MPP LV6548 or Growatt SPF5000ES?

[zox]

MPP LV6548 or Growatt SPF5000ES? I'm building a new off grid house. The only 240 volt loads are a 3 hp submersible
pump and a 3 ton Carrier Infinity variable speed heat pump. Propane will heat the water and
cook the food. I have 6 new EG4-LL 48V batteries. I'm undecided on inverters. I'm considering 2 LV6548 inverters and 32 455W panels
with 4S2P per PV input which was covered in a previous thread. Or, 2 Growatt SPF5000ES inverters and yet to be determined panels.
I'm new to solar. The indecision comes from two facts. The first is the LV6548 does not communicate with the EG4-LL BMS. The second is the Growatt has to deal with a transformer which would suggest the selection of a 5kW 5000ES and transformer kit from SS. I would appreciate any suggestions and reasons for selecting one over the other.
Or, is there another inverter that would be a better choice? Thanks.

 

[Quattrohead]

Of the 2 the 2xLV6548 are the better match, 13kW of output and enough PV input (16kW) to handle all of your panels, assuming you can make the VOC work out.
However, a transformer based design might be better for that hefty pump so how about 2x LVX6048. Transformer output 6kW each and parallel-able upto 54kW output. However only 6kW of PV input per unit, so you would want to add a separate charge controller.
Don't worry about battery comms, the BMS will take care of the batteries and you get way more info monitoring them.

 

[zox]

Excuse my limited knowledge. Is there an advantage to the inverter being able to communicate with the BMS? I remember reading something about the inverter modifying and slowing the rate of charge as the batteries approached 100% which would increase the life of the batteries. Or is this a non issue?

 

[Quattrohead]

Some do and have preset settings to make setup easy, but the BMS does the best job because it can sense each cell and balance 24/7 if it needs to.

 

[zox]

Thanks. I'll check out the LVX 6048.

 

[MichaelK]

Here is a pump chart originally supplied by another member, Mike94945 (I think). What is shows is that a 3hp pump has a 77amp starting surge. That is HUGE for a solar system, and works out to be a 17,700W starting surge. So, whatever you put together needs to be able to handle that kind of starting surge. I myself have a 1hp pump, and my measured starting surge is ~38A, so almost spot on with what the chart indicates. You need clamp meter that can measure "inrush current". I use a Uni-T 216C which I always recommend. You can also use it to determine the starting surge of your heat-pump. With whichever inverter you chose, first make sure it can handle the starting surge. As QH indicates, a low-frequency transformer-based inverter better handle these big starting surges. I have a Schneider XW+6848.

 

[solardad]

Here is a pump chart originally supplied by another member, Mike94945 (I think). What is shows is that a 3hp pump has a 77amp starting surge. That is HUGE for a solar system, and works out to be a 17,700W starting surge. So, whatever you put together needs to be able to handle that kind of starting surge. I myself have a 1hp pump, and my measured starting surge is ~38A, so almost spot on with what the chart indicates. You need clamp meter that can measure "inrush current". I use a Uni-T 216C which I always recommend. You can also use it to determine the starting surge of your heat-pump. With whichever inverter you chose, first make sure it can handle the starting surge. As QH indicates, a low-frequency transformer-based inverter better handle these big starting surges. I have a Schneider XW+6848.
View attachment 81891

Use a soft start device to get around the large inrush (of really any fixed device- HVAC, Well Pump. Mini splits do not need one since they ramp up slowly by design.

 

[zox]

The pump hasn't been installed yet. I asked the driller to if a soft start is possible. He's investigating. My well is 800' deep, water @ 620', 3gpm.

 

[solardad]

@zox suggest that you watch this video

Not an expert by any stretch of the means but there are a various options to help address the overall electric/surge demands of well pumps. I think it would be better to purchase a well pump that is designed to be soft start out of the box vs. adding that feature later. The SQ series of pumps mentioned in the video would support your situation I believe after doing a quick check on their site: https://product-selection.grundfos.com/us/products/sq-north-america?tab=products good luck

 

[Samsonite801]

Consider getting a Grundfos SQFlex pump, they are natively soft-start, and can accept AC or DC voltages all the way up to something like 300v or something...

 

[Samsonite801]

@zox suggest that you watch this video

Not an expert by any stretch of the means but there are a various options to help address the overall electric/surge demands of well pumps. I think it would be better to purchase a well pump that is designed to be soft start out of the box vs. adding that feature later. The SQ series of pumps mentioned in the video would support your situation I believe after doing a quick check on their site: https://product-selection.grundfos.com/us/products/sq-north-america?tab=products good luck

Oh yeah, you just beat me to it. That's the way I'm gonna go, I want to use the Grundfos SQFlex, as it can run on DC or AC...

Check out this video too, he just runs the pump right off of solar power directly. It makes a lot of sense to store some water at ground level too (for easy access if your deep well pump has some issue later).

 

[zox]

It's a gravity system, so the tank is another 100' up a hill.

 

[KPSA]

DC is more efficient for the pump.

 

[zox]

RPS solar pumps sells a pump kit that will meet my requirements. It includes panels, controller and 3 phase 220v motor and pump.
That would reduce the 240 load at the house to just the heat pump. I'll probably go with it.
During construction, I'll be living in an RV. I will be installing a mini split in the RV for cooling and heating.
I'd like to power the RV with one LV6548, (16) 455W panels and (6) EG4-LL batteries which I already have. Once the
house is completed, I'll add another LV6548 and (16) more panels. Does this sound feasible?

 

[MrM1]

I'd probably still consider the 6548 for a low frequency inverter and it's better ability to start inductive loads. If you're building your own place on site seems to me you'd need an inverter that will start large saws consistently, every time for a while long time.

 

[zox]

MrM1, I think you're suggesting what I'll probably do. (1) LV6548, (16) 455W panels, (6) EG4-LL 48V batteries,
all to power the RV, a separate solar kit from unbound for the well pump, and a 9200W generator for tools. Is
that correct?

 

[MrM1]

MrM1, I think you're suggesting what I'll probably do. (1) LV6548, (16) 455W panels, (6) EG4-LL 48V batteries,
all to power the RV, a separate solar kit from unbound for the well pump, and a 9200W generator for tools. Is
that correct?

My bad. I was referring to the LVX 6548 low frequency not the LV6548 hi frequency. Low frequency would start the tools more consistently / reliabily. Low frequency would do the pump too.

 

[Samsonite801]

My bad. I was referring to the LVX 6548 low frequency not the LV6548 hi frequency. Low frequency would start the tools more consistently / reliabily. Low frequency would do the pump too.

I believe you're meaning to say the LVX6048 which is the split-phase (in single inverter), LF inverter (with a heavy transformer), where the LV6548 is the HF inverter (but also with a transformer, according to MPP Sales, at least that how they called it in an email back to me)...

 

[MegaErtz]

I'm interested in building pretty much the exact same system. Can you post a breakdown of your costs? Thanks.

 

[zox]

scottvanv is the fella I'm watching. He's further along than me. I think he's using (2) LV6548s and (32) 455W panels. I don't know what he's using for batteries. I'd like more info on his build. I need to make a correction on the well pump kit. It is from RPS solar pumps.