Help on how to run small fridge on solar power not connect to house wiring
- Thread starter Onebyone
- Start date
I suggest you check the power requirement label on the fridge and then go to a website that tells you how many panels you'll need for that power demand. (Don't forget power controller, Inverter and expensive deep cycle backup batteries.
Without doing the math, I'd say FORGET IT. My guess is that it will cost you $1000 for the solar set-up. Was that what you were expecting?
Your asking to power a relatively high power demand appliance with one of the MOST expensive and LEAST efficient methods of electrical power generation.
Without doing the math, I'd say FORGET IT. My guess is that it will cost you $1000 for the solar set-up. Was that what you were expecting?
Your asking to power a relatively high power demand appliance with one of the MOST expensive and LEAST efficient methods of electrical power generation.
Hold up there.
It can be done.
A fridge can use 500 for a energy efficient one to 4600 for an old outdated monster.
Most Common Fridges use 1500-2000 per day.
My small fridge uses 200 watts when running so it does not need a huge inverter, and a total of 1200 per day, which for a small fridge is a lot but its old.
It will depend on where you live, but in GA in summer we have 5.1 hours of sun per day.
Converting one of the Crosley deep freezers $590, into a fridge with an external control $90 from http://www.backwoodssolar.com/ it will use 325 Watts Per day.
I find backwoods solars prices a little high on somethings so I think you might find them cheaper. Try sunelec.com for modules inverters etc.
325/5= 65 * 1.3 (30% inefficiency) = 85 Watts of Solar Modules.
Many small systems have been setup with 12 Volt batteries from Walmart, they will go a couple of years with out too much trouble.
There are also DC freezers and Fridges but they are more expensive up front.
Also look at http://www.builditsolar.com/ and http://www.homepower.com/home/
Tell me more and I'll see if I can help.
NEW FREEZER: 10 cu ft Energy Star Rated
CROSLEY CHEST FREEZER 120 VOLT AC LOW POWER CHEST FREEZER
Can convert into ultra-low power chest REFRIGERATOR
The CROSLEY chest freezer is 10.0 cubic feet. (Please note: the 12 cuft CROSLEY has been discontinued)
Features includes 2 sliding baskets, defrost drain, white exterior color, door lock and interior light.
ONE year warranty on all parts and labor; 2-5 year parts and labor covered on sealed cooling system; 6-10 year coverage on compressor part.
Power draw: 95-135 watts
ENERGY STAR listed model has foam insulation in 2.625 inch walls and 2.375 inch lid. Backwoods Solar has finished testing this new 10 cuft model. Freezer temperature was set at a range of -2 to +10 degrees F. Room temperature was held at 66 degrees F. Power consumption was 500 watt-hours per day.
42" W x 25" D x 34." H (weight: 120 lbs)
CANADIAN CUSTOMERS: Unfortunately our agreement with CROSLEY does NOT allow us to sell their product line, including this WCC10/E in Canada.
R-CROSLEY WCC10/E: 10 cubic foot Chest Freezer: Regularly $590 with shipping INCLUDED in lower 48 states. Add this item to the shopping cart
Due to size, 30 day return privilege does not apply to this item.
[Remote Bulb Thermostat, Contact Current Rating Resistive @ 120VAC 22 Amps, Contact Current Rating Resistive @ 240VAC 22 Amps, Inductive Rating @ 120 VAC 16 Amps, Inductive Rating @ 240 VAC 8 Amps, Differential 3 to 12 Degrees Fahrenheit, Switch Action SPDT, Temperature Range -30 to 100 Degrees Fahrenheit, Application Heating/Cooling, Bulb Length 4 Inches, Bulb Depth 3/8 Inches, Capillary Length 8 Feet, Height 4 7/16 Inches, Width 2 3/16 Inches, Depth 1 3/16 Inches, Dustproof]
External thermostat turns this Crosley freezer into a chest refrigerator, no modification to freezer is required. Energy consumed is roughly 325 watt-hrs per day with the same parameters as the freezer testing above. Temperature Range -30 to 100 Degrees Fahrenheit. Once installed, the Crosley's interior light and external operating LED only illuminate when the Crosley is drawing power.
R-4E047: $90
It can be done.
A fridge can use 500 for a energy efficient one to 4600 for an old outdated monster.
Most Common Fridges use 1500-2000 per day.
My small fridge uses 200 watts when running so it does not need a huge inverter, and a total of 1200 per day, which for a small fridge is a lot but its old.
It will depend on where you live, but in GA in summer we have 5.1 hours of sun per day.
Converting one of the Crosley deep freezers $590, into a fridge with an external control $90 from http://www.backwoodssolar.com/ it will use 325 Watts Per day.
I find backwoods solars prices a little high on somethings so I think you might find them cheaper. Try sunelec.com for modules inverters etc.
325/5= 65 * 1.3 (30% inefficiency) = 85 Watts of Solar Modules.
Many small systems have been setup with 12 Volt batteries from Walmart, they will go a couple of years with out too much trouble.
There are also DC freezers and Fridges but they are more expensive up front.
Also look at http://www.builditsolar.com/ and http://www.homepower.com/home/
Tell me more and I'll see if I can help.
NEW FREEZER: 10 cu ft Energy Star Rated
CROSLEY CHEST FREEZER 120 VOLT AC LOW POWER CHEST FREEZER
Can convert into ultra-low power chest REFRIGERATOR
The CROSLEY chest freezer is 10.0 cubic feet. (Please note: the 12 cuft CROSLEY has been discontinued)
Features includes 2 sliding baskets, defrost drain, white exterior color, door lock and interior light.
ONE year warranty on all parts and labor; 2-5 year parts and labor covered on sealed cooling system; 6-10 year coverage on compressor part.
Power draw: 95-135 watts
ENERGY STAR listed model has foam insulation in 2.625 inch walls and 2.375 inch lid. Backwoods Solar has finished testing this new 10 cuft model. Freezer temperature was set at a range of -2 to +10 degrees F. Room temperature was held at 66 degrees F. Power consumption was 500 watt-hours per day.
42" W x 25" D x 34." H (weight: 120 lbs)
CANADIAN CUSTOMERS: Unfortunately our agreement with CROSLEY does NOT allow us to sell their product line, including this WCC10/E in Canada.
R-CROSLEY WCC10/E: 10 cubic foot Chest Freezer: Regularly $590 with shipping INCLUDED in lower 48 states. Add this item to the shopping cart
Due to size, 30 day return privilege does not apply to this item.
[Remote Bulb Thermostat, Contact Current Rating Resistive @ 120VAC 22 Amps, Contact Current Rating Resistive @ 240VAC 22 Amps, Inductive Rating @ 120 VAC 16 Amps, Inductive Rating @ 240 VAC 8 Amps, Differential 3 to 12 Degrees Fahrenheit, Switch Action SPDT, Temperature Range -30 to 100 Degrees Fahrenheit, Application Heating/Cooling, Bulb Length 4 Inches, Bulb Depth 3/8 Inches, Capillary Length 8 Feet, Height 4 7/16 Inches, Width 2 3/16 Inches, Depth 1 3/16 Inches, Dustproof]
External thermostat turns this Crosley freezer into a chest refrigerator, no modification to freezer is required. Energy consumed is roughly 325 watt-hrs per day with the same parameters as the freezer testing above. Temperature Range -30 to 100 Degrees Fahrenheit. Once installed, the Crosley's interior light and external operating LED only illuminate when the Crosley is drawing power.
R-4E047: $90
Dr Prepper,
You've got me confused with your post.
At one point you've posted a power draw of 90-135 watts. So what is this 325 watts per hour per 24 hrs per day?
regardless
325 watts per hour x 24 hrs per day (most modern fridge compressors run 22hrs per day) = 7800 watts per day.
NO? Where did I go wrong here?
None the less, 325 watts at 120V = 2.7 Amps
120v @ 2.7a is not an insignificant amount of power for a small solar system. That power have got to be stored in a battery system and then inverted to 120VAC by a less than 100% efficient inverter.
She'd if she wants to go off the grid in my opinion she'd be better off with a propane or 12v DC powered fridge.
Dr Prepper I followed the link you post and went to the web site. I quickly found this info....
"REFRIGERATOR / FREEZER Older ,Standard, non-Energy Star refrigerators and freezers use so much power battery charge is depleted very quickly. With solar electric powered homes, it is not practical to use these older, standard electric refrigerator or freezer. Super efficient refrigerators designed and tested for solar power, listed in Backwoods catalog, operate on less than half the usual power.
Ordinary AC refrigerators and freezers run on over 200 watts AC, and run many hours a day. Most have less than 2 inch insulation. Fortunately, special refrigerators and freezers are available which use less than 30% as much energy.
SUNFROST products have 4- to 6-inch insulation, and a quality compressor on top where it can’t put heat back into the box. The RF-12 model runs 50 watts for 12 hours a day, totaling 600 watt hours a day. This needs only 3 to 6 solar modules, depending on the climate. "
This line in itself tells me all that I need to know "This needs only 3 to 6 solar modules, depending on the climate." They are saying you need 3-6 solar panels (modules) to power one of their super efficient Fridges with triple insulation!
At their site I picked one panel at random
Unisolar S-US64 64watt 3.88A 16.5v $395
This is $395 sale price for ONE solar panel, not including the charge controller, not including the battery system, not including the inverter?
I don't think OnebyOne has any interest in paying this much money, when she asks for saving money by not connecting it to the grid.
You've got me confused with your post.
At one point you've posted a power draw of 90-135 watts. So what is this 325 watts per hour per 24 hrs per day?
regardless
325 watts per hour x 24 hrs per day (most modern fridge compressors run 22hrs per day) = 7800 watts per day.
NO? Where did I go wrong here?
None the less, 325 watts at 120V = 2.7 Amps
120v @ 2.7a is not an insignificant amount of power for a small solar system. That power have got to be stored in a battery system and then inverted to 120VAC by a less than 100% efficient inverter.
She'd if she wants to go off the grid in my opinion she'd be better off with a propane or 12v DC powered fridge.
Dr Prepper I followed the link you post and went to the web site. I quickly found this info....
"REFRIGERATOR / FREEZER Older ,Standard, non-Energy Star refrigerators and freezers use so much power battery charge is depleted very quickly. With solar electric powered homes, it is not practical to use these older, standard electric refrigerator or freezer. Super efficient refrigerators designed and tested for solar power, listed in Backwoods catalog, operate on less than half the usual power.
