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Is inverter output amps equal to solar panel output amps?

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  • Is inverter output amps equal to solar panel output amps?

    If a panel has 250 Watts and 8 Amps then the output voltage would naturally be 31.25 VDC.

    Q: if the panel output voltage is regulated down to 12 VDC, based on the Watts/Volts=Amps, does that mean the panel output Amps goes up to 20.83? As in 250 Watts /12 Volts = 20.83 Amps? Or, does the panel Amps stay at 8 Amps no matter what.

    So what kind of amperage can the inverter put out?

    Thanks

  • #2
    Originally posted by rafbo View Post
    If a panel has 250 Watts and 8 Amps then the output voltage would naturally be 31.25 VDC.

    Q: if the panel output voltage is regulated down to 12 VDC, based on the Watts/Volts=Amps, does that mean the panel output Amps goes up to 20.83? As in 250 Watts /12 Volts = 20.83 Amps? Or, does the panel Amps stay at 8 Amps no matter what.

    So what kind of amperage can the inverter put out?

    Thanks
    Where is the inverter in all of this? And are you talking about output amps at 120 volts or something else? And without batteries, you are not going to get anywhere. What do you mean by "regulator". Most of what you ask has already been answered elsewhere.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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    • #3
      A panel is never just rated at 250 w and 8a. A panel always gives its open circuit voltage . If for a 12v battery system somewhere between 17 to 21v. Its wattage rating is also given.

      It will usually give its full load amp rating. Usually the figures are optimistic as they are lab ratings and under conditions that cant be duplicated in most places in sunlight.

      The question about the inverters amp output is hard to understand. As there is no mention of what the inverters advertised output in watts is nor its output voltage.
      A 500w inverter at 120v will have a output amp draw under full load of about 4a but if 240v it will only be a bit above 2a,.But this has nothing whatsoever to do with the solar panels.An inverters performance is mostly governed by the battery/ies its connected to.

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      • #4
        electric car setup

        Current setup: one 12VDC deep cycle battery at 160ah >> 2000watt 110VAC inverter (87% efficiency) >> Nissan Leaf charger. I get a 10 minute charge at 110VAC and 15.4 amps before the battery level drops below 10.25 VDC and the inverter shuts down. Not bad actually, that gives me about one bar which is about 6 miles extra range.

        The inverter can handle the load but only as far as the battery amp-hour would last. I'm thinking using solar panels in full sun light, with the correct amperage, will provide hours of charge without having to lose deep cycle battery level. My thinking is that if a solar panel under best conditions can output at least 12VDC and 16 amps I can charge my car for as long as the conditions are good.

        New setup: solar panel(s) >> 12VDC voltage regulator >> 2000watt 110VAC inverter >> Nissan Leaf charger.

        So if the basic math of Watts/Volts=Amps applies then one panel will do the job?

        Thanks.

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        • #5
          Originally posted by rafbo View Post
          Current setup: one 12VDC deep cycle battery at 160ah >> 2000watt 110VAC inverter (87% efficiency) >> Nissan Leaf charger. I get a 10 minute charge at 110VAC and 15.4 amps before the battery level drops below 10.25 VDC and the inverter shuts down. Not bad actually, that gives me about one bar which is about 6 miles extra range.

          The inverter can handle the load but only as far as the battery amp-hour would last. I'm thinking using solar panels in full sun light, with the correct amperage, will provide hours of charge without having to lose deep cycle battery level. My thinking is that if a solar panel under best conditions can output at least 12VDC and 16 amps I can charge my car for as long as the conditions are good.

          New setup: solar panel(s) >> 12VDC voltage regulator >> 2000watt 110VAC inverter >> Nissan Leaf charger.

          So if the basic math of Watts/Volts=Amps applies then one panel will do the job?
          Not in your wildest dreams. You only know enough to be very dangerous. No one would ever contemplate charging a 400 volt battery with a 12 volt battery. That is just plain crazy talk.

          A Nissan Leaf has a battery capacity of 24 Kwh. Assuming you discharge to 80 DOD and have a 4 Sun Hour Day it would take a 7000 Grid Tied Solar system to fully recharge the battery in a single day. If you were to use an off-grid battery solar system it would take 8400 watts of panels to recharge fully. If you were to use a Lead Acid battery to store that charge for you to recharge at night, that battery would weigh 7000 pounds and cost around $24,200 and need replaced about every 5 years. But with it you could fully recharge in 1 hour at night with a battery system.
          MSEE, PE

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          • #6
            this is why there is a HOMEOWNER forum separate from the technical forum.....

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            • #7
              I get a 10 minute charge at 110VAC and 15.4 amps before the battery level drops below 10.25 VDC and the inverter shuts down. Not bad actuallyNOT BAD ??? you have to be joking?? anyone that would discharge a 12v battery to 10.5 v is just stupid. No lead acid battery is going to last more than a few cycles discharging to that. 12v is EMPTY.

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              • #8
                I would never consider charging an EV off an off-grid battery system. Even if the charger on my Volt pulls at 12A and 120V, it would not be wise. You have so many extra charging losses in an off-grid setup that you would be very misguided to do this. Ok, well, I do know a guy who is entirely off grid and has a large setup. He does charge his Volt during the summertime when his batteries are topped off. But he wouldn't take them down deep just to charge the car. BTW - a Volt full recharge needs 13kWh off the wall socket at 120V and 12.5 at 240V.

                Charge off the grid. If you have solar, set it up grid-tied. If you really really need standby batteries, don't use them when the grid is down to charge an EV. Use them to run lamps in the house or maybe a water pump if you live in a rural area.
                PowerOne 3.6 x 2, 32 SolarWorld 255W mono

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