do lower watt inverters use lower watts on idle?

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: do lower watt inverters use lower watts on idle?

    Are you trying to go off grid/planning for the worst (and praying for the best), or will you have grid power for the foreseeable future?

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

    i would love to go off grid, but i don't have the luxury. this small project would teach me sustainability if anything should happen and i could always rebuild it with assurance that i can do it.

    sad thing though a lil too late into neat projects such as these, you guys are awesome with knowledge. thank you all for your help.

    i might end up dismantling the entire thing and move... they are rezoning my area to zone 3... and they raising our property taxes like crazy!

    future unknown. i need to find new ways to make money since no one is hiring around my area.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: do lower watt inverters use lower watts on idle?

    That is why we had "Proposition 13" all those decades ago... My parents were in great fear that they would not be able live in their home when they retired because of dramatically increasing property taxes. At least that was successful for them (kept the house 'till they died).

    Did not really slow down the other tax increases (income, sales, etc.).

    Solar can be very interesting, and at times, be a cost effective solution (typically places not near existing power lines). But otherwise, conservation is usually the best "investment". Almost always better than solar Grid Tied or Off Grid solar for homes/locations with utility power.

    Good luck for the future and to your family.

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

    After reading all the posts from everyone and the original posters questions.I cant understand at all why there has been any importance put on the idle current draw when its going to be run 24/7??. Its kinda like worrying if money could be saved by reducing the wattage of a fridge bulb from 15 to 12 on a 20cft fridge.. Well yes it could but by a miniscule amount and not worth persuing.
    It also seems that the size of the motor is going to be small as its only recirculating water in a hydrophonics system Its not drawing water for a 100 acre farm from a 200ft deep well. I would be visiting a boat supply shop and asking about pumps, and be looking at a 24v DC pump. Also look at bilge pumps.No inverter and all of its losses .Boat parts supply shops are a good source of many useful things for "going solar"
  • erne
    erne Solar Expert Posts: 41
    Re: do lower watt inverters use lower watts on idle?

    Why not reverse your water from the tank to the grow bed? That way you can put the pump on solar and DC. pump to a separate tank from the pond to a tank higher than the grow bed. Then use a a valve to regulate the water into the dump for the grow bed. The dump dumps by gravity balance. Common for aqua-phonics. You have to let the roots get air also, so you must dump and let the water drain into the fish and do so every 30 to 45 minutes. This can be gravity feed using no electric. you pump up in the morning for day usage, and in the afternoon for night usage. no battery or inverter needed. A Sure-flow pump uses about 2,5 amps and can fill a 55 gallon tank twice a day with ease.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: do lower watt inverters use lower watts on idle?
    john p wrote: »
    After reading all the posts from everyone and the original posters questions.I cant understand at all why there has been any importance put on the idle current draw when its going to be run 24/7??. Its kinda like worrying if money could be saved by reducing the wattage of a fridge bulb from 15 to 12 on a 20cft fridge.. Well yes it could but by a miniscule amount and not worth persuing.
    It also seems that the size of the motor is going to be small as its only recirculating water in a hydrophonics system Its not drawing water for a 100 acre farm from a 200ft deep well. I would be visiting a boat supply shop and asking about pumps, and be looking at a 24v DC pump. Also look at bilge pumps.No inverter and all of its losses .Boat parts supply shops are a good source of many useful things for "going solar"


    See my post #29, which asks the same question!

    On a side note,, off gird battery based system is never going to be cheaper than simply plugging into the wall.

    Tony
  • Volvo Farmer
    Volvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: do lower watt inverters use lower watts on idle?
    john p wrote: »
    I would be visiting a boat supply shop and asking about pumps, and be looking at a 24v DC pump. Also look at bilge pumps.No inverter and all of its losses .Boat parts supply shops are a good source of many useful things for "going solar"

    We use 500GPH 12V bilge pumps to recirculate water in a 1200 gallon tank in a solar heated greenhouse. They don't last in that application at all. We are running them solar-direct off a 50W panel when the sun is shining. I don't think we have ever gotten more than 6 months out of one and are on out 4th or 5th one now. They only cost $20 or so for the cartridge, but in a 24/7 application, I think he'd be buying 4 or 5 bilge pumps a year. I'm trying to find a way to limit the power to ours so it turns slower and maybe lasts longer but my experience has been that a bilge pump running anywhere close to 50% duty cycle daily wears out the bearings (or maybe the seals) in short order.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: do lower watt inverters use lower watts on idle?

