Enough power for rainy days...

[SunshineHarvey7]

Okay, another question for the experts ????:

 

I ran into a friend recently who said, if you hook up more solar panels than your charge controller is rated for, the charge controller will just dump (or it just won't use) the extra power. Is that true?

 

For example, let's say my charge controller will take 60-110v PV input, and it's rated at 3000 watts (re. charging from PV to batteries). So, I'd take it, if I have 375w panels that have an open voltage rating of around 37.5v (and thus 10 amps), and I hook them up 2 in series to get 75v, then I could connect (almost) 4 sets of panels (3000 watts). So far, I think this is the "normal"/"standard" way of figuring the max number of panels.

 

However, if my friend is right, I could connect up twice the number of panels, as long as I maintain the voltage of 75v (or whatever's under the max of 110v), and then if it's a cloudy day and the panels are running at 50% of their normal output, I might get full power (since I have twice the "max" number of panels). If it's a sunny day, the extra power just wouldn't get used. Is this correct?

 

Of course, it does seem to me, a more beneficial way to use those extra panels (and not a lot of extra expense) is to connect them to a second charge controller. Then on a sunny day, my batteries would charge twice as fast (provided I'm not charging too high an amperage for the batteries to take). Does that make sense? Is there any problem with having two charge controllers connected to one bank of batteries, provided that the max output of both charge controllers doesn't exceed the current the batteries are rated for taking?

 

Thanks for your valuable answers!

[Crossy]

Your charge controller will probably have a "recommended" maximum solar power value but generally the better units will just not use excess power and the cheapo units will simply blow up.

 

Two charge controllers will usually play together just fine particularly if of the same make and model.