ac refrigerator on inverter

want to use a conventional refrigerator with my 3000 watt inverter..is there any units out there that are efficient enough to run on a small solar system? Dont want to use propane ! Recently purchased a new magic chef 10 cu.ft. fridge 1.96 amps ..but after 3 months of use it quit working ...its under warranty but i noticed that the manual says "this unit is not designed to run on an inverter".. Any suggestions !!

Comments

  • WindsunWindsun Solar Shogun Posts: 1,164Solar Expert admin
    Re: ac refrigerator on inverter
    ....but i noticed that the manual says "this unit is not designed to run on an inverter".. Any suggestions !!

    What that really means is that they are not designed to run on a modified sine wave inverter.

    We use standard off the shelf Energy Star rated refrigerators etc all the time in our off grid installations, but we also only use sine wave inverters, such as Outback, Magnum, or Xantrex.
  • BB.BB. Just some guy Posts: 24,223Super Moderators admin
    Re: ac refrigerator on inverter

    Link to True Sine Wave Inverters (yea, WindSun's online store ;) ) and a couple Inverter FAQ's where you can read about TSW and Modified Square Wave Inverters.

    -Bill

    PS: TSW inverters (which are, overall, more efficient) are much more expen$ive than MSW inverters--So, one option is to get a smaller TSW inverter for sensitive loads, and a large (and cheap) MSW inverter for running power tools and a well pump.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: ac refrigerator on inverter

    I ran a standard 16 Cu. Ft. Frigidaire off 3kW MSW inverter for years - no problem, except it made 'clattering' noise when starting: the motor had a hard time getting up to speed. Because of this and other motor needs, I replaced the MSW with a True Sine Wave and now everything runs better. I suspect your 'frige's motor burnt out from the extra effort of trying to run off what it saw as 'low voltage'.
    The MSW are really only good for light bulbs. I agree with BB about getting a small one just for the 'frige as a viable solution: mine only draws 500 watts at defrost, and running draw is about half that (it varies with conditions).
  • BB.BB. Just some guy Posts: 24,223Super Moderators admin
    Re: ac refrigerator on inverter

    And, I should add, if you don't have one yet, get a Kill-A-Watt meter...

    Really helpful to measure and understand your AC loads (note, Watts are not the same as Volt*Amps or VA). Also can help you understand your total power used during the day and figure out where you can conserve.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nigtomdawnigtomdaw New User Posts: 705Solar Expert
    Re: ac refrigerator on inverter
    The MSW are really only good for light bulbs. .

    Sweeping comments like this dont really help anyone, Im not having a pop at Cariboocoot but MSW Inverters and especially MSW Inverter Chargers have a place in the market place. They will run TVs ,Satalite Reciever , Power Tools , Fridges , not all but many basic types without fancy digital and electronic controls without problems. Yes there is a fry and die list and these items can easily be avoided with a little research but as I said in an earlier post many people live happily full time with a MSW inverter charger and are happy with there life style. I ran a DR2424E for two years and my mate two years after me. Yes I m on TSW now, but when my permanent home was still a holiday home I was glad to leave an inexpensive but totally adaquate MSW insitu for our needs. The times I needed TSW forcharging laptop and power tools I waited till the genny was running, if MSW inverters were only good for light bulbs I dont think Xantrex would have bothered to upgrade there Dr units to the new TR models with PFC with low volume sales for a light bulb only unit.

    MSW arent the be all end all but the are certainly more versatile than just fit for light bulbs and come with a considerable price saving over TSW .

    IMHO
  • crewzercrewzer Solar Shogun Posts: 1,830Registered Users, Solar Expert
    Re: ac refrigerator on inverter

    Links to discussions re MSW vs TSW inverters:

    http://www.xantrex.com/support/readfaq.asp?did=268&p=1348
    http://www.xantrex.com/web/id/260/docserve.asp
    http://www.homepower.com/article/?file=HP99_pg128_Letters_3

    FWIW, I use both MSW and TSW inverters. My small MSW model works well for charging laptop computers in my truck. I use only TSW inverters at home, and the instructions for my cordless tools' battery charger state to not use an MSW inverter.

