supplier. They make many different sizes from ones that are about six pack sized to 80 quarts.
  • rplarry
    rplarry Solar Expert Posts: 203 ✭✭
    Re: Solar Refrigerator
    Holling wrote: »
    Hi all,
    I'm a total noob looking for some advise. My daughter is an insulin dependent diabetic. Insulin needs to be stored in a refrigerator or it will go bad due to warm temperatures. A loss of electricity for a few days in the summer (Phoenix) would be deadly for her. I want to put up a solar system to run a small refrigerator but I do not know where to start.
    I'm looking for an efficient refrigerator along with what ever it will take to run it.
    Thank you for your input.
    Holling

    Holling
    I recently did the freezer to refer that BB referred to in his post. It uses around 300 watts a day of power. I bought the freezer (used)and thermostat for less the $150. How I did it is here: http://www.talkbaja.com/showthread.php?t=3718
    I am already on solar power, but you would need to get the solar panel, charge controler, inverter and battery also. To generate 300 watts a day you would need, and I am just going off the top of my head here, an 80 watt solar panel, mounted on your roof, a 10 amp charge controller, a deep cycle battery, and an inverter, not sure which inverter, it would depend on the startup power of what ever freezer you get. Probaly something that will surge to 12 amps or so. Of course you would need the wires and fuses to put it all together. You are probably looking at a total investment or $1500 to $2000.
    If you look around you can find systems already put together for around that price. Here is one I found after a google search: http://www.mysolarbackup.com/
    Good luck,
    Larry
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solar Refrigerator

    Larry,

    I think the system you are suggesting may be a bit small in solar panel + battery for a long term solution...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rplarry
    rplarry Solar Expert Posts: 203 ✭✭
    Re: Solar Refrigerator

    Bill
    Maybe, my thinking is convert a freezer to a fridge, it draws 300 watts a day and an 80 watt panel in Pheonix with 6 hours of sun should put out 480 watts less 40% for loses = 192watts so you are right a little small, so a 120 watt panel should do it no problem. The OP said he just wanted it for power outages, a week maybe so long term didn't really figure into it. I don't really know his situation but if his daughters life is on the line then there is no limit.
    Larry
    PS Bill, thanks for posting that link, I had completely forgotten about it. Haven't heard from wayne in NS or Jay and others for a long time. Fun to reread that old stuff.
  • Holling
    Holling Registered Users Posts: 7
    Re: Solar Refrigerator

    Thanks for all the input. The more I think about it, 100% self sustaining is the way to go. It sound like a 120 watt panel and a converted freezer may be the ticket. It is kind of scary to think that my little girls life depends on the electrical grids reliability.
  • monoloco
    monoloco Solar Expert Posts: 103 ✭✭
    Re: Solar Refrigerator

    It seems to me that if you don't need a lot of volume for storing the medicine you could get a very small Engel or Weico fridge and just plug it in to the cigarette lighter of your car in an emergency or a small honda generator to power your household fridge. A chest freezer and solar system to power it might be overkill for your application.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solar Refrigerator

    Roughly, Pheonix averages 4.8 hours of sun in winter--say 4 hours (remember, this is a 20 year average--having back up power such as grid and/or generator is still important if you NEED the power). Assume 0.52 end to end efficiency. 300 WH per day:
    • 300 WH * 1/4 hours of sun * 1/0.52 eff = 144 watts of panels minimum
    Battery size--assume 0.85% efficient inverter, 3 days of no sun, 50% maximum discharge, 12 volt battery bank:
    • 300 WH per day * 1/12 volts * 1/0.85 eff * 3 days no sun * 0.50 max discharge = 176 AH of battery bank @ 12 volts
    Note, picking the right inverter is important. To small of inverter will not start the load. Too large of inverter wastes power. Getting an inverter that has "search mode" will be nice for this setup. Use a mechanical thermostat as a conversion... Keeps the freezer off unless cooling is needed. Inverter "sleeps" most of the time, just turning on for a few cycles looking for an AC load--then turns on.