Ordinary AC refrigerators and freezers run on over 200 watts AC, and run many hours a day. Most have less than 2 inch insulation. Fortunately, special refrigerators and freezers are available which use less than 30% as much energy.
SUNFROST products have 4- to 6-inch insulation, and a quality compressor on top where it can’t put heat back into the box. The RF-12 model runs 50 watts for 12 hours a day, totaling 600 watt hours a day. This needs only 3 to 6 solar modules, depending on the climate. "
This line in itself tells me all that I need to know "This needs only 3 to 6 solar modules, depending on the climate." They are saying you need 3-6 solar panels (modules) to power one of their super efficient Fridges with triple insulation!
At their site I picked one panel at random
Unisolar S-US64 64watt 3.88A 16.5v $395
This is $395 sale price for ONE solar panel, not including the charge controller, not including the battery system, not including the inverter?
I don't think OnebyOne has any interest in paying this much money, when she asks for saving money by not connecting it to the grid.
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Windy Ridge
Veteran Member
Some RV fridges run on 12 volt, propane and house current. I suggest you start with one of these. You wouldn't need an inverter with one. They are quite expensive when new but can also be bought used. I think Lehmans might also have something in this line.
Windy Ridge
Windy Ridge
You know what, just listen to Double A, it's just too much darn work arguing with people here sometimes.
The OP did NOT SAY she wanted to save money, she said she wanted the cheapest possible solar system to run it.
Maybe it's a prep item, ever think of that?
Double A obviously knows how much money you want to spend, and has configured everything under the sun.
Not sure why he can't figure out running watts, vs Watt hours though.
The OP did NOT SAY she wanted to save money, she said she wanted the cheapest possible solar system to run it.
Maybe it's a prep item, ever think of that?
Double A obviously knows how much money you want to spend, and has configured everything under the sun.
Not sure why he can't figure out running watts, vs Watt hours though.
Hmmm .... I've been looking at solar backup for a 1.7 amp device that runs about 8hours per day.
The local solar dude told me that a 20 watt solar panel plus charge controller might be enough to charge my van battery, given 8 hours of sunlight. That would run me something like $260 for a package. I've just seen 30 watt panels on the internet for about the same, $200 range, $30 for the charge controller.
Since you'd want to run it at least twice as much per day, I'd guess that you would need something like a 40-60 watt panel together with a car battery (unless you are willing to spend the big bucks for a deep cycle battery).
As long as you're forking out money for solar panels, you might as well get a 12v powered refrigerator, which would be a lot more efficient than having to use an inverter.
Maybe one of those powered car coolers that plug into the lighter socket would do the trick, probably wouldn't have to run it at night if it's insulated enough. They might be too small for your purposes though.
I'm sure Loup will be here soon to give more authoritative advice.
The local solar dude told me that a 20 watt solar panel plus charge controller might be enough to charge my van battery, given 8 hours of sunlight. That would run me something like $260 for a package. I've just seen 30 watt panels on the internet for about the same, $200 range, $30 for the charge controller.
Since you'd want to run it at least twice as much per day, I'd guess that you would need something like a 40-60 watt panel together with a car battery (unless you are willing to spend the big bucks for a deep cycle battery).
As long as you're forking out money for solar panels, you might as well get a 12v powered refrigerator, which would be a lot more efficient than having to use an inverter.
Maybe one of those powered car coolers that plug into the lighter socket would do the trick, probably wouldn't have to run it at night if it's insulated enough. They might be too small for your purposes though.
I'm sure Loup will be here soon to give more authoritative advice.
OBO - you do know that you cannot run anything directly off the solar panels, right? You have to have a set of automotive-size batteries and an inverter (to provide the a/c for the fridge) and some kind of charging mechanism.
According to my calculations, you'll need to supply 161 watts.
Note however, that compressors routinely require 3x the amps for startup as they do while running. So your 161 Watt frige will need about 500 watts at startup. Additionally, you'd want the inverter to not be stressed during startup, so IMO you'd want one rated at least 750 watts and 5 amps.
homepark
Resist
Over the past 7 years I have gradually picked up two 3way coolers and and Engle AC/DC cooler. None of them were cheap, but I did shop carefully and found good deals on the first two. The Engle freezer/fridge only draws 45 watts AC when running.
I picked up a 45 watt solar panel kit from Harbor Freight a while back when it was on sale. If I hook the solar kit to a few car batteries, it can run the Engle with no problems at all. At the moment I run it on AC and use it as a soda fridge. I hqve also run it in the Jeep. It draws very little power.
The 3 way portable coolers, one of which can run as a freezer as well, can use propane, ac/dc. These I keep going on ac most of the time. I switch to propane during power outages. These units are gas absorption, so the electric elements do draw 120 to 160 watts each. That draw is pretty much constant.
Take your time, look around and see what fits your needs best.
I picked up a 45 watt solar panel kit from Harbor Freight a while back when it was on sale. If I hook the solar kit to a few car batteries, it can run the Engle with no problems at all. At the moment I run it on AC and use it as a soda fridge. I hqve also run it in the Jeep. It draws very little power.
The 3 way portable coolers, one of which can run as a freezer as well, can use propane, ac/dc. These I keep going on ac most of the time. I switch to propane during power outages. These units are gas absorption, so the electric elements do draw 120 to 160 watts each. That draw is pretty much constant.
