DC optimisers in a off grid system

[Raul]

Just looking if there is a solution in off grid with multiple mppt's to split array's on different orientations and deal with partial shading . I know solar edge optimisers are dc-dc and mppt and operate at 370vdc . There are charge controllers that take 600vdc so this combination could in theory work or would it be a conflict ?
The other option is TIGO, no mppt here but a impedance balancer of some sort and ability to bypass the shaded panel of the string so the mppt of the charge controller will be optimised to the unshaded panels.
I'm I wasting my time with the dc optimisers and for a split array the best solution would be parallel charge controllers?

[Naptown]

Tigo's MAY work
Solar Edge no they have to communicate with inverter.
Best thing is 2 charge controllers

[Sunking]

I'm I wasting my time with the dc optimisers and for a split array the best solution would be parallel charge controllers?

On the right track. It is not two parallel chargers. It is two separate controllers operating into a common battery. Or two separate systems charging a common battery.

[Raul]

Thank you both. Dereck that's exactly what I meant , each CC has its own array feeding a common bank. Now that's cleared, lets imagine that I have 1 string of 3 panels on one CC and that mppt will optimise for that string . On 2nd CC I have 2 strings of 3 panels ; is this single mppt will have to optimise both strings equally? What happens if one of this strings gets partial shade ? will it bring the other down to? thank you.

[sensij]

Thank you both. Dereck that's exactly what I meant , each CC has its own array feeding a common bank. Now that's cleared, lets imagine that I have 1 string of 3 panels on one CC and that mppt will optimise for that string . On 2nd CC I have 2 strings of 3 panels ; is this single mppt will have to optimise both strings equally? What happens if one of this strings gets partial shade ? will it bring the other down to? thank you.

Yes, you understand correctly.

[inetdog]

Just to complete the picture, Raul, if you have two equal length and type strings pointed in two different directions, then as long as neither of them have partial shade during prime production hours you can put both strings on one MPPT input.

[Raul]

Thank you . That makes sense . What I got at the moment is one CC with 2 strings of 3 panels orientated SE. No shade at all , it harvests very efficient and by 10 am is on float. That would be ok if I'm going out for the day . It is not the case for every day so when we stay in , we use most of the heavy loads during peak production and since this is my Holliday place I tend to have friends guests afternoon consumption goes up as the sun passes the ridge of the house to the west. By 4 pm the harvest diminishes as we draw more and that's why I wanted to add a west array without compromising the SE one in the morning hrs.
I got a new the same power CC and on my first visit there ( early spring ) I will put more panels on the west side but how many panels?
The SE is 2x3of 240w poly trina. I seen these array pushing constant before and at noon in exces of 1550w consistently not only brief moments . When we use the washing mashine and well pump kicks in it draws most of it from the panels. Now I can't get anymore of these trina but I have 3 solar world 260s , 2 LG285s , or 3 HHV 260s all mono. I got space for 6 but I tend for the 2 LG's .
Battery bank is 200ah at 48v agm and have DC disconnect for each array if I would like to switch to the west as needed and turn of the East . Still got time till spring and I may have some more panels till then. I think my safe margin is 50 charging ah max.

[Mike90250]

The closer you you can match the new array (Vmp, Voc, Imp) to the old, will allow you to parallel with the existing array.
Changing brands, will cause some mismatch as the controller tries to figure a mid-point setting.
The Vmp is most critical thing to match.
You don't need to match the same # of strings, but you do want to be careful of cooking your batteries with too much amps.

[Raul]

The closer you you can match the new array (Vmp, Voc, Imp) to the old, will allow you to parallel with the existing array.
Changing brands, will cause some mismatch as the controller tries to figure a mid-point setting.
The Vmp is most critical thing to match.
You don't need to match the same # of strings, but you do want to be careful of cooking your batteries with too much amps.

Even if I use a new separate CC? The hole idea was to add the west array on separate mppt so they can work independent but still charging a common bank.

[Mike90250]

Sorry, missed that. (adding a 2nd controller)

So having 2 arrays, and 2 controllers myself, the only flaw is that the West controller has gone through the Bulk and Absorb cycles by noon (because your South controller did all that work) it will only maintain the Float voltage as your loads ramp up.
If it's programmable, set the re-bulk voltage on your controller a little higher, so it won't deplete the battery as much before it kicks in.

With only a 200ah battery, you may need more for your loads.

[Raul]

Thank you , yes I can change the re bulk on the 2nd CC that is a very good thinking. As for the loads not a problem ; we stucture ourselfs to use most on sun up and the battery is the for the night loads only . I even installed a water tank in the loft so if the battery is full and panel power is available the well pump is on to fill it up for night use.

[Ben25]

Tigo's MAY work
Solar Edge no they have to communicate with inverter.
Best thing is 2 charge controllers

There is a little device that you can plug into each string of Solaredge optimizers that will disable the safe voltage feature and allow the optimizers to be used with other inverters. It's called the Solaredge Key. Never seen or used one, but it's out there.

[sensij]

There is a little device that you can plug into each string of Solaredge optimizers that will disable the safe voltage feature and allow the optimizers to be used with other inverters. It's called the Solaredge Key. Never seen or used one, but it's out there.

It only works with Optimizers that are built with the IndOP technology.

http://www.solaredge.us/groups/retrofit/opi

[Raul]

Looks like the 350's can be disabled with the solar edge key but you still can't run different strings lengths . Would be nice to have mppt at panel level ; it accepts different orientations with multiple equal strings .

[Qtips]

Just looking if there is a solution in off grid with multiple mppt's to split array's on different orientations and deal with partial shading . I know solar edge optimisers are dc-dc and mppt and operate at 370vdc . There are charge controllers that take 600vdc so this combination could in theory work or would it be a conflict ?
The other option is TIGO, no mppt here but a impedance balancer of some sort and ability to bypass the shaded panel of the string so the mppt of the charge controller will be optimised to the unshaded panels.
I'm I wasting my time with the dc optimisers and for a split array the best solution would be parallel charge controllers?

A Tigo setup would be able to deal with multiple orientations and partial shading. With a Tigo setup, each panel on the system can be different and have a different orientation. The only limitation is not with Tigo but with the main inverter. Your main inverter may require a certain voltage to function properly. That may means having a minimum of 7 to 8 non-shaded panels at all times.