    The above system has a relatively large battery bank and, what works out to a minimum needed solar panel. If you wanted--you could double the amount of panel I have given above and still have a well balanced system.

    The more panel you have, the more power you can draw, and the less (hopefully) generator you would have to run during the winter time.

    One other thing--at least in California--you can/should register your home with the utility that you have a medical need for power. Normally, they will try and bring your home online first (and there are other issues like they will not turn your power off for non-payment without contacting you first, etc.--If I recall correctly).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Holling
    Holling Registered Users Posts: 7
    Re: Solar Refrigerator
    monoloco wrote: »
    It seems to me that if you don't need a lot of volume for storing the medicine you could get a very small Engel or Weico fridge and just plug it in to the cigarette lighter of your car in an emergency or a small honda generator to power your household fridge. A chest freezer and solar system to power it might be overkill for your application.

    Like this?
    WAECO CF-035AC110 Coolmatic 33 QT AC/DC with Touch Control Refrigerator and Freezer
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solar Refrigerator

    It is a little difficult to recommend one of these without somebody measuring their power usage first... A Kill-a-Watt meter for AC power usage. A DC Amp*Hour / Watt*Hour meter for DC side.

    I really like to recommend a Battery Monitor as a good way of keeping track of the battery bank state of charge--but they are not cheap.

    Some are very good--and others use about as much power as a full sized refrigerator/freezer.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dmiller
    dmiller Solar Expert Posts: 68 ✭✭✭✭
    Re: Solar Refrigerator

    A twelve volt compressor based fridge will be the most efficient, allowing the smallest system. Danfoss is the "gold standard" of 12v compressors. They don't make finished products, AFAIK. A 12v based compressor based units simply uses an converter to run on 120v. You don't want to design a system that goes 12v to 120v back to 12v.
    I have a large Engel chest that is excellent, as well as a danfoss based built in fridge.

    The little inexpensive fridges are Peltier devices and too inefficient for this type of application.

    Engel, Waeco and Arb are three popular brands of compressor based portable chest refrigerator. Engel may make the Arb units.
  • monoloco
    monoloco Solar Expert Posts: 103 ✭✭
    Re: Solar Refrigerator

    Engel makes models down to 14 quarts and the smallest Waeco is 19 quarts I believe. I would just go to the Engel and Waeco home pages for more info. The Waeco's us a Danfoss compressor and the Engels use a swing motor design with only one moving part.
  • dmiller
    dmiller Solar Expert Posts: 68 ✭✭✭✭
    Re: Solar Refrigerator
    Holling wrote: »

    Yes, but that price is a bit high for that unit. I agree that you may not need a solar based system. A lot depends on what you consider the worse case scenario.
  • monoloco
    monoloco Solar Expert Posts: 103 ✭✭
    Re: Solar Refrigerator
    BB. wrote: »
    It is a little difficult to recommend one of these without somebody measuring their power usage first... A Kill-a-Watt meter for AC power usage. A DC Amp*Hour / Watt*Hour meter for DC side.

    I really like to recommend a Battery Monitor as a good way of keeping track of the battery bank state of charge--but they are not cheap.

    Some are very good--and others use about as much power as a full sized refrigerator/freezer.

    -Bill
    I monitored my Engel all last winter and never saw more than 2.5 amps at 12 volts. I used it as a fish freezer and it would run fairly constantly when turned down all the way but when I turned it up slightly it would cycle. It was expensive, but overall I have been very pleased with it, it is also very nice when traveling to have a cooler that doesn't need ice. When using as a refrigerator, you need to be careful not to bump the temperature control, my wife threw her purse in the back and inadvertently bumped it and froze all our beverages rock solid in a very short time.
  • Holling
    Holling Registered Users Posts: 7
    Re: Solar Refrigerator

    Would this be a better choice?
    http://www.americanrvcompany.com/Dometic-CDF-11-Waeco-Portable-Refrigerator-Freezer-DC-Only-Trailer-Camper-RV_p_2417.html#

