do lower watt inverters use lower watts on idle?

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ElideN
ElideN Solar Expert Posts: 32 ✭
in Solar Water Pumping #1
do lower watt inverters use lower watts on idle?

wat is a good inverter that uses almost no watts during idle?

i saw a Belkin 140 watt stating it uses .02 watts during stand by... is that good, because i knoticed alot of inverters don't even list that..
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #2
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    Re: do lower watt inverters use lower watts on idle?

    less than 100ma from the packaging
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #3
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    Re: do lower watt inverters use lower watts on idle?

    What also matters is how efficient it is while working. Generally MSW inverters (which I would guess said Belkin is a MSW) are not very efficient. Consider a Morningstar Shuresine 300 as a good, low idle current, very efficient true sine wave inverter.

    Tony
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  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    #4
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    Re: do lower watt inverters use lower watts on idle?

    I dont believe the .02 w idle for a 140w inverter.
    average inverter idle powers are
    below 300w MSW about 4w TSW about 8w
    400 to 800w MSW about 5w TSW about 10w
    1000 to 20000w MSW 10 w TSW about 15w

    Icarus I dont know why you said this ""Generally MSW inverters (which I would guess said Belkin is a MSW) are not very efficient" ???? You cant possibly believe it???
    I have NEVER seen a TSW inverter same wattage as a MSW that was even as effecient as it.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #5
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    Re: do lower watt inverters use lower watts on idle?

    Again I agree with icarus. The SureSine 300 (I have two in continuous operation, and one is sending you this message) are EXCELLENT True Sine Wave inverters, and especially in the search mode, watching for a possible load, the idle power is very low.

    Actually, I have an old (about 15 years) Statpower 150 watt MSW that has a standby idle current of only 20ma. But they don't make them like that any more. The new ones tend to be power pigs.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #6
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    Re: do lower watt inverters use lower watts on idle?

    JohnP.

    Most small (read cheap) MSW inverters, like you get at the auto part store are notoriously inefficient. I would challenge anyone to actually measure such an inverter and claim that it is more efficient than a good pure sine wave, like the Suresine 300. (Not to mention if you use a MSW on certain loads, the load itself will draw more current,, adding to inefficiency.

    Tony

    Tony
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #7
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    Re: do lower watt inverters use lower watts on idle?
    icarus wrote: »
    (Not to mention if you use a MSW on certain loads, the load itself will draw more current,, adding to inefficiency.
    Tony

    AC induction motors for example may draw close to 18% more energy if powered by the average MSW inverter, and thus run hotter. That's one reason why fridge compressors usually meet an early death (a year or two) if powered by MSW.
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #8
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    Re: do lower watt inverters use lower watts on idle?

    i don't need any high watts that high i only need less than 100 watts...
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #9
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    Re: do lower watt inverters use lower watts on idle?
    john p wrote: »
    I dont believe the .02 w idle for a 140w inverter.
    average inverter idle powers are
    below 300w MSW about 4w TSW about 8w
    400 to 800w MSW about 5w TSW about 10w
    1000 to 20000w MSW 10 w TSW about 15w

    Icarus I dont know why you said this ""Generally MSW inverters (which I would guess said Belkin is a MSW) are not very efficient" ???? You cant possibly believe it???
    I have NEVER seen a TSW inverter same wattage as a MSW that was even as effecient as it.

    can you re-rate those in amps? because that's the only thing i can understand.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #10
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    Re: do lower watt inverters use lower watts on idle?
    ElideN wrote: »
    can you re-rate those in amps? because that's the only thing i can understand.

    Take the watts, divide by the supply volts, and BINGO, you have the amps! It really is that simple :)
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #11
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    Re: do lower watt inverters use lower watts on idle?

    Power = Volts * Amps...

    So a 10 Watt loss on a 12 volt battery bank:
    • Amps = Power / Volts = 10 watts / 12 volt battery bank = 0.833 amps
    If you want some more information on TSW vs MSW inverters:

    All About Inverters
    Choosing an inverter for water pumping

    In the end, around 80% of devices will probably work OK on MSW inverters and about 10% will not (fail in minutes/hours).

    The problem is knowing which is which.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    #12
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    Re: do lower watt inverters use lower watts on idle?

    Icarus I was not really talking about the super cheap auto store MSW inverters, BUT the result is the same ,some from those stores claim on the box to be TSW BUT the only thing they have in common with a good TSW inverter THEY DO USE MORE CURRENT AT IDLE. But as to being sine wave.welll... hmmmmmmm,only if you define sine wave as something slightly better than a square wave.
    I still say I have never MEASURED a similar watt rated TSW inverter to be even same current draw at idle as MSW .ALL draw more when measured usually double.
    Trust me I have measured hundreds of them. I dont go by the "brochures or the adds". I do this just about every working day. We take ALL measurements of everything that enters the facility.they we get to test and usually destroy them , and get paid to do so.NOt much leaves my test area alive.
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  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    #13
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    Re: do lower watt inverters use lower watts on idle?

    average inverter idle powers are assuming 12v
    below 300w MSW about 4w 300ma TSW about 8w 650ma
    400 to 800w MSW about 5w 400ma TSW about 10w 800ma
    1000 to 20000w MSW 10 w 800ma TSW about 15w 1200 ma
    These are aprox for many inverters of average consumer grade available to purchase now.
    Yes you can find better and conversly you can find worse.
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #14
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    Re: do lower watt inverters use lower watts on idle?

    does anyone have skype or vent who can help me with my project?
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #15
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    Re: do lower watt inverters use lower watts on idle?

    84807096.png

    so far this is what i came up with so far...

    this is for my 15watt pump
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #16
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    Re: do lower watt inverters use lower watts on idle?

    Backing up a moment... What are:
    1. The loads you want to drive (type, watts/amps/volts)?
    2. How long do you want to use them (1 minute, 1 hour, 1 day per day)?
    3. Summer Weekends/Cabin/RV use or 9+ months cabin/home?
    4. 120 VAC vs 12/24/etc. DC?
    5. How much room and/or weight can you allow for batteries (portable, fixed)?
    6. How much room for solar array(?)
    7. Where will this be installed (amount of sun)
    8. Backup power (generator, grid)?
    9. And, frankly, are you looking to do this for as little money as possible?
    10. Any special needs?
    I am sorry to ask the questions again--But it is easy to lose the forests for the trees.

    Identify the loads and ensure that you have addressed the conservation issues first (i.e., small laptop vs big desktop computer--can save thousands of dollars in solar panels and batteries). Then define the loads. Next the inverter/battery/solar panels/backup genset all pretty much fall out of the defined loads/location/power needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #17
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    Re: do lower watt inverters use lower watts on idle?

    Why don't you use a dc pump? Please describe what you're trying to do?

    Tony
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #18
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    Re: do lower watt inverters use lower watts on idle?

    What is the 15 watt pump? Can you replace with a 12/24 volt DC unit?

    Also, what is the duty cycle of the pump... Frequently, people only run pumps for a few minutes per hour... So the actual pump power and inverter AC load efficiency is not near as important as what happens the other ~95% of the time.

    For example if your pump only runs 20 minutes of out 24 hours that is a 1.4% duty cycle. If you can get the DC standby power way down--then you could have a pretty inefficient inverter/pump combination and still be very happy.

    For example the MorningStar 120 VAC TSW 12 volt inverter can operate in "standby mode"... Basically it only runs 120 VAC for a 1/30th of second for per second which averages around 55 mAmps (0.055 amps) or:
    • 0.055 amps * 12 volts = 0.66 watts
    This could allow you to use the regular AC switch/float/etc. to control the pump without any modifications (if waiting up to 1 second for pump to turn on is OK with you).

    Or, you can even hook up the DC "inhibit/remote on/off switch" to the inverter and it will draw:
    • 0.025 amps * 12 volts = 0.3 watts
    • 0.3 watts * 24 hours = 7.2 Watt*Hours per day in remote on/off mode
    So, if your pump switch can be operated at 12 VDC, this would be another way to run your system.

    Again, trying to give you ideas of what I/we are looking for--Not trying to change your system design/requirements (I/we are not there).

    -Bill

    PS: I guess this is the thread describing a bit about the pump:

    setting up my solar panel system to run my pump!

