Club 80-90 Forums

Why are you forbidden from doing uneven panel numbers on a single MPPT?

I have 3x in series already and would like to add an uneven number in parallel, either 1x large panel or 2x medium to make the voltage very closely matched to the existed array of 3x in series.

I don't get why this is roundly rejected online as forbidden, to have uneven series strings in parallel, what is the problem if they are discreet packs? I know it is wrong but haven't understood why.

Is a single one in parallel to an existing series string also a no-no?

This significantly changes my plans if so. It seems overkill to have to buy another 3x panels taking up way more room just to get an equal set, even when they will be different panels anyway, as I don't want to use the same kind.

Ye I know I can get another mppt but I want to make full use of this one somehow but it seems many roads are blocked.

So any other ideas how I could get a big other panel fit onto the existing mppt? or some other permutation of that, to be equivalent to one big panel? like and extra 600-700W or so?

I spent all day researching furiously and when I think I have found a great solution I see online it is verboten.

Generally the panels I've looked at give best power output at around 19v, so three in series will be about 57v. Bigger panels will supply a higher current, but usually voltage will be very similar, so one big panel is 19v. You don't want to connect that in parallel to 57v.