    Sorry for my ignorance, I just want to come up with the right solution the first time.
  • rplarry
    rplarry Solar Expert Posts: 203 ✭✭
    Re: Solar Refrigerator

    I am not so sure that a 12v compressor would be more efficient than a freezer conversion, but even if it is, now you are talking much more money. With a freezer you can pick up a used 5cf freezer on Craig's list for between $50 and $100, the digital thermostat is $68 dilivered. So for less than $200 he can buy the refer part of what he needs. Typically they use less than 300watts a day but for arguments sake I quoted it at 300. If he uses an AGM battery his system will even be more efficient. As far as an inverter, if he used a pure sine wave, that would add some cost but I suspect that since the refer only runs a few minutes an hour that a modified sine wave would work fine since the freezer compressor does not run long enough to heat up.
    Any way there are several ways to skin this cat. Not sure what I would do if I were in his situation
    Larry
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solar Refrigerator

    One question I would have is the use of digital thermostat... If this was an AC system running with an inverter in "search mode" (inverter on for a few cycles, then off for a few seconds, then back on--looking for >8 watt load)--I would check out the digital controller and make sure:
    1. It does not get confused by the cycling AC power
    2. It does not draw 6-8 watts (probably does not) and force the inverter into "On" mode (wasting more power).
    The mechanical thermostat may not be a nifty--but it may just work in this type of setup. Throw a small AC computer fan on the switched output so the fan turns on when the compressor turns on to mix the air (if needed).

    If Holling goes with the DC powered refrigrator, don't use the 0.52 derating but use 0.61 instead to account for no inverter (not a big difference anyway).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dmiller
    dmiller Solar Expert Posts: 68 ✭✭✭✭
    Re: Solar Refrigerator
    Holling wrote: »
    Would this be a better choice?
    http://www.americanrvcompany.com/Dometic-CDF-11-Waeco-Portable-Refrigerator-Freezer-DC-Only-Trailer-Camper-RV_p_2417.html#

    Sorry for my ignorance, I just want to come up with the right solution the first time.

    Yeah, the Waco's a good one. That's the best price I've seen on this type of unit. As long as it's big enough.
  • Holling
    Holling Registered Users Posts: 7
    Re: Solar Refrigerator

    So here is the info that Waeco puts out:

    WAECO CoolFreeze CDF-11 4.29
    Portable compressor cooler for refrigeration and deep-freezing

    Gross capacity: approx. 10.5 litres
    Voltage: 12/24 volts DC
    Power input: approx. 30 watts
    Current consumption: 0.36 kWh/24 h
    Temperature range: +10°C to -18°C, continuously variable via electronic thermostat
    Insulation: Full polyurethane foam insulation
    System: Compressor with integrated control electronics, low voltage protection (can be disabled), electronic fuse/automatic reverse pole protection
    Material: Cabinet and lid: PP
    Colour: Pale grey/dark grey
    Weight: approx. 8.8 kg
    Quality features: Electronic thermostat with digital temperature display, 3-stage battery monitor, LED interior light, adjustable shoulder strap, two drink holders, easy and secure fastening with the vehicle safety belt
    Scope of delivery: DC connection cable
    Test mark: CE, e-approved to 2006/28/EC (Automotive EMC Directive)
    Item designation: CoolFreeze CDF-11
    Ref. No.: 9105100007
    Accessory Mains adapter 230 V > 24 V
    Ref. No.: EPS-100W

    So if I was to set of a solar panel system with a battery bank how many watts would I conservatively need for this to run indefinitely?
    Would this work?
    http://www.amazon.com/Sunforce-50044-60-Watt-Solar-Charging/dp/B000CIADLG/ref=sr_1_1?ie=UTF8&s=hi&qid=1281837295&sr=8-1
    Once again, please excuse my ignorance, I'm doing this for my daughter.
    Thank you,
    Holling
  • dmiller
    dmiller Solar Expert Posts: 68 ✭✭✭✭
    Re: Solar Refrigerator

    I'm sure someone here that does a lot of designs can give you a precise answer on the power calculation.

    My hesitation is about solar and a refrigeration unit that likely won't even be used yearly. Compressors don't like to sit. For battery your talking about a UPS setup of holding the battery at full charge. Is a solar charge controller best for that? I don't know.

    I think you need to consider a system for keeping your home fridge running. Not necessarily solar. Nothing unusual about a "must work" system. There are home medical devices like Oxygen makers that fall into that category. The solution to use solar and a backup fridge seems a bit rushed. Have you asked a diabetics forum about this issue?

    I bet we could come up with fifty ways to keep a small quantity of medicine reliably cold for a couple weeks. I'll also bet that the solution discussed here wouldn't make the top ten. It's not going to be the top solution for reliability. And it certainly is not going to be the top solution for cost.

    If your feeling panicky you need this NOW, maybe buy the chest unit and an appropriate inverter, fill it with blue ice freezer blocks, set it to the lowest temp, and plug it into the wall. That gives you a few days of "backup cold". You can make more cold by plugging it into the car.

    Then you can take more time getting the solar or whatever right. A system you actually use for something daily will be more likely to work when you need it.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solar Refrigerator

    Holling,

    The difference between running at ~35F and 0F is quite a bit of difference in power consumption--So could where you will be running it (A/C cooled home, vs power failure/no AC and scorching hot summer--but of course, you get 6+ hours of sun--so you have more solar power to burn).

    Notice they say it runs 30 watts and ~0.36 kWH (360 Watt*Hours) per day... That is roughly 30 watts 12 hours a day (1/2 hour on, 1/2 hour off???).

    If you have a 12 volt battery + charger, and want to "invest" in an Amp*Hour meter (like this one for ~$60)... Purchase the refrigerator (assuming it is large enough for your needs)--then run it for a few days to get a baseline power reading. Then you can size the panels+batteries more accurately.

    Even then, there is variability of weather... From this document (1961-1990) December runs from ~3 hours to ~6 hours per day depending on local weather patterns. But--other than one or two years, Phoenix gets >4 hours per day in December.

    Solar power is not that exact (any guesses closer than 10% error are pure luck :roll:). But, we don't want to waste your money either--And too small a system or too large can do exactly that.

    If we assume that for refrigeration mode in your typical home environment 360 Watt*Hours per day load, minimum of 4 hours of sun per day, 0.61 system efficiency, 12 volt battery bank (although, 24 volt appears to be just fine too):
    • 360 watt*hours per day * 1/4 hours per day * 1/0.61 eff = 148 watts of solar panel
    • 360 watt*Hour per day * 1/12 volts * 3 days no sun * 1/0.50 max discharge = 180 Amp*Hours @ 12 volts
    So, around 150 to 300 watts of solar panels, 180 AH of 12 volt batteries, and a charge controller.

    If it was my system... I probably would go like this:
    1. Kyocera KD210GX-LPU 210 Watt Solar Panel ($560)
    2. Rogue 30 amp MPPT Solar Charge Controller ($295)
    3. Trojan T105-RE 6 Volt, 225 AH Deep Cycle Battery (2*$145 each)
    4. 40 amp Circuit Breaker for Charge Controller ($11.50)
    5. 15 amp Circuit Breaker for 12 volt refrigerator ($11.50)
    6. Box for DIN 1-4 Breakers ($28.80)
    7. Trimetric TM-2025A Battery Monitor ($150 -- Sort of optional)
    8. Freas HD98C Precision Hydrometer Set ($42 -- Only for flooded cell batteries)
    9. Morningstar SureSine, 300 Watt Sine Wave Inverter 115VAC ($265 plus 80 amp circuit breaker--optional but nice to have)
    10. Iota DLS-15: 12 Volt 15 Amp Battery Charger ($129--optional)
    11. Iota IQ4: plugin 4-stage controller for Iota chargers ($30 for Iota charger)
    12. Xantrex Truecharge2 12-Volt, 20-Amp Battery Charger + optional remote battery temperature sensor ($264--optional, possibly instead of Iota)
    13. Misc. Wiring and solar panel mounting hardware (we can talk details later)
    14. Honda eu2000i or eu1000i generator set (plus 10-20 gallons of fuel + fuel stabilizer)
    The 210 Watt panel is bigger than the ~150 watt minimum--but we don't know the exact power requirements and the increase in price for the 210 watt panel is not that much.

