Newbie solar question on hookup

[gizmoguy]

I have 4 24v panels (2) 155W panels and (2) 120W panels that I need to wire to my 6024 MPPT charge controller.  The input for this controller requires 48v so I know I need to do a series/parallel configuration.  However I don't know if I need diodes anywhere and if I do, where do they go?  With the charge controller I know I don't need any diodes going to the controller but I don't know if any are needed between panels.

Thanks for the help!

Gizmoguy

[snake]

i dont think that solar panels will need diodes coz its not like wind turbines.diodes are added to wind turbines so as not to allow the current from batteries to power the turbine when there is no wind.

solar panels give energy but it does not take energy.

its what i believe

someone please confirm

thanks

[ghurd]

I would suggest leaving out "Blocking" diodes, anywhere in the system.

Some people argue the higher voltage panels will back feed the lower voltage panels,

but I don't believe it happens in this context.

There could be an argument for "Bypass" diodes, if some cells will be shaded in times of strong sun.

I would be more inclined to believe they will help a 48V input and 12V output, than 48V input and 24V output.

Pretty good chance 24V PVs of that size have bypass diodes installed from the factory.

Something to keep in mind for several years:

If the output drops drastically, check the bypass diodes first.  They seem to have a tendency of failing to short.

G-

[dave ames]

hi gizmoguy,

sounds like you are squared away with the diode question.

there is an odd quirk to be aware of with these sb series controllers. when we first come online (bat to controller first) the unit wants to see a battery bank at a 100% charge level to do the initial setpoint settings. at less than full charge our set points won't be right.

if for some reason we can't bring it online with the bank at the top of it's charge the folks at blue sky offer a "voltage calibration" tool to do our initial settings. ($20 for a $1.50 thermister)

http://www.blueskyenergyinc.com/bulletins/

see tech bulletin #100209

cheers, dave

[gizmoguy]

Very handy info to know.  Thanks for the heads up!

Gizmoguy