[ARCHIVED THREAD] - BOL Chest Freezer Conversion, Solar Panels, Evaluation WORKING GREAT! (Page 1 of 3)
Posted: 6/4/2010 10:14:41 AM EDT
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Chest Freezer, Solar Panels, Evaluation
Last week I picked up a GE chest freezer, measures 35" wide by 21" by, well it's pretty deep. Cost was ~$200 at Sams. Powering it with 2 Sharp 224 watt solar panels, Outback MPPT controller, large battery bank, and a new Xantrex ProSine 1800 inverter I installed right before hooking up the freezer. Monitoring is being done with a Kill-A-Watt meter [incredible devices for $20] an indoor/outdoor digital thermometer and a Harb Frt infrared thermometer [great accuracy and cheap at around $10]. Starting from warm with one bottle of Gator Aid in it the freezer, it has logged 40 hours and 1.1 KW used on the KAW meter. That's about 27 watts per hour power consumption. Temperature dropped to about -5F or better and Gator Aid was frozen like a rock. Remember, freezing stuff takes a lot of energy and if I had the chest filled up, energy consumption until the material was frozen would have been much greater. Laws of physics and the important property of water freezing is that it takes a LOT OF HEAT REMOVAL to get it to change state from liquid to solid. Of course it absorbs the same when it changes back to liquid. Our mission is to use the freezer at a much warmer setting than it was designed for to reduce energy consumption and so that it holds our stuff at about 35F. That will reduce HOLDING TEMP energy reqmts to about half or less I'm guessing. And avoid "change of state" losses. No use freezing stuff and then loosing all that energy it took while thawing it out. Other folks may want to use the freezer as it was intended -as a freezer for long term storage, -we don't. Right now. I may have to change the thermostat to make the freezer operate at these higher temps. The solar panels in Summer can produce about 2700 watts during an average 6 hours of sun. Less sun, cooler days, less load from the freezer. So far I'm pretty happy. |
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Thanks Way, I didn't include inverter and other inefficiences in my numbers above so factor in 20% overall losses and that should be very safe.
Also, a simple control. to turn the freezer off during most of the night so as not to run down batteries might have some use. I'm thinking about whipping up a microcontroller to do that if I ever have to use smaller batteries. |
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What did the SP set up end up costing you with the batt. Panels were about $550 each, Outbacks are abt $500, Xantrex are all over the place and Samlex inverters are cheaper. My batts were bought used and were about $100 each for ~600 amp 2 volt cells. Actually, with very careful mgmt of the freezer time of running, and light use of it, I think golf cart bats would work. I.e. run it during the day full blast off the panels alone with the golf cart bats being a short term buffer. |
Hi EXPY37, another solution for using a chest freezer as a fridge would be to get an external bulb type electronic controller. 
Buddy of mine built a kegerator out of a chest freezer, 2x10's, extra insullation, caulk, a computer fan and a Johnson controller http://garagebrewers.com/forum/viewtopic.php?t=808 He used a control unit similar to this http://www.climatedoctors.com/items/item.aspx?itemid=827548 $54. 
He also had some problems with temperature stratification and the solution was put a computer fan in the chest that would run when the compressor was on. 
The Johnson A419ABC-1C is a 120/240V single stage temperature control. Sensor with 6.5' wire is included. Features: * Wide Setpoint range: -30 to 212° F (-34 to 100° C) * Adjustable differential from 1 to 30° F (1 to 30° C) * Adjustable anti-short cycle delay from 0 to 12 Minutes. * Switch-Activated temperature offset function that allows the users to shift the setpoint based on an external switch such as a time clock. * User selectable sensor failure mode. Allows the user to determine how the controller will operate when the sensor or sensor wire fails. * Operates in either heating or cooling mode. * Remote sensor. The sensor can be located up to 500 feet from the control so long as a large enough wire gate is used. * Easily replaceable sensor. No cutting of wires or soldering is required. Specifications: * Setpoint Range: -30 to 212° F (-34 to 100° C) * Differential Range: 1 to 30° F (1 to 30° C) * Supply Voltage: 120VAC or 240VAC * Power consumption: 1.8VA maximum * Control Ambient Temperatures o Operation: -26 to 140°F (-32 to 60°C) o Shipping: -40 to 185°F (-40 to 85°C) * Ambient humidity: 0 to 95% RH Non-condensing; Maximum Dew Point 85°F (29&C) Relay Output Ratings - NO (NC) 120VAC 208VAC 240VAC Horsepower 1 (0.25) hp 1 (0.33) hp 1 (0.5) hp Full Load Amperes 16 (5.8) A 9.2 (4.0) A 8.0 (4.9) A Locked Rotor Amperes 96 (34.8) A 55.2 (24) A 48 (29.4) A Non-inductive Amperes 15 (10) A 10 (10) A 10 (10) A |
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thanks for the documentation, I ran a chest freezer on solar power for a few years but did not document it.
