Additional SCC vs overpaneling

[ericfx1984]

For those of you that have do it yourself off grid systems... I was wondering what your experience has been

Does it make more sense to overpanel an existing solar charge controller? Obviously you're not going to get much more, if any, additional peak output... But it will definitely smooth out your overall output meaning that you will probably reach charge a little sooner and charge later into the day and be running at full charge for a longer period

Where does it make more sense to just add another controller?

One thing that I've noticed about running additional controllers is oftentimes the additional panels and solar charge controllers rarely see their full potential as far as output goes... In my case I had added a few 60 amp MPPT solar charge controllers, while my overall production certainly increased significantly... I found that by and large one of the controllers always seem to take the lead especially in the last 20% of battery charge... Not to say that we never saw higher outputs... Just that I never seem to get anywhere near full output that the controller should have produced

For instance a 750 watt array may only put out 600 Watts at most and might average somewhere in the 4 to 500 watt range

Best as I can tell what causes this is that the controller that's putting out the most power has its voltage red by the other controllers in the system... This causes the other controllers to stand down from a more aggressive charge to a float charge... Oftentimes resulting in anywhere from 25 to 50% reduction in energy production

Curious what everybody has seen, what their thoughts are...


Additionally I might ask if anybody has any familiarity with the EPever link kits? Not sure what they're actually called but basically it makes one controller a master and all the controllers after that slave... Which seems to help keep them in the correct mode

 

[sunshine_eggo]

Multiple chargers only benefit when in the bulk phase of charging. Once absorption is hit, voltage is constant and current tapers. More charge current means more voltage rise with charging. They're not "reading each other," but their respective inputs all influence the measured voltage.

Charging from multiple sources

One can have as many independent charging sources running concurrently as they like provided they are programmed properly for the voltage of one's battery bank. Examples (some or all at once, even multiples of a single type, different brands, etc.): Solar PV via MPPT Solar PV via PWM AC-DC...

diysolarforum.com

If you want to eliminate that, using a single open circuit voltage measure fed to the controllers does the trick. Victron smartshunt in VE.Smart network with Victron MPPTs works like that. The MPPT also supposedly work together better by "sharing" charge duty more proportionately and staying in the same charge phase as the others.

Why not in stages?

Overpanel first. If that meets your needs, you're done. If not, add a MPPT to utilize the "over"-panels.

 

[ericfx1984]

If you want to eliminate that, using a single open circuit voltage measure fed to the controllers does the trick. Victron smartshunt in VE.Smart network with Victron MPPTs works like that. The MPPT also supposedly work together better by "sharing" charge duty more proportionately and staying in the same charge phase as the others.

It seems like EP ever has the capability of doing that when you link the controllers... Basically it causes all the other controllers to operate in whatever state the controller assigned as primary or master happens to be in

Of course the problem I run into is that by the time I get to peak solar for the day... I'm already nearly charged so I never actually get to experience full charge capability as the other controllers start to taper off

Interestingly enough the Victron is the one that keeps pounding through the entire charge cycle

And then the EP ever is taper off little by little

I'm honestly considering getting rid of my 3, 60 amp EPevers My 40 amp EP ever, and my Victron 100/50

I figure if I do that I can buy 2, 100 amp EPevers and a link system... And probably have some cash left over in my pocket

 

[ericfx1984]

Multiple chargers only benefit when in the bulk phase of charging. Once absorption is hit, voltage is constant and current tapers. More charge current means more voltage rise with charging. They're not "reading each other," but their respective inputs all influence the measured voltage.

Charging from multiple sources

One can have as many independent charging sources running concurrently as they like provided they are programmed properly for the voltage of one's battery bank. Examples (some or all at once, even multiples of a single type, different brands, etc.): Solar PV via MPPT Solar PV via PWM AC-DC...

diysolarforum.com

If you want to eliminate that, using a single open circuit voltage measure fed to the controllers does the trick. Victron smartshunt in VE.Smart network with Victron MPPTs works like that. The MPPT also supposedly work together better by "sharing" charge duty more proportionately and staying in the same charge phase as the others.

Why not in stages?

Overpanel first. If that meets your needs, you're done. If not, add a MPPT to utilize the "over"-panels.

So I've been reading that my EP ever 6415AN (60 amp) can be linked together... I have three of those units

So I think what I could do is link those together and then tell my Victoron 100/50 and the EPever 40 amp controller to stop charging at a little bit lower voltage

This would allow the three, 60 amp controllers to keep hitting the batteries hard until fully charged

Thoughts?

 

[sunshine_eggo]

So I've been reading that my EP ever 6415AN (60 amp) can be linked together... I have three of those units

So I think what I could do is link those together and then tell my Victoron 100/50 and the EPever 40 amp controller to stop charging at a little bit lower voltage

This would allow the three, 60 amp controllers to keep hitting the batteries hard until fully charged

Thoughts?

Not sure how well EPever coordinates between controllers. if you want to take the Victron and 40A Epever out of the equation earlier, sure that will work.

 

[ericfx1984]

Not sure how well EPever coordinates between controllers. if you want to take the Victron and 40A Epever out of the equation earlier, sure that will work.

I would assume if they have parallel boxes that they should coordinate fairly well