MPP Hybrid/offgrid inverters?

[Steve Fractals]

Just gone live with an MPP 6048MT hybrid (offgrid mode) inverter and it never seems to totally use PV solar power with always using at least a little from the grid/utility but I would have thought that if enough solar available then it would use it all to power loads instead of some from grid.

For example, just put max loads on and it can currently draw at least 800w from solar (only 4x400w panels currently installed) as maxed it out with loads and that's what it seemly can produce at this very moment. However, if I then drop my loads to say 300w then it only draws 150ish and takes the other 150 from the grid. No matter how low I make my loads it always pulls some from the grid.

I did post a similar request for info in the AIO forum another day but got no responses so wondering if this forum might be a better place.

Any ideas e.g. am I missing some setting?

 

[rodrick]

One of the features of that unit is a critical load design L1 is critical L2 is non critical when only one power source is available L1 will only have power there are other settings such as timers for load sharing from what I can tell is you need 2 power sources in this operation
do you any battery supply also how are your panels wired

 

[Steve Fractals]

One of the features of that unit is a critical load design L1 is critical L2 is non critical when only one power source is available L1 will only have power there are other settings such as timers for load sharing from what I can tell is you need 2 power sources in this operation
do you any battery supply also how are your panels wired

Hi Rodick, my panels are wired in series and currently no battery. My loads are all connected to L1 critical with no current loads connected to L2 and no timers set.

The issue I'm having is that even when I know my PV can supply say 800 watts it never supplies its full possible output unless I'm trying to draw a bigger load than it can supply or unless I turn off my AC-in but then of course without a battery it will shut down the inverter should my load exceed what my PV can produce. I know for sure when say I'm running with a total load of say 300w that my PV has more to give as if I say turn on a bigger load e.g. cooker then it instantly draws most of that from PV, yet if I remain at 300w total load then it will only draw 100w from the PV with 200w from grid/AC-in.

It seems like it will always draw some from AC-in/grid if available even though it could use all from PV. I wonder if this is some sort of protection set in firmware to prevent any export to grid by ensuring always drawing less from PV than needed for loads so no poss export. It could also be that once I install a battery then this issue will disappear with the inverter drawing everything poss from PV to charge battery and feed to loads but then suspect (cannot confirm) that it will draw at least some from the battery whilst simultaneously charging etc.

Like I've said if I turn off AC-in breaker then it will use all from PV only as that's its only option but my array isn't big enough to leave ACin isolated unless I'm only using very small loads. I am in communication with MPP who now want a copy of my logs but it will be difficult to prove that my PV has more to deliver without a battery. I do plan on batteries but just don't want to invest in Lithium at the moment with decent half priced other tech e.g. Sodium about to launch.

 

[rodrick]

The way they set this unit up they try to use 2 sources from what I can tell when only 1 source is available it shifts to critical L1 so most likely something in the software must have a glitch.you being able to pull near full power of pv output on L1 on single power input mode tells me it’s in the settings or software wanting to share loads. in the manual there must be a setting for this if not mpp needs a software upgrade

 

[rodrick]

This is a new design so I think you might be the Guinea pig / Trail Blazer

 

[Go2Guy]

any update on this?

 

[Steve Fractals]

any update on this?

Yes it was all sorted. The board was faulty and has now been replaced. MPP sent me the new board and I fitted it. I also now have a 5.2kwH battery and the system is running great.