Hmm fair enough...

Quote Originally Posted by blackburn mark View Post
this charge controller will take 38v open circuit, i'm sure that's pretty typical for a cheap 250w panel
But does it accept 38V with a 12V battery on the output, or just with a 24V battery? Looks like you've got this one, but the listing isn't helpful:

800W Wind Solar Hybrid Mppt Controller (600W Wind + 300W Solar) 12V/24V Auto | eBay

It looks like at least some support having a lower voltage battery, but I'd want to be sure before connecting it up...