Take your time, look around and see what fits your needs best.
The way I see it, Dennis, is that as long as Onebyone is paying big bucks for solar setup, maybe it wouldn't be a big deal to get a different refrigerator, something like one of Homepark's coolers that can run directly off a DC power source instead of needing an inverter.
Without an inverter being involved, maybe Onebyone could get by with less solar power.
You wont even defend your suggestions?
I know ohms & watts law, what confused me was is all your stuff about about energy star ratings like this "A fridge can use 500 for a energy efficient one to 4600 for an old outdated monster.
Most Common Fridges use 1500-2000 per day."
What electrical UNITS are you talking about when you say 1500-2000 per day?
When OnebyOne said least possible solar cost, I did make a huge assumption that she wanted to save money, granted I assumed save on her electricity bill, my bad.
As I said in my second post if this is a prep item, she could get something running off of Propane or 12V
No Dr. Prepper don't listen just to me. Just like I won't listen JUST to you. The people on this board have collectively much more experience than BOTH of us times 10. Which is why I come here, to get collective knowledge and experience of ALL.
Don't go away pissed off. I approached it from one direction (based on an incorrect assumption) you approached it from a different point of view.
If I can be frequently wrong, so can you.
D_A
night driver
ESFP adrift in INTJ sea
WELL, GUYS, shall we use specific units that work for everyone???
How about some one come up with the amount of BATTERY that you need in AMP-HOURS, to NOT draw more than half the battery down on a normal day....
Once you do THAT then you can talk about pannels and the rest....
How about some one come up with the amount of BATTERY that you need in AMP-HOURS, to NOT draw more than half the battery down on a normal day....
Once you do THAT then you can talk about pannels and the rest....
gelatinous
Eyes WIDE Open
We have been running a freezer as a frig for several years now on our solar panels. This is very efficient as freezers typically have thicker walls with better insulation. The only modification that I did was to disable the defrost timer. (this puts a 700 watt heater load on the system that isn't needed) We use an external thermostat that you can purchase at a brew store.
It runs maybe 2-3 times per hour for just a few minutes unless the door has been opened. Current consumption is about 10 amps at 12volts according to the readout on the inverter.
It runs maybe 2-3 times per hour for just a few minutes unless the door has been opened. Current consumption is about 10 amps at 12volts according to the readout on the inverter.
You would think someone would come up with a complete kit---fridge and power source in one package.
Anyway---here's a link to the Engle brand fridges that are 12 volt---and pricey. Smaller one on sale for $395.
http://www.global-merchants.com/home/freezer.htm
Anyway---here's a link to the Engle brand fridges that are 12 volt---and pricey. Smaller one on sale for $395.
http://www.global-merchants.com/home/freezer.htm
WFK
Senior Something
Some things said above are important:
1. fridge won't START if BATTERY is too small (forget what inverter can do)
As guy above casually states "a couple" of car batteries (right!)
2. sort out your Watts and Watthours, then you can talk to each other.
3. don't say 5 hours or three hours of sunlight. The issue is how many hours WITHOUT sunlight can you tolerate? THAT will determine the size of the battery.
And what do you do when the battery runs down and the fridge won't start?
All solar too expensive unless it HAS to be solar...
1. fridge won't START if BATTERY is too small (forget what inverter can do)
As guy above casually states "a couple" of car batteries (right!)
2. sort out your Watts and Watthours, then you can talk to each other.
3. don't say 5 hours or three hours of sunlight. The issue is how many hours WITHOUT sunlight can you tolerate? THAT will determine the size of the battery.
And what do you do when the battery runs down and the fridge won't start?
All solar too expensive unless it HAS to be solar...
les_stockton
Inactive
You'll need enough panels to not only run the frig during the daylight hours, but enough to adequately charge batteries so that when the sun goes down, the frig will continue to keep things cold until the next morning.
WFK
Senior Something
A few more points:
After extended no-sun condition the batteries are run down and the fridge wants power and the batteries want to be recharged.
At that point the batteries are incapable of STARTING the fridge, but the fridge is certainly trying to start... nice technical issue!
Has anyone worked that out succcessfully, really with an installation???
The way to size the thing is:
Max watthours to be supplied from batteries, multiply that number by anything larger than 2 to keep the batteries from being killed prematurely.
hours per day of available sunshine:
How quickly do you want to recharge a half discharged battery.
How do you prevent the battery from being discharged more than half?
That will give you an idea about the size of solar panels.
Take the advertised wattage and the open circuit voltage and determine the max CURRENT the panel(s) will supply. Now yoy are getting somewhat realistic.
Consider that a charge regulator will take care of the BATTERY. That means it will gradually become totally inefficient as the battery approaches full charge.
Just don't assume that the 5 hours of sunshine will be converted just because the mechanism is there. But that is your starting point: fully charged batteries,
maybe night, maybe rain for days. Think where your system can end up and what will happen then.
This is a full size energy audit for a minimum system.
Watthours demand (ride-through)
Peak Load demand (start)
Recharge mechanism (charge controller)
Efficiencies of conversion (solar panel wattage to stored battery Watthours)
(inverter itself)
I think the answer to the total solution is already known by the camper owners..
After extended no-sun condition the batteries are run down and the fridge wants power and the batteries want to be recharged.
At that point the batteries are incapable of STARTING the fridge, but the fridge is certainly trying to start... nice technical issue!