as far a temp control you could use a small diode ( heat shrunk on to a small wire and draped between the lid and chest) as the sensor and an opamp for the control and feed that to a solid state relay. just put a few mv of hysteresis in the opamp. or if you want to get fancy use a 1wire temp sensor and a pic, that way you can program no run times (like at night, or when batteries are low) and even add a high temp alarm. If you are using a modified sine wave inverter you can use the peak ac voltage to get a good indication of battery state of charge. MSI's just pump up the voltage 11 or 12 times and then use a xsistor bridge to change polarity, so at full charge it may read 150V and low it may read 130V peak. |
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thanks for the documentation, I ran a chest freezer on solar power for a few years but did not document it. as far a temp control you could use a small diode ( heat shrunk on to a small wire and draped between the lid and chest) as the sensor and an opamp for the control and feed that to a solid state relay. just put a few mv of hysteresis in the opamp. or if you want to get fancy use a 1wire temp sensor and a pic, that way you can program no run times (like at night, or when batteries are low) and even add a high temp alarm. If you are using a modified sine wave inverter you can use the peak ac voltage to get a good indication of battery state of charge. MSI's just pump up the voltage 11 or 12 times and then use a xsistor bridge to change polarity, so at full charge it may read 150V and low it may read 130V peak. That's interesting Em... |
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state change is energy neutral, you get back what you put in, if you want to reduce night time consumption and associated battery looses it
may be better to run the fridge when the sun shines and let it coast over night, the problem is finding a liquid that changes state at 35 degrees, some oils may fit that role but the only hav a 30 x heat of fusion (water is 100 x), there are many things that will lower waters freezing point but none that raise it. but even putting 20 gallons of water in the bottom will make a big flywheel. |
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I bought a thing on amazon for running a chest freezer as a refrigerator. I think mine came from johnson controls and it is from the beer keg section. Currently using it that way but I don't have a kill a watt meter. It just has a temp probe you stick in the freezer and it turns the power on and off to the freezer by how you set the temp. I got a little holiday chest freezer from lowes for about 150 with a 20 dollar rebate, after taxes I will have around 140 to 150 in it I guess but I did not worry much about specific numbers. I think mine is a 5.5 cubic foot internal size. In talking to some folks who do hvac stuff they mentioned that running a freezer as a chest fridge could cause some issues over time since it is not really running as designed with this item from amazon just cutting power to the freezer when the desired temp is reached. I don't pretend to really understand it all and just wanted something other than the normal fridge/freezer everyone has in their kitchen. I have found that with monitoring the temps it is probably best to stick a small fan in it as already mentioned, I have not done so yet but will probably do so because using it in this fashion is causing various temps in the freezer. I think with the fan it would help the chest fridge to be more consistant and steady on temp swings between shutoff and startup. I will be needing to get a kill a watt meter to see how this affects my electric bill because I just installed window ac units 2 days ago and those are going to jack up my electric bill from a new low of 32 bucks for 31 days to who knows what. |
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I have found that with monitoring the temps it is probably best to stick a small fan in it as already mentioned, I have not done so yet but will probably do so because using it in this fashion is causing various temps in the freezer.
I think with the fan it would help the chest fridge to be more consistant and steady on temp swings between shutoff and startup. Exactly. A fan is not to needed run full time, it'd be counterproductive just recirculating warming air. Only needed when the compressor is working and you are moving cool air. My beer mentor got the temperature differential to within a couple degrees between top and bottom, where it had been nearly 20. He's just running the fan when the compressor is running.  This is not a kegerator hijack, just one experience using a chest freezer for normal temps.
One other challenge is condensate. Water *will* collect. If the chest you have has a drain. make a trap sealed with silicone caulk or whatever needed to run the condensate to a drain. You may need to set the chest up on bricks to get this clearance. Old chest freezers usually don't have this feature, but the coils run around the walls, not the floor, so a crafty person could make a drain through the floor and seal it. This could be 1/2 inch vinyl tube or most anything in a "U" shaped trap to keep a water trap sealed. Else you get to sponge this water out. 
