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oadkins
oadkins Registered Users Posts: 19 ✭✭
Is there a combiner box that lets you use 2 inverters  to power house to one circuit breaker panel

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
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    What brand/model of AC inverters do you want to use? Are you trying to connect two independent 120 VAC TSW inverters to one home 120/240 VAC main power panel, or a pair of inverters that are designed to "stack"?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
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    Your question makes me think you are talking a 120/240 V type of setup?  Most inverters that can sync are called stackable, like the Outback inverter chargers.
    Another option is the auto-former http://www.solar-electric.com/x-240.html


     
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  • oadkins
    oadkins Registered Users Posts: 19 ✭✭
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    connect two independent 120 VAC TSW inverters to one home 120/240 VAC main power panel, want 120 volt not 240 want to increase watts
  • oadkins
    oadkins Registered Users Posts: 19 ✭✭
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    would like to use 2 2500 watt inverters xant
  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
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    oadkins said:
    connect two independent 120 VAC TSW inverters to one home 120/240 VAC main power panel, want 120 volt not 240 want to increase watts
    Two issues (maybe 3)...

    1) depending on how it is wired, there may be a shared neutral.  On a 240 volt power panel the two phases can share a neutral without exceeding its ampacity.  If you have a shared neutral you may cause a fire when both circuits are sharing the neutral at the same time.

    2) make sure all 240 volt appliances are disconnected.  A 240 volt appliance could be a "short" between the two inverter outputs.

    3) (not sure if this is an issue).... electrical codes... I don't know if this is allowed.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
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    If you have a 100 Amp main panel, you should be able to run 50 Amp TSW inverters as 120/120 with a shared neutral.

    What you should not do is run, for example, a standard Red+Black+White "2 circuit" wire to 120 VAC appliances at rated wire current. The problem being that the two TSW inverters are not "in sync" and it is possible for the two 120 VAC "Hot" Circuits to add on the return "netural" wire (i.e., 15 amps on each "hot" in a standard split phase 120/240 VAC system would add up to zero current in the neutral phase because the two hot circuits are 180 degrees out of phase. With a pair of non-synced 120 VAC TSW inverters, it is possible for the two "hots" to be in phase, and 15 amps on Black+Red can add to 30 amps in the return/white/neutral phase).

    You would not need any special main panel to wire up your two inverters... I would suggest that you wire the two inverters through a pair of breakers rated at most, 50% of the main panel capacity. And tie the two returns to the main return/ground bus bar (most TSW inverters have "floating" outputs and you can ground bond one connection to make it the Neutral--earth bonded).

    Now, whether this is to "code", I do not know. And has anybody tried this here and has experience--I would be interested to hear.

    It is not an uncommon thought--I wonder, a little bit, if the two inverters "beat" against each other (say one is 60 Hz and the other is 61 Hz--There could be a 1 Hz beat frequency that, for example, could cause your lights to dim a bit at 1 Hz).

    I think people have done this--But don't remember any feedback (positive or negative) about doing this.

    The advantage of wiring this way--You can, later, simply bring in utility power when it is available. The disadvantage is that you are limited to maximum inverter power (i.e., 2x 2kWatt inverters vs 1x 4kWatt inverter). Not sure there is a cost advantage or any energy savings, unless you, for example, have two sets of circuits--One that runs 24x7, and another that only runs at (for example) night.

    Otherwise just have two main panels (one for each inverter) and call it a day. Certainly, having one main panel lets you move loads from the A to B inverter much easier (balance loads, 24 hour vs "night time" power, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset