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.
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.
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