1 Big and 1 Small Inverter

ywhic
ywhic Solar Expert Posts: 621 ✭✭
in Off Grid Solar & Battery Systems #1
Noticed this in another post.. and someone mentioned they have 2 inverters..

1 for large loads and 1 for small loads..

I know I can split my breaker panel in 1/2 and use 1 leg for the small and 1 leg for the big stuff.

It has a separate BACKBONE for the LOAD leads..

I have an incoming 2000 watt pure sine inverter (0.3-0.8A no-load).. which I had intended to run 'everything' in my little cabin..

None of my loads will be over the 2000w continuos even pretty much all turned on..

My items in use daily..

Fridge TBD
Water Pump 90w max (and on a pressure switch and manual switch..)
2-13w CFL's
1-14w laptop
1-Accubreeze Celing fan 10-68 watts
1-TV 45 watts

Should I run with the single 2000w or should I also buy a smaller 1000w pure sine for the smaller stuff.??

The difference is $100 between the 1000w and the 2000w.. maybe I should buy another 2000w??

Whats setups do you folks RUN/USE in your buildings/cabins/sheds/garages??
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Comments

  • Dill
    Dill Solar Expert Posts: 170 ✭✭
    #2
    Re: 1 Big and 1 Small Inverter

    300W Morningstar 300 (super low idle usage) and I plan on moving my ProWatt SW 1000 to the cabin for the bigger stuff. The ProWatt will be off probably 97% of the time.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: 1 Big and 1 Small Inverter

    Al;

    When you split inverter loads up like that it's generally using something like a Morningstar 300 for the little things (very small draw in search mode for those items that are on only as needed) and a bigger (1kW or more) inverter for the large loads - providing they can be used selectively.

    That's the trick; how well can you control load use? Things that need power on demand like refrigerators can make a mess of the plan. If the big inverter is going to have to be on/available anyway - what's the point in having a small one?

    Somewhere on here I went through the rigamarole with my wife's suggestion of a separate small inverter for the office. The cost of buying the extra equipment for the dual system could also expand the large system so that the energy draw was not an issue. Likewise I have tried my inverter in search mode and found what it saved in energy per day wasn't that much due to the repeat demands of switching on the 'frige.

    That is a big one: refrigeration. For the most part if you run an electric 'frige the small inverter will be of no use and the large one will have to be available all the time anyway.

    It's a bit different from starting a 5kW gen to run the washing machine while using a 1 kW inverter to run everything else. You really have to figure out your loads and how you will use them.
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  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
    #4
    Re: 1 Big and 1 Small Inverter

    Al, did you order a specific model or do you just know you are getting a 2000 watt inverter? I know you've been bouncing back and forth between different models so I'm just curious if you made a final decision. I can't see much of an advantage to having 2 inverters other than having a backup if one goes down. If you are running both inverters at the same time you would be drawing more idle current than just running one. If you want 2 inverters I personally would get another 2000 for only $100 difference. That way either inverter can run the entire system. There isn't that much of a difference in no-load draw between a 1000 and a 2000. But I would start with one and see how it goes before buying a second. My first Prowatt 2000 did have a problem so I can see the value in having a backup on standby but only if money allows. Mine just happened to die before a 7 day power outage so I had to use my modified sine wave Cobra inverter. Thankfully I had a backup but I wish I had the pure sine wave inverter for the outage because I didn't want to run my lcd tv on the msw since the tv makes a buzzing noise on that inverter. This was before I had my small solar setup so I used my Prius to run what I needed.
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #5
    Re: 1 Big and 1 Small Inverter

    @ Wxboy.. Yes I ordered the Xantrex ProWatt SW 2000 and it will be in-hand Tuesday..

    I will have some money coming in now as I am back to work.. and was thinking outloud about a 2nd inverter..

    I was thinking the Fridge and Water Pump on one unit.. and per se the Kitchen circuit..

    Then another unit for the 'rest'..

    The only other appliances I can possibly see to be used would be either a small 700w Microwave or 900/1200w hot plate..

    Hence the possibility of splitting the loads..

    Kitchen (Fridge, Water Pump, Microwave).. The 'rest' on another.. I was thinking a 1000 watt Xantrex ProWatt for that since the no-load consumption is also low.. Though true a 2nd 2000w model couldn't hurt..
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #6
    Re: 1 Big and 1 Small Inverter

    I have one Morningstar 300 on 24/7. Runs ALL my lights inside and out, computer, TV & Sat receiver, chargers, air exchanger and a bunch of other stuff.
    The Prowatt 1800 is only ever on for the very few heavy loads, when they need power.
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #7
    Re: 1 Big and 1 Small Inverter

    Well if we could figure a ballpark on what a normal fridge runs in AMPS to start...

    I know the MS300 would run all the small stuff.. the problem I have would be the fridge, the microwave, and then during the super-hot days the A/C unit.. which we have found out will run on the 2000W Xantrex.. (thanks to 2manytoys)..