    Xantrex does indeed make MSW inverters, and some are quite poplular. But, they also make several TSW inverter models, and their literature addresses some of the application advantages:

    http://www.xantrex.com/web/id/7/p/1/pt/8/product.asp
    http://www.xantrex.com/web/id/9/p/1/pt/5/product.asp
    http://www.xantrex.com/web/id/10/p/1/pt/7/product.asp

    HTH,
    Jim / crewzer
  • CariboocootCariboocoot Gone Fishing... Posts: 17,615Banned
    Re: ac refrigerator on inverter

    Anybody here started out with an MSW and not either switched to or added TSW?

    By "light bulbs" I of course meant simple applications. I have used MSW to run 'frige and computer set-up, and I still recommend TSW if you're going to do that. It is essential for AC induction motors; they may run on MSW, but their lifespan will be shortened.
  • n3qikn3qik New User Posts: 741Solar Expert
    Re: ac refrigerator on inverter

    Ran a 4 Cu. Ft. Magic Chef off a MSW this summer. I listed the current draw and temps of the motor between the MSW and grid power somewhere here.
  • crewzercrewzer Solar Shogun Posts: 1,830Registered Users, Solar Expert
    Re: ac refrigerator on inverter

    "Somewhere here": http://forum.solar-electric.com/showthread.php?p=20837&highlight=inverter#post20837

    HTH,
    Jim / crewzer
  • sub3marathonmansub3marathonman New User Posts: 297Solar Expert ✭✭
    Re: ac refrigerator on inverter

    A 3kw inverter seems pretty big to run a refrigerator.

    During the hurricanes here in Florida back in 2004 I ran an energy star refrigerator off of my APC SmartUPS 750XL. It ran fine, I think it is a true-sine-wave power supply. But my mom's refrigerator, non-energy star, would trip the UPS so it wouldn't run. I had to run back and forth between my in-law's house that had electricity to charge it up occasionally.
  • n3qikn3qik New User Posts: 741Solar Expert
    Re: ac refrigerator on inverter

    Thanks crewzer

    Too many changes here, forgot to go and find it.
  • blwncrewchiefblwncrewchief New User Posts: 17Registered Users
    Re: ac refrigerator on inverter

    Also keep in mind there are vast differences in "MSW" inverters. In fact, a lot of what are called MSW inverters really are not modified sine wave. They are really modified square wave or just plain square wave inverters. MSW inverters can have a wide range of wave forms and unless the information is available or you put it on a scope you have no idea what your really getting. Needless to say if you have a $99.00 3000 watt inverter, well you probably have a $99.00 wave form:roll:. The Xantrex DR/TR inverters (and I would guess the Magnum) are some of the best MSW inverters and are in no way comparable to a cheap "MSW" inverter. In fact, the Xantrex SW inverters were really a MSW inverter that have a wave form so good that they could classify it as a true sine wave. But many people that have switched from SW inverters to Outback, Magnum, or the XW inverters have noticed a noted improvement in the operation of some equipment like refrigerators and microwaves. I would plug almost anything into a DR/TR inverter but I would not plug anything worth more than 99 cents into a cheap "MSW" inverter. So just keep in mind "buyer beware" when it comes to "MSW" inverters.;)
  • RCinFLARCinFLA New User Posts: 1,280Solar Expert
    Re: ac refrigerator on inverter

    There are only two compressor manufacturers, Samsung is one, other is also Korean but don't remember name.

    New refrig compressor achieve energy star improvement with variable speed compressor. They should be run on true sinewave inverters.
  • jacobsjacobs New User Posts: 72Solar Expert ✭✭✭
    Re: ac refrigerator on inverter

    We've used modified sine wave inverters exclusively for over 26 years for refrigeration, 240 volt submersible well pump, laundry, large and small shop tools, electronics & etc. We live in an area that no one has commercial power and most of our neighbors have MSW inverters and have had NO problems powering various loads including refrigerators. MSW inverters are more efficient, less expensive, and less complex that TSW inverters. I personally see no reason to switch to a pure sine wave inverter. Simplicity is beautiful!
  • BB.BB. Just some guy Posts: 24,223Super Moderators admin
    Re: ac refrigerator on inverter

    I am very glad that your MSW inverters are working well for you... Since they are so much less expensive--if somebody can use them, it often does not make sense to use a TSW.

    However, MSW inverters are not more efficient when you look at the entire battery to load connection... Especially if that load is inductive (transformers and electric motors).

    Simply, because of the shape of the wave form (square wave), there are a whole lot of higher frequencies (above 50/60Hz) in the square wave that motors and transformers cannot use. These extra frequencies only are converted into heat... Approximately 10-20% of energy usage.

