MPP LV2424 - max AC input current

[danb35]

I'm considering building a system around a LV2424 inverter for use in my shop. As I read the manual, I see it calls for overcurrent protection on the grid input. However, I don't see anywhere in the manual a specification for max AC input current. Is it just a matter of making sure it doesn't exceed the capability of the circuit it's connected to? Easy enough if so--it would be on a 120V, 30A circuit, so it'd be easy enough to use a 30A breaker. But if there's a reason it should be limited to a lower current, I'm not seeing it het.

 

[sed6]

It's only going to draw the current it needs. 2400w/120v = 20 amps. That's 20 amps at max load which you probably won't draw all the time. I used a 20 amp breaker on my LV2424 setup. 30 amps breaker is okay but probably oversized for the 10-15 amps you'll draw continuously. You can pull out the 30 amp breaker and replace it with a 20 amp if you so desire.

 

[Mac6792]

It's only going to draw the current it needs. 2400w/120v = 20 amps. That's 20 amps at max load which you probably won't draw all the time. I used a 20 amp breaker on my LV2424 setup. 30 amps breaker is okay but probably oversized for the 10-15 amps you'll draw continuously. You can pull out the 30 amp breaker and replace it with a 20 amp if you so desire.

there's is also the consideration of whatever battery bank being used and the charging amperage that requires. In addition, there could be a circumstance where the batteries are charging at the same time the inverter is pushing a full 20 amp load. That may exceed the 30 Amps. You can, however configure how much amperage is used for charging so 30amps is likely just fine for most applications

 

[danb35]

It's only going to draw the current it needs. 2400w/120v = 20 amps.

...not accounting for charging. At 60A (the maximum) of utility charge, that would add another 12-14 amps, assuming a perfectly-efficient charger. You're right that I'm not intending to run it at full load continuously, but it doesn't seem like a good plan to cripple the thing unnecessarily. And now that I've written this, I see Mac has said pretty much the same thing.

You can pull out the 30 amp breaker and replace it with a 20 amp if you so desire.

I'm not changing the breaker in the main panel, unless I can see that stepping it up a bit would be permitted by code--which I doubt. That breaker would, I'm sure, count as the circuit protection the device says it requires. However, I'll be installing breakers near the inverter--partly as additional protection, partly to protect at a lower rating if called for (which it doesn't sound like it is), partly to have a convenient way to disconnect all input to the inverter.

 

[sed6]

...not accounting for charging. At 60A (the maximum) of utility charge, that would add another 12-14 amps, assuming a perfectly-efficient charger.

Good thinking! However the AC charge (in from grid) and AC out (to his loads) are on different circuits with the LV2424. A 20 amp breaker (or maybe 30) are needed on each circuit.

 

[mrdavvv]

Just FYI the manufacturer recomends 40A breaker for AC Input for a single one, and 80A for a parallel conection. Its a little hidden in page 33.

 

[sed6]

Just FYI the manufacturer recomends 40A breaker for AC Input for a single one, and 80A for a parallel conection. Its a little hidden in page 33.

Great observation! Reading the manual is always helpful! I disregarded then forgot about that because I don't plan to charge from AC and went w 20 amp in. However most US wiring is 12 gauge protected by a 20 amp breaker and safely feeding higher input amperage will require running new wiring in his home which is a whole other ball of wax.

 

[danb35]

However the AC charge (in from grid) and AC out (to his loads) are on different circuits with the LV2424.

But they're both fed by the grid, when the unit is running on grid (which mine would be a good part of the time).

40A breaker for AC Input for a single one, and 80A for a parallel conection. Its a little hidden in page 33.

Hidden indeed--thanks for the spot, I'd missed that. Seems like that's something that should have been mentioned on page 6, where it says you're supposed to use a breaker on the grid input. Though that leaves me wondering why it's that high...

 

[sed6]

Though that leaves me wondering why it's that high...

40 amp is a shit suggestion by the Mfgr. Because a) I mentioned wiring in the US and b) it can charge up to 60 amps from AC. So 40 amps is too high for US wiring and not high enough for the allowed 60a input.

 

[mrdavvv]

But they're both fed by the grid, when the unit is running on grid (which mine would be a good part of the time).

Hidden indeed--thanks for the spot, I'd missed that. Seems like that's something that should have been mentioned on page 6, where it says you're supposed to use a breaker on the grid input. Though that leaves me wondering why it's that high...

Probably because of inverter (2400W / 4800W surge) + AC Battery charger, it can use up to 60A @24v (1400W or higher considering itts not 100% efficient), thats around 3800W, and a little higher during surges.... so youll need to be charging your batteries at maximum 60A and also turn on your microwave, dishwasher and compressor to achieve that!. And not even sure if the inverter can handle that, maybe ill shutdown itself to avoid overheating.

I couldn't even source breakers that big (Needed 80A for my double setup), so i went for 60A (30A each).

40 amp is a shit suggestion by the Mfgr. Because a) I mentioned wiring in the US and b) it can charge up to 60 amps from AC. So 40 amps is too high for US wiring and not high enough for the allowed 60a input.

Our installations have higher gauge Wire coming from utility, and from the main breaker its downsized for the house, as my inverters are next to the main panel, i can use 10 or 8 AWG from there and use a bigger fuse. But indeed you need to size according to your cabling.

 

[danb35]

So 40 amps is too high for US wiring and not high enough for the allowed 60a input.

It's too high for "US wiring" if you were planning to just plug it in to a wall outlet for its grid input--I don't think that's really what this system's designed to do. And yes, it has 60 amps charger output, but that's output to the battery, at battery voltage. If I use Will's recommend absorption charge voltage of 29V, that's 1740W, which is (if you assume 100% efficiency in the charger) 14.5A AC. Add that to 20A to feed the 2.4KW output, account for inefficiency in the charger, and I guess that explains the 40A spec.

 

[danb35]

I couldn't even source breakers that big

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Oh, need two of them for two inverters?

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[mrdavvv]

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Need automation components and parts? Check out ASI's vast inventory of electronic components for automation and industrial applications.

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Oh, need two of them for two inverters?

Electronic Components & Supply Online Store | ASI

Need automation components and parts? Check out ASI's vast inventory of electronic components for automation and industrial applications.

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Im outside US and didnt even bother to do a good search, i dont think ill need more than 60A as my main charging source will be solar.

 

[dokmartin]

I'm trying to figure this out, as well.

I'm going with a 3048LV. Assuming the max AC load output capacity is 3kw and the battery charger max is 2.8kw i assume i need to spec the incoming wiring and protection for about 6kw. Thats only if the battery charger will run at max while also bypassed and serving 3kw by bypass.

I know i can program an amperage limit and some bypass features, but i need to figure this out to spec my genset.

 

[dokmartin]

The more i look at it the more i realize that there is no reason to assume the AC circuit in transfer mode has the same capacities as the internal inverter. It's safe to assume that the circuit's connections are designed to the inverter specification, but I wouldn't be surprised if these units will deliver more wattage when input is connected than the inverter output max.

 

[mrdavvv]

The more i look at it the more i realize that there is no reason to assume the AC circuit in transfer mode has the same capacities as the internal inverter. It's safe to assume that the circuit's connections are designed to the inverter specification, but I wouldn't be surprised if these units will deliver more wattage when input is connected than the inverter output max.

You are probably right, im thinking that while working from utility, the units only acts as a passtrough for the current, so who knows that the real limits are.... not sure about it... what it calls my attention its top right option:



Overload Bypass when utility is available?.

I'm going with a 3048LV. Assuming the max AC load output capacity is 3kw and the battery charger max is 2.8kw i assume i need to spec the incoming wiring and protection for about 6kw. Thats only if the battery charger will run at max while also bypassed and serving 3kw by bypass.

I know i can program an amperage limit and some bypass features, but i need to figure this out to spec my genset.

What fuses MPP solar recomends for your unit?.

I purchase a 2KW genset considering that it will be extremely rate to have the use it, as 95% of the time i will be running solar / battery / utility. And if i ever need the generator, ill just turn off all the no essentials and leave it for battery charging / fridges

 

[dokmartin]

MPP doesn't seem to recommend fuse size in any of these manuals. I did find a line in the specifications for "Line Mode" that says "Max bypass current " and that might be good guidance. I've sent an email to them asking for clarification.

 

[mrdavvv]

In the 2424 it its in the middle of the booklet, in the paralleling inverters section, maybe yours is the same.

 

[madmax]

40 amp is a shit suggestion by the Mfgr. Because a) I mentioned wiring in the US and b) it can charge up to 60 amps from AC. So 40 amps is too high for US wiring and not high enough for the allowed 60a input.

60amp at 24VDC -1440 watts. at 29v, 1740 watts. Thats 14.5 amps which is under most household outlets of 15A. The reason the inverters are at 2400 and not some other number is because 2400 is exactly 20amps, which is avaliable on most branch circuits in america. I can only assume that was by design.

 

[mrdavvv]

60amp at 24VDC -1440 watts. at 29v, 1740 watts. Thats 14.5 amps which is under most household outlets of 15A. The reason the inverters are at 2400 and not some other number is because 2400 is exactly 20amps, which is avaliable on most branch circuits in america. I can only assume that was by design.

Well but can the inverter work as an AC passtrough and at the same time charge the batteries at 60A?, if the passtrough its 20A and the battery charging 15A, wouldnt the 40A fuse have some sense?.