two inverters to make 240
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John Frum
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The alternating current has to be synchronized.
Unless one or both of these inverters can synchronize with the other yer outta luck.
Bud Martin
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The output of the two have to be 180 degree out of phase from each other for you to get 240VAC, so the unit has to be designed to be able to sync and put out the correct phase.
Austin68
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Then would connecting both inverters to say a buss bar double the wattage I have available at 120v? Or would 1 inverter fight the other?
John Frum
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Again they would need to be synchronized.
acdoctor
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You could dedicate circuits to each inverter. So two separate systems.
Austin68
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OK. I have a 3000w inverter and was hoping if i used another one i could double it to 6000w on one 120v circuit
Unless the electronics inside the inverter are designed to be in sync what will happen is you will get a HUGE flash, and a lot of magic smoke…
120V ac is a 170-0 waveform, and the fets that COORDINATE this wave, in order to produce a wave of +170 to -170 in sync is needed… not what the average inverter can do.
It CAN be done, it just takes understanding the inverter setup.
I watched a video where a guy did just this. I will look in my way back machine and see if I can find the video.
I think it was this one…
Austin68
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I appreciate the video. But that is going to be a bitttt beyond my comfort level. LOL
Zwy
Emperor Of Solar
What inverter do you have? Makes a huge difference. Some support split phase, some have split phase and others can't be split phase.
Austin68
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The manual shows a output voltage up to 240 but doesnt say anything beyond that. http://www.giandel.com/DownView.asp?ID=7
Bud Martin
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It is only made to output the Voltage you spec for when you purchase the unit. Did you specify that you want 120V output?
Austin68
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Yeah, wasn't any other option for that inverter
Yeah, especially, since most larger inverters have BANKS of capacitors and transformers… he was using a MSW cheapo inverter… likely nothing similar with yours… but is shows that it can be done… but is in NO WAY as simple as tying two inverters together.
Sell your current one, and buy one with the features you need… far simpler.
I think it is impossible to change the output from 120V to 240V by yourself,because their transformers are different,and you may loss warranty. Giandel has 220V inverter for selling,why not connect them directly to buy a 220V inverter directly?
Yes, this would work but only when connected to an active grid with a grid-tie inverter. A single phase 120VAC grid-tied inverter synchronizes to the utility phase then ups the voltage some to provide the amperage to provide power to the house over the utility and if there is surplus, back-feed the utility. If the inverter supports a current transformer (CT) tap on the utility line it could stop itself to ensure there is zero feed back to the utility, thus avoiding Net Metering.
So on grid or grid-tied, you can have multiple non-communicating 120VAC or 240VAC grid-tie inverters on the same legs. By design they all first read the existing utility phase, then they synchronize to it.
In off-grid, it fails when you try to use two non-communicating 120VAC Inverters to create 240VAC because their output phases have to be 180 degrees out of phase. Without the inverters communicating to synchronize a 180-phase shift, one Inverter would not know what the phase is of the other inverter. At the load, measuring across L1 and L2 you would see a constant voltage anywhere between zero to 240 VAC depending on what the phase shift was between the two inverters. Add in a slight drift in the 60 HZ clock and the voltage across L1 and L2 would very slowly change from zero to 240VAC and back because the two inverters don't know the other exists.
In off-grid, a similar problem would arise if you tried to parallel two non-communicating inverters on the same 120 VAC leg. One would not know the phase status of the other. In this case, unless the phases just happened to be synchronized, you would be guaranteed to have a short.
So off-grid, two or more inverters must be designed to communicate on their phase status and be programmed with a phase shift with one being a master. Either a zero-phase shift to parallel two or more 120VAC inverters on the same 120VAC leg, or a 180-degree phase shift to achieve 240VAC between two separate 120VAC legs.
