what refrigerator for off grid system

Hello everybody

I am trying to chose right refrigeration for remote area meeting place, where sometimes can be 100 or more people for few days. So this is not home where will be one ref, but possibly little more.
my consideration is:

-DC refs , but I found here on forum that they have so limited guarantee and they are pretty expensive 2000 per box, if I need 3 boxes it is hugh amountof money

- normal AC refs, I found that they can take 1.2KWh per day that means that I will have to use 400W of panels and two surretes s530 (for example) to keep them in ecological way without use generator.

- I also think about propain refs, but I heard that they like to broke. I don't know yet how is service system in my area (Baja California Sur) of them.

The simplest looks to me use AC refs (one ref around 400$) put panels, and if is a problem then service is everywhere.

We have pretty high temperatures here in summer seazon (but from other way in summer is not a tourist season so probaly two of those ref will be off) and our kitchen is outdoor.
And also is importand for us keep ecological enviroment,so not use generator (almost at all, only in emergency)

I will appreciate any input

best wishes from Mexico

Daniel

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,804 admin
    Re: what refrigerator for off grid system

    RV refrigerators tend to be Propane type--and they can last for many years. Some other "fuel" fridges, like kerosene, tend to have more maintenance issues (soot, wicks, etc.?).

    I too would stay away from a DC/solar fridge. Very expensive, tend to be small, and some brands have issues with quality, sweating door gaskets, etc.

    A standard Fridge (or a chest freezer converted to a fridge with a small air circulating fan and a refrigerator type thermostat) is probably the best bet, and they are very efficient.

    For your situation, an ice box, and pre-chilling (and pre freezing) the food and simply storing it in a thick insulated container is probably the better choice (if you are there 4-5 days a couple times a month)...

    Problem with solar is that they really make economic sense if the power is used 365 days per year--if you start only using it 10 days per month in the summer--the rest of the power is wasted (if there is nobody there) and the price per generated (used) kWatt*hours become extremely high (and one can argue that this is not a good use of resources regarding the solar panels).

    If your usage of the site is so low, your best bet is a good (or a couple) of gas or diesel generators makes most economic sense (if an ice box won't work).

    If, however, you can use the power when there is not a hundred people there (neighbors, irrigation, caretaker, eventual full-time living, etc.), then going solar (with generator backup) can make a good investment into the future.

    Your last alternative would be to use a generator to charge batteries during the day (or before/after gatherings). It would keep place quiet, and the batteries (with a small solar panel + charger controller) would last for years with the light use (and good maintenance).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: what refrigerator for off grid system

    I am sory for not super clear my post

    Generaly this is mediation center, with some retreats during the year then can be around btw 100-200max people

    Rest of the time we will have small casitas for rent.


    Generally few times at year more people (100-200)max, rest of time not to many (maybe 5 only maybe 15 or maybe sometimes 20)


    System will be operate 24hrs anyway because of light and all year around.


    My refs during the retreat will be working 100% all 3 and during the quiet time probably one ref and one freezer.

    one importand point is: no pollution if is not needed (generator only for emergency)

    If somebody can give me link how to do it from chest freezer refrigerator ?

    If you thinnk that I should write more specs about plan of this solar system including 21 houses meeting building and library, if that can give more clear about what to do with kitchen I will do it. (any way I will write soon other post regarding this special issue)


    Thank you

    best wishes

    Daniel
  • BB.BB. Super Moderators, Administrators Posts: 32,804 admin
    Re: what refrigerator for off grid system

    Here is one thread with lots of discussion about the conversion (it is not hard, and may use up to 1/2 the energy of a standard fridge)...

    Also, try the SEARCH function with the terms "chest freezer fridge" and you will find a lot of threads on related topics (DC, Propane, etc.).

    In the end, your best bet would be to figure out how much power you will want to run the facility--It may turn out that just by adding a few extra panels or even just sizing the batteries a bit bigger, you may be able to run the extra fridges without much extra money in solar.

    Also, if your large retreats are only during good weather (usually a given that people plan retreats for when the sun is shining and not during the rainy/cloudy times), it is possible that sizing your needs for 365 days per year would leave more than enough power for the few times you need the extra power during the "sunny" times of the year.

    Check out the US Government's Energy Star program... They have a listing of some pretty energy efficient appliances. It is interesting that some of the very expensive DC solar/battery powered fridge/freezer units are not even efficient enough to meet the standards that a home fridge/freezer unit must meet.

    Also, adding features (like auto defrost, ice makers, etc.) do add to the energy draw--if you don't need them, getting the very simple appliances can save some more energy too.

    Depending on weather and other issues, you probably will still want a backup generator too--I understand that you want to reduce pollution--but it is better to have solar supply 95%+ of your needs rather than oversizing it by 2x-4x to handle the last few percent (bad weather, the very occasional large conference, if a charge controller or inverter fails, etc.).

    To do solar does require a lot of planning and pre-designing in for conservation... While you can always throw more "solar" at a problem--the system gets big and expensive real fast.

    I assume that you don't have utility power at this location? Because, if you do have utility power it would be much better for you to go with a Grid-Tied solar system (your solar panels supply power during the day and spin your meter backwards, but at night the utility supplies your power). In very rough numbers, you can do this for something like $0.25 per kWhr (US prices--don't know Mexico)...

    Trying to do the same thing but off-grid (no utility power), your price for electricity is going to be more in the $1.00 per kWhr (which is typically 5-10x the cost of utility power in the US).

    So, designing a community focused around conservation (CFL lights, energy efficient appliances, using natural air flow, insulation, no air conditioning--if possible, solar powered well pumps, ability to shift loads to when the sun is shining--like washing, etc.) will greatly affect the price of your solar power system.

    Also, it is kind of difficult to distribute DC power around a large community... AC power is easier to deal with (use transformers to step up and down voltage for transmission), but you would probably have more losses.

    Designing a central core with heavy appliances (washer, fridge, microwave, well pumps, A/C for clinic, etc.) with a large solar system... And using small distributed arrays+batteries for lighting, radio, etc. in the sleeping cabins.

    I am certainly not an architect or solar village designer--but working the issues out ahead of time could affect the end costs (of your solar power system) by a factor of ~2x--depending on the final outcome of the design process and the needs of those working/living there.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: what refrigerator for off grid system

    Daniel,

    Check this old discussion thread: http://forum.solar-electric.com/showthread.php?t=9&highlight=freezer

    HTH,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: what refrigerator for off grid system

    Thank you, thank you, thank you

    It claryfyi my issue pretty much


    That how I was thinking also, use transformers, central station and shared power , in case of overloading use additional power from generator.That way my fridges will be working almost for free (But that will be in my other topic).

    Generaly DC fridges not recomended: not really economical and not efficient,problems with guarante plus like to broke.

    Recomended options: propain, AC (in case of shared power) or very interesting (and economical) option,change chest freezer into ref.

    Best wishes

    Daniel
    (preparing another issue question)
  • BB.BB. Super Moderators, Administrators Posts: 32,804 admin
    Re: what refrigerator for off grid system

    I forgot to include a link to the Energy Star website for Fridges/Freezers.

    Also, in general, check out the larger appliances. Typically, the efficiency should go up with the size of the box (volume goes up with the cube of the dimensions, surface area goes up with the square of the dimensions--so less surface area per cubic foot of food storage for larger cold boxes--and less heat loss per cubic foot of storage).

    Also, you will need to measure/calculate your loads. And, be aware that a 24 hour by 7 days a week load will frequently draw more kWhrs than a large, but infrequently used) appliance (for example; desk top computer vs microwave).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: what refrigerator for off grid system

    I'd suggest Energy Star fridges, they are not too expensive, and nearly as efficient as the best DC fridges.

    I'll 2nd the suggestion for Grid Tie, if you have power in the area.

    3) Perhaps plan on using a generator for only an hour or 2 in the morning, to bulk charge the batteries, and let the solar finish the charge.

    Maybe if the place is empty for a couple of days, shut down an empty fridge, and turn it back on 24 hrs before the food arrives. That will save some power too.
    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 ,

  • BB.BB. Super Moderators, Administrators Posts: 32,804 admin
    Re: what refrigerator for off grid system

    Being in Mexico, Grid Tied solar systems may not be legal... So, there are some hybrid type systems avialable where you can use solar to backup the grid power--and use the solar to reduce your bill--but not turn the meter backwards (which is illegal in many areas).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SolarJohnSolarJohn Solar Expert Posts: 202 ✭✭
    Re: what refrigerator for off grid system

    Hi Daniel,

    In your situation, I would go for the freezer to refrigerator conversion that someone else mentioned. I recently bought an Energy Star rated 25 cubic foot refrigerator/freezer that is rated at 499Kwh/year (1.36Kwh/day). My chest freezer uses 0.8Kwh per day.

    John
  • BB.BB. Super Moderators, Administrators Posts: 32,804 admin
    Re: what refrigerator for off grid system

    John,

    How many Cubic Feet was your freezer conversion?

    By the way Daniel, one reason the chest freezer->fridge conversion can save more energy is that the lid opens from the top, so cold air cannot flow out--very helpful if it is opened many times per day.

    However, the downside is that you will have to pull up baskets and rummage around to get items--not near as easy to reach as the typical vertical refrigerator.