Don't just run a hose straight out the bottom of the drain or all the cold air will also flow out. Bread trays cut to fit will keep the bottom inch out of any water. My electrical usage is similar to the original post. I have a 15 cubic foot chest freezer that averages about 45 watts an hour holding food at -15. Get a Kill-A-Watt meter ! Good twenty dollar investment. |
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ok so im new with making your own energy but this sounds like something we've been wanting to attempt...if i'm reading the OP correctly, you're creating more energy than you're using right? if yes then what are you doing with the excess energy?
a noob thanks you keeblerelf |
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ok so im new with making your own energy but this sounds like something we've been wanting to attempt...if i'm reading the OP correctly, you're creating more energy than you're using right? if yes then what are you doing with the excess energy? a noob thanks you keeblerelf Good observation Keebler! On a sunny summer day 2 224 watt panels can generate about 6 or 7 times 450 watts, so about 2700 watt hours per day. That's best case.. The freezer only consumes about 35 watts per hr times 24 so that's about 1000 watts per day. Winter time, generation and consumption roles reverse. What am I doing with the extra capacity, really nothing. But it's nice to have if I want to do something with it. Oh, once in a while I'll charge up the manlift since I installed the Xantrex sinewave inverters, but usually the extra energy is a missed opportunity. Normally I don't like to waste opportunites but this doesn't bother me. |
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Chest Freezer, Solar Panels, Evaluation Last week I picked up a GE chest freezer, measures 35" wide by 21" by, well it's pretty deep. Cost was ~$200 at Sams. Powering it with 2 Sharp 224 watt solar panels, Outback MPPT controller, large battery bank, and a new Xantrex ProSine 1800 inverter I installed right before hooking up the freezer. Monitoring is being done with a Kill-A-Watt meter [incredible devices for $20] an indoor/outdoor digital thermometer and a Harb Frt infrared thermometer [great accuracy and cheap at around $10]. Starting from warm with one bottle of Gator Aid in it the freezer, it has logged 40 hours and 1.1 KW used on the KAW meter. That's about 27 watts per hour power consumption. Temperature dropped to about -5F or better and Gator Aid was frozen like a rock. Remember, freezing stuff takes a lot of energy and if I had the chest filled up, energy consumption until the material was frozen would have been much greater. Laws of physics and the important property of water freezing is that it takes a LOT OF HEAT REMOVAL to get it to change state from liquid to solid. Of course it absorbs the same when it changes back to liquid. Our mission is to use the freezer at a much warmer setting than it was designed for to reduce energy consumption and so that it holds our stuff at about 35F. That will reduce HOLDING TEMP energy reqmts to about half or less I'm guessing. And avoid "change of state" losses. No use freezing stuff and then loosing all that energy it took while thawing it out. Other folks may want to use the freezer as it was intended -as a freezer for long term storage, -we don't. Right now. I may have to change the thermostat to make the freezer operate at these higher temps. The solar panels in Summer can produce about 2700 watts during an average 6 hours of sun. Less sun, cooler days, less load from the freezer. So far I'm pretty happy. Just out of curiosity, how much money do you have tied up in the solar equipment (panels, controller, and inverter). |
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Chest Freezer, Solar Panels, Evaluation Last week I picked up a GE chest freezer, measures 35" wide by 21" by, well it's pretty deep. Cost was ~$200 at Sams. Powering it with 2 Sharp 224 watt solar panels, Outback MPPT controller, large battery bank, and a new Xantrex ProSine 1800 inverter I installed right before hooking up the freezer. Monitoring is being done with a Kill-A-Watt meter [incredible devices for $20] an indoor/outdoor digital thermometer and a Harb Frt infrared thermometer [great accuracy and cheap at around $10]. Starting from warm with one bottle of Gator Aid in it the freezer, it has logged 40 hours and 1.1 KW used on the KAW meter. That's about 27 watts per hour power consumption. Temperature dropped to about -5F or better and Gator Aid was frozen like a rock. Remember, freezing stuff takes a lot of energy and if I had the chest filled up, energy consumption until the material was frozen would have been much greater. Laws of physics and the important property of water freezing is that it takes a LOT OF HEAT REMOVAL to get it to change state from liquid to solid. Of course it absorbs the same when it changes back to liquid. Our mission is to use the freezer at a much warmer setting than it was designed for to reduce energy consumption and so that it holds our stuff at about 35F. That will reduce HOLDING TEMP energy reqmts to about half or less I'm guessing. And avoid "change of state" losses. No use freezing stuff and then loosing all that energy it took while thawing it out. Other folks may want to use the freezer as it was intended -as a freezer for long term storage, -we don't. Right now. I may have to change the thermostat to make the freezer operate at these higher temps. The solar panels in Summer can produce about 2700 watts during an average 6 hours of sun. Less sun, cooler days, less load from the freezer. So far I'm pretty happy. Just out of curiosity, how much money do you have tied up in the solar equipment (panels, controller, and inverter). Sharp 224 watt panels were ~$550 last year, Outbacks are about $550, batteries were used and about $100 per 2 volt cell for pretty big ones, Xantrex sinewave inverters were about $600 on ebay, but are all over price wise but Samlex inverters might be a better deal. |
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Yesterday I set the freezer thermostat to the warmest temperature. This evening it was +5F in the chest and in 31.6 hours the freezer used 760 watts. That's 24 watts average per hour. Not bad at all. you know once you fill it up it will actually be more efficient. the more mass in it the less it will actually run. |
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Yesterday I set the freezer thermostat to the warmest temperature. This evening it was +5F in the chest and in 31.6 hours the freezer used 760 watts. That's 24 watts average per hour. Not bad at all. you know once you fill it up it will actually be more efficient. the more mass in it the less it will actually run. I've heard that many times. Would you explain why this is so? |
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Chest Freezer, Solar Panels, Evaluation Last week I picked up a GE chest freezer, measures 35" wide by 21" by, well it's pretty deep. Cost was ~$200 at Sams. Powering it with 2 Sharp 224 watt solar panels, Outback MPPT controller, large battery bank, and a new Xantrex ProSine 1800 inverter I installed right before hooking up the freezer. Monitoring is being done with a Kill-A-Watt meter [incredible devices for $20] an indoor/outdoor digital thermometer and a Harb Frt infrared thermometer [great accuracy and cheap at around $10]. Starting from warm with one bottle of Gator Aid in it the freezer, it has logged 40 hours and 1.1 KW used on the KAW meter. That's about 27 watts per hour power consumption. Actually that would be 27.5 watt-hours per hour. It always bugs me when people get the units wrong. Temperature dropped to about -5F or better and Gator Aid was frozen like a rock. Remember, freezing stuff takes a lot of energy and if I had the chest filled up, energy consumption until the material was frozen would have been much greater. Laws of physics and the important property of water freezing is that it takes a LOT OF HEAT REMOVAL to get it to change state from liquid to solid. Of course it absorbs the same when it changes back to liquid. You must remove 144 BTUs of heat per pound to get water to change from liquid to solid. Gaterade is probably not much different than water. 144 BTUs is about 42.3 watt-hours. Our mission is to use the freezer at a much warmer setting than it was designed for to reduce energy consumption and so that it holds our stuff at about 35F. That will reduce HOLDING TEMP energy reqmts to about half or less I'm guessing. And avoid "change of state" losses. No use freezing stuff and then loosing all that energy it took while thawing it out. Other folks may want to use the freezer as it was intended -as a freezer for long term storage, -we don't. Right now. I may have to change the thermostat to make the freezer operate at these higher temps. So basically you want to convert a freezer into a frdige? Why not just buy a fridge in the first place? The solar panels in Summer can produce about 2700 watts during an average 6 hours of sun. Less sun, cooler days, less load from the freezer. perhaps 2700 watt-hours. :) So far I'm pretty happy. |
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"So basically you want to convert a freezer into a frdige? Why not just buy a fridge in the first place? "
I don't know what a " frdige" is but you are right, we didn't want to buy a fridge in the first place. We want to use a chest freezer as a frig because we don't want to loose the coldz when we open the doorz. And this is cheaper and will do what we want it to do. In fact, it's doing what my SO want's it to do right now! And it's only drawing 24 watts.
