Hi there,
Is it acceptable with Victron MPPTs to install parallel strings of the same module type on different orientations? EG, 3 modules facing west, paralleled with 3 modules facing east, into the same input on the MPPT?
Cheers, Anne
asked
Paralleled strings of same panels on different orientations
Hi @Anne Wilson
It is 'acceptable', but may not fully optimize the output of each array. The mpp tracker will optimize the V of the combined arrays, but that V mightn't suit either perfectly. So there may be some efficiency losses, but you will get more power overall than your first array alone. And probably for longer over the day.
I'll do similar myself soon, and expect good results. Not perfect, nor excellent, but good.. :)
In my opinion, there is a loss but not too significant. At my own house I have equal panels 45 degrees apart, on one MPPT. When comparing kWh per Kwp installed, it’s maybe 5-10% less yield that a comparable site with dedicated MPPTs. That being said, it’s accepted best practice to have an MPPT for each orientation.
In my opinion, it is a very good thing to do. I do this deliberately especially with E-W strings to reduce the noon peak and get flatter production over a longer day. I find it so successful that any future expansion/projects will be done with this in mind.
I try to avoid clipping. My MPPT's are sized for the peak, or should I say my panel strings are increased until the MPPT's peak.
I can get usually more than 60% - 100% more panels on the same MPPT, than if all panels faced the ideal tilt North. With more panels, at all tilts and orientations, I can still make more usable power over a day.
True, I have bought more panels, but I consider panels cheap and MPPTs expensive.
A nice discovery was to find out on an overcast day panel orientation doesn't really matter.
I may only get 5% of the power rating from any of my panels, North, East or West.
The tilt actually matters more when overcast, a flat panel is best in those conditions. So throw that into the mix as well.
That's when having 70% more panels really makes a difference, even though you are at low power. Because that is when every watt really counts.
Don't concern yourself about different voltages not matching, a panel is up to full voltage even at very low current. Just look at the PV V & I output curves.
Using the same type of panels in each string, the significant gains outweigh the insignificant losses.