    Since we don't know any of the details about the OPs application, things like duty cycles, lift, gpm etc it is increasingly hard to make any cogent recommendations to him.

    As an editorial note, it is frustrating to be here to help when people don't make any effort to help themselves by providing critical information, even after repeated requests to do so.

    My rant for the day,

    Tony
  • Volvo Farmer
    Volvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: do lower watt inverters use lower watts on idle?

    Well, not everyone wants their neighbors knowing that they are hydroponically growing tomatoes in the dead of winter. I mean, what if the SHTF and some biker gangs come and steal all your tomatoes or something? You might get stuck with all this nifty off grid solar stuff and no tomatoes! Sometimes a little secrecy is in order, you know.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: do lower watt inverters use lower watts on idle?

    Tomatoes,,, oh right,, I get it. He's not from BC is he? They grow great hot house tomatoes!
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: do lower watt inverters use lower watts on idle?

    careful guys as there's no need to go this route and scare off somebody that wants advice.
  • telljf
    telljf Registered Users Posts: 26 ✭✭
    Re: do lower watt inverters use lower watts on idle?
    john p wrote: »
    After reading all the posts from everyone and the original posters questions.I cant understand at all why there has been any importance put on the idle current draw when its going to be run 24/7??. Its kinda like worrying if money could be saved by reducing the wattage of a fridge bulb from 15 to 12 on a 20cft fridge.. Well yes it could but by a miniscule amount and not worth persuing.
    It also seems that the size of the motor is going to be small as its only recirculating water in a hydrophonics system Its not drawing water for a 100 acre farm from a 200ft deep well. I would be visiting a boat supply shop and asking about pumps, and be looking at a 24v DC pump. Also look at bilge pumps.No inverter and all of its losses .Boat parts supply shops are a good source of many useful things for "going solar"

    The idle current is drawn by the inverter whether it is loaded or not. If the inverter consumes 25W AC under no load, then that need to be added to the total load while designing the system.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: do lower watt inverters use lower watts on idle?
    telljf wrote: »
    The idle current is drawn by the inverter whether it is loaded or not. If the inverter consumes 25W AC under no load, then that need to be added to the total load while designing the system.

    Just to clarify, "idle" current is what an inverter consumes under no load. Sometimes it is called "stand-by current". This can be significantly less than when it uses when producing power.

    A couple of examples:
    Morningstar 300: stand-by current 55 mA, running current (no load) 450 mA
    Outback 3524: idle power use (search) 6 Watts, idle power use (full) 20 Watts

    Note two different companies using two different terminologies to define essentially the same thing. This is what leads to confusion. In each case the first figures indicate power used by the inverter when it is not producing for a load, the second when it is producing (less the load demand of course). As John said, if it's going to be "on" 24/7 the first number is irrelevant. As telljf said, the second number has to be included in figuring the load the batteries must supply.

    Standardizing the terminology would make it easier to compare one brand to another, but that is unlikely to happen as all manufacturers of everything like to present their products in the best light - which sometimes means expressing things in somewhat confusing ways. :grr
  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: do lower watt inverters use lower watts on idle?

    And of course if a given inverter happens to have a 20 watt "idle" consumption, and an efficiency of 85% when producing 1000 watts, the power lost in the inverter goes from 20 watts, up to 150 watts.
  • john p
    john p Solar Expert Posts: 814 ✭✭✭
    Re: do lower watt inverters use lower watts on idle?

    There is only one accurate way to measure an inverters idle current ,no load current, wet tuesday current, load current,overload current, black current.

    Your best friend is a DC amp meter for low current draw, or a shunt and millivolt meter for high current draw.

    I have always advocated that a shunt should be left in series between battery/ies and inverter. Observing the millivolt meter using the inverter under different loads or no loads will show where ALL losses are.. No calculations needed, Its useless trying to measure the inverter power consumed by measuring the AC side.Its just far to inaccurate for most instruments.
    You will be amazed what you can learn about your inverter and the current draw of items powered by it by observing your millivolt meter or amp meter.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: do lower watt inverters use lower watts on idle?

    The only problem with measuring actual current draw under varying load conditions is that they don't let you do that before you buy an inverter. When you're trying to make the choice of which to purchase you have to rely on the info provided by the manufacturers.