Has anyone worked that out succcessfully, really with an installation???
The way to size the thing is:
Max watthours to be supplied from batteries, multiply that number by anything larger than 2 to keep the batteries from being killed prematurely.
hours per day of available sunshine:
How quickly do you want to recharge a half discharged battery.
How do you prevent the battery from being discharged more than half?
That will give you an idea about the size of solar panels.
Take the advertised wattage and the open circuit voltage and determine the max CURRENT the panel(s) will supply. Now yoy are getting somewhat realistic.
Consider that a charge regulator will take care of the BATTERY. That means it will gradually become totally inefficient as the battery approaches full charge.
Just don't assume that the 5 hours of sunshine will be converted just because the mechanism is there. But that is your starting point: fully charged batteries,
maybe night, maybe rain for days. Think where your system can end up and what will happen then.
This is a full size energy audit for a minimum system.
Watthours demand (ride-through)
Peak Load demand (start)
Recharge mechanism (charge controller)
Efficiencies of conversion (solar panel wattage to stored battery Watthours)
(inverter itself)
I think the answer to the total solution is already known by the camper owners..
night driver
ESFP adrift in INTJ sea
Tri-fuel fridge from scrap camper with a small to medium solar set up providing TWELVE VOLT power to the tri-fuelled fridge, with the capability to go propane or other tiny flame source....would be my choice for covering back up options as well as powering the thing for the long haul....
ANd almost any of the medium to larger China freight system can handle the requirements if you stay 12 volt and don't go to inverted 110.....
But that is only my opinion....
To do otherwise than my first paragraph you AER going to need to go through the math...ALL of it. and you will STILL need to cover the backup considerations....
++++++++++++++
BTW, WFK it's nice to see you,,, Have you been hiding or have I been oblivious???
ANd almost any of the medium to larger China freight system can handle the requirements if you stay 12 volt and don't go to inverted 110.....
But that is only my opinion....
To do otherwise than my first paragraph you AER going to need to go through the math...ALL of it. and you will STILL need to cover the backup considerations....
++++++++++++++
BTW, WFK it's nice to see you,,, Have you been hiding or have I been oblivious???
LoupGarou
Ancient Fuzzball
As Dennis said, 161 watts when running. The startup wattage, which may last only a few seconds, but is important as well, may be 500-900 watts, so make sure that your inverter has at least a 1000 watt rating, unless you know the startup wattage needed. Knowing that the startup surge demand is short, we can drop it from the solar power calculations as long as the inverter has the overhead.
So, we know that we need at least 161 when on, and that comes from the 115V * 1.4A. Now, if we take that same wattage and factor it against a 12.8V system (the input of the inverter), we get 12.578125 Amps (161W / 12.8V). So, as long as we can provide at least 13 amps (let's give the inverter something to work with as inefficiency), then we know that we can keep the fridge running when it needs to run.
Now we just have to figure out how many hours a day the fridge is running, versus how many hours the fridge is off. Most of my fridges in "normal" temperature rooms run for about 15-20 minutes an hour, or a duty cycle (on vs. off time ratio) of between .25 (15 min) and .33 (20 minutes), and when the weather gets hot, .5 (30 minutes). So, out of 24 hours a day, the fridge is on between 6 and 8 hours, and as many as 12 hours in the heat.
Now that we know that, and the wattage it needs when on, we can calculate the total watthours per day that the fridge is going to draw.
.25dutycycle * 24hours * 161Watts = 966WH (WattHours a day)
.33dutycycle * 24hours * 161Watts = 1,288WH (WattHours a day)
.5dutycycle * 24hours * 161Watts = 1,932WH (WattHours a day)
We now know that the fridge is going to need between 966WH and 1,288WH, with a maximum of 1,932WH when the temperature gets high. This means that we will need a battery bank capable of supplying at least that much power in usable capacity per sunny day. So if you take the worst case figure (1932WH) and divide by 12.8V, you get around 150AH. And if you live where it never really gets "hot", then you could go with the lower figure of 1,288WH, which is about 100.6AH. That is the needed "usable" capacity.
Now, that means that if we have clouds every other day, we need to double our battery bank's capacity. PLUS, batteries are rated in TOTAL CAPACITY, now USABLE CAPACITY. If you use a battery so that it provides it's total capacity (rated AH on battery), it will be at 0% SOC (State of Charge) and will not last but a few cycles of that use. Batteries like to be discharged slightly and then recharged soon afterwards, not sucked dry and left for a few days. Standard "Wet Cell" "Deep Cycle" batteries can be discharged 20% of rated (total capacity). This means that you can safely use 20AH from a 100AH Wet Cell battery (leaving 80AH still in the battery) without really hurting it (you should get thousands of good cycles). With AGM batteries, you can discharge it up to 50%, (50%SOC), leaving 50AH left in the battery from a 100AH rated battery. What these two factors mean together is that if we have clouds every other day, AND are using Wet Cell batteries, that 100.6AH to 150AH of needed "usable" capacity, now represents (100.6AH / .2 * 2)=1,006AH to (150 / .2 * 2)=1,500AH of rated total capacity. The .2 represents 20% discharge and the 2 is to calculate the doubling of the every other cloudy day. A 1,500AH battery pack can easily be built using a string of 30 Golf Cart batteries (205AH rated "total" capacity), hooked up in 15 parallel pairs of two batteries in series each. Each battery is going to run about $70 each, so the pack is going to end up costing you about $2,100.
