Automatic DC Isolation Switch

I no sooner posted this than I think I figured it out. Figured I'd keep the post so others that might be interested can see...

All I need do is connect the solar and wind into separate charge controllers and to the batteries. That should isolate everything from everything.

Sounds like a job for Diode man.

It's all DC - why not just use a few large Diodes?

2 ways I can think of doing this first way as stated by oldfefan earlier use a diode on the supply from the solar panels. some panels have them fitted from factory to prevent feeding back from batteries / power supplies.

The second way would be to use a relay controled by the output of the power supply with change over contacts (double throw/ NO & NC with a comon terminal) preferably useing a double pole relay switching both +ve & -ve wires but not totally nessecary .

The common terminal connecting to the charging circuit, the NC contact to solar panels & NO contact to the power supply. this will disconect panel & connect the power suply at the same time when the power supply is turned on until the power supply is turned off & the relay returning to normal state connecting the panels. I have seen & used this system on emergency lighting in buildings & in caravan wiring systems.

If a relay with change over contacts is not available you could use a relay with only NC contacts to disconnect the panels leaving the power supply constantly connected. In this case the relay should be controled from the AC low voltage side before the bridge rectifier to stop the power from the panels feeding back & energising the relay. If AC relays are not easily obtained a seperate small bridge rectifier can be used just for the relay control circuit.

I would prefer to use the relay even though it may cost slightly more to set up, because the diode on the supply from the panels will reduce the output voltage of the panels thus reducing the charge capabilities slightly. It will not have much affect on sunny days but on overcast days it will.

Well I found a nice solution. The PV panel will connect to a charge controller then the to batteries. Then I've found an AC to DC inverter that also has a built in charger, controller, AND an automatic transfer switch. Connect that from the mains and to the batteries, and run the AC outlets to my laptop, and network devices. All DC devices will connect directly to the batteries. Power fails and the transfer switch picks up DC from the batteries and converts to AC. I like it as it's nice and simple and I can get it up and running before I get the PV panel installed.