    But, it still not clear to me exactly what the pump is doing and how long per day you need it to operate... Assuming you are around North/Central Texas?
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #19
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    Re: do lower watt inverters use lower watts on idle?

    @Tony I am trying to run my pump 24/7.

    @BB.
    1) running a water pump, watts is 15watts 12volts (used killawatt meter and it said this for my pump)
    2) 1 day per day
    3) home
    4) 120VAC(house) 12V(battery)
    5) yes i can allow for batteries
    6) i got a back yard
    7) roof or backyard
    8) deep cycle battery (offgrid)
    9) yes
    10) help me! im looking for most low watt efficient inverter as possible for 1 pump to run 24/7.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #20
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    Re: do lower watt inverters use lower watts on idle?

    But can you run a DC pump instead? What are you pumping? How hig, how much pressure, how many gpm/gpd? Is this a circ pump?

    Tony
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #21
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    Re: do lower watt inverters use lower watts on idle?

    i wish you guys have skype or vent... so we can chat instead...

    eco 264 pump
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #22
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    Re: do lower watt inverters use lower watts on idle?

    Yes,, but wht are you doing with it?

    Tony
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #23
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    Re: do lower watt inverters use lower watts on idle?

    i want to run the pump 24/7
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #24
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    Re: do lower watt inverters use lower watts on idle?

    So, this is the pump?

    www.horticulturesource.com/product_info.php?products_id=877

    Submersible/low head/high volume pump (horticultural/fish pond circulation pump)? 6' max head, 4.4 gpm flow...

    On of the big issues with "moving water" and other phycsical jobs is that they can use lots of power. And off-grid solar systems are not very good at providing lots of power "cheaply".

    By the way, is this seasonal or year round (winter/summer sun)? Is there backup power available (grid/genset/etc.)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #25
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    Re: do lower watt inverters use lower watts on idle?

    yeah that is the pump

    right now it is connected to the house wall...

    i want to use it all year round...

    yeah a deep cycle battery
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #26
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    Re: do lower watt inverters use lower watts on idle?

    But you are still not answering the question! What are you using the pump for?!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #27
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    Re: do lower watt inverters use lower watts on idle?

    At this point, assuming it is water--I guess it does not matter too much.

    The issue is that off grid battery backed solar power will (almost always) cost you 10x what your local power does (i.e., $1-$2+ per kWH vs $0.10-$0.20 for most people in the US).

    Also, sun may vary over the seasons by a factor or 2 or 3x... You have to design to meet your needs for the appropriate season(s).

    Generally, a external pump mounted below the water level is the most efficient form of pumping. The worst is probably a pump drawing 10+ feet of suction. Sumerged pumps tend to cost more and may not last as long (because of water leaks).

    Your power needs are not great by themselves, but when you multiply everything out (24 hours per day, pump/inverter/battery losses, backup power--if needed).

    Just to pick some round numbers. Say you can do this with 20 watts 24 x 7 and you need it off grid 12 months a year (ignoring a days/week of bad weather--you almost always need to curtail loads and/or use a backup power source--pure solar would be horrendously expensive)...
    • 20 watts * 24 hours per day = 480 Watts*Hours per day
    Assume Fort Worth Texas with PV Watts. Fixed array, 1 kW (default) solar array and 0.52 system derating:
    "Station Identification"
    "City:","Fort_Worth"
    "State:","Texas"
    "Lat (deg N):", 32.83
    "Long (deg W):", 97.05
    "Elev (m): ", 164
    "PV System Specifications"
    "DC Rating:"," 1.0 kW"
    "DC to AC Derate Factor:"," 0.520"
    "AC Rating:"," 0.5 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 32.9"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 9.7 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 4.32, 66, 6.40
    2, 4.77, 66, 6.40
    3, 5.50, 82, 7.95
    4, 5.98, 85, 8.24
    5, 6.02, 86, 8.34
    6, 6.25, 84, 8.15
    7, 6.39, 87, 8.44
    8, 6.31, 86, 8.34
    9, 5.83, 78, 7.57
    10, 5.56, 80, 7.76
    11, 4.43, 65, 6.30
    12, 4.10, 63, 6.11
    "Year", 5.46, 929, 90.11
    So, the minimum (20 year average) sun is 4.10 hours of sun (great weather there).
    • 480 Watt*Hours * 1/0.52 PV system derating * 1/4.1 hours of sun = 225 Watts of solar panel minimum
    In reality, you should probably plan on 30% to 50% more solar panels to allow for a bit of bad weather and other issues.