This also means that you will need at least 150AH(what the fridge actually needs per day) * 14.4V (Charging voltage for Wet Cells to cover overhead of charging needed) = 2,160WH per day of actual solar charging power. If you get 5 hours of good strong sun a day, then that could be provided by 2,160WH / 5hours = 432W (minimum) of panels. If you only get three hours of good strong sun, then you would need 720W of panels (minimum).
Now, if you have less cloudy days, or your fridge is less power hungry than noted, then the number of panels needed will go down. If you go either the AC with inverter route, or the DC cooler version, INSULATE the unit real well with extra insulation, since a BTU wasted is wattage wasted.
Loup
So solar alone is out for anyone with a limited income. Another possibility is to do what they did before electricity .... cut ice blocks from frozen ponds or lakes in the winter, and then pack them in sawdust in an ice house. Then one would put the ice blocks into the top of an ice chest.
Oh, you live in Georgia. Scrap that idea.
Oh, you live in Georgia. Scrap that idea.
LoupGarou
Ancient Fuzzball
Not necessarily. It all depends on how far you want to take it, and how much work you are willing to do.
For example, a good 12V peltier ("thermoelectric" ) cooler will take between 4 and 7 amps as 12.8V to get "chilled". And they usually run between 50% duty cycle and 80% duty cycle, so it works out to (12.8V * 4 * .5 * 24)=614.4WH a day, to (12.8V * 7 * .8 * 24) =1,720WH. This represents a LOT wider range than it's freon compressing counterpart.
BUT.
If we took raw peltier modules, say 12 matched units from one of the following surplus dealers:
(Surplus peltier modules)
http://www.allelectronics.com/cgi-bin/item/PJT-7/search/40MM_X_44MM_THERMOELECTRIC_COOLER_.html
http://www.alltronics.com/cgi-bin/category.cgi?item=04U005
http://www.alltronics.com/cgi-bin/item/99U009/40/2.5A-Peltier-Junction
http://www.alltronics.com/cgi-bin/item/23U202/40/Thermoelectric-Cooler,-Peltier-junction
http://www.alltronics.com/cgi-bin/item/04U004/40/Tellurex-CZ1-1.4-127-1.65-peltier-junction
And then wired them in strips of four each in series, and then connected the finished strips (all three of them) together in parallel, we would end up with a system that would take 75% of the power that a single peltier module would take (current divided by four, then multiplied by three), but would spread the cooling power over a much larger area. This would mean that the peltiers would probably stay on 100% of the time, but since the amperage is less than what one module would take, the overall power consumption would be down.
Now, take an old chest freezer that the "guts" have died in, and strip out all of the old tubing and the other parts. This should leave the back in good shape to mount the array of peltier modules on. Use thermally conductive cement to "glue" the modules (cold side towards the chest wall, and "hot" side away). This will allow the cold on the plates (where the heat is being "pumped" away from) to chill the freezer area. The "hot" side of the modules will either need to have heatsinks put on them, or better yet, a water heat exchanger (a surplus CPU water cooler unit works good). This will transfer the heat that has been extracted from the chest to somewhere else. If you use the 5 amp modules, that equates to (5A / 4_modules_in_series * 3_module_strings_in_parallel)=3.75A or 48 watts. 48W * 24 hours = 1,152, but you are back to a full size freezer, and once it gets sold enough, that figure will drop.
Yes, it would be a LOT of work. And yes, you have to be careful with the modules, but I have made a small fridge using this trick, and it worked out great. I insulated the thing with LOTS of high R-value insulation, and it takes next to nothing once down to temp.
More on the Petlier effect:
http://en.wikipedia.org/wiki/Peltier_effect#Peltier_effect
Loup
jed turtle
a brother in the Lord
thanks Loup. even i managed to grasp that. job very well done, thanks!
my guess is that the cost of the battery bank alone will sink OBO's hopes.
not all is lost yet.
there is the possibility of finding a natural gas refrigerator [eta: http://www.google.com/products?hl=en&q=natural+gas+refrigerator&um=1&ie=UTF-8 ] and either:
a commercial source of natural gas
or
make yer own methane (natural gas) from animal manures. there's certainly a lot on the internet about that, so it's not beyond one's ability to find the info and translate it into reality. and it making methane down on the homestead has been done in China and India for several decades.
my guess is that the cost of the battery bank alone will sink OBO's hopes.
not all is lost yet.
there is the possibility of finding a natural gas refrigerator [eta: http://www.google.com/products?hl=en&q=natural+gas+refrigerator&um=1&ie=UTF-8 ] and either:
a commercial source of natural gas
or
make yer own methane (natural gas) from animal manures. there's certainly a lot on the internet about that, so it's not beyond one's ability to find the info and translate it into reality. and it making methane down on the homestead has been done in China and India for several decades.
momof23goats
Deceased
homepark
Resist
Some things said above are important:
1. fridge won't START if BATTERY is too small (forget what inverter can do)
As guy above casually states "a couple" of car batteries (right!)
2. sort out your Watts and Watthours, then you can talk to each other.
3. don't say 5 hours or three hours of sunlight. The issue is how many hours WITHOUT sunlight can you tolerate? THAT will determine the size of the battery.