    Only with true resistive loads (heaters filament lamps) do MSW and TSW inverters approach equal efficiencies (modern TSW inverters are getting really good at being efficient).

    With more complex electronics (CFL's, Microwaves, electronic devices), you pretty much are left to getting a kill-a-watt meter and running the loads on TSW and MSW sources and seeing how they perform.

    For motors that run a short time (say a well pump running 10 minutes a day), the losses with a MSW inverter are not that great. However, for something that runs many hours per day (fridge, lighting, home electronics, fan, etc.) the losses may be more substantial (as well as the possibility of equipment damage from long term accumulation of heat build up).

    I believe I read somewhere (here?) that, for example, a Microwave oven on a MSW inverter takes longer to heat. However, there is a Panasonic "Inverter" Microwave Oven that does very well on MSW (looking on Amazon, the Inverter Ovens have a very mixed bag of love/hate reviews, and may not be available at this time).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jacobsjacobs New User Posts: 72Solar Expert ✭✭✭
    Re: ac refrigerator on inverter

    A very high percentage of electronics built today including CFL's employ a bridge rectifier at the input to change ac to dc. It doesn't matter if it's fed pure square wave, modified sine wave, pure sine wave, OR 144 volts dc. Transformers and their inefficiencies are mostly a thing of the past. Microwaves are only used a few minutes a day. You are correct an ac electric motor is more efficient when fed pure sine wave but when you consider the total load used in an average off grid home, the ac motor equation is insignificant. I stand by my original statement.....modified sine wave inverters are more efficient due to their simpler design. KISS (keep it simple.....)
  • BB.BB. Just some guy Posts: 24,223Super Moderators admin
    Re: ac refrigerator on inverter

    Actually, a bridge rectifier/voltage doubler front end on most electronic devices of any size has pretty much gone away (by US and International requirements) because of the very poor power factor (only take current very near the peak of the AC voltage waveform, giving a very narrow, very high amperage current spike 120x per second). The poor power factor is from a bridge front end causes large losses in the building wiring and transformers--both because of the spectrum content (high frequencies) and because of the I^2*R heating losses cause by the amplitude of the current spike.

    You can read a bit about the issue here:
    A particularly important class of non-linear loads is the millions of personal computers that typically incorporate switched-mode power supplies (SMPS) with rated output power ranging from a few watt to more than 1 kW. Historically, these very-low-cost power supplies incorporated a simple full-wave rectifier that conducted only when the mains instantaneous voltage exceeded the voltage on the input capacitors. This leads to very high ratios of peak-to-average input current, which also lead to a low distortion power factor and potentially serious phase and neutral loading concerns.

    A typical switched-mode power supply first makes a DC bus, using a bridge rectifier or similar circuit. The output voltage is then derived from this DC bus. The problem with this is that the rectifier is a non-linear device, so the input current is highly non-linear. That means that the input current has energy at harmonics of the frequency of the voltage.

    This presents a particular problem for the power companies, because they cannot compensate for the harmonic current by adding simple capacitors or inductors, as they could for the reactive power drawn by a linear load. Many jurisdictions are beginning to legally require power factor correction for all power supplies above a certain power level.

    Regulatory agencies such as the EU have set harmonic limits as a method of improving power factor. Declining component cost has hastened implementation of two different methods. To comply with current EU standard EN61000-3-2, all switched-mode power supplies with output power more than 75 W must include passive PFC, at least. 80 PLUS power supply certification requires a power factor of 0.9 or more.[3]
    Also, with AC bridge rectifiers running on MSW inverters--they can run into serious under voltage issues.... The typical MSW peak voltage is very near that of the AC RMS voltage of 120 volts... The peak voltage of a pure sine wave is sqrt(2)*120 volts AC RMS = 170 volts (voltage doubler front ends, typically used with 120/240 VAC switchable power supplies, would be 240 vdc on MSW vs 340 vdc on TSW).

    With many electronics (and motors) being "constant power" devices, anything that lowers the useful voltage or pumps in unusable current will increase overall power consumption (power needed plus power losses due to MSW AC power).

    With the new PFC supplies, they should run pretty well on MSW inverters as they "emulate" the transfer characteristics of a resistive load (the "ideal" load).

    Modern TSW designs, while not cheap, can approach 95% efficiency just on the conversion from DC to AC for even very large systems (like the Xantrex XW family--up to 6kW click on technical specs. for PDF download).

    I am not arguing that MSW does not work for you--but there are many reasons that many folks would end up being much happier with a TSW inverter to run their loads.

    -Bill

    PS: Here is a nice PDF Download / Power Factor Correction paper... It is written convince people/mfg'ers to upgrade their products to PFC and 80%+ efficient designs--so the paper still has an editorial slant... But it does a through job of addressing the isssue.

    You can look at the efficiency graph of the 300 watt TSW MorningStar inverter... ~6 watt idling load; roughly 0.6 watts if in standby (waiting for an 8 watt minimum load).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Title:User Posts: 6,207Solar Expert ✭✭✭
    Re: ac refrigerator on inverter

    If you happen to have a fridge that does not like MSW (most are actually a square wave, with a step in them), you have to replace the fried motor fairly often. What model/brand fridge do you have that works well with the MSW inverter ? That would help a lot of folks in their shopping.
    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 ,

  • jacobsjacobs New User Posts: 72Solar Expert ✭✭✭
    Re: ac refrigerator on inverter
    mike90045 wrote: »
    What model/brand fridge do you have that works well with the MSW inverter ? That would help a lot of folks in their shopping.

    Refrigerator: Kirkland Model ST18HPXKQ02 energy star made by Whirlpool (Previously used very successfully on msw) Currently using a 15 year old 12vdc RF19 SunFrost powered by an Iota converter on 144vdc. Iota, Todd, and Progressive Dynamics converters will all run on 120vac or 144vdc. They all have bridge rectifiers on their front ends.

    Freezer: 9 year old 15 cubic foot GE Model FCM15SAB on modified sine wave.

    Some of our lighting is CFL's on 144vdc. Most CFL's DO work on 144vdc.

    With the success we've had, we sure don't need pure sine wave. Maybe there's a difference in waveform between different brands of msw inverters?
  • BB.BB. Just some guy Posts: 24,223Super Moderators admin
    Re: ac refrigerator on inverter

    True PFC converters/equipment should also run fine on DC too (check with Mfg. first).

    How are you making the 144 VDC? Multiple solar chargers chargers on series connected batteries? Or something else?

    Did you address any code issues with the >60 VDC of NEC--or it does not matter in your area (being way off-grid--it probably does not matter).

    Sounds interesting in any case.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Title:User Posts: 6,207Solar Expert ✭✭✭
    Re: ac refrigerator on inverter
    jacobs wrote: »
    With the success we've had, we sure don't need pure sine wave. Maybe there's a difference in waveform between different brands of msw inverters?

    Oh yes ! There are inverters that have 20+ "steps" in the output, the original Mod Sine Wave. then there are the ones with 2 steps, one more than a square wave. The 2 step mod-sine is really more like a square wave, and that's what's toasting folks stuff.
    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 ,

  • jacobsjacobs New User Posts: 72Solar Expert ✭✭✭
    Re: ac refrigerator on inverter

    We have 3 sets of 11 12volt panels wired in series. The reason for the high voltage is in 1980 when we started building our home, our wind generator was about 1500' from the house and we had to go with 120vdc to keep voltage losses within reason. At that time PV's were selling for over $20 a watt. Adjusted for inflation that's about $50/watt today. Later when PV prices came down, we abandoned the wind generator and installed PV's and upgraded to 144vdc. We've since added even more panels.

    We had electrical inspections while we were building but the NEC wasn't as stringent as it is today. They didn't care what voltage or what type voltage (ac or dc) you were using. You could even install your batteries under your bed if you wanted to! The big issue then was grounding. At that time, the NEC only applied to anything over 50 volts and it didn't address off grid installations.
  • BB.BB. Just some guy Posts: 24,223Super Moderators admin
    Re: ac refrigerator on inverter

    How are you doing the charge controlling? From what little I know--I have not seen any commercial 144 VDC solar charge controllers out there...

    Did you make your own? Dump type controller?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MangasMangas New User Posts: 452Solar Expert ✭✭
    Re: ac refrigerator on inverter

    Interesting reading which may explain the problem I had with my HVAC.

    Three years ago, I had a furnace ignitor circuit problem. Everything in the Off Grid house ran perfectly from high end electronics, computers, A/C, fans, security system, appliances, well controls, etc except the furnaces wouldn't cycle properly.

