Inverter Upgrade

jmdraft
jmdraft Registered Users Posts: 5 ✭
in Off Grid Solar & Battery Systems #1
Now that my house has finally gotten comfortable, it’s time to upgrade my inverter to run stuff like refrigerator, microwave, stereo system, computer, household appliances, air compressor etc. I want something with hardwire terminals. Over the years of researching it, I’ve always heard that I should get pure sine wave but I’ve heard form some that modified sine wave is good enough if the wattage is high enough.

My house: http://geriatricgourmet.com/Home_Off_Grid.html

So now I want to hear form some folks who have actually been living off grid for some years. How much wattage, pure or modified, what brands etc? Any suggestions?
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Comments

  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #2
    Re: Inverter Upgrade

    Pure sine wave because you won't have any problems ;)
    From the loads you listed it looks like a 3kW unit should do the trick. You might be able to get away with less, but then you'll have to be careful about what you turn on when, e.g. no compressor while the microwave is on etc. Looks like you're in the US, so Outback and Magnum would be good choices. Outback gives you modular field-replaceable parts, while magnum gives you the option of split phase on some of their models if you need that for any loads.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Inverter Upgrade

    Welcome to the forum.

    Considering what you want to run, do not waste your time with an MSW inverter. It is not simply a matter of Watts, it's a matter of waveform. Some things just do not get along with less than pure sine. This would include motors like in the refrigerator and electronics like in the microwave. Oh it may work, but then again it may not. Or it may simply cause the device to die an early death rather than a later one.

    The items you list you will need to get specific information on. For instance "household appliances" could be a blender than uses 60 Watts or a toaster that uses 1500 Watts. There's a big difference between the two. The refrigerator will use less than 200 Watts running, but its start demand is likely going to be over 1 kW.

    Air compressor? Same thing: how big? Even a little one has a heavy start demand, especially if it has to start against a tank of air. I have a small pancake unit for my air tools and it has an unloader valve, but still draws heavy current; runs at 1200 Watts.

    Get a Kill-A-Watt meter and measure what you want to run, both in terms of its peak draw (you will not see start surges recorded; they happen too fast) and how many Watt hours you typically use them for. This information is vital if you want the system to work.

    Depending on how much of this stuff you want to run simultaneously, you're looking at 3 to 4 kW inverter. A microwave will use 1 kW itself. It doesn't run long, so it won't rack up the kW hours but you still have to be able to supply the needed power when it does run.

    Likewise the battery bank has to be sized to accommodate the total kW hours per day and be able to handle the momentary highest power demand. And then the array & controller must be large enough to recharge that battery bank.

    Upgrading a small system to a large system is very difficult. Most of the time you end up starting over with all new equipment.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #4
    Re: Inverter Upgrade

    TSW preferred as it goes well with everything, MSW has some issues

    you did not tell us what voltage you are using now.... you need 24 or 48V

    Another option is to have a larger Inverter to run the appliances 1500 - 2500W with sleep or idle mode and a smaller 300 -800W inverter that runs lights and small electronic loads that runs 24/7.

    Do you want AGS, auto bypass switch, True Generator support ?
    ( See post http://forum.solar-electric.com/showthread.php?18459-Demonstration-of-Generator-Support)
     
    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
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #5
    Re: Inverter Upgrade
    westbranch wrote: »
    Another option is to have a larger Inverter to run the appliances 1500 - 2500W with sleep or idle mode and a smaller 300 -800W inverter that runs lights and small electronic loads that runs 24/7.

    That's what I find works awesome for me. Morningstar 300 watt inverter is on 24/7 and runs everything in the house EXCEPT the big draw items like water pump, washing machine, microwave, shop tools etc. Those are on a separate circuit powered from the Xantrex Prosine 1800 that's in power save mode. And all are Pure Sine Wave. I learned to stay away from MSW some years back.
    Very pleased with this setup except if I had known, would have gone 24 volts instead of the 12 volts I'm stuck with.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #6
    Re: Inverter Upgrade

    I run the whole house (sans fridge ) on the Shursine 300. I leave the power tools to the genny.

    Tony
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #7
    Re: Inverter Upgrade
    icarus wrote: »
    I run the whole house (sans fridge ) on the Shursine 300. I leave the power tools to the genny.

    Tony

    That SureSine 300 is one almighty awesome inverter. Got to be best in it's class. So sad it's only available in 12 volts :(
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #8
    Re: Inverter Upgrade

    It is also too bad t hey don't make it 600 running watts!

    Tony
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: Inverter Upgrade
    icarus wrote: »
    It is also too bad t hey don't make it 600 running watts!

    Tony

    Well if they made them "stackable" ... it would necessitate more complexity and thus expense.

    Maybe they should have a 500 Watt version with enough surge capacity to handle a 'frige start-up. If the 300 can go to 600 momentarily, a 500 could kick 1 kW for a couple seconds.

    Then they could make them stackable and you could increase your system size by "plugging in" another 500 Watts at a time ...
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  • firerescue712
    firerescue712 Solar Expert Posts: 95 ✭✭
    #10
    Re: Inverter Upgrade

    Looking at the items on the MidNite forum, it seems they are working on a "500-watt", "stackable", "24- or 48-volt" TSW inverter. It should be out later this year. The items in the "" marks indicate discussion requests, but nothing has officially been leaked as to the inverter's specs. I am anxiously awaiting the release. If the OP has time, it might be worth waiting on to see what MidNite might bring to the table. I do agree that the Suresine is a great inverter. Maybe they will come out with a higher wattage or 24-volt inverter soon?
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #11
    Re: Inverter Upgrade

    I agree that there is a need for a small inverter that works on 24 or 48 volts. Exeltech makes some, but I hope to find something with a lower no-load draw. I really like the specs on Victron's Phoenix inverters. They have a 24 volt 750 watt model with a 5 watt no-load draw (2 watts in search mode). It is listed for marine use (it has built in outlets), but not for hard wiring in a home.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #12
    Re: Inverter Upgrade

    Or you can feed both sides of a split phase panel with two. That won't solve the fridge issue, but would allow 600 watts total pretty easily.

    Tony
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  • jmdraft
    jmdraft Registered Users Posts: 5 ✭
    #13
    Re: Inverter Upgrade

    Sorry, I forgot to mention: My NM house is 24V.
    I only live there in summer to escape Texas heat. My NM house is at 9000 ft. and I’m an old sissy about snow………..too much of it during my Air Force days in Germany. I think I have about 1200 watts on the roof (panels)……..bad memory. I actually have 2 battery banks with about 10-12 12v in each. I never run much at one time: lights, power tool chargers, radio, laptop; not much more. But my wife wants to use our microwave more often so I need to upgrade. Our fridge is propane and I have a solar ice maker (I invented it) so that’s covered. My air compressor is a little pancake. Next year I need to run a table saw a little and a metal chop saw. I mostly weld with gas but have a tig and might like to try it.

    Googleing around this morning, I looked at these:
    http://www.buycheapr.com/us/product.jsp?prodpar=sc&prodid=110920193&ga=us15&ts=go#
    http://www.amazon.com/Neiko-Power-Inverter-4000Watt-Surge/dp/B000RFTU54
    http://www.powerbright.com/

    http://www.donrowe.com/inverters/1000_5000_watt.html
    http://www.donrowe.com/inverters/pw6000.html
    http://www.donrowe.com/inverters/wagan_3000.html
    http://www.donrowe.com/inverters/wagan_5000_c.html
    http://batterychargersbu.blogspot.com/2012/11/go-power-gp-sw2000-12-2000-watt-pure.html

    But I’m an armature so they’re probably wrong.

    Note: I tried to upload an avatar by clicking on the blank picture but nothing happens.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #14
    Re: Inverter Upgrade

    One thing you've got going for you: 9000 feet of elevation. Your panels are going to run more efficiently than we'd typically expect. Probably 85% with the controller (mine will do 82% @ 3200 feet).

    Ten 12 Volt batteries is not good. That's five parallel strings for 24 Volts. This is likely to have current sharing problems.

    Tell you what I got away with this past year: bulk charge early with the gen, let the panels take over, and I could run my power tools (including compressor) without worry.

    We have a microwave too, but it only gets occasional use usually midday when the panels are providing "free" energy anyway. Still, it's 1200 Watts use vs. 560 from the panels.

    Buy cheap equipment and you get cheap equipment. As long as that's all you're expecting ...

    That "Powerbright" looks like the Samlex/Cotek line.
    Check out our host's listing of quality inverters: http://www.solar-electric.com/inverters.html
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  • jmdraft
    jmdraft Registered Users Posts: 5 ✭
    #15
    Re: Inverter Upgrade

    Thanks,

    Can you tell me how to load my avatar?

    Yes, I know abut the strings of batteries and the problems with them but it’s my predicament. I only live there in summer and I’m my only heavy lifter so I only bring batteries (about 4 new each year) that I can carry……..easily. The banks are, and have to be, well hidden because we have unwanted “guests” during winter. Big ones would be hard to hide. It’s not the best situation but I’ve been doing it for 20+ years and I’m accustomed to the routine. It has all worked ok so far but we’re just getting old and want a few more conveniences e.g. microwave.

    I have another off grid house in Texas (where heat is the issue) but there, I have neighbors who watch the house and I can have bigger batteries. I got them from an Air Force base……….government stuff. It is double envelop with deep basement and greenhouse on south side to pull the cool air up through the walls and it stays cool enough with one small window AC unit.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #16
    Re: Inverter Upgrade

    You can try loading your Avatar using this link:

    http://forum.solar-electric.com/profile.php?do=editavatar

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #17
    Re: Inverter Upgrade

    Victron from Holland is another good brand that has smaller units, see table at the bottom, 12, 24, 48 V models

    http://www.victronenergy.com/upload/documents/Datasheet%20-%20Phoenix%20Inverter%20180VA%20-%201200VA%20-%20rev%2005%20-%20EN.pdf
     
    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
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