And what do you do when the battery runs down and the fridge won't start?
All solar too expensive unless it HAS to be solar...
Correctamundo. The Engle fridge/freezers are expensive, but so much more energy efficient, lessening the need for large extremely expensive solar arrays. Also, the Engles have a very good track record.
I think that in a SHTF scenario, flexibility is key. If you have several ways to charge your batteries, solar, intermittant ac supply, generator, etc, you are not dependent on any one of them.
Lessening your power needs seems to me, to be the prudent way to go.
night driver
ESFP adrift in INTJ sea
If you find a Nat Gas fridge it is my understanding that you can convert it to Propane by simply changing the orifice for the tiny flame....
I stand by my comments made in POST #2 of this thread.
"I suggest you check the power requirement label on the fridge and then go to a website that tells you how many panels you'll need for that power demand. (Don't forget power controller, Inverter and expensive deep cycle backup batteries.
Without doing the math, I'd say FORGET IT. My guess is that it will cost you $1000 for the solar set-up. Was that what you were expecting?
Your asking to power a relatively high power demand appliance with one of the MOST expensive and LEAST efficient methods of electrical power generation."
D_A
"I suggest you check the power requirement label on the fridge and then go to a website that tells you how many panels you'll need for that power demand. (Don't forget power controller, Inverter and expensive deep cycle backup batteries.
Without doing the math, I'd say FORGET IT. My guess is that it will cost you $1000 for the solar set-up. Was that what you were expecting?
Your asking to power a relatively high power demand appliance with one of the MOST expensive and LEAST efficient methods of electrical power generation."
D_A
Yep, that's why I prefer lowtech solutions that only need people power (or horse power).
That's just my cognitive style: to find the simplest and cheapest solution to a problem ..... others may love complexity and creativity in their solutions.
Donald Shimoda
In Absentia
If yer going with PV Panels, yer gonna have DC output from 'em.
Howdy, Folks!
So...go with a DC motor on the fridge.
This is a great article:
http://www.backwoodshome.com/articles/hackleman56.html
Form the above:
Power conversion (electric)
The standard household refrigerator in the United States is designed to operate at the 110-Volt, 60-cycle AC (alternating current) supplied by the local utility company. Obviously, if you’re not using utility electricity, the “stock” refrigerator isn’t going to work “as is” with DC (direct current, as from batteries) at lower Voltages. What do you do? You either match the system to the refrigerator, or the refrigerator to the system. Here are a variety of possibilities.
17. Modify the motor-compressor unit.
If the power source is batteries—at 12-, 24-, 32-, or 110-Volts DC—one of the best ways to match them to a refrigerator is to remove the AC motor that drives the compressor and replace it with one of the correct DC Voltage. This is a difficult undertaking if the motor and compressor are “hermetically sealed” (built as one unit - see #18 below), but older refrigerators have a motor separated from the compressor by a belt (and pulley) or a star-coupler. If this is the case, the entire assembly should be removed from behind (and underneath) the refrigerator. Next, remove the AC motor and pull the fan blade off its shaft.
Select the DC motor carefully. It must generally match the old motor’s HP (horsepower) and RPM (revolutions per minute) ratings. DC motors have conservative ratings when compared with AC motors. For this reason, you may select a DC motor which has a HP rating ¼th to 1/3rd smaller than the AC motor you pull off. Look for a HP tag on the AC motor. No luck? Find the motor’s wattage rating. Or multiply the Amp (A) rating by the voltage (Volts, or V) rating of the refrigerator. The resultant is wattage which, when divided by the value 750, will give an approximate HP rating. This value is usually less than 1 horsepower, and as long as ¼ HP. Small variations in motor RPM ratings—between the old AC motor and the new DC motor—aren’t significant. If the values are close, bolt it up. Larger variations in RPM ratings must be adjusted. Vary the ratio of pulleys in the belt-drive to achieve a match. If a star-coupler was originally used, either go to a pulley drive (and match RPM with the correct ratio of pulleys) or find a motor of correct RPM rating.
Other factors? Change the light bulb in the interior to one of the correct Voltage. Change the motor relay to its DC equivalent (see Fig. 5). Leave the old thermostat alone. It should work fine. Now’s a good time to think about sticking the motor-compressor unit, along with the HDC (see #12 above) elsewhere (outside?). You may not have a choice. The modified motor-compressor unit may not fit back into its original refrigerator space. If you’ve cut the refrigerant lines, re-connect the lines and re-charge them with new refrigerant (or have this done). Finally, insulate the refrigerator in the area once occupied by the motor-compressor unit.
Another useful article:
http://www.backwoodshome.com/articles2/yago102.html
Good luck!
[FWIW - For preps, I went with a propane powered fridge, and have large tanks to run it. Silent, and discreet - no one can see shiny PV arrays on my home, and the fridge can simply run quietly in my garage for months.]
Howdy, Folks!
So...go with a DC motor on the fridge.
This is a great article:
http://www.backwoodshome.com/articles/hackleman56.html
Form the above:
Power conversion (electric)
The standard household refrigerator in the United States is designed to operate at the 110-Volt, 60-cycle AC (alternating current) supplied by the local utility company. Obviously, if you’re not using utility electricity, the “stock” refrigerator isn’t going to work “as is” with DC (direct current, as from batteries) at lower Voltages. What do you do? You either match the system to the refrigerator, or the refrigerator to the system. Here are a variety of possibilities.
17. Modify the motor-compressor unit.
If the power source is batteries—at 12-, 24-, 32-, or 110-Volts DC—one of the best ways to match them to a refrigerator is to remove the AC motor that drives the compressor and replace it with one of the correct DC Voltage. This is a difficult undertaking if the motor and compressor are “hermetically sealed” (built as one unit - see #18 below), but older refrigerators have a motor separated from the compressor by a belt (and pulley) or a star-coupler. If this is the case, the entire assembly should be removed from behind (and underneath) the refrigerator. Next, remove the AC motor and pull the fan blade off its shaft.
Select the DC motor carefully. It must generally match the old motor’s HP (horsepower) and RPM (revolutions per minute) ratings. DC motors have conservative ratings when compared with AC motors. For this reason, you may select a DC motor which has a HP rating ¼th to 1/3rd smaller than the AC motor you pull off. Look for a HP tag on the AC motor. No luck? Find the motor’s wattage rating. Or multiply the Amp (A) rating by the voltage (Volts, or V) rating of the refrigerator. The resultant is wattage which, when divided by the value 750, will give an approximate HP rating. This value is usually less than 1 horsepower, and as long as ¼ HP. Small variations in motor RPM ratings—between the old AC motor and the new DC motor—aren’t significant. If the values are close, bolt it up. Larger variations in RPM ratings must be adjusted. Vary the ratio of pulleys in the belt-drive to achieve a match. If a star-coupler was originally used, either go to a pulley drive (and match RPM with the correct ratio of pulleys) or find a motor of correct RPM rating.
Other factors? Change the light bulb in the interior to one of the correct Voltage. Change the motor relay to its DC equivalent (see Fig. 5). Leave the old thermostat alone. It should work fine. Now’s a good time to think about sticking the motor-compressor unit, along with the HDC (see #12 above) elsewhere (outside?). You may not have a choice. The modified motor-compressor unit may not fit back into its original refrigerator space. If you’ve cut the refrigerant lines, re-connect the lines and re-charge them with new refrigerant (or have this done). Finally, insulate the refrigerator in the area once occupied by the motor-compressor unit.
Another useful article:
http://www.backwoodshome.com/articles2/yago102.html
Good luck!
[FWIW - For preps, I went with a propane powered fridge, and have large tanks to run it. Silent, and discreet - no one can see shiny PV arrays on my home, and the fridge can simply run quietly in my garage for months.]
Thanks Loup on the t.e.coolers:
some other thread resources:
http://www.timebomb2000.com/vb/showthread.php?t=73657
http://www.timebomb2000.com/vb/showthread.php?t=213224
http://www.timebomb2000.com/vb/showthread.php?t=186450
some other thread resources:
http://www.timebomb2000.com/vb/showthread.php?t=73657
http://www.timebomb2000.com/vb/showthread.php?t=213224
http://www.timebomb2000.com/vb/showthread.php?t=186450
jed turtle
a brother in the Lord
saw this at sun electronics:
SOLAR POWERED FREEZER SYSTEM 8.1 cu FT. Works great in hot areas (up to 110 degrees) with 1 Panel!
This system comes with 1 Solar World 155 Watt Module ($635 at $4.10/watt) and the Sun Danzer DCF225 Freezer($898).
You will also need a charge regulator($55 each), two small 12 volt batteries($50 each) and 30 to 50 foot AWG #10 2c Wire.($10) the total of this package FOB Miami only comes to $1,737!.
Think about it. A large 8.1 cu ft Freezer that works anywhere even in 110 degree heat with only one solar panel. It will work 24 hours a day 365 days a year for over 25 years! At that time you will have a PV panel that will last another 15 to 25 years!
You will get a free thermostat that is simple to install and to change from freezer mode to refrigerator mode. When running in refridgerator mode you only use half the solar power produced from the panel, only 75 watts! You can use the rest of the power to power your lights, radio, or cd player as well in that case! Take advantage of this great energy efficient system. Anywhere in the world for frozen food, ice, on islands, in cabins, for fun, emergency or remote natural living!
http://www.sunelec.com/
SOLAR POWERED FREEZER SYSTEM 8.1 cu FT. Works great in hot areas (up to 110 degrees) with 1 Panel!
This system comes with 1 Solar World 155 Watt Module ($635 at $4.10/watt) and the Sun Danzer DCF225 Freezer($898).
You will also need a charge regulator($55 each), two small 12 volt batteries($50 each) and 30 to 50 foot AWG #10 2c Wire.($10) the total of this package FOB Miami only comes to $1,737!.
Think about it. A large 8.1 cu ft Freezer that works anywhere even in 110 degree heat with only one solar panel. It will work 24 hours a day 365 days a year for over 25 years! At that time you will have a PV panel that will last another 15 to 25 years!
You will get a free thermostat that is simple to install and to change from freezer mode to refrigerator mode. When running in refridgerator mode you only use half the solar power produced from the panel, only 75 watts! You can use the rest of the power to power your lights, radio, or cd player as well in that case! Take advantage of this great energy efficient system. Anywhere in the world for frozen food, ice, on islands, in cabins, for fun, emergency or remote natural living!
http://www.sunelec.com/