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MPP Solar 6048 AIO Inverters - details and specifics of operation not clearly shown in the "Manual"

OffGridForGood

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I have twin MPP Solar 6048 AIO Inverters.
These are unique, in that they operate differently than the more popular MPP 6548, or the Low Frequency LVX 6048.
Universally, all MPP Solar products ship with a pamphlant of information imagined to be a 'manual' but really is a summary user guide at best. The pamphlant is not very detailed, includes no information on the interal wiring and circuitry and contains many poorly explained sections that lead to more questions than answers for the user, especailly those new to solar.
All that said, I feel that although the forum has sprinklings of information on certain AIO inverters, often buried within other discussions, it would be a helpful resource if we had postings specific to certain AIO units that put all the specifics, quirks and insights for that specific quipment (and not all the others) in one place.

A few things of interest about the MPP 6048
These are high frequency inverters, quite unlike the LVX 6048 model.
These 6kW AIO units are really twin 3kW units internally, but this feature enables a single unit to output 120/240 and this is a handy feature especially for small systems and for people new to solar just starting out. The 120/240 output allows mixed loads without need of a separte auto-transformer and avoids some potential dangers of those set ups. Unlike other AIO inverters, the 6048 has four input and output terminals, Grd, L1 L2 N (not three). This makes connecting to an electrical panel a simple matter. More on this later.

I started with one MPP 6048 almost two years ago, and added the second unit a year ago. These units allow a beginner an easy set up, to get operational, even without PV (I started with a single MPP and a single SS 100Ahr server rack battery) and expansion is very easy as these units are designed to be paralleled together to increase available power output: ie 6kW, 12kW, 18kW etc. To parallel the units, the AC inputs can be connected to bus bars, and then those bus bars connected to an AC source. Ditto for the output AC, each unit can be connected to separate bus bars, and then those bus bars connected to a load centre (distribution panel).
The down side, though is the relatively high standby consumption of the units. Since each MPP 6048 is internally two 3kW units, the standby consumption is higher than say the MPP 6548, but a single 6048 unit can output 120 & 240VAC while the 6548 will need two units to accomplish this output. So it all depends on what loads you have to power.

Setting two 6048's in parallel, requires comms between the units (each unit comes with the required interconnections) and a load sharing cable is also required - again each unit comes with the 'required' cable but when you see the load sharing wire you will be less than impressed, as it is 16AWG wire, and you start to wonder just how much load sharing is going to pass through this tiny cable. I installed the wire that came with the units and after some months of use, and noticing them getting hot, testing amperate passing, upgraded the wire to 12AWG perhaps out of an abundance of caution more than measuring urrents high enough to need 12AWG.
The main thing to watch for with parallel units: you need to set one MPP as the master and the other the slave, with dip switches located on the bottom of the units. If you miss this step they will not function together properly. Also these units are capable of 120 L1-L2 (if you don't need 240 for example) or you can set them for 240 instead of 120, perhaps a good feature for those in the UK/EU, and to go with this there is a setting to chose 50Hz or 60 Hz they can even be set up for 208v if you need.

Battery set up is a #$%#$# - okay the fact of the matter, these units are factory set for Lead Acid batteries, and most of us these days are no longer using those. Program setting 5 allows you to select 'USE'- (user-defined) setting so that the default lead acid settings are not applied to your battery bank. But, this means you need to set a number of other programable settings to new values, and for some reason, they don't make the other parameters Prog 6,7,8,9, no no, they put them at Prog 12, 13 16 etc and if you don't go looking through all the available parameters checking what you need to set, then those default (suitable for lead acid) settings remain active, and lead to frustration and perhaps poor battery management. The MPP 6048 has CAN and RS 232 inputs to allow comms between the AIO and server rack batteries with these communication protocols, one caution, I am told that some server rack BMS units will not communicate with MPP Inverters while others will. I have used the Signature Solar 100Ahr 48v rack, a similar one from Solar Parts Store (Orangeville Ontario) and had success with the rack batteries playing nice with the AIO. I don't know enough about the comms to know which BMS units will work and which don't, and often (it seems) the server rack batteries do not specify which BMS they are using internally.