    The question would be if the fridge kicks on will the A/C unit go off if I put them on the same 2K inverter?? :blush:

    Would a chest freezer be better than a fridge for my (South TX) situation??
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  • 2manytoyz
    2manytoyz Solar Expert Posts: 373 ✭✭✭
    #8
    Re: 1 Big and 1 Small Inverter
    ywhic wrote: »

    None of my loads will be over the 2000w continuos even pretty much all turned on..

    Keep in mind the 2000W rating is for 5 minutes. The Prowatt SW2000 is rated for 1800W continuous. Even at that rate, that's a massive amount of energy from the battery bank. Short - heavy loads are fine, things like a microwave oven. Running it near capacity for long, you'd need a very large battery bank indeed.

    I've run multiple inverters at my last house, but that was a different setup. I ran CFL lighting from a 400W MSW inverter. I used a remote setup to turn the inverter on/off as needed. No parasitic load with the inverter off. I had grid power most of the time, so that ran my fridge and the rest of the house. When the grid went down (common issue in FL), the loads transferred to a Prosine 1800W inverter in the Power Save mode. When it detected a load, it powered up and ran the appliances. When the grid came back online, the loads transferred back, and the Prosine went back to sleep.

    The parasitic load of the Prosine was significant when left powered up all the time (not in power save mode). So in that case, it made more sense to use two inverters.

    The new Prowatt SW2000 doesn't have a Power Save feature, but it has a very low idle current. Consequently, I no longer have a need to run a second, smaller inverter.

    I did keep the older Prosine, and it's wired up next to the Prowatt. It has a separate power feed, 250A fuse, and Blue Sea switch. It can be powered up if needed to run another heavy load, or in case one inverter has a failure (unlikely, but possible). Hurricane season is here, and having a Plan B is a good thing!
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #9
    Re: 1 Big and 1 Small Inverter
    ywhic wrote: »
    The question would be if the fridge kicks on will the A/C unit go off if I put them on the same 2K inverter?? :blush:

    Would a chest freezer be better than a fridge for my (South TX) situation??
    The AC won't go off when the fridge starts, UNLESS you have a relay to remove it's power whenever the fridge starts. Depending on the AC power requirement, as well as the start surge of the fridge, AND the surge capacity of the inverter, the combined load MIGHT overload the inverter and cause it to shut down.
    Chest freezer converted to fridge won't let the cold air flow out when you open the door, but it quickly becomes a pain in the butt to have to dig down to the bottom to find those leftovers from 3 wks ago. Been there, done that.
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  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
    #10
    Re: 1 Big and 1 Small Inverter

    If the AC is running and the fridge compressor kicks in I think you would be fine. The AC running should be around 500 watts give or take and the surge of the fridge starting might be 1,000-1,200 watts(again approx.) so that's well within the limit of the inverter even with other small loads running. Now if the two tried to kick on at the exact same time that would cause a problem but that may be unlikely???
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  • Wxboy
    Wxboy Solar Expert Posts: 70 ✭✭✭✭
    #11
    Re: 1 Big and 1 Small Inverter

    Thinking this through a little more...if the fridge was running and you had a few other small loads running and then the AC compressor tried to kick on that could overload the inverter. It all depends on what the start-up surge is on the AC but if it's between 2,500 and 2,800 watts then you don't have much headroom. It's not something I would worry about right now but it will be interesting to see how things go in your real world testing.

    I still think if you need a second inverter that another Prowatt 2000 would be a good choice. And again I choose that because for the money I think it's worth having the extra capacity over the 1000. I originally wanted a Prowatt 1000 but my dad picked me up the 2000 and I'm glad he did. Not that I can run 1800 watts continuously with my small setup but having the extra surge rating is nice.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #12
    Re: 1 Big and 1 Small Inverter
    Wxboy wrote: »
    I still think if you need a second inverter that another Prowatt 2000 would be a good choice. And again I choose that because for the money I think it's worth having the extra capacity over the 1000. I originally wanted a Prowatt 1000 but my dad picked me up the 2000 and I'm glad he did. Not that I can run 1800 watts continuously with my small setup but having the extra surge rating is nice.

    And what is the difference in self consumption just to run the two inverters? Perhaps there is little difference, I don't know myself, but generally the more powerful the inverter, the heavier it's self consumption. Something to consider if you have limited power sources, and why many of us run a little MS 300 for all but the large loads.
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #13
    Re: 1 Big and 1 Small Inverter

    @ wayne..

    The 1000w is rated at 0.6 amp no-load, and the 2000w is rated at 0.8 amp no-load.. though in real testing 2manytoys shows 0.3 amp in no-load on the 2000w model..
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  • erne
    erne Solar Expert Posts: 41 ✭
    #14
    Re: 1 Big and 1 Small Inverter

    I used a chest freezer and had the same dislikes (hunting and digging) I switched to a upright freezer and my consumption increased from 200 watt/hrs. per day to 300. It is worth the extra 100 watt/hrs and still 700 watt/hrs better than any refrigerator on the market. also remember if you have any 2 way switches on a single inverter you can overload the neutral and create a fire hazard.
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #15
    Re: 1 Big and 1 Small Inverter
    erne wrote: »
    I used a chest freezer and had the same dislikes (hunting and digging) I switched to a upright freezer and my consumption increased from 200 watt/hrs. per day to 300. It is worth the extra 100 watt/hrs and still 700 watt/hrs better than any refrigerator on the market. also remember if you have any 2 way switches on a single inverter you can overload the neutral and create a fire hazard.

    What type/make/model of upright???

    300w beats 900-1000w per day anytime..

    Does that overload also occur if you do neutral/ground bonding on the feed panel??
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  • erne
    erne Solar Expert Posts: 41 ✭
    #16
    Re: 1 Big and 1 Small Inverter

    The freezer is a Kenmore 12 cubic foot. the External thermostat is a Johnson controls thermostat with a built in plug wire plug that goes into the wall and the freezer plugs into the plug that just controls the hot wire. That way there is no change to the freezer or the warranty. My warranty left long ago though. For the two way or three way switch what happens is one switch is on one circuit while the other is on the other, thus allowing both sides to be run on a single unfused neutral. The amperage can double without tripping a breaker and the neutral can heat due to the overload of both circuits returning on a single wire.
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #17
    Re: 1 Big and 1 Small Inverter
    erne wrote: »
    The freezer is a Kenmore 12 cubic foot. the External thermostat is a Johnson controls thermostat with a built in plug wire plug that goes into the wall and the freezer plugs into the plug that just controls the hot wire. That way there is no change to the freezer or the warranty. My warranty left long ago though. For the two way or three way switch what happens is one switch is on one circuit while the other is on the other, thus allowing both sides to be run on a single unfused neutral. The amperage can double without tripping a breaker and the neutral can heat due to the overload of both circuits returning on a single wire.

    Is that like the Johnson Controls KEG type?? Manually set a temp and the unit shuts down the KEG freezer??
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #18
    Re: 1 Big and 1 Small Inverter

    Would a neutral/ground bond in the sub-panel the inverter is hooked to eliminate the neutral overload condition???

    (I made a new thread for this topic under the WIRING section)..
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #19
    Re: 1 Big and 1 Small Inverter

    erne.. Your reply got deleted, lost, or something..
    erne wrote:
    If the switches are wired independent you can’t shut down from one switch to the other, they can be wired safely but they are built to run on two separate legs which you don’t have if you jumper the inverter so both sides are being used by the same 110 inverter circuit. A T-240 or two inverters in classic setting (180 degrees out of phase) is what is needed.

    I don't plan on crossing the inverters at any point.. 2 separate inverters.. Each inverter powering different ends of the cabin.. the ceiling fan would be on a straight run of outlets with 12/3 wire.. and then 2 independant switches with 12/4 wire as a jumper between the two for just the ceiling fan..

    I still don't see how a single inverter can cause and issue using switches..

    The other post about the switches is http://forum.solar-electric.com/showthread.php?16656-Inverter-and-2-way-switches-and-possible-issues
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  • erne
    erne Solar Expert Posts: 41 ✭
    #20
    Re: 1 Big and 1 Small Inverter

    I don’t know what KEG is but all it does is shut off the electricity to the freezer. There is a temperature sensor that goes into the freezer that tells the Johnson control thermostat when to come on or off.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #21
    Re: 1 Big and 1 Small Inverter
    ywhic wrote: »
    ... and then 2 independant switches with 12/4 wire as a jumper between the two for just the ceiling fan..

    I still don't see how a single inverter can cause and issue using switches..

    I really am having trouble seeing just what you are referring to here, and how the two separate inverters are involved. Could you supply a simple schematic or drawing? I am worried that this either has the possibility of connecting the two inverters or else will not do anything that could not be done by a simpler method.
    SMA SB 3000, old BP panels.
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #22
    Re: 1 Big and 1 Small Inverter

    I was thinking of using 2 inverters.. nothing to do with switches for inverters.. this topic got way off..
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #23
    Re: 1 Big and 1 Small Inverter
    erne wrote: »
    also remember if you have any 2 way switches on a single inverter you can overload the neutral and create a fire hazard.

    No! This is NOT true.
    There is no way a "2 way switch" can overload an inverter any more than it can grid power.
    They DO NOT connect to the "two legs" in the circuit breaker panel, or fuse panel.
    I have them in my home and they operate exactly the same way on either grid, or inverter. All they do is interrupt power to whatever it is they control, same as a single switch does, except you can do it from more than one location.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #24
    Re: 1 Big and 1 Small Inverter
    waynefromnscanada wrote: »
    No! This is NOT true.
    There is no way a "2 way switch" can overload an inverter any more than it can grid power.
    They DO NOT connect to the "two legs" in the circuit breaker panel, or fuse panel.
    I have them in my home and they operate exactly the same way on either grid, or inverter. All they do is interrupt power to whatever it is they control, same as a single switch does, except you can do it from more than one location.
    For whatever historic reason, the circuit which allows two switches to control one light is usually called a three-way switch circuit.
    SMA SB 3000, old BP panels.
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