Solar to run a fridge.

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Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.

    The connection between charge controller and batteries is one circuit. The connection between the batteries and inverter is another. Each need the proper wiring and circuit protection. The inverter circuit (usually) has much more current potential than the controller circuit. As such it would have heavier wiring and higher fuse rating accordingly.

    Not sure what model inverter you have. If it is not a true sine wave inverter then you have issues with grounding.
    There are also concerns with NEC regulations regarding the AC wiring, DC wiring, and grounding for both and the panel frames.

    The shortened version of "good practice" grounding:
    Panel frames & mounts are grounded to reduce the possibility of lightning energizing. As such the wire is run outside the building straight to its own ground rod.
    The (-) of the DC system is grounded, as are the (metal) cases of the charge controller & inverter. This would usually be the same ground rod as the AC.
    On the AC side, the neutral line is bonded to the ground. If it is not a true sine inverter do not do this, as MSW inverters often go up in smoke if you do.

    NEC regs complicate things. They now require DC ground fault protection on the panel wiring. There is argument against this.
  • DavidOHDavidOH Solar Expert Posts: 109 ✭✭✭
    Re: Solar to run a fridge.

    A great exercise guys. Even if it's just to run one item. One minor note, I replaced the light bulb in my fridge with an LED. Every little bit helps! :)
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Solar to run a fridge.
    DavidOH wrote: »
    A great exercise guys. Even if it's just to run one item. One minor note, I replaced the light bulb in my fridge with an LED. Every little bit helps! :)

    And have you looked inside to make sure that it goes off? :-)

    On a more serious note, reducing the watts used by light bulbs counts double in those cases where the waste heat is warming an area which you are also trying to cool, whether it be a refrigerator, freezer, or air conditioned room.

    The incandescent bulb in the bathroom ceiling is comfortable on cold winter mornings, but during the summer an energy efficient lamp is better. :-)
    SMA SB 3000, old BP panels.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Solar to run a fridge.

    i wouldn't worry about the light inside a refrig as you don't have it on much over the life of the refrig anyway. if you do have it open that much then my advice is to shut the door as you are wasting electric leaving it open as it will need to run more to cool back off again. for awhile on an older refrig that i had the bulb burned out and i never bothered to replace it, but that was in my days as a bachelor.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Solar to run a fridge.
    niel wrote: »
    for awhile on an older refrig that i had the bulb burned out and i never bothered to replace it, but that was in my days as a bachelor.

    If the bulb is burned out, you spend more time looking for the food with the door open, unless the fridge only has beer in it. :-)
    SMA SB 3000, old BP panels.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Solar to run a fridge.

    Especially if it's a teenage eating machine that is looking...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: Solar to run a fridge.

    I agree with Neil. We have a propane frig in addition to our electric one and the light is powered by 2 D batteries. I think we have replaced the batteries once in the last four years, though the light is getting a little dim lately.
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.

    I put in a compact flourescent about 4 years ago, and its still going strong. .. didn't think it would, but it is. . .

    One of the guys at work told me I have a few options. . . raise the temp on the fridge, so it does not have to work so hard. . . add more insulation. . and disconnect the defroster. . . still looking into it. . .
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Solar to run a fridge.
    inetdog wrote: »
    If the bulb is burned out, you spend more time looking for the food with the door open, unless the fridge only has beer in it. :-)

    no, i could see in there just fine with the kitchen light on. i usually know what i want from the refrig and just get it without fooling around. i looked no longer without the light than i would've if i had the internal light on. of course i don't see as well now so the light stays. it's my other half that will look and look and look. the trouble is not the light in the refrig, but the one that's above her head tends to be dim sometimes.

    the point is the 40w bulb that is usually in there is on for what 10 seconds or less for me. if i were to do this even 20 times a day, which doesn't happen, this amounts to 200 seconds/day or 3 minutes and 20 seconds. over a month this is 30 x 200sec = 6000sec or 100 minutes. at 40w this is 1.67hrs x 40w = 66.67whrs. the led uses probably 25% of the power and the difference is about 50whrs extra used. how long does anybody think it will take to get a kilowatt hour to pay the extra 10-20 cents?

