Applications: use as catch diode or blocking diode.
1) Old poly-crystalline solar panels need a blocking diode to stop reverse current flow in night time situations (new solar modules have this fitted).
2) To switch motors (including pumps & fridges) a catch diode is required.
Many useful devices like electric motors, solenoids, relays etc, have a coil or coils of wire wound around an iron core, to create a magnetic field.
When current being supplied to this type of device is interrupted or turned off, the internal magnetic field that exists, collapses, and can cause a very large voltage to be "induced" in the winding that set up the field in the first place. This can be many hundreds of volts for a fