24v 48 v solar panel system

[thirteen]

I have a question. Is there a hidden problem with having 2 seperate solar panel voltage sections on the same 24v system.
I have 4 panels 24 v wired into my 24 v system The are 26 feet from the Midnite 60 controler
After being up there this winter I have found out that I nee to have another set of solar panels farther up the mountian. I have only 1 hr of sunlight in Dec. / Jan. In order to get my batteries fully topped off I need more input.
Bacause of the distance of 400ft. I am thinking of putting up 6 more panels and having them at 48v.
This is because of the distance needed for the use of smaller wire.  Less $$
I would like to install this into my same 24v system. The controler should be able to regulate the higher voltage down to a workable 24 voltage . They will both be hooked to the same inverter. I know there is a problem somewhere in there.
I may put a diode in my power line from the MidNite 60 controler. I will have a controler MidNite 80 on my incoming higher voltage from the newer 48 v solar panel system.
So where is my problem going to show up?
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I have a mountian problem to work around. I will lose sun light on my 48 v panels in the afternoon but my 24v panels will have it. During the summer but during the winter I will have just the oposite. More power coming from the 48 v panels.

A lot of this will be elimnated in 2 years when I put my micro hydro system in. (I hope)$$ is the question.
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[RandomJoe]

If I'm reading this correctly, you have no problem at all.

Two separate charge controllers, one for the 24V array and one for the 48V array, both connected to the same battery bank.  Right?

If so, no need for diodes they'll work just fine.  That's exactly how you connect multiple arrays, normally because of too many panels for a single charge controller but your reason is good too.

This isn't a "problem", but you will probably see that one of the charge controllers is "dominant" - during absorb or float it will be supply most of the power while the other one drops back to almost nothing or might even shut off.  This is caused by the CCs seeing very slightly different battery bank voltages for one reason or another (component tolerances, wire lengths, etc).  During bulk charging though both should be doing as much as possible.

[thirteen]

Yes same bank. I had to replace one of my new battereis already. It had a dead cell to start with.  The controler would show good but it would only give me 20 seconds of power then the inveerter would shut down . It then registered low voltage.  It was my mistake for not checking the batteries before I left town. It was a 100 mile trip to replace it. There will be only a couple of hours that they will both produce max power at the same time.

[jack11]

I'd make sure that the charging setpoints for begin/end of each charge phase and equalization are exactly the same for the 2 controllers you use feeding one battery pack/inverter. And, I think you need to use mppt controllers when you blend different panel Voc like that (simple on/off controllers would connect 24v panels to 48v panels at some point).

The controllers I use do networking via modbus protocol to synchronize their charging operation when more than one controller feeds the same battery. Of course that system voltage must be the same for both controllers, but the panels connected to each one may have different Voc/Vmp (the mppt function in the controller takes care of that).

[bart]

 Midnite 60 controler?
controler MidNite 80?
   Are you referring to the Classics !50 and 200?
If they are the Classics then I believe they can be data linked together.
Question would be better asked on the Midnite forum, if that is what they are
http://midnitesolar.com/smf_forum/index.php