East West orientation with double MPPT's, wich setup its better?

[mrdavvv]

Hello!.

So the setup is:
- 4 x 400W panel (Gray), 6 x 405W (Light blue), and the rest in 410W (Blue). Total of 26 PV.
- East west orientation
- Solark / Deye 8K (10K of PV max).

This are our option, put an east and west string in a single MPPT:


Or put all east in a single MPPT, and same for al west:

 

[Rocketman]

Are all the voltages and amps practically the same on those three different panels? (Assuming they are- if not that’s a different can of worms).

my gut says #2. Morning sun will blast one side - the other side will produce “some” power, same in the evening, so I think you will overall get more power. Where as, #1, when morning sun is on those panels, the other panels will not be able to contribute anything.

 

[Steve_S]

That setup should work fine and give you power generation from first light to end of day provided no trees or other obstructions are in the way.
As for Volts/Watts/Amps I'm sure that you have everything set to within normal operating parameters for each MPPT Controller and if you remain within the allowable specs, you ought to be good to go as well.

You do not show your string setup and how you are combining the panels per side. There are advantages to having a "Long String" but there are cons too, especially when panels get shade/cloud etc... One long string will be affected by shade whereas a set of smaller strings will not be so affected. The cons is setting up the combiner which would require a breaker per string. It is NOT a Do or Die thing but these tweaks when worked out properly can provide more resilience.

It may be worth pondering but you would have to look at and record how the sun is casting onto the surfaces through the day and how shadows cross the panels from clouds etc. Assume the East Side is broken into 3 strings of 4 panels, often not all panels are shaded by a cloud moving past but if all one string the entire string takes the hit, but with 3 strings 1 or 2 strings may be shaded while %3 is still getting full sun, OR strings 1 & 2 get full sun while #3 is shaded.

Case in point. I have 2 strings 4 panels across the top & 4 panels across the bottom. I've discovered this is inefficient especially in winter time with low sun angles. By reconfiguring to 4 panels on the "east" and 4 on the "west" side it's increased production by about 5-8% and less fallout overall.

Just something to consider.

 

[mrdavvv]

Are all the voltages and amps practically the same on those three different panels? (Assuming they are- if not that’s a different can of worms).

my gut says #2. Morning sun will blast one side - the other side will produce “some” power, same in the evening, so I think you will overall get more power. Where as, #1, when morning sun is on those panels, the other panels will not be able to contribute anything.

Yeah between each type of panel, they are the same brand / model / voltage.

I also like #2, but not sure if the inverter could have problems for having MPPT1 at 100%, while the other its at 30% or less, wich will happen at the beginning and end of the day.

While with #1, the MPPTs would be perfectly balanced,... i think ive read something about this in the manual, but not sure, im checking.

That setup should work fine and give you power generation from first light to end of day provided no trees or other obstructions are in the way.
As for Volts/Watts/Amps I'm sure that you have everything set to within normal operating parameters for each MPPT Controller and if you remain within the allowable specs, you ought to be good to go as well.

Yep all good, the roof its tall and not a single shadow in sight.

You do not show your string setup and how you are combining the panels per side. There are advantages to having a "Long String" but there are cons too, especially when panels get shade/cloud etc... One long string will be affected by shade whereas a set of smaller strings will not be so affected. The cons is setting up the combiner which would require a breaker per string. It is NOT a Do or Die thing but these tweaks when worked out properly can provide more resilience.

The inverter works from 150 to 425V, so we are triying to work between that:




In this one the wattages are a little different (Because the panels that are different), but its close to real.

--- And this is the configuration of the series:




Thanks for the insight!

 

[Steve_S]

Everything looks great IMO. Myself, I'd put array 1 & 2 on the west side.
Options A & B oh boy.
Default thought says A but then thinking on it maybe B is better. Either will work fine I think.
When I think about the continual load on an SCC, day after day it ages things the higher it's all pushed. Each SCC would be getting more or less 1/2 the solar power AM to PM, versus one SCC getting it all in the morning and the other getting it all in the afternoon. The sacrifice I think might be the output charge amps to the battery bank 'maybe'. Ideally, you want to get the most amps you can into the batteries for as long as you can, right.. lol.

 

[mrdavvv]

When I think about the continual load on an SCC, day after day it ages things the higher it's all pushed. Each SCC would be getting more or less 1/2 the solar power AM to PM, versus one SCC getting it all in the morning and the other getting it all in the afternoon. The sacrifice I think might be the output charge amps to the battery bank 'maybe'. Ideally, you want to get the most amps you can into the batteries for as long as you can, right.. lol.

That makes a lot of sense.
Its an easy decision, the batteries are only there as a backup, we dont even use them most of the time. So mixed strings to maybe increase the lifespan of the inverter sounds like our best option.

I just remember that i talked with Hedges about this some time ago..., and he also agrees.. you guys are my solar masters

As for panels, rather than a charge controller dedicated to a panel orientation, I would put two orientations on one charge controller or Sunny Boy. About 50% over-paneled, but same peak watts and spread out over more hours.

Two strings of different orientations into one MPPT charge controller loses about 2% because Vmp slightly different between the strings.
It lets you put 50% extra panels beyond charge controller capability, without clipping (if 90 degree angle, area presented to sun is 0.7x as much)
Off-angle panels will produce fewer Wh/day than they would with optimum orientation.
Spreading power over the day reduces battery cycling, leaves more charge as night comes.