to use or not to use combiner box with charge controller

[Bodacious]

Good day everyone, I have some experience with grid tied systems, but very little with off grid. My question is when designing- installing a off grid system. I need a combiner box to join all my panels together, sometime multiple combiner boxes. In each case would I need a charge controller for each combiner box and how would i size the charge controller. Each unit i have looked at seems to be very small in size. I have already fried one charge controller by hooking it up directly to the panel.

[Mike90250]

A combiner box won't cause a charge controller to "fry". Maybe something else is wrong?

Combiner boxes with fuses are needed after 2 strings. When you go to 3 strings, 2 can back feed a failed string, and cause problems, so thats why combiner boxes and fuses.

1 or 2 strings can feed a charge controller directly, or one fat wire from combiner box can feed controller.

Usually, too high of voltage frys things. What's your panel voltage, and how many panels in series ? What's the model of charge controller? If you are below the max volt input, I'm not sure what can be wrong.

[Bodacious]

Thanks Mike, you are correct the charge controller was not equiped to handle the (4) 240 V panels I had connected. The second part of my question would be in cases where multiply combiner boxes are used. Would I have to use multiple charge controller and would there be something used to join them before running them to the batteries?

[Mike90250]

Charge controllers (MPPT style) can be fed by several identical arrays (same panels, strings, orientation) up to their max wattage, then you are just wasteing arrays, as the controller throttles it's output back to it's max Amps, regardless of the battery voltage.

If you have more arrays/strings than the controller can handle, you will need another controller.

I think Midnight is coming out with a high voltage DC charge controller, and also, next spring, Xantrex is planning a 600V controller.

Otherwise, I think all the current charge controllers in common use, have a max input around 145VDC.

[melody]

Thanks Mike, you are correct the charge controller was not equiped to handle the (4) 240 V panels I had connected. The second part of my question would be in cases where multiply combiner boxes are used. Would I have to use multiple charge controller and would there be something used to join them before running them to the batteries?

yes, there should be like fuse, breakers some time lighting protections, and need to be mathed to your system size.