    After bedevilling the electricians and furnace manufactuerer for a couple of months (unfortunately for me during the winter) it turned out a simple $20 capacitor installed on each furnace immediately corrected the problem. They have run and cycled perfectly ever since.

    Since we had installed four SWs' this was an unexpected problem. I wonder if installing the newer XWs' would have avoided the problem.

    Always learning something new here.
    Off Grid System: 2 x pair stacked Schneider XW 5548 Plus inverters (4), 2 x Schneider 800 Charge Controllers, 2 Xanbus Generator Start and Air Extraction System Modules, 64 Trojan L16 REB Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar panels, Cummins Onan RS20 KW Propane Water Cooled Genset, Rastra House Construction, 2 x high efficiency three ton Central A/C units and 2 x Air handlers
  • rplarryrplarry New User Posts: 203Solar Expert ✭✭✭✭
    Re: ac refrigerator on inverter

    jacobs
    I was not nearly as fortunate with my Kirkland refers, 18cf energy star made by Whirlpool. The first one I bought at Costco lasted about 6 months of full time use on a cheap msw inverter. I returned it to Costco and they gave me another and at the same time I upgraded to a X brand DR2412. The second refer lasted 10 months of full time use before the motor burned out. Took it back to costco and got my money back. Costco is a great place to do business. I then went to sears and got an 18 cf Kenmore and also bought an Outback VFX 2812, that was 4 years ago and have had absolutly no refer problems. In my case the pure sine wave inverters are well worth the exta money.
    Larry
  • jacobsjacobs New User Posts: 72Solar Expert ✭✭✭
    Re: ac refrigerator on inverter
    BB. wrote: »
    How are you doing the charge controlling? From what little I know--I have not seen any commercial 144 VDC solar charge controllers out there...

    Did you make your own? Dump type controller?

    -Bill

    There's a charge regulator factory installed in the inverter. The inverter was made by Michigan Energy Works. Prior to purchasing this 144vdc, 3kw, 10kw surge transformerless inverter in 1999, I constructed my own dump type charge regulator.
  • Robin GudgelRobin Gudgel Frequent Poster Posts: 58Registered Users, Solar Expert ✭✭✭
    Re: ac refrigerator on inverter

    High quality MSW and TSW inverters are very similar in efficiency. The idle power of the TSW inverter will be higher than the TSW though. Two to three times! Some one mentioned that the TR was an upgrade and power factor corrected? It is not power factor corrected and was redesigned to be built in China rather than the US. It may be a good inverter though. I have looked inside mine and was for the most part very impressed over my DR design from 1992. I have not turned it on though. Magnum has the only PFC charger in a MSW inverter to my knowledge. PFC charging makes a HUGE difference in efficiency! The DR charger was probably 35% efficient. The Magnum is about 90%.
    Fridges do run hotter on MSW, but it is not usually a problem. It all comes down to how well the compressor was built. Things seem to be made cheaper and cheaper these days, so it is probably more of an issue now vs. when all there was were MSW inverters twenty some years ago. I was the mechanical engineer for all the Trace inverters, some Xantrex, all the OutBack and some of the Magnum products. As inverters go, everything is better today than back in the days where you bought a Trace or a Trace. Appliances have become fussier though. UL is going to quit approving MSW inverters soon. There are compatibility issues.
  • WindsunWindsun Solar Shogun Posts: 1,164Solar Expert admin
    Re: ac refrigerator on inverter
    ...Some one mentioned that the TR was an upgrade and power factor corrected? It is not power factor corrected and was redesigned to be built in China rather than the US.

    According to the Xantrex website specs:
    New power factor corrected (PFC) charging, combined with a more sophisticated multi-stage battery charging algorithm, reduces electricity draw and generator run-time..

    Are you saying they really are not. Now even I am confused :confused:
  • WindsunWindsun Solar Shogun Posts: 1,164Solar Expert admin
    Re: ac refrigerator on inverter
    Fridges do run hotter on MSW, but it is not usually a problem. It all comes down to how well the compressor was built. Things seem to be made cheaper and cheaper these days,

    From what I read a while back.. someplace.. the reason that some new appliances have problems with MSW is because they have been redesigned to meet Energy Star standards, and one way of doing that is to use smaller more compact motors, which means they also have more of a problem in dissipating heat.
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