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What is the benefit of a "hybrid" inverter/charger?

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  • What is the benefit of a "hybrid" inverter/charger?

    I see expensive inverter/chargers like this Magnum 3000W that list "hybrid" as a feature: https://www.amazon.com/gp/product/B00G6LROW4

    What is the benefit of this "hybrid" feature? This is how it's described by Magnum:

    Hybrid technology: Most inverters only use one source of energy to power loads, either from AC power (shore or AC generator) or from the batteries. The MSH-M Series combines the energy from both sources to power loads. This allows the inverter to recharge the batteries when there is surplus power or deliver more power to the loads if they require more than the AC input can supply itself.
    Wouldn't a separate charger and inverter have the same capability? The charger can be charging the battery while the inverter is draining the battery, right? I don't understand how the hybrid feature is any different.

  • #2
    Originally posted by createthis View Post
    I see expensive inverter/chargers like this Magnum 3000W that list "hybrid" as a feature: https://www.amazon.com/gp/product/B00G6LROW4

    What is the benefit of this "hybrid" feature? This is how it's described by Magnum:



    Wouldn't a separate charger and inverter have the same capability? The charger can be charging the battery while the inverter is draining the battery, right? I don't understand how the hybrid feature is any different.
    The difference is that the hybrid inverter can also function as a grid tie inverter working with either shore line or generator power. That way you can power a load larger than either inverter or generator alone could handle. Or it can operate as a standalone inverter with all power drawn from the DC source (battery and DC output of panels).
    The fact that it also integrates the battery charging function is a separate issue and may or may not be better than a hybrid inverter only combined with a separate charger.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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    • #3
      Originally posted by inetdog View Post
      The difference is that the hybrid inverter can also function as a grid tie inverter working with either shore line or generator power. That way you can power a load larger than either inverter or generator alone could handle. Or it can operate as a standalone inverter with all power drawn from the DC source (battery and DC output of panels).
      The fact that it also integrates the battery charging function is a separate issue and may or may not be better than a hybrid inverter only combined with a separate charger.
      That is similar to what is found in most RV's. It allows you to charge the coach battery as well as works with an on board generator or shore power.

      I am not sure how it would work with solar panels.

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      • #4
        Originally posted by inetdog View Post
        The difference is that the hybrid inverter can also function as a grid tie inverter working with either shore line or generator power. That way you can power a load larger than either inverter or generator alone could handle. Or it can operate as a standalone inverter with all power drawn from the DC source (battery and DC output of panels).
        The fact that it also integrates the battery charging function is a separate issue and may or may not be better than a hybrid inverter only combined with a separate charger.
        You're saying the inverter can exceed it's own power ratings? This is the power rating section of the user manual:




        Are you saying this inverter can exceed 25 amps AC output continuously when plugged into shore power? If so, that's pretty awesome.

        If not, it seems like a battery + charger + inverter setup where the inverter is rated at 25 amps AC output continuous and the charger is appropriately sized would be able to accomplish the same thing.
        Last edited by createthis; 09-21-2016, 02:12 PM.

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        • #5
          So, doing more research, it does not appear the inverter can exceed it's own specs. Here's what the manual says:

          3.2.2 LoadSupport
          While in the Standby Mode and the charger is enabled, the MSH-M Series inverter/charger has the ability to work in parallel with the incoming AC source to support the AC loads using current from the batteries. During the Standby mode, the current and voltage from the AC source and the AC load current are continually monitored. When loads that exceed the available current from either the shorepower grid or the generator are connected, the Load Support feature is automatically activated. The Load Support feature causes the MSH-M inverter/charger to reduce/stop the battery charging operation and begin the inverting operation to allow any available current from the batteries to be used to ensure the AC loads are powered and the current does not exceed the capacity of the AC source, or trip its output breakers or fuses. The Load Support feature turns off once the load demand decreases and spare power from the incoming AC source is available; when this happens, the battery charger is again activated and begins charging the batteries.
          For the Load Support feature to automatically function, the following needs to occur:
          1. An AC source (shorepower/AC generator) must be connected. 2. The inverter must be enabled (INV LED is on).
          3. The battery voltage must be 0.5 volts (for a 12-volt system) or 1.0 volts (for a 24-volt system) than the LBCO setting.


          So, again, wouldn't we be able to do the same thing with a AC charger -> battery -> inverter setup?

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          • #6
            Originally posted by createthis View Post
            What is the benefit of this "hybrid" feature?
            It's also called generator support by some inverters. Basically you can plug into a low-capacity source (like a 15A 120V outlet, which is good for about 12A continuous) and still power your 20A air conditioner. When the A/C needs 20A, then the inverter/battery will supply 8A and the outlet will supply 12A. When the A/C cycles off, then the inverter/battery will draw 12A from the outlet to recharge.
            Wouldn't a separate charger and inverter have the same capability?
            Yes, if they were series connected. The benefit of generator support is that the inverter itself does not have to be able to supply 20A, nor does the charger have to be able to supply the full power the load needs. It's also more efficient since you don't have that double conversion step.

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            • #7
              Originally posted by jflorey2 View Post
              It's also called generator support by some inverters. Basically you can plug into a low-capacity source (like a 15A 120V outlet, which is good for about 12A continuous) and still power your 20A air conditioner. When the A/C needs 20A, then the inverter/battery will supply 8A and the outlet will supply 12A. When the A/C cycles off, then the inverter/battery will draw 12A from the outlet to recharge.

              Yes, if they were series connected. The benefit of generator support is that the inverter itself does not have to be able to supply 20A, nor does the charger have to be able to supply the full power the load needs. It's also more efficient since you don't have that double conversion step.

              But... the inverter *is* supplying 20A in that case. It's just pulling 12A from AC and 8A from the battery. The inverter is still rated for 25A and it's still supplying 20A.

              I see the point regarding efficiency. If the 12A from shore power goes straight to the load there are (Maaaaaybe) fewer conversion losses. I suppose whether or not that matters depends on how tied to shore power or generator you plan to be. However, what happens in the case of a modified sine wave generator? Surely the inverter is turning that into a pure sine wave as it adds in battery power, right? Seems like there would be conversion losses associated with that, or else you wouldn't have a clean wave form.

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              • #8
                Originally posted by createthis View Post
                But... the inverter *is* supplying 20A in that case. It's just pulling 12A from AC and 8A from the battery. The inverter is still rated for 25A and it's still supplying 20A.
                Not quite. The inverter (the thing that turns DC into AC) is supplying 8A. It is connected to a wire (the shore power) that is supplying 12A. Kirchoff's Current Law says that therefore 20 amps has to go somewhere - in this case to the load. (There are current sensors on those lines to ensure the numbers add up correctly.)

                What that means in practice is that although the wiring inside the inverter _box_ has to carry 20 amps, the inverter itself only has to generate 8.
                I see the point regarding efficiency. If the 12A from shore power goes straight to the load there are (Maaaaaybe) fewer conversion losses. I suppose whether or not that matters depends on how tied to shore power or generator you plan to be.
                Right - and how much you want to pay for the inverter/charger. A 20 amp inverter plus a 20 amp charger is generally going to be more expensive than a hybrid inverter capable of 8 amps generation and 12 amps charging - and in the example above both deliver the same power to the load.
                However, what happens in the case of a modified sine wave generator? Surely the inverter is turning that into a pure sine wave as it adds in battery power, right? Seems like there would be conversion losses associated with that, or else you wouldn't have a clean wave form.
                You can't (legally) feed MSW into an AC line, because all that harmonic energy will go right back out the line.

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                • #9
                  Originally posted by jflorey2 View Post
                  Not quite. The inverter (the thing that turns DC into AC) is supplying 8A. It is connected to a wire (the shore power) that is supplying 12A. Kirchoff's Current Law says that therefore 20 amps has to go somewhere - in this case to the load. (There are current sensors on those lines to ensure the numbers add up correctly.)

                  What that means in practice is that although the wiring inside the inverter _box_ has to carry 20 amps, the inverter itself only has to generate 8.
                  I would be more impressed if this meant a 25A inverter could supply 37A with shore power, but that doesn't appear to be the case according to the manual of this one inverter. I could be mistaken.

                  Originally posted by jflorey2 View Post
                  Right - and how much you want to pay for the inverter/charger. A 20 amp inverter plus a 20 amp charger is generally going to be more expensive than a hybrid inverter capable of 8 amps generation and 12 amps charging - and in the example above both deliver the same power to the load.
                  Maybe. I haven't looked. I'll revisit this in a bit perhaps. On the flip, if any part of the machine breaks, you have to replace the whole rather than individual components.

                  Originally posted by jflorey2 View Post
                  You can't (legally) feed MSW into an AC line, because all that harmonic energy will go right back out the line.
                  Whoa. I think you're missing the point. In this example shore power was replaced by a MSW inverter generator. No one is feeding MSW onto the grid, or anything onto the grid for that matter.

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                  • #10
                    Originally posted by createthis View Post
                    Whoa. I think you're missing the point. In this example shore power was replaced by a MSW inverter generator. No one is feeding MSW onto the grid, or anything onto the grid for that matter.
                    Well, that's the problem - in generator support mode you ARE feeding power into a grid connection. The reason it isn't considered backfeeding the grid is that the aforementioned law (Kirchoff's Current Law) prevents power from being backfed as long as you manage the currents correctly, which is why the current sensor is important. If you are ever at risk of backfeeding, the control circuit back off inverter power so that no NET power ever flows back into the grid.