Grid power supply charging, when you need grid supply to charge the battery rack, or to supply power in by-pass, the MPP has settings you can set up to limit the amperage the MPP will utilize from the grid. This is an important feature, and they have a wide range of available pre-sets from 10A to (IIRC) 60A. I have a 30A 240Vsource available so set up the MPP to use only up to 30A, in testing my meter indicates the MPP is using 28.9A so I feel the system works well. One interesting point on charging is to carefully check the low voltage cut-off (the battery voltage that will trigger the Utility source to begin charging the battery(ies) , and the battery return voltage (the battery voltage that when reached, the utility charging will end, and battery use will again supply energy to the loads). For summer use, I found it best to pick a narrow range between 48V low voltage cutt-off and 51V battery return voltage, as during summer the chances were high that solar input would be not far down the road. However during November, (my worst month for PV) it has been a better strategy to program the battery return as "Full" which is not what you think, it is the full charge sequence using Bulk and Float and at the end of that sequence then the MPP returns the loads to the batteries, and for my situation this is better since Nov - April is also when we are more likely to see utility outages from storms.

The high standby current is off set in my system with additional PV panels, this is due to the large available roof areas I have available facing South. Although I have a lot of roof area available, I found that using higher wattage panels made the most efficient use of racking, shortened the home-run main lines back to the inverters, and shortened up the amount of PV/Rack grounding required. My panels are Canadian Solar 440 bifacials, and before someone chimes in that bifacials are not appropriate for a roof mount, know that my roof mounted PV do not sit parallel to the roof, they are tilted up (summer 30-degrees, Winter 60-degrees) and where I live, half the year the sun rises NE and sets NW so I have considerable time each day with the sun shining on the back of my panels, so yes they are bifacial and for good reasons. The 6048's and PV strings - I was not very happy with my first PV input with the MPP Solar 6048's let me explain:
Each 6048 has twin inputs for PV with 40A 124VDC max per input. When I first connected PV to just one MPP it didn't seem to make any difference at all if I had 2S-2P or 2S-4P I got the same input. That made no sense to me, but changing the PV input so that about equal PV input was going to MPP1 and MPP2 then everything worked properly. I really don't know why this is exactly, but I can report that as I added more PV to the system, keeping the input 'about equal' on each of the two MPP 6048's has resulted in the best performance. {edit: I may have missed in the settings early in my system set up to change the programed max charging amperage, which can be set anywhere from 10A to 220A, but at this point I don't know for sure what limit on charging I had at the time the PV was first connected.}

Other MPP Solar 6048 settings to pay attention to:
There is a setting for automatic reset of the MPP after an overload event, this will save you a lot of frustration especially if you have only one 6048, not two, or only one 100Ahr rack battery instead of two or more, which means you have higher chance of overload. The 6048 has limited un-equal loading - remember these are really two 3kW inverters installed into one housing, so putting full load on L1 with nothing on L2 is not accommodated well with these units. As an example: when I had only one 6048 and one server rack battery, putting a big load on L1 with 'nothing' on L2 tripped the 6048 on 'out of balance load' - adding a load to L2 (shop lights only) which increased the total load on the MPP solved the out of balance issue, just by adding some load to L2.
There is a setting to shut off the inverter 'beep' and this is the very first setting to change from the factory default.
If you have a utility connection available for by-pass or battery charging, then the use of the Neutral should be carefully handled, to avoid a loop between say the incoming circuit, the Inverter and your subpanel the inverter supplies. The 6048 has an internal relay that shorts Gnd to N only during battery/PV power supply. In by pass mode the inverter is not supplying the power and is irrelevent, the MPP opens the relay during bypass. As others have noted in their postings on this inverter, there is an internal bonding screw with an access hole available to permit the user to remove the bond altogether if you wish. I have not seen a need to do this with my set up.
 

Attachments

  • LV6048 split phase manual-20201120.pdf
    3.8 MB · Views: 19
Last edited:
Summary of the specs (these are shown on the label on the side of each inverter) and apply per inverter.
Operating Temperature Range -10 to 50 Degrees C (14 to 122 Degrees F).
Rated Power 6000VA

DC input 48VDC 137A (from battery to the inverter)
AC output L1,L2,N,Gnd 110/120/208,240 50Hz/60Hz
35A per phase
DC Output 54VDC Max 60A, default 30A
AC Output L1,L2,N,Gnd, 110/120VAC,
50/60Hz, 27.3A per phase
Solar Charge Mode:
Rated Current: 80A
System Votage 48VDC
Min.Solar Voltage: 40VDC
Max. Solar Voltage VOC: 145 VDC

They don't list here (but should) the idle consumption of the inverter (depends upon loading) is up to 100W meaning it can be chewing up to 2.4kW per 24hours if loaded all the time, less if light loads overnight etc.
 
