Using MPPT with combination of different panels

[MountainMan]

How close does the nominal "max power voltage" of differnet panels need to be to be still reasonably controlled by the one MPPT conytroller? I realise that ideally they should all be the same, but over the years I've upgraded and I would say their characteristics would be different.

Are there problems (other than$$$) with having two MPPT controllers feeding the same battery bank?

Thanks

[SteveC]

No problems with two controllers. I actually have three MX60s for one battery bank. I've had these set up for almost five yr. and had zero trouble. The differing voltages in the panels won't be a problem. You have to configure the panels [wire them together, I mean] in such a way as to make sure the maximum amperage you expect for each of your controllers does not exceed it's limit.

For example, I have my array wired in 36-volt sets of panels. This was because the collection of panels I had could not all be used in any other configuration [24 v., 48 v., etc.] without my having to leave out a panel or two, which I simply did not want to do. [Give up panels!!!] I have two 36 volt sets feeding each controller [via a combiner box] and that keeps me within the 60 amp output limit of each controller. [output to the battery bank] At least that is what works with my model of controller and my variety of panels.

Works great.

[Sunking]

Very simple math problem you need to work out.

Series circuits voltage adds and current will be limited to the lowest value in the series chain. So if you have 10 amp panels and 1-6 amp panel in the string 6 amps is all you get, you waste 4 amps.

In parallel circuits currents adds and voltage is limited to the lowest value in the pairings. So if you have 24 volt panels and 1 is 12 volts, you get 12 volts.

Hint:
Watts = Voltage x Amps

[Naptown]

In other words no matter how you wire them together if each is not on its own inverter or controller the entire series or parallel string of modules will perform to the lowest performing module.