Should there be a form of blocking diode?

[metobi1]

Hi all,

I have read that most modern charge controllers have an internal blocking diode that prevents current flowing the other way at night when the pane is in an off (no power state). Does this still apply when both the input from the solar panel and government power supply are being used simultaneously to charge the batteries (government power supply is erratic where I live)?

The terminal from the charge controller and from the inverter converge at the battery heads, and during daylight and when there is the said alternate power supply they can both charge the batteries. My solar panel system is as simple as this image Solar sys.jpg, with no diodes, fuses etc.

My problem is that after working the first day (there was no external/government power supply), on the second day there was also the external power supply the charge light on the controller was blinking as if there was an issue (it is a basic one with no display just LED to indicate charging load and batteries). After about 30 mins the controller started to smoke out and had to be disconnected, which is why I came to the conclusion that the problem was from an absent blocking diode, that can block any spill over voltage from the inverter.

Any thoughts on this please?

[Sunking]

You are barking up the wrong tree. Your problem has nothing to do with diodes. You either have faulty equipment (at least your charge controller is now toast), or installation error of some kind.

What do you mean by Government Power? You are showing a Stand Alone Battery system in your picture. There should be no other connections.

[metobi1]

You are barking up the wrong tree. Your problem has nothing to do with diodes. You either have faulty equipment (at least your charge controller is now toast), or installation error of some kind.

What do you mean by Government Power? You are showing a Stand Alone Battery system in your picture. There should be no other connections.

Hi, and thanks for the response, I meant normal power supply(from electric grid) which charges the battery though the inverter, I have the inverter installed at home as a backup(i don't have a generator), as there is often power failure, so the solar is to charge the battery.

The issue occurred when both the current from the solar/charge controller and electric grid through the inverter were charging the batteries. This is how I have been seeing it setup with friends.

[Mike90250]

The name brand charge controllers, have the internal blocking diode, your sketch, appears OK.