[Gotta go work on a trail to the cliff...] |
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Yesterday I set the freezer thermostat to the warmest temperature. This evening it was +5F in the chest and in 31.6 hours the freezer used 760 watts. That's 24 watts average per hour. Not bad at all. you know once you fill it up it will actually be more efficient. the more mass in it the less it will actually run. I've heard that many times. Would you explain why this is so? more thermal mass means it keeps cool/cold longer. its just like the difference in using ice cubes vs a block of ice. take a 5lb bag of cube ice and take a 5lb block of ice and see which last longer. the more mass you have in the freezer the longer it stays cold which results in the freezer running less often which in turn means less power used. make sense? |
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Yesterday I set the freezer thermostat to the warmest temperature. This evening it was +5F in the chest and in 31.6 hours the freezer used 760 watts. That's 24 watts average per hour. Not bad at all. you know once you fill it up it will actually be more efficient. the more mass in it the less it will actually run. I've heard that many times. Would you explain why this is so? more thermal mass means it keeps cool/cold longer. its just like the difference in using ice cubes vs a block of ice. take a 5lb bag of cube ice and take a 5lb block of ice and see which last longer. the more mass you have in the freezer the longer it stays cold which results in the freezer running less often which in turn means less power used. make sense? Mylt, I hear what you're saying. Consider for a moment the closed system [for entropy] that the freezer is. No matter what thermal mass it encloses, the heat transfer through the system containment is for all practical purposes constant,at given inside and outside temps. So if the freezer were filled with water and allowed to stablize at a set temperature [ and that would take a LONG time to extract the heat from the mass], vs the same empty frig allowed to stablize at the same temp, thereafter the energy requirements, at least to my mind, appear to be equal to maintain said temp. Now I agree that if power is lost, a large thermal mass in the frig would keep the inside cold a very long time and is a very good strategy. |
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Great review.
Have you considered this: http://www.roadtrucker.com/engel/medium-large-43-quart-engel-12-volt-acdc-fridge-freezer.htm 
Straight 12 volt application. You could by-pass the inverter and simply recharge the bats as needed. ETA: I believe this is the one Paul (Site Staff) uses and he likes it. |
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Great review. Have you considered this: http://www.roadtrucker.com/engel/medium-large-43-quart-engel-12-volt-acdc-fridge-freezer.htm http://img41.imageshack.us/img41/2553/engel12voltacdcfridgefr.jpg Straight 12 volt application. You could by-pass the inverter and simply recharge the bats as needed. ETA: I believe this is the one Paul (Site Staff) uses and he likes it. Taft, that is a very nice cooler and I think several members here have one. Yes, I considered it. For our application, it is too small says my SO. It is also expensive. The chest freezer is appearing to be just the ticket for our application. Sam's had 2 sizes of chest freezer and we went with the larger one. We will have the new Johnson Controls thermostat soon to hold the temp above 32F and the energy consumption will likely be cut close to in half. Today, the hourly watts usage is 25 and it has been warmer. |
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One thing I noticed about the GE freezer is the condensing coils are inside the sheet metal cover and right next to the insulation that isolates the cooling area. The whole right side and back of the case gets warm.
I plan on looking at what mods might be done to relocate the condenser coils to separate them from the insulation. Possibly cutting them out of the freon circuit and substituting external coils from a small window AC or something. |
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If you have an external condenser you should be able to loosen and maneuver it to let you slip 1" or more of isocyanate insulation between it and the box,
you loose effectiveness quickly with more than 2" of insulation but pencil it out for the best compromise for the remaining surfaces. I rebuilt an old norcold unit with a custom inverter for the swing motor and got it to >120 wh/day, it had 3" Styrofoam added to the exterior and other voids filled with spray foam, also several seals for the door, it was only 1.4cu' though. |
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Reset the Kill A Watt the other day. Latest data:
2100 watts used, in 91.5 hrs. So, ~23.9 watts/hr. Chest temp 5F, ambient temp ave ~75F. Will have a Jornson Control thermostat installed in a couple of days and will raise the temp to ~33F to see power consumption. |
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.1 kilowatt frige
i've been reading this over and over. he seems to have a lot of luck. can't wait to do it myself. |