I was wondering about the ground-neutral bond relay. I couldn't find any documentation on it at all. Do we know for sure it has it?
My critical load subpanel (connected to 6048 output) is not bonded as I have an interlocked relay between it and the main panel in case the inverter stops working for whatever reason I can quickly bypass the inverter entirely and get power from the grid.
I also kept the panel unbonded assuming the inverter does have that function.
 
I can confirm the MPP 6048 has the input and output Gnd tied together inside the case attached to the case side, it has an active N-G bond, it activates only during inverting mode. That is, is closes and connects N to Gnd while inverting 48vDC to AC output.
In the first attachment, I opened the case front panel (I flipped it up onto the case top, so I wouldn't need to unplug anything) you can see the MPP 6048 is really just two 3kW units side by side in one wide case. (actually they are more than 3kW, we will get back to this in a moment after your question).
In the second attachment, I put the camera right up close to one of the two holes you can see in the main picture, and I used a light to show you what is behind these holes. Yes, it is a symbol indicating ground, and a picture of a screw. Using a #2 star magnetic screwdriver (so you don't drop the screw down into the rest of the electronics) this screw can be removed. There are two of these.
From my own testing, the unit forms a N-Gnd bond during inverting mode, but with the screws removed, it does NOT form this bond during inverting.
If you plan to remove the screw, ensure you have a N-Gnd bond elsewhere in your system. Filterguy helped me with sorting out the N-Gnd issues with my pair of MPP 6048's, a Reliance 306 CLP, Utility charging and a MTS for switching from Utility charge to Generator Charge. I needed to also remove the N-Gnd bond in my generator in my situation.
 
The other point to know about the MPP6048, it has a max output of 27.3A 240vAC continuous load rating.
27.3 x 240 = 6,552W not 6,000W
Some people pick the 6548 over the 6048 assuming it has 500W higher output, but it doesn't. The 6048 with the two side by side inverters in one case allows this single unit to output both 120vAC and 240vAC with just one AIO, while the 6548 requires two AIO units to produce 120v and 240v.
The 6048's have higher standby consumption than the 6548's.
 
I was sent a service manual for the MPP to assist with replacment of the Comms board - see my up in smoke post for more details on why I need a new comms board.
Since this has actual internals of the unit and wiring illustrated, I thought I would post the manual here.
@FilterGuy may be interested to see the guts of the MPP 6048
 

Attachments

  • LV5048_6048 disassembly guide 201903A.pdf
    4.6 MB · Views: 15
I have read several times on this forum critical comments about MPP-Solar's "lack of support".
Recently I fried my Solar Assistant (one end of the comms cable touched battery pos 48v while the other end) was still plugged into the SA. POOF!. When the new SA came in, it only would communicate with one of my two inverters. When the mishap occured the second inverter was still plugged into SA, and it must have also got zapped. Swapping cables made no difference, so I swapped the MPP's comm boards and got comms with Inverter #2, but lost comms with #1, swapped the comms boards back and the problem followed the #2 board.
I took a photo of the comms board s/n and the Inverter's s/n and sent it to maximumsolar (who I bought both inverters from) and they forwarded to MPP tech support cc'd me in on the email. Tech support asked a couple questions (checking if the display was still working or not, and if any other operations had also stopped working, - I confirmed display and other functions all working except comms port output) and within two days I had a firm quote to send me a new communication board for $5.31 ! (but the shipping was $30).
I got the new comms board in 15 days, to my door, and it fit & worked perfectly.
I think this is pretty good support and the price was surprisingly low (I was prepared for a lot more). Maybe I just got them on a good day, but seemed worth mentioning.
 
Last December I bought a dedicated back up generator, heavy 30A 240 4-wire cord, and Generator-wall plug for the solar set up.
We run the genny every three months, needed or not, to exercise it/run some fuel through it, confirm it's working. Today was a run day.
I noticed something interesting: while the generator is running, the system is charging the batteries with both "utility" (generator) and with solar at the same time. I had thought the MPP's could not do this.
thought this may be interesting for those that have or are looking at the MPP 6048 model.
 
Last December I bought a dedicated back up generator, heavy 30A 240 4-wire cord, and Generator-wall plug for the solar set up.
We run the genny every three months, needed or not, to exercise it/run some fuel through it, confirm it's working. Today was a run day.
I noticed something interesting: while the generator is running, the system is charging the batteries with both "utility" (generator) and with solar at the same time. I had thought the MPP's could not do this.
thought this may be interesting for those that have or are looking at the MPP 6048 model.
What mode were you in?
 
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