    instead you pay $20-$30 for an led to save a few pennies over the 40w bulb. it does save on electric, but is wayyyy out of line for cost vs savings to be not worth it.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Solar to run a fridge.

    there is a recent thread here about adding insulation to the outside of a fridge.http://forum.solar-electric.com/showthread.php?16560-adding-insulation-to-external-refrigerator&highlight=insulation+refrigerator
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.

    thanks for the link. The picture he has there kinda looks like mine, a big box with foam on it... I did an experiment a year or so ago, and added ANOTHER 2 inches of foam on it, it only cut it down by about .1 - .2 of a killowatt a day. . . now, maybe I will put it back on. . .:blush:
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.

    Nothing wrong with the Trimetric meter. You do have to program it correctly from the start. But do you really need it? For daily use systems it is quite an asset, and nearly a necessity for AGM batteries. For occasional back-up use you might save money and buy MidNite's battery meter http://www.solar-electric.com/mnbcm.html (not as precise as a battery monitor). Particularly if you get flooded cell batteries - and a hydrometer. I don't know what kind of budget you're looking at. Victron also makes a good battery monitor.

    I am going to get FLA batteries, and probably a hydrometer, so is the trimetric a better choice ? I am about to drop the cheque in the mail, and noticed that you said (not as precise as a battery monitor) - so I should get the battery MONITOR ?
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.
    The connection between charge controller and batteries is one circuit. The connection between the batteries and inverter is another. Each need the proper wiring and circuit protection. The inverter circuit (usually) has much more current potential than the controller circuit. As such it would have heavier wiring and higher fuse rating accordingly.

    Not sure what model inverter you have. If it is not a true sine wave inverter then you have issues with grounding.
    There are also concerns with NEC regulations regarding the AC wiring, DC wiring, and grounding for both and the panel frames.

    The shortened version of "good practice" grounding:
    Panel frames & mounts are grounded to reduce the possibility of lightning energizing. As such the wire is run outside the building straight to its own ground rod.
    The (-) of the DC system is grounded, as are the (metal) cases of the charge controller & inverter. This would usually be the same ground rod as the AC.
    On the AC side, the neutral line is bonded to the ground. If it is not a true sine inverter do not do this, as MSW inverters often go up in smoke if you do.

    NEC regs complicate things. They now require DC ground fault protection on the panel wiring. There is argument against this.

    how big of a wire for the ground ?
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.

    A battery monitor actually keeps track of current going in and out of the battery to give an accurate SOC reading moment by moment. That is provided it is programmed correctly. Get that wrong and its readings will be wrong. Eventually it will be wrong as battery capacity goes down over time and there's no way around it. You have to judge the change and reprogram at some point.

    The MidNite battery meter looks at Voltage only and keeps track of whether or not the battery has been brought up to Absorb Voltage in the past week/two weeks. It is not as precise as a properly programmed battery monitor, but it is better than just a Volt meter (as in charge controller or inverter display) and is fool proof for set up. It's also about 1/3 the price of the Trimetric.

    You have to weigh the advantages/disadvantages of the two.
    Were it me, for an occasional-use system with a generator available I'd go with the battery meter rather than spend the money on the battery monitor.
    FWIW I do not use either. I use the hydrometer. Since my system works I can judge SOC fairly accurately based on the inaccurate Voltage readings. The key to that is to stay away from anything that looks like 50% SOC. :D I have the inverter's low Voltage disconnect set at 24; if it goes below 24 while under load and shuts down the batteries will 'rebound' up in Voltage, which is a guarantee they aren't at 24 Volts resting and therefor are above 50%.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.
    Skippy wrote: »
    how big of a wire for the ground ?

    Normally 6 AWG wire is sufficient for electrical safety ground. Remember it doesn't have to handle full current as it ordinarily doesn't carry any; it just needs to be able to make a short circuit path long enough to trip circuit protection on the supply side.

    It gets a bit gray when dealing with panel frame grounding and local inspectors. In all cases local codes supersede NEC or 'good practice'. (Sometimes to the detriment of the system.)
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.

    Thanks for the replies, and sorry about all the "quick" posts. . I was on the library computer at the time, and the time was ticking down to "0".
    I have rewired the battery bank, so it is not laddered. Three days ago, I turned on my computer,monitor, and a light, and watched movies for about 1.5 hours, battery voltage dropped to 11.91 or so. . . two days later, did the same thing again, and the battery voltage only dropped to 12.36 . . does that mean the charge controller is giving these neglected (sitting on a shelf for 5 years, fully charged every 6 months) batteries a "better" charge, and giving them a bit more life ? I know, wishfull thinking, but they are not as dead as they were. . . I don't think these batteries have ever been held at the "float" charge of 14.1 volts (had to check that number), all day, so that may be the difference. .. According to the killowatt meter, I was using about 150 watts, for the 1.5 hours contin. = .4 killowatt/hour total, from 3 - 33 amp hours batteries (99 amp hour ?)
    This little experiment is at 1 AM, so no input from panels, and power consumption is ALOT lower when compared to the laptop . . :D

    Thanks for explaining the whole meter thing in more detail, I agree with ya, in this case cheaper would do the job...

    I will be grounding the system this weekend, using the 6 gauge.

    Thanks.
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.

    12.36 is certainly better than 11.91 for the same usage. Sounds like the 'orphaned' batteries in the chain are being included now. However don't expect miracles; sulphation is no doubt well under way and once it hardens on the plates ... that's it. No place to go but down. In fact that's all batteries do from the moment the plates are 'formed'. All you can hope for is to slow the descent as much as possible by keeping them charged.

    What would be best is if you could charge and check each battery individually, so that you know which ones have 'good' Voltage available and which ones don't. Some may be so bad that instead of contributing to the power available they detract from it.
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.

    Not sure if you can see the numbers on the tops of the batteries in the picture , but the way I tested them, is to connect the inverter to each individual battery, apply a 240 watt load, and see how long it takes for the lvd to kick in. . . I now know, that is really bad for the batteries, but all three of the batteries "on line" were able to take that load for about 30 - 40 minutes. . . so hopefully they are closely matched in capacity ( and equally abused :blush: )

    I have three more batteries - same size and type - but the test time for those three - with that load - is something like 5 min. - 15 min - and 20 min. - since these were given to me free, I may hook these three together, and leave them connected to the panels for a few days, to see what happens. . . since I am concerned with overheating and such, I will probably do the first day when I am home and can keep an eye on things. . . although, someone told me that all three solar panels are the equivalant to a trickle charger. . .
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Solar to run a fridge.
    Skippy wrote: »

    I have three more batteries - same size and type - but the test time for those three - with that load - is something like 5 min. - 15 min - and 20 min. - since these were given to me free, I may hook these three together, and leave them connected to the panels for a few days, to see what happens. . . since I am concerned with overheating and such, I will probably do the first day when I am home and can keep an eye on things. . . although, someone told me that all three solar panels are the equivalant to a trickle charger. . .

    For FLA batteries:

    For logistical reasons (limited sun time each day, and minimum required charge rate) giving a string of batteries an equalizing or reconditioning charge is best done using either POCO power or a generator. That way you will be able to keep a high current, at the gassing voltage, for long enough to potentially do some good, and you will be able to circulate potentially stratified electrolyte.

    For AGM batteries: Ditto, except that "equalization" in its simplest form is not really applicable to AGM, since too much gassing will cause the cells to vent, permanently losing electrolyte.
    But a long conditioning charge at the current and voltage recommended by the manufacturer is again easier done with an AC or generator driven charger.
    SMA SB 3000, old BP panels.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Solar to run a fridge.

    Skippy, can you post the make and model of those batteries, each manufacturer uses slightly diff charging specs... especially for EQing
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.
    inetdog wrote: »
    For FLA batteries:

    For logistical reasons (limited sun time each day, and minimum required charge rate) giving a string of batteries an equalizing or reconditioning charge is best done using either POCO power or a generator. That way you will be able to keep a high current, at the gassing voltage, for long enough to potentially do some good, and you will be able to circulate potentially stratified electrolyte.

    For AGM batteries: Ditto, except that "equalization" in its simplest form is not really applicable to AGM, since too much gassing will cause the cells to vent, permanently losing electrolyte.
    But a long conditioning charge at the current and voltage recommended by the manufacturer is again easier done with an AC or generator driven charger.

    These are AGM batteries, and keep in mind, nothing else is hooked to the panels - a really expensive battery charger :cry: - for now ;)
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Solar to run a fridge.

    Some AGM brands will recommend a top of range charge as an EQ but that is brand specific (Absolyte)
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.
    westbranch wrote: »
    Skippy, can you post the make and model of those batteries, each manufacturer uses slightly diff charging specs... especially for EQing

    Sorry about that, I missed this the first time around, I think I have a picture of the info somewhere, post it when I can. . .

    I am going to guess, that since the inverter draws the heavy current, it needs the heavy wire, so I can switch the already fused "battery" terminals (existing set up - #4 wire ) over to the inverter terminals - and- Since the charge controller only handles the current from the panels (charging batteries) and is only rated at 20 amps, it can use a slighly lighter wire to go the 3 feet from the controller to the batteries ? So I just need to get another fuse block, and the new wire to do the change over... correct ?

    I have a bunch of #4 wire that I would like to return for $$ . . then I can get the lighter wire for the change over...

    I did a google search on "turning off auto defrost" and found nothing ! Guess it may not be a good idea. . it works, I should leave it alone.. :-)
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.

    Yep: controller to batteries is one circuit, batteries to inverter is another. They interact, but each has a considerably different maximum current.

    Chances are 4 AWG will not fit in your charge controller's terminals. Chances are it may be too light for the inverter.

    The considerations for wiring are: A). it must be of sufficient size to handle the maximum continuous current expected in the application; B). it must be of sufficient size to keep Voltage drop across the distance to an acceptable level.

    Refrigerators are getting more complex. There was a time when some included a switch/control for turning off auto defrost; came about right after they had switches for turning on defrost, which came after "take everything out, turn of 'frige, wait for flood to appear on kitchen floor ..."
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.

    I picked up the grounding wire today, now to find the time to get it put in !
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.

    a few questions for you guys.... in trying to decide how big of an inverter go get, I came up with the idea, that if I picked one up that would put out the same power as a household 120 V outlet (20 amp breaker in basement ) that would be (?) 120 V x 20 amps = 2240 watts ? . . . if I went this route, anything I could plug into my house, I could plug into the inverter. . without worry about overloading the inverter. .
    The weak spot in the system would then be the battery capacity/panel output . . . I did do a little test on my toaster oven, it plugs into 1 - 120 volt outlet, and it draws 1200 watts at 10 amps - on and off - . . the one that I would really like to run is the washing machine, since I am already using renewable rain water, it would be nice to use renewable energy as well, but as soon as I turn on the washing machine, the killowatt meter overloads on the start up surge . . but it still only runs on a 120 V - so I cannot quote a power figure.

    1. Lets assUme,:p , worse case - that the toaster oven is on for one full hour - drawing power continuous, so that would be 1.2 kwh ? 10 amp hours ? How would that dent a 400 AH battery ? If correct, that would use a bit more than 1 full day of "fridge time" for 1 hour of cooking. . Can't really guess at the washing machine, but if it draws the full 2240 watts continuous, would that kill the battery as well ?

    2. Correct me if I am in error here, but in the summer time, when there is a month straight of sunlight, and I have sized the battery to run the fridge for 3 days (no sun) would it be possible to run somthing else in there ? So, let the batteries charge all week (while running the fridge) and on the weekend do 1 load of laundry? Or am I running into the newbie mistake of "writing checks my panels can't cash":blush:

    3. I just recieved an email advertising solar panels at 89 cents a watt. . . 220 watt panel for 189 $. .could get another one of these to "help out" so too speak . . would the extra power fit into this idea ?

    As for the fridge system, I managed to switch the inverter directly to the battery bank, and wow what a difference. . . before, I would get the output up to around 300 watts, and every second, it would flash - on - off - I figure I was overloading the "load" center on the charge controller. . NOW, I have been able to run a continuous 500 watt load, with surges of 725 watts. .
    Last night, I heard the fridge autodefrost come on, so I went in and plugged it into the batteries. The killowatt meter was reading 689 watts just for the autodefrost, then that clicked off, and the fan was running for 6 watts. Shortly after that, the compressor kicked on, and for a couple of seconds it was drawing 700 watts, then dropped down to 150 watts. So, total "possible" power draw, if both the defrost and the compressor come on at the same time would be a surge of a bit over 1,400 watts - for two seconds - enough to fry the 700 watt inverter I have. . . but if they don't run at the same time, like last night, I have run my fridge off it for a short time. The only reason I pulled the plug and switched back over last night, was the killowatt meter was reading "dc" when I checked the "hz" . .not good. .

    4. "A store" has an inverter on sale right now, 3000 watt - modified sine wave - 179 $ - considering that I need an inverter to run my fridge motor (and possibly surge to run my washing machine) - is it a good deal ? or leave it there. Keeping in mind, that I am still a bit miffed at "this store" for selling me a misslabeld unit, so if its not a good deal, no problem leaving it there. The misslabeling is still happening by the way, I went in under the same premise as last time, I had the criteria that I needed a 700 watt inverter (continuous - NOT surge), and sure enough, they have a unit there labeled 700 watts. BUT - when you look at the specifications, that is the units MAXIMUM surge output, not the continuous output. . . I call that mislabeled :grr

    Sorry, I still have not found that picture of the battery info, will leave a sticky note for myself :D - I am going to have a closer look at this inverter that is on sale, just not sure how the modified sine will run the fridge motor. . (overheat)
    One of the guys at work tells me that installing a solar system is just one big "math" problem. . I think he's right :p
    The midnite meter is ordered and on its way !
    Thanks guys !
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.

    Yes you can size an inverter as "one outlet's worth". Usually it is done for a 15 Amp standard, which is 1800 Watts or a 2kW inverter. If the surge rating on the inverter is good it will perform like any household outlet. If it isn't some bigger loads (like motors) may fault it upon starting due to momentary current above 15 Amps. Most of the time it works.

    1.2 kW hours on a 12 Volt system is 100 Amp hours, not 10. On 400 Amp hours of battery that 1/4 the capacity, meaning it would be about all the power you'd normally allot for a day used up in one hour. Especially once you add in the inverter draw, conversion factor, and Peukart effect. It will seriously deplete the battery bank.

    2240 Watts continuous? That is an unlikely high load for a washing machine or anything else. But it is nearly double the numbers above. We're talking dead battery in an hour here.

    Once the batteries are fully charged and you still have sunlight on the panels they have the potential to produce more Watt hours which won't be utilized without taking advantage of 'opportunity loads'. The maximum of this is limited by how much power is needed to maintain Float and how much power the panels are capable of. The difference, less losses, can be used to run things without drawing from the batteries.

    The 220 Watt panel: what are the specs? Would it actually fit with your existing panels electrically? Chances are it is not the same Vmp or Imp and thus connecting it would be necessitate another charge controller, most likely of the MPPT type as panels in that Wattage range tend to be around 30 Vmp.

    The compressor and defrost should never come on at the same time. They don't work that way. The compressor will come on immediately following the defrost cycle to re-cool what has been warmed up by the defrost heating element. This is also why its initial draw afterwards is so high, as opposed to standard cooling cycle which will use less power. If that inverter is MSW, btw, the K-A-W probably won't read the power right.

    There is no point in buying an MSW inverter to run a refrigerator or other motors. They will operate better on a sine wave inverter. More money, more power consumption for the inverter, but better on the appliances. Listing the surge Watts as the rating is definitely misleading, useless, and unethical. I wouldn't trust them.

    Yeah, it's a big math problem. We use a lot of proven short-cuts around here to save people the nightmare of seeing just how much calculation would really go in to a beginning-to-end design process. Net result is that the short-cuts get you a balanced working system 95% of the time. :D
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Solar to run a fridge.

    I will take a shot at this--Hope it does not get to confusing...
    Skippy wrote: »
    a few questions for you guys.... in trying to decide how big of an inverter go get, I came up with the idea, that if I picked one up that would put out the same power as a household 120 V outlet (20 amp breaker in basement ) that would be (?) 120 V x 20 amps = 2240 watts ? . . . if I went this route, anything I could plug into my house, I could plug into the inverter. . without worry about overloading the inverter. .

    Yes and no--Straight power draw, yes. Surge current, it depends... An AC outlet is (if I recall correctly) rated to supply ~5x rated power (current). Most AC inverters are rated, at most, for surge at ~2x rated VA for a few cycles.
    The weak spot in the system would then be the battery capacity/panel output . . . I did do a little test on my toaster oven, it plugs into 1 - 120 volt outlet, and it draws 1200 watts at 10 amps - on and off - . . the one that I would really like to run is the washing machine, since I am already using renewable rain water, it would be nice to use renewable energy as well, but as soon as I turn on the washing machine, the killowatt meter overloads on the start up surge . . but it still only runs on a 120 V - so I cannot quote a power figure.

    AC motors are known for drawing ~3-5x rated current during starting... Depending on inverter, battery+wiring, and devices being powered (i.e., an electric table saw--if the voltage sags during startup--who cares. If a washing machine with computer controller sags the power enough to reboot the computer--it will never start correctly).
    1. ...1.2 kwh ? 10 amp hours ? How would that dent a 400 AH battery ? If correct, that would use a bit more than 1 full day of "fridge time" for 1 hour of cooking. . Can't really guess at the washing machine, but if it draws the full 2240 watts continuous, would that kill the battery as well ?

    1.2 kWH and 10 AH is at 120 VAC... For a 12 volt battery bank, that would be 100 AH (power = voltage * current; AH = Amps*Hours--no voltage in the equation).

    A washing machine (and gas drier) does not use that much power... Probably around 0.25 kWH per load (lots of variation--but at least a starting number). Your kWH meter should be able to measure these easily.

    For surge current, you would need to buy a more expensive meter (Fluke, others) that is designed to capture peak current readings (those first few A/C turn on cycles).
    2. Correct me if I am in error here, but in the summer time, when there is a month straight of sunlight, and I have sized the battery to run the fridge for 3 days (no sun) would it be possible to run something else in there ? So, let the batteries charge all week (while running the fridge) and on the weekend do 1 load of laundry? Or am I running into the newbie mistake of "writing checks my panels can't cash":blush:

    It is a game of numbers... Starting surge, running loads, and the total kWH used per day vs that recharged per day by panels (and the ~50% losses from solar array marketing numbers to usable AC power).
    3. I just recieved an email advertising solar panels at 89 cents a watt. . . 220 watt panel for 189 $. .could get another one of these to "help out" so too speak . . would the extra power fit into this idea ?

    Starting in the middle (or Tony's Ready, Fire, Aim)... You may come out OK--Or you may spend more money than you really wanted (solar power is not cheap--Roughly 10X that of grid power in North America).
    As for the fridge system, I managed to switch the inverter directly to the battery bank, and wow what a difference. . . before, I would get the output up to around 300 watts, and every second, it would flash - on - off - I figure I was overloading the "load" center on the charge controller. . NOW, I have been able to run a continuous 500 watt load, with surges of 725 watts. .

    I am not sure what you are saying here... Using "jumper cables" or other temparay wiring is usually not good... For a 1,200 watt load, you are talking about 100+ amps on a 12 volt battery bank. That is a real killer if not wired correctly (and not enough battery bank to supply that current for hours at a time).
    Last night, I heard the fridge autodefrost come on, so I went in and plugged it into the batteries. The killowatt meter was reading 689 watts just for the autodefrost, then that clicked off, and the fan was running for 6 watts. Shortly after that, the compressor kicked on, and for a couple of seconds it was drawing 700 watts, then dropped down to 150 watts. So, total "possible" power draw, if both the defrost and the compressor come on at the same time would be a surge of a bit over 1,400 watts - for two seconds - enough to fry the 700 watt inverter I have. . . but if they don't run at the same time, like last night, I have run my fridge off it for a short time. The only reason I pulled the plug and switched back over last night, was the killowatt meter was reading "dc" when I checked the "hz" . .not good. .

    Many modern refrigerators will "reset" the auto defrost timer if the power is interrupted (typically, will start a defrost cycle immediately). So--it is unclear what happened after the power swap.

    You may get an ice maker heater for a minute or two+motor starting. Hopefully, you will not see the compressor+600 watts of defrost heaters at the same time (but that is why you monitor your loads and oversize your power system a bit to carry through the unplanned hits). The "DC" on the kW meter is probably because of low AC voltage or MSW waveform. Most meters will probably not even turn on if connected to pure DC (and the inverters/loads will not function if DC output--they simply cannot output 120 VDC).
    4. "A store" has an inverter on sale right now, 3000 watt - modified sine wave - 179 $ - considering that I need an inverter to run my fridge motor (and possibly surge to run my washing machine) - is it a good deal ? or leave it there. Keeping in mind, that I am still a bit miffed at "this store" for selling me a misslabeld unit, so if its not a good deal, no problem leaving it there. The misslabeling is still happening by the way, I went in under the same premise as last time, I had the criteria that I needed a 700 watt inverter (continuous - NOT surge), and sure enough, they have a unit there labeled 700 watts. BUT - when you look at the specifications, that is the units MAXIMUM surge output, not the continuous output. . . I call that mislabeled :grr

    Things happen--hopefully the store addressed the problem for you.

    To run a full sized energy star rated fridge---You are probably looking at a 1,500 watt inverter minimum... I would push a TSW inverter for full time/off grid usage--But that is going to be 10x the cost of the MSW inverter--Your wallet, not mine.
    One of the guys at work tells me that installing a solar system is just one big "math" problem. . I think he's right :p
    The midnite meter is ordered and on its way !

    A fridge will use around 1-1.5 kWH per day... If you design your system to support the fridge--it will also support other smaller/random loads too (as long as they do not draw a lot of power 24x7 and run the kWH per day past what your panels+batteries can supply).

    So--Do you want a 1 kWH per day system that can power small loads (no fridge, no hot plates, probably no washer/drier/etc...)--Just smaller loads plus maybe a 12 volt water pump to pressurize house plumbing?

    Or, do you want a 3.3 kWH per day system that can run a fridge/washer/pump/lighting/laptop computer/etc...

    Give us some "real numbers" and we can help design a system... Or, I can "do the math" for a 1/3.3 kWH per day system based on your location so you can price it out and see how much power you can get (by season) and see how it maps up against your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SkippySkippy Solar Expert Posts: 301 ✭✭
    Re: Solar to run a fridge.

    O.k., here is the info on the side of the inverter box, have not had time to read the replies yet, short on time, so here goes :

    modifieded sine wave - stepped waveform
    3000 watt

    cont. - 2500 watt
    5 min - 3000 watt
    surge - 5000 watt

    115 VRMS AC +/- 10 % 60 HZ +/- 1HZ

    reg price 349.99
    Sale price 174.99

    I will be back to read up on your replies, goto go to work :cry:
    2 - 255W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    Apricus solar water heater with Tempra 12 on demand for backup.
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Solar to run a fridge.

    what is the DC input voltage for that inverter? (12/24/48)

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