    Also, a chest conversion will tend to sweat on the inside--so you may have to add a set of plastic drip catchers on the inside below the evaporator coils on the side of the freezer to divert water to the drain... Not difficult to do--but only you can decide it the work to make the conversion is worth the energy saved....

    As always, it is probably better to buy one and do the conversion/experiment and see if doing more is worth it to you.

    Also, since, I guess, you will be working with 120 VAC @ 60 Hz, getting a Kill-A-Watt meter is a $25-$30 "no-brainer" to measure the real power consumed by your appliances (up to 15 amps--normal US three prong plug).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SolarJohnSolarJohn Solar Expert Posts: 202 ✭✭
    Re: what refrigerator for off grid system

    Bill,

    I didn't convert my freezer. Sorry if I misled anyone, it wasn't intentional, I was just trying to say that a freezer conversion sounds like a good idea to me.

    I use my freezer as a freezer. I wasn't looking for the most energy efficient freezer at the time that I bought it, so I suspect that I could do even better if I shopped around. I do run the freezer off of my solar panels in order to avoid wasting energy, and I use it to keep food from spoiling when the grid goes down. I add to my PV system as my budget allows, and I eventually hope to be able to power my new 25 cubic foot refrigerator/freezer with it. For that reason, I searched for the most energy efficient refrigerator I could find (without going to a sundanzer), and ended up with a 499kwh/year Kenmore. I decided to go with a fairly large one in order to minimize trips to the grocery store. Gas is expensive too ya know!

    John
  • khottonkhotton Solar Expert Posts: 38
    Re: what refrigerator for off grid system

    I was planning on using a SunDanzer refrigerator (at 24VDC), but I am worried about reliability. This thread give the impression that DC refrigerators (SunDanzer included I assume) are not that reliable. Is this true?

    Kevin
  • BB.BB. Super Moderators, Administrators Posts: 32,804 admin
    Re: what refrigerator for off grid system

    I believe that the DC refrigerators generally use electronic commutator (like a DC computer fan). The ones I looked at don't use a DC motor or pump with external motor (problem with brush wear, belts, or leaking refrigerant seals)...

    Many are pretty expensive compared to the standard units you can buy from your local appliance dealer (can buy more solar panels, inverter, batteries with money saved)... Lastly, check your warranty terms (local dealer nearby for repairs, etc.).

    I don't have any DC fridges (other than one old propane one in an RV), but you can read Wind-Sun's editorial about one vendor and issues with the solar / RE refrigeration industry.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: what refrigerator for off grid system

    Guys,
    I already have parts, It took me a while to driving around SJD to pick things together (Mexico has little diferent rules of marketing) but finnaly I bought in refrigerator service anolog thermostat (that was so cool how I wonted explain to the tech guy what I wonna do, and he said "hmm. yeah that makes sense, this is what you need"), on the box is sticker: Cold Out +1.5C; Cold In + 5C; Warm In + 12.5C; switch is on 250AC, electric box plastic hangar with suck-in rubber sticker and I am lucky becuase I bought time ago whirpool ( I believe 11 cu), but I was starting being myself as thermostat and turning this on and off, to don't get my botles of beer exploded or milk frozen :)

    in 15 minutes I am starting combinate ;)


    Muchas Gracias amigos
    Thank you all for advices

    Daniel
    blue sky
  • RCinFLARCinFLA Solar Expert Posts: 1,470 ✭✭✭✭
    Re: what refrigerator for off grid system

    From the sound of your useage profile you have a unique situation. Efficient refrigerators are not quick recovery refrigerators. For that many people you need a pretty large unit or multiple units with pretty quick recovery.

    I just bought a new energy-star 25 cu ft side by side that takes about half the average power per day of by 10 year old 25 cu ft. Old one was 4.2 kWh per day, new one is 2.4 kWh per day but when stocking from grocery store once each week, the new one takes about 4 hours to bring temp back down to 37 deg F. There is a turbo button to speed this process. It has a varible speed compressor and the 'turbo mode' runs it up to max speed.
  • System2System2 Posts: 6,290 admin
    Re: what refrigerator for off grid system

    I am thinking to buy now 25cu freezer and do it on ref

    and left my 11cu as freezer that will work for us a while

    hmm...
    Maybe I just bypass my new termistor and put on freezing for a while ? - if I will needmore cold.

    I am happy right now already. I had freezer which main point was to freeze ice to put to the coolers :)

    The proces in our center will be going pretty slow. Can happens something big next year. But I think that I have at least 2 years to adjust various components to work.

    thank you for advice, yeah it looks like I should have switch ref/freezer hmm..

    blue sky
    Daniel
Sign In or Register to comment.