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That last article is what made me buy the johnson's thermostat control and a 5.5 cubic foot chest freezer lowes had with a 20 dollar rebate. Have less than 200 bucks in everything. My control for the thermostate is just a metal dial, no digital anything and when I get around to ordering a kill a watt meter I do plan to check it by itself to see if it uses any power while off. I don't believe it does but I have not measured it myself. I ran the temp probe through the top, just ran it in on the back side but plan to put the freezer up on a pedastal and run the probe through the factory drain hole when I get around to it. The computer fan will help keep temps constant and I think I can rig it up off the plug for the freezer so when the freezer runs the computer fan gets power and when the thermostat cuts power to the freezer the fan also cuts off. You will have condensation to deal with in this setup, a normal fridge has a drip pan but these chest freezers don't have anywhere for the moisture to go without you doing something. So far it is not an issue, putting something like a case of yogurt packs still in cardboard in the bottom of the fridge will let the cardboard absorb whatever water, it is not much, and then the cardboard gets tossed out when I open it up to get out my yogurt. Some people put a towel in the bottom of the thing. Since my freezer has a drain plug I plan to rig up a gooseneck drain and insert the thermostat probe through that as well and I should be done with water issues for the most part, will still get some condensation if you bought a lot of stuff at the grovery or whatever. My freezer came with one basket but I could see making or buying another basket. I keep commonly used stuff in the basket so I can just remove the basket and have what I want for a sammich in the basket and I don't need to get meat and cheese and mustard and onions and other stuff seperately. I might also just get some stacking plastic baskets for the bottom of this thing to some extent. I have never had a good method for using large coolers while camping and this chest fridge is making me think about better ways to do what I want to do. Best thing I did was go without a fridge for a month so I could figure out what I really wanted in the fridge and what was just taking up space and not really needed. The cooling coils for my freezer are in the front of the freezer so the front gets warm while it is running, the brand is holiday if it matters. The compressor and stuff is on the right hand side as you look at the front of the freezer and I left it plenty of space for lots of airflow all around the freezer. I think mine runs a lot more than what that article talks about but it does not run nearly as much as the old fridge my landlord left me, that thing had a problem because it was running 30 or 40 bucks on the electric bill and normally a kitchen fridge will run about 20 bucks a month in my experience. But that is with my use and your methods may vary. I consider the computer fan or other fan a requirement. I moniter temps using one of those indoor/outdoor thermometer setups and put the extra temp sensor in the fridge by the thermostat. I consider this a requirement to at least make sure the setup is working ok. I plan to leave it in place since it will show any problems quicker than I might notice without it in there. I wanted a drain in the freezer in case I wanted to really clean the thing out. I also wanted a small chest freezer to start with so I could see what I thought. If I did not like how it worked I was going to use it with a 15 cubic foot freezer for getting a half a cow, talking to others a half a cow might fit in a 15 cubic foot freezer and it might need a bit more space so having a small extra freezer seemed like the solution for that as well as when the 15 cubic foot model got close to empty it could be emptied and fill up the little freezer. A lot of folks won't like going this route if they are set on having the doors of the fridge hold stuff and having drawers and all sorts of stuff normal kitchen fridges have these days. I rather like it since I don't keep a lot of stuff in the fridge and figuring out how to organize it is getting me ready for having a larger freezer. I will be getting a kill a watt meter when I get my next check, it is on the list of amazon toys to order. My last electric bill was only a few dollars more than the previous one with 2 days less on the last bill so I am happy with it not using a ton of energy but I don't know exactly what it is using for energy a month. |
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Got the Johnson Control thermostat and wired it up Took a 3 wire light gauge extension cord, cut the center out so I had M and F ends about 20" long and stripped the ends and connected to the control.
Had to extend the sensor probe about 3 feet so I could neatly route the wiring around the back of the frig. Used something I had around, 18 ga, most any nice looking wire will work, even an extension cord. I soldered the splice, but grey wire nuts would work fine w/out the need to solder. I drilled a hole from the inside of the cooling compartment to the outside about an inch and a half from the bottom. Be careful where you drill anywhere on the cabinet so as not to hit a freon line. Also put plastic cable clamps with sheet metal screws a few places on the outside of the cabinet to make the wire routing neat to the stat. I mtd'd the stat on the right side near the front and installed 2 small sheet metal screws into drilled holes to hold it. The holes were about 1 1/2" from the top ledge to avoid hitting a freon line. After a few hours when I last checked, the power consumption was only about 10 watts/hour. That is very good IMO and I'm monitoring the temp remotely and wirelessly via an IP cam [from 100 yds away at the moment] and last I looked it was 34F. Now my SO wants another freezer so she has one for a frig and one for a freezer. Combined power req'ments look like abt 35 watts/hour, or 840 watts per day excluding inefficiencies. Let's say worst case 1000 watts per day, so that takes the power of the panels for about 2 1/2 hours per day. |
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Bierre, today before I added the thermostat, the freezer had been running since last week without being checked.