    The Rogue 30 amp MPPT charge controller is a bit large for your system--but if you need more power, you will not need to add another controller. You could use a smaller/cheaper charge controller if price is an issue--Would work OK.

    Trojan battery set is not too expensive and should last 3-6+ years, depending on how much it is used and how well you take care of it.

    You could go with "maintenance" free AGM batteries (they are really nice--and will probably last at least as long), but they are much more expensive (Sun Xtender PVX-2580L AGM Sealed Battery is ~$585). Frequently, first time solar/off-grid folks buy a cheap(er) "training set" of batteries first--then spend more for the next set).

    Circuit breakers to protect wiring and give you the ability to turn things off for servicing/testing. You should check battery charge level and electrolyte levels at least once per month.

    I like a battery monitor because you can, at a glance, just look at the current state of charge of the battery bank... If the battery goes below 75% state of charge--you want to figure out why and get them back charging again. If they stay below 75% state of charge for days/weeks/months--the batteries will quickly sulfate and "die". Measuring with a hydrometer is the "gold standard"--but a battery monitor is something that you can tell others to watch (like in a cabin that family is borrowing for the week) to monitor their power usage. Not a requirement--but can save battery bank from early death.

    A 120 Volt AC inverter was not part of your requirement--but you may find it very useful in a power emergency... Charging cell phones, a couple small CFL lights, radio, etc. The MorningStar is a great little 12 volt true sine wave inverter. Purely optional.

    For a belt and suspenders type setup... You should have an alternate means of charging your battery bank (stone through solar panel, a stretch of bad weather, etc.). Iota would be a fine backup or even "float" power supply. IQ-4 makes it a bit more automatic. The new Xantrex 20 amp battery charger is a great unit--but quite a bit more expensive. Both should run fine on a small genset.

    A backup genset--if you have a good place to store fuel (siphon it into your car/truck once per year and replace fuel+stabilizer to keep fresh). The small Honda's are quiet and pretty fuel efficient. At something like $700-$1,000 each--they are not cheap. Your choice.

    Also, since the batteries are the one part of your system where poor maintenance can mean a quick death for an expensive system component... Take a look through these battery FAQs:

    Deep Cycle Battery FAQ
    www.batteryfaq.org

    The above is purely a suggestion as a starting point. There are lots of other fine choices out there. Also, I am not in the solar business and I am not an installer/configuration/sales person.

    Please do your own research, ask questions, and verify the price delivered to your front door (shipping can be expensive). Many of the links go to our host's web-store (NAWS; they fund this site and provide software support for the forum)--But you are welcome to purchase from anyone that makes sense to you.

    -Bill

    PS: I would stay away from the sunforce system... In general, those panels seem to under perform their 60 watt rating. Also, amorphous solar panels are typically about 2x the surface area as a crystalline panel of the same rating.

    The above system I have spec'ed out should be able to run your system 365 days a year (except for periods of heavy weather > 3+ days in length) assuming 360 Watt*Hours per day power usage.

    If price is a big issue--we can talk about less expensive components and cut back closer to the 150 watt panel (and you could use a smaller battery bank) to get you going and after a few years--you can decide where to go from there.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Holling
    Holling Registered Users Posts: 7
    Re: Solar Refrigerator

    Thanks Bill! That is exactly what I was looking for.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Solar Refrigerator

    Your welcome Holling,

    You could also start with the battery bank + charger + circuit breaker + hydrometer (and battery monitor?) first.

    That will give you three days of standby power for the refrigerator (6+ days if your truly in an emergency and run the battery 100% dead--remembering that a 100% dead battery will need to be replaced).

    And, you could add the genset, solar panels + charge controller, and the 120 VAC inverter as funds and situations permit.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset