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Sanity check: 240V system

onmountainuphigh

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Joined
Jun 9, 2022
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Background:
Building an offgrid setup (my first) to power a small cabin. I'm trying to follow Will's guide, but some of the components he is using are out of stock. I'm trying to swap the inverter out with a 6548 and the batteries with SOK. I'm hoping I can get some input on how I'm planning to proceed.

Load requirements:
Well pump
240 V
2.05 kW
11.2 A
Soft start

Other:
5 or 6 light bulbs
Laptop/phone charger
Wireless hotspot
Mini-fridge
Chest freezer

Target battery capacity: 10kWhr

System components:
Inverter: MPP6548
Comment: I understand this is the same as the LV6548 (which is currently out of stock)

2x SOK Battery
100Ah 48v

4x 200 Watt 12 Volt Monocrystalline Solar Panel
 
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One thing I'm curious about is whether I could get away with using a transformer to get to 240V from a 120V inverter. Seems there are a lot more options and availability for 120V AIO systems.
 
One thing I'm curious about is whether I could get away with using a transformer to get to 240V from a 120V inverter. Seems there are a lot more options and availability for 120V AIO systems.
You could do that. Yes there are probably a lot of inexpensive 120 volt inverters out there. There are a lot of choices of 240 volt split phase UL listed inverters as well. It all depends on where you are standing. I would not think about a 120 volt inverter so I have not really paid attention to that decision criteria.
 
You mention a soft-start for your pump, but do you know what the actual starting surge is? Is that the 11.2A value? 11.2A running sounds like a 1.5hp pump to me.

I think your best option is going with a native split-phase inverter rather than fiddling with a transformer. What inverter you select is really going to depend on your starting surge. Unless the starting surge is very low, the MPP6548 is not likely to start it.

For a fairly low starting surge, Magnum on Conext SW would be fine, but for a serious pump, then upgrade to a Schneider XW or Outback Radian. The starting surges for all these inverters are listed, with surging times of 5 to 60 seconds.
 
You mention a soft-start for your pump, but do you know what the actual starting surge is? Is that the 11.2A value? 11.2A running sounds like a 1.5hp pump to me.

I think your best option is going with a native split-phase inverter rather than fiddling with a transformer. What inverter you select is really going to depend on your starting surge. Unless the starting surge is very low, the MPP6548 is not likely to start it.

For a fairly low starting surge, Magnum on Conext SW would be fine, but for a serious pump, then upgrade to a Schneider XW or Outback Radian. The starting surges for all these inverters are listed, with surging times of 5 to 60 seconds.
Yeah, I think you are right on the split-phase inverter. I'm going to go with the Growatt SPF 6000 TDVM-MPV because it seems to be the only one in stock with signature solar. This is a low frequency inverter, so according to what I know, it should be fine to use inductive loads on it.

The 15SQE10-220 advertises having a Soft Start feature, and its spec sheet says that "the motor starting current is equal to the highest value stated on the motor nameplate". My understanding is that it does this by slowly ramping RPMs over a 2-second period. I think this allows for the load to stay in phase with the voltage coming from the inverter, which removes the startup current spike.
 
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