It was holding at 5F. The Kilowatt Meter showed 321 hours [~13 days] and 6500 watts used in that period. That's only 20 watts per hour and at 10 cents/KW [for examp] only 65 cents for the period. The only external insulation I can see to easily add is on the top cover because the condenser coils depend on the outer surface of the freezer to radiate heat away. WalMart has wireless temperature monitors for about $8 in the garden dept. I put one infront of the IP cam that is monitoring other temps and stuff and can watch it [as soon as I get the new D-link router hooked up] anywhere in the world. The transmitter goes in the freezer. Very cool. |
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Yesterday I set the freezer thermostat to the warmest temperature. This evening it was +5F in the chest and in 31.6 hours the freezer used 760 watts. That's 24 watts average per hour. Not bad at all. you know once you fill it up it will actually be more efficient. the more mass in it the less it will actually run. I've heard that many times. Would you explain why this is so? If it is full of frozen stuff, then it will take much longer for the temperature inside to rise enough to trip the thermostat than it would if it were empty. The thermal mass of frozen stuff is much greater than the thermal mass of empty freezer space. Think of it as "resistance to temperature change". Of course, it will take a while (and energy) to freeze a chest freezer full of stuff in the first place, but once frozen, it will actually help maintain that temperature. We keep bottles of water in our refrigerator/freezer in the garage when we don't have other stuff filling it up, for two reasons: 1) to help maintain the temperature, and 2) a supply of chilled bottled water is always good.
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Also, an interesting feature of the Johnson control recommended here is a 'setback' function.
There is a contact that when pulled to ground via a switch, relay, timer, whatever, will cause the control to revert to a secondary setpoint temperature. So, if you had a lot of mass in the frig, and a too small battery bank, you could command the control to only run the frig when the solar panels were generating, during the daytime. |
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We added a chest freezer onto the other panel/battery bank about a week ago.
In the past 170 hrs, the chest FREEZER has used 6000 watt-hrs, or 35.3 watts/hr. It's been set at -5F and the temperature outdoors has been hot in the daytime and cool in the evening, mostly. Don't know abt the chest frig because the KillOWatt meter has been tied up on the freezer. Chest Frig is set at nominal 35F. |
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This is all very cool ! I am glad my beer brewing buddy experience has pioneered the way. I saw what he had done ( actually helped him tweak the design with the cooling fan ) and it has worked out great for him. The Johnson controller is what makes it all work without having to modify anything else. That is a slick little unit for fifty bucks.
The time delay feature is gold, in my opinion, aught to built into *every* compressor driven appliance. It's a sickening sound when the lights flicker and you hear 2 refrigerators, AC and freezer all straining against locked rotor amps until the cheesey thermal overload kicks out. Meantime the windings have had a couple thousand watts of heat being dumped into them as the motor strains. |
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Pretty cool - bit on the spendy side if you bought all the PV stuff retail. About the same as a Sundanzer DCR225 setup tho - $1300 + $100 charge controller + $600 PV. I'd prefer a specialized PV Fridge, SD is well engineered and a good rep for longevity/reliability. I wonder about the durabilty of a $200 GE compared, but its was local, the GE is a cheaper failure point and it offers ya more versatility to power other AC items. Surprised at your energy consumption - you been tracking your actual ambient temps at the chests location? |
 Closer to the efficiency to SD's expensive, purpose built, heavily insulated design than I'd expected, especially with the inverter - but you're only measuring net usage on the 120V side - not gross requirements, correct - figuring a 20% loss? GE units still better than I thought, or ambient [interior] temps are lower than I could make out from above. Assume you're seeing a similar gradient in line with temps? Lot of variables tho - regardless interesting setup. |
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Yes. Is true. I have a 15 cubic foot "Energy Star" chest unit I keep at -10. It averages about 35watts an hour. By comparison, a ten year old Kenmore averaged about 80watts an hour. So better insullation in the walls effectively cut my energy use in half.
As measured over a couple days with a Kill-A-Watt meter. |
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Quoted: 27 watts to run a chest freezer? Are you sure of this? I guess I haven't owned a freezer in years, I'm used to huge energy bills from them. Can anyone that has one confirm energy usage? Obviously lot has to do with ambient temps - constant 65F in a A/C basement vs 90F avg in a uninsulated garage/cabin/clinic has a significant difference. Efficiency is good on even low end models anymore and getting better all the time. |