Decision on Inverter

TKB4

Solar Enthusiast
Joined
Dec 2, 2019
Messages
208
I currently have MPP LV5048 used in split phase. 12,600 was 42 panel 300 watt tillable pv array. I need more wattage available at times and a significant part of the day My consumption is around 7,000 watts in a large home. I currently have 30 kwhr of lithium battery hoping to increase to at least 60 kwhr. I would like to run HVAC and well and lighting computers etc. I dont mind cutting HVAC off when using oven ,dryer, etc either manually or with relay. Hot water is propane tankless and direct solar with heat exchanger. I off course would love not to have to cut power to HVAC but I also need to start it a 2 stage 5 ton unit with scroll compressor not inverter type.

I am not selling to grid just using it as a backup. I plan to have an electric vehicle in 1-2 years also.

I bought the MPP LV5048 alone because at the time they only had 1 available even though I planned on getting 2 units or possibly 3 units if 2 not enough and I wanted to get at least partially up and running. Now I am ready to get another unit with everything set up already for parallel units but like others I now see they have the MPP LV6548 available.

I am believe I will end up getting 3 LV5048 s or another inverter. I considered 2 sunny boy island 6,000 watt inverters as well as Solark 12 which I really liked but would really need 2 and thats way too costly at around 13,000.

So I researched some more especially the Growatt 12k unit and pair of LV6548 . It has low PV volt input at 150v and also very low pv watts input at 7,000 watts unless they mean per MPPT controller large peak power at 36kw due to its low frequency transformer and extra boards available cheap and 240 split phase by itself.

The low PV input is a no go and borderline even if 14kw total. The low PV voltage input is also undesirable but similar to LV5048. So I am leaning against this one.

The MPP LV 6548 has desirable 250v pv input so I could double from 3 to 6 panel strings and/or have less power loss in transmission. The 13kw is almost as much as 3 LV 5048 s and I believe the peak would be ample to start the HVAC since it starts as 1 st stage (about 3 ton) then if needed increases to stage 2 which is unusual but its a geothermal and runs the well at same time though it is soft start and never requires more than 1500 watts so no start-up peak. I would likely be using 3,000 to 6,000 watts (or could limit it to this amount) when the HVAC would need to start so I assume with 26kw peak it would have at least 20kw available to start the HVAC which is the same as 2 LV 5048 s with no load .

Sorry for the long post but my question is What do you think?
1. 2 LV5048 s for now realizing I will probably need a third.
2. Get a pair of the MPP LV6548 s for less than 2 more LV 5048 s and a little less power and take up less room. (Might keep Lv 5048 for emergency but more likely sell it or use at another location.
3. Growatt 12 k which I have already ruled out unless something I haven't thought of.
4. Some other inverter that does split phase and will provide 13kw with 26kw peak for the same or a little more cost than 2 MPP LV6548 s which is around $2600. I would pay some more for better quality or 15kw and 30kw peak output etc or just considered better quality with good support.

Any thoughts or comments appreciated.

Thanks
 

snoobler

Solar Honey Badger
Joined
Jul 10, 2020
Messages
8,430
Location
HBR, AZ
MPP Solar/Growatt high frequency units do not have meaningful surge capabilities. You can't count on them at all for motor start surges.

Sunny Island and Sol Ark are good units and should do the trick.

I would be looking at these units too:


You will need separate charge controllers for the above and the Sunny Island.
 

Delmar

Solar Addict
Joined
Dec 9, 2019
Messages
457
Location
Lake Conroe area in Texas
That sounds like serious equipment just for backup. Are your ultimate plans to go off-grid?

After snooping your profile I understand you run generators. I am toying with the idea of an engine-driven generator-compressor package. Will be more efficient than driving the electric AC compressor from the generator or inverter, and eliminate your massive planned upgrade. Depending where you are natural gas is cheap.

The engine can auto-start when connected to your thermostat, and while running also recharge the batteries. And auto run whenever the oven or dryer is required.

Pipe the engine exhaust through a gas water heater as a massive muffler. Can replace your tankless and direct solar heat. Poor mans co-gen.
 

TKB4

Solar Enthusiast
Joined
Dec 2, 2019
Messages
208
Delmar
I have several generators a 7500 gas generator that is too loud to run where I live (HOA) etc unless truly urgent need. I also have a Honda 2000 that I use with a 48 volt golf cart charger to charge the lithium batteries if not adequate pv or disconnect the pv and use it continuously for about 45 kwhr per 24 hours if I need to. I also have a large unit run by tractor PTO that I could have home in an hour but doesn't stay here. I currently use the LV 5048 to run a 3 ton inverter HVAC that draws max 3,000 watts and 110v circuits that are mainly lights. I can cut off breaker to 5 ton dryer and oven and run whole house in emergency managing the microwave refrigerator and fridge. So in short I offset my bill continuously for now and would like to use the geothermal and use grid as backup. I want to keep it simple though it sounds complicated. I rarely run any generator for any reason. The larger one is actually for my office in emergency. At present I should be able to supply all my electricity from april to october on sunny days and about 1/2 day backup. With triple the batteries should be able to go 2 or more days without sun depending on ambient temperature. Guess I should have gotten a 4 ton geothermal and used ground closed loop. thats another reason I would use Solark 12 since it will blend in extra energy from grid as supplement to pv and battery. Again since the output is only 9,000 watts max I would need 2 and I am not going to spend that now. I did geothermal DIY for about $4500 and I wanted a climate master or Waterfurnace inverter unit but these are not available DIY and apparently Daiken discontinued one they had. Starting over I would add 2 or 3 small mini splits .
 

