Making it work?

lalakailalakai Registered Users Posts: 12 ✭✭
Aahhh, religated to being a noob once again; story of my life. Tried searching for similiar topics and no luck, so hopefully I can give folks a new situation to ponder.

Just starting to put first solar system together; looking for a portable system that incorporates batteries, inverter, and direct feed from solar panels. At current the power usage would be light; recharging cell phones, laptops, rechargeable batteries, running simple lights. Biggest question is whether or not I can use an old http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SU1400NET as the battery/inverter component? I have a decent idea of how to wire it in, but before i replace the batteries, I'm trying to determine if it's a viable option. lol once I cross that hurdle, then I'll have a few more questions. So any help or input would be appreciated. Thanks.

Comments

  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Making it work?
    lalakai wrote: »
    Aahhh, religated to being a noob once again; story of my life. Tried searching for similiar topics and no luck, so hopefully I can give folks a new situation to ponder.

    Just starting to put first solar system together; looking for a portable system that incorporates batteries, inverter, and direct feed from solar panels. At current the power usage would be light; recharging cell phones, laptops, rechargeable batteries, running simple lights. Biggest question is whether or not I can use an old http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SU1400NET as the battery/inverter component? I have a decent idea of how to wire it in, but before i replace the batteries, I'm trying to determine if it's a viable option. lol once I cross that hurdle, then I'll have a few more questions. So any help or input would be appreciated. Thanks.

    Well, for a start, it looks like that UPS would not contain the necessary circuitry to charge the battery from a DC source like your panels, so you would have to add that. In terms of battery charging, there is no such thing as direct feed from solar panels unless you are looking only at trickle charging a car battery. And the combination of battery and inverter are designed for maximum power out, potentially to near 100% discharge, with the rest of the time spent mostly on float charge. That is not the ideal design for frequent partial discharge with recharge from an external source.

    If the price is right, it might work OK but with greatly reduced battery life. You would have to mange it yourself to limit the State of Charge (SOC) to no lower than 60% to preserve the battery.
    SMA SB 3000, old BP panels.
  • lalakailalakai Registered Users Posts: 12 ✭✭
    Re: Making it work?

    inetdog, thanks for the input. If the basic system looks feasible, I'll add in a way to monitor battery levels though from the info from APC it looks like this particular ups has an auto shutdown when batteries reach a certain level of discharge. I had thought since the ups was designed for frequent use/discharge, that the batteries would be designed for more active use, versus a float charge. The pre-packaged system of battery and inverter for mobility seemed ideal, when teamed with solar panels that could be used to recharge the batteries. May need to do a bit more research
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Making it work?
    lalakai wrote: »
    i I had thought since the ups was designed for frequent use/discharge, that the batteries would be designed for more active use, versus a float charge.

    Most UPS units that I have seen use only the line AC when it is available, regardless of the amount of load applied. For most people power outages would be infrequent, and short. That does not match my definition of frequent use/discharge. The typical portable off-grid system would be used on and off for a day or two at least a few times per month. That is closer to my idea of frequent. If you would be using it 50% or more of the time, then that would definitely be frequent.

    Some "always on" UPS systems are always converting the input AC to DC and using that to run an inverter for the output. This gives them zero switching time when the AC fails. But even then, there is usually no load whatsoever on the batteries as long as the AC input is on.
    SMA SB 3000, old BP panels.
  • peakbaggerpeakbagger Solar Expert Posts: 341 ✭✭✭
    Re: Making it work?

    If you want oget up to speed on all things solar, pick up a subscription to Home Power magazine. They used to have a deal where you could get an archive CD of their first 10 years of issues. It may take some searching but there is almost always an article that will match what you want to do.
  • lalakailalakai Registered Users Posts: 12 ✭✭
    Re: Making it work?

    Hi Peakbagger. Thanks, i'll check into it and see if they still have that option for viewing the past issues.

    Considering the cost of the replacement battery for the ups unit, i could pick up a decent deep cycle battery with more amp hrs. Still trying to make it work using the existing components of the ups; the inverter plus the ability to use ac power to recharge the battery if needed, makes it seem like it combines some nice options. Then again, can't push a rope so.......i'll post some updates of which direction i go and how it works.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Making it work?
    lalakai wrote: »
    Aahhh, religated to being a noob once again; story of my life. Tried searching for similar topics and no luck, so hopefully I can give folks a new situation to ponder.

    Just starting to put first solar system together; looking for a portable system that incorporates batteries, inverter, and direct feed from solar panels.
    What do you mean by "direct feed from solar panels"? With only a few exceptions, you don't want to power anything directly from solar modules. On an off grid system, modules feed a charge controller, charge controller feeds batteries, batteries power the load (DC or inverter).
  • lalakailalakai Registered Users Posts: 12 ✭✭
    Re: Making it work?
    ggunn wrote: »
    What do you mean by "direct feed from solar panels"? With only a few exceptions, you don't want to power anything directly from solar modules. On an off grid system, modules feed a charge controller, charge controller feeds batteries, batteries power the load (DC or inverter).

    I realize i'll need a charge controller between the battery and the panel but from what i thought, some charge controllers would allow you to run a direct line from the controller to another unit via an option such as the cigarette lighter adapter module, without having to go through the battery. Maybe this is an incorrect assumption on my part; part of the learning curve. The basic system I'm thinking of, is something that is portable, can be used to charge a battery or provide power directly from the charge controller.:confused:
  • BB.BB. Super Moderators, Administrators Posts: 29,702 admin
    Re: Making it work?

    The voltage between the array and the charge controller is, more or less, unregulated (between zero and 21 volts or so for a "12 volt" array). Most inverters would not "be happy" with that power.

    You place your inverter on the battery bank side, and the solar charge controller + battery bank will share the inverter/DC loads.

    If the batteries are charged, and the sun is up, the charge controller will be supplying the current to the DC loads (as long as the loads are less than the charge controller/array's available current). As the sun goes down (and/or loads go up), the battery bank will begin to supply current too.

    This is pretty much how the electrical system in your car operates. Just using solar panels instead of the alternator.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Making it work?
    lalakai wrote: »
    I realize i'll need a charge controller between the battery and the panel but from what i thought, some charge controllers would allow you to run a direct line from the controller to another unit via an option such as the cigarette lighter adapter module, without having to go through the battery. Maybe this is an incorrect assumption on my part; part of the learning curve. The basic system I'm thinking of, is something that is portable, can be used to charge a battery or provide power directly from the charge controller.:confused:

    Some charge controllers (CC) do have Load terminals which are energized only when the panels are producing power, and possibly only when not all of the panel output can be sent into the batteries. Details vary with the CC.
    SMA SB 3000, old BP panels.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Making it work?
    lalakai wrote: »
    I realize i'll need a charge controller between the battery and the panel but from what i thought, some charge controllers would allow you to run a direct line from the controller to another unit via an option such as the cigarette lighter adapter module, without having to go through the battery. Maybe this is an incorrect assumption on my part; part of the learning curve. The basic system I'm thinking of, is something that is portable, can be used to charge a battery or provide power directly from the charge controller.:confused:
    You don't go "through" the battery in any case; the battery is in parallel with the charge controller output and the inverter input. You can tap that line (also in parallel) for DC loads.
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