                    But even though you can manage to not backfeed the grid, you are still connected directly to the grid - and thus if your inverter is noisy (which MSW's are) then you are feeding all that noise back to the grid as well.
                    I would be more impressed if this meant a 25A inverter could supply 37A with shore power, but that doesn't appear to be the case according to the manual of this one inverter. I could be mistaken.
                    From the manual:
                    "While in the Standby Mode and the charger is enabled, the MSH-M Series inverter/charger has the ability to work in parallel with the incoming AC source to support the AC loads using current from the batteries. During the Standby mode, the current and voltage from the AC source and the AC load current are continually monitored. When loads that exceed the available current from either the shorepower grid or the generator are connected, the Load Support feature is automatically activated. The Load Support feature causes the MSH-M inverter/charger to reduce/stop the battery charging operation and begin the inverting operation to allow any available current from the batteries to be used to ensure the AC loads are powered and the current does not exceed the capacity of the AC source, or trip its output breakers or fuses. The Load Support feature turns off once the load demand decreases and spare power from the incoming AC source is available; when this happens, the battery charger is again activated and begins charging the batteries."

                    The max AC power out is 60 amps (transfer switch rating.) Max inverter output is 25 amps. Max charger input is 18 amps. Default setting for shore power limit is 30 amps. So if you set the shore power limit to 30 amps and enabled "Load Support" I'd expect you to be able to get something like 55 amps output (again provided everything downstream of the transfer switch can handle that current.)

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                    • #11
                      Originally posted by jflorey2 View Post
                      Well, that's the problem - in generator support mode you ARE feeding power into a grid connection. The reason it isn't considered backfeeding the grid is that the aforementioned law (Kirchoff's Current Law) prevents power from being backfed as long as you manage the currents correctly, which is why the current sensor is important. If you are ever at risk of backfeeding, the control circuit back off inverter power so that no NET power ever flows back into the grid.
                      What? The reason it isn't backfeeding the grid is because the grid isn't attached to anything. What are you talking about?

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                      • #12
                        Originally posted by createthis View Post
                        What? The reason it isn't backfeeding the grid is because the grid isn't attached to anything. What are you talking about?
                        Generator support (or load support as this inverter calls it) works only if there is an external AC input - either a grid or a generator. "Shore power" generally means grid power, but the same functionality applies to both.

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                        • #13
                          Originally posted by createthis
                          Whoa. I think you're missing the point. In this example shore power was replaced by a MSW inverter generator. No one is feeding MSW onto the grid, or anything onto the grid for that matter.
                          Originally posted by jflorey2 View Post
                          Well, that's the problem - in generator support mode you ARE feeding power into a grid connection. The reason it isn't considered backfeeding the grid is that the aforementioned law (Kirchoff's Current Law) prevents power from being backfed as long as you manage the currents correctly, which is why the current sensor is important. If you are ever at risk of backfeeding, the control circuit back off inverter power so that no NET power ever flows back into the grid.

                          But even though you can manage to not backfeed the grid, you are still connected directly to the grid - and thus if your inverter is noisy (which MSW's are) then you are feeding all that noise back to the grid as well.
                          Originally posted by jflorey2 View Post
                          Generator support (or load support as this inverter calls it) works only if there is an external AC input - either a grid or a generator. "Shore power" generally means grid power, but the same functionality applies to both.
                          Maybe a diagram would help:

                          Grid -> Nothing


                          Battery (8A) --------------+
                          ...........................|
                          ...........................\/
                          Generator (12A) -> Inverter/Charger -> Load (20A)


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                          • #14
                            Originally posted by createthis View Post





                            Maybe a diagram would help:

                            Grid -> Nothing


                            Battery (8A) --------------+
                            ...........................|
                            ...........................\/
                            Generator (12A) -> Inverter/Charger -> Load (20A)


                            What you need to understand is that the generator is supplying 12A of AC, and the inverter/charger is synchronizing with that and adding 8A of AC that it generates by taking DC (probably ~100A) from the battery.
                            The inverter itself is apparently capable of providing 20 or 25A generated entirely from battery power, and in addition allowing up to about 40A of AC to pass through from the grid or generator connection. That 60A limit is based on the rating of the transfer switch inside the inverter. That transfer switch is what disconnects the grid/generator connection completely to allow the inverter to operate independently when neither grid nor generator are working.
                            A critical feature that a hybrid inverter must have is that it must not try to generate more AC power from panels or battery that the load is using when the generator is connected (which could destroy the generator) but it does need to be able to generate more power from battery or panel input when the grid is there (sell back to POCO.)

                            All of this versatility is one reason that hybrid inverters, whether or not they are also inverter/chargers, are more expensive than either normal grid tie or normal off grid inverters.
                            SunnyBoy 3000 US, 18 BP Solar 175B panels.

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                            • #15
                              Looks like the input and output AC breakers on this inverter are 60A. Maybe you're right. Maybe the inverter can supply 25A continuous in addition to 35A AC pass-through. I wish they'd just freaking say that in the manual though. It's not clear. Maybe I'll call them to confirm tomorrow.

                              I wish it had a battery preferred mode. Seems to prefer grid power. I think it would be more interesting to prefer battery power and just sip from the grid when necessary.

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