TKB4

Solar Enthusiast
Joined
Dec 2, 2019
Messages
208
Snoobler
Thanks for suggestions . I looked at the link. The HP 12.000 watt unit might not supply enough continuous power and the 15kw and 18 kw would be good especially the 18 kw unit but they require a 4 unit order minimum. I believe you may be thinking of a different Growatt inverter. the 1200dvm says it is a low frequency inverter type and it weighs 75kg or about 150lbs which sure sounds like it is and it also claims to be able to start two 4ton HVAC units with 36kw peak but not high enough pv watts or voltage input.

Surely 3 LV5048s at 15,000 watts continuous and 30,000 watts peak would start the first stage of a 5 ton unit that draws about 17 amps or 4,000 watts running at most. They should provide a short peak of 125 amps and the 2 LV6548 s should peak 108 amps or so . I could also put a soft start capacitor on it if needed. The 240 v fan portion of it is inverter controlled. I know they are not known for starting reserve power but they would provide about 3- 4 times the rmax running amps continuous. Really want all in one though I also can charge different set of batteries with MPP MG 5048 now I got for dedicated west panels several hundred feet from unit use 400 volt of panels open circuit.
 
Last edited:

snoobler

Solar Honey Badger
Joined
Jul 10, 2020
Messages
8,430
Location
HBR, AZ
Snoobler
Thanks for suggestions . I looked at the link. I believe you may be thinking of a different Growatt inverter. the (1) 1200dvm says it is a low frequency inverter type and it weighs 75kg or about 150lbs which sure sounds like it is and it also claims to be able to start two 4ton HVAC units with 36kw peak but not high enough pv watts or voltage input.

(2) Surely 3 LV5048s at 15,000 watts continuous and 30,000 watts peak would start the first stage of a 5 ton unit that draws about 17 amps or 4,000 watts running at most. They should provide a short peak of 125 amps and the 2 LV6548 s should peak 108 amps or so . I could also put a soft start capacitor on it if needed. The 240 v fan portion of it is inverter controlled. I know they are not known for starting reserve power but they would provide about 3- 4 times the rmax running amps continuous. Really want all in one though I also can charge different set of batteries with MPP MG 5048 now I got for dedicated west panels several hundred feet from unit use 400 volt of panels open circuit.

(1) Not sure why you've thrown the 1200DVM in as it's the first time you've mentioned it. I was talking about their high frequency inverters.

(2) Nope. You absolutely would have to put a soft starter on that. Their peak watts are typically for only milliseconds. They are not sufficient for starting big motors. Your surge current will likely be about 85A. If your unit has the locked rotor current value printed, there's your answer.

For high frequency inverters, you need to size them according to their continuous rating, not their surge rating, i.e., if something has a surge higher than the continuous rating, it likely won't work. An exception would be a microwave where there is a massive spike in current, but it only lasts for 1/60th of a second.
 

TKB4

Solar Enthusiast
Joined
Dec 2, 2019
Messages
208
Snoober
I mentioned the Growatt as low frequency transformer with 36 kw peak in initial background post just not the model number. I think the LRA is about 100 but thought it might be less when set to limit to first stage so I will look further even so a soft start would likely be able to get it to 75 amps or less. I will try to get the actual data and/or borrow a good meter to measure inrush amps. I was thinking the MPP was rated peak for 5 seconds not 20 or 30 seconds like many inverters
Actually I just looked it up the manual says 10 seconds for up to 150 % load and 5 seconds for over 150% load. I would still want to get the soft start and starting amps as low as possible below that. I guess I need to do that first before deciding further on inverter.
 

TKB4

Solar Enthusiast
Joined
Dec 2, 2019
Messages
208
I did some more research and it appears I can reduce my surge to start the HVAC unit with Sure-start unit down to 40 amps or below which I can produce with my current plans. I am going to measure the inrush current tomorrow and then again after I receive the sure-start unit and install it.
 

DanF

Solar Addict
Joined
Nov 26, 2020
Messages
98
Location
Ohio
Snoober
I mentioned the Growatt as low frequency transformer with 36 kw peak in initial background post just not the model number. I think the LRA is about 100 but thought it might be less when set to limit to first stage so I will look further even so a soft start would likely be able to get it to 75 amps or less. I will try to get the actual data and/or borrow a good meter to measure inrush amps. I was thinking the MPP was rated peak for 5 seconds not 20 or 30 seconds like many inverters
Actually I just looked it up the manual says 10 seconds for up to 150 % load and 5 seconds for over 150% load. I would still want to get the soft start and starting amps as low as possible below that. I guess I need to do that first before deciding further on inverter.
Sounds about right,
The new LV-6548 manual says she can do 2* Rated power (6500W) for 5 seconds as well.
 

DanF

Solar Addict
Joined
Nov 26, 2020
Messages
98
Location
Ohio
Sounds about right,
The new LV-6548 manual says she can do 2* Rated power (6500W) for 5 seconds as well.
Overload protection would kick it out before that. Sounds the same as what you posted on the 5048
 

chrisski

Photon Sorcerer
Joined
Aug 14, 2020
Messages
2,351
I did some more research and it appears I can reduce my surge to start the HVAC unit with Sure-start unit down to 40 amps or below which I can produce with my current plans. I am going to measure the inrush current tomorrow and then again after I receive the sure-start unit and install it.
If you're talking measuring quick spikes, I'd like to know how you measure in rush current.

I use my Battery Monitoring system to measure volts and amps, but that is inadequate to truly measure a short spike like @snoobler mentioned. I have a clamp on meter, but that would not provide the data, and neither would my multimeter. A killawatt meter doesn't provide peak watts as in the starting draws, but the steady highest watt draws. Other equipment to measure these quick spikes would be beyond my budget.
 

TKB4

Solar Enthusiast
Joined
Dec 2, 2019
Messages
208
To Chriski
I have a meter capable of measuring inrush amperage at the HVAC unit and I guess it could do the same anywhere along the wiring to the unit like if solely connected to the inverter directly. I am away right now but expect to make the direct measurement by tomorrow. I can't help but think the inrush current will be lower when using stage 1 by itself also but maybe not since the mass etc of compressor though I would think it may be starting against less total pressure. An inexpensive meter that measures inrush is the MeterK 005 model and maybe the 06 model. This one is more expensive but also measures inrush current.
 

TKB4

Solar Enthusiast
Joined
Dec 2, 2019
Messages
208
To Dan F yes that is true but to use for 240 split phase I would have 2 units that can produce continuous 13 kw which is about 54 amps and I would not need any surge at all. Total inverter cost about $2600.
 

TKB4

Solar Enthusiast
Joined
Dec 2, 2019
Messages
208
to Joe Ham Thanks for that information I have looked briefly at the link and will investigate further. Once 250v pv like the MPP 6548 it doesn't matter as much to me but it would be nice . I just would like it not to be around 100v which would increase the size wire I would need for pv connection from 10awg to 8 or even 6 awn a significant price difference.

I do find the ability to "blend" grid power with whatever battery and pv power available a significant advantage . This is why I would love to have 2 Solark 12 units but $13,000 is just too much to spend for this privilege I would rather spend that on more batteries and never use the grid. There are also MPP units meant for european 230v single phase that blend power from grid but I would need 3 large transformers and 4 inverters to meet my needs. The transformers would be one for grid input and one for inverter output. Just too complicated etc.
 

Fahmula

Solar Enthusiast
Joined
Oct 7, 2020
Messages
123
I'm considering 2 LV6548's or the growatt 12k also. I'm leaning more towards the growatt though as I much rather a single unit as I'll be shipping it to a another country.
Btw, there's another version of the growatt 12k that has a 250v pv input. SPF 12000T DVM-MPV.
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
8,365
Sunny Island can be had for a bargain on eBay new in the box. Also some taken off DC solar trailers. A pair of them would be worth considering.

I use AC coupled PV (Sunny Boy) together with grid power, net metering. It makes a good grid backup or off-grid system. My battery is undersized and I've programmed for 85A max into 48V (about 4500W) charging but make 10kW AC for direct use by appliances like A/C and laundry.

If DC Coupled power will be drawn from battery to avoid exceeding programmed grid AC current limit. If DC charge controllers are set higher then it will backfeed for net metering. But I prefer mostly AC coupled.
 

Maast

Compulsive Tinkerer
Joined
Oct 31, 2019
Messages
770
Location
Washington State
I second the Sunny Islands from ebay, here's a auction for two 6048s for $3800. Which is a steal. There were a bunch of these being sold off from the bankrupcy of DC solar. Top quality inverters.
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
8,365
Or this package, for the same price:


(DC Solar's design didn't give the recommended spacing for airflow, but you can probably live with it or improve it.)
 

Maast

Compulsive Tinkerer
Joined
Oct 31, 2019
Messages
770
Location
Washington State
Or this package, for the same price:


(DC Solar's design didn't give the recommended spacing for airflow, but you can probably live with it or improve it.)
Dude! With 2x Midnite charge controllers! Thats a HELL of a deal and if I didnt already have my rig I'd have jumped on that.
 
Top