    Battery bank wise, you would be looking at 1-3 days of no sun and 50% maximum discharge. Pick 2 days and 50% max discharge:
    • 480 WH * 1/12 volt battery bank * 1/0.85 inverter losses * 2 days * 1/0.50 max discharge = 188 AH
    Battery charging is recommended to be around 5% to 13% of battery bank AH capacity (20 Hour Rate). Pick 10% as a nice healthy sized solar array:
    • 188 AH * 14.5 volts charging * 1/0.77 solar+charger losses * 0.10 rate of charge = 354 Watt Array "Nominal" suggested size
    So, your solar array should be around 225 to 354 watts rated for "optimum" based on 20 watt 24*7 in December (really, I would suggest that ~355 watts be the minimum array).

    You can put these equations into a spread sheet and play with pumps/inverter/etc. and see what works out best for you.

    Note that an inverter that runs 6 watts of "tare losses" is almost 1/3rd of your pumping costs... These Little Losses (tare, battery cycling, panel deratings, etc.) all add up...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #28
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    Re: do lower watt inverters use lower watts on idle?

    THANK YOU FOR THIS....

    also wats a good inverter?

    im guessing any inverter that has 75watts so i can plug up my pump right?

    should i worry about pure or modified inverters?

    im looking for a low idle watt inverter so it doesn't drain my battery during the night...
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #29
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    Re: do lower watt inverters use lower watts on idle?

    Clearly you are not inteeted in answering what you are using the pump for. I have another question,,why are youo concerned about the stand by currrent if you plan on using the pump 24/7?


    I would be concerned with a motor load on a MSW inverter.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #30
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    Re: do lower watt inverters use lower watts on idle?

    I am confused--Running the pump 24 hour per day or not? And if not, how many hours per day (if you can pump only during sunlight hours--i.e., roughly 9am-3pm or so--you may be able to skip the battery bank/charge controllers/inverters completely--That will save you a huge amount of money and frustrations).

    There are lots of good inverters out there--But generating 120 VAC is lossy and if not needed (for example you can find good DC pumps and the run from the battery bank to the pump is only a 5-10 feet or so away), then DC may be a better solution (there is the issue that many DC pumps are brushed motors, which will only run 6-8 months or so 24x7.).

    It is a big shell game to build an optimum system (i.e., a 120 VAC inverter so you can use inexpensive brushless pumps--but cost you because of inverter, larger battery, larger array, more losses--And it may work out that a DC pump will cost more, but the balance of system cost less because of less hardware and lower overall power needs).

    Or, if the pump is 100' away from the battery bank, then you are almost forced to 120/240 VAC to have acceptable losses or are forced to use "huge" diameter copper wire because of the losses of sending out 12 volt power any distance (again, there are 24 and 48 volt DC pumps too).

    You probably will need to go through a self education and search for "optimum" DC and AC pumps for your needs... Then the rest becomes (more or less) a couple paper designs with plug-in numbers and searching of components that meet the design needs at the price you can afford--And you do this several times (different pump options, AC vs DC, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • ElideN
    ElideN Solar Expert Posts: 32 ✭
    #31
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    Re: do lower watt inverters use lower watts on idle?

    oh aquaponics, im new to all of this. i recently just got layed off... im hoping to grow my own food... i stated that last in the other thread bb posted...

    im worried about it because i am limited on cash, so my battery bank is also limited... that is why i am concerned about the stand by current which is at night...

    right now i am using the pump on the wall and the inverter i currently have was draining my battery to half way... :(

    the pump is giving me 11-15watts at 12v dc...
    https://www.youtube.com/watch?v=_TOSnabjBBQ


    tomato plants growing tall right in the middle of winter...

    i will move it out door and build a greenhouse hopefully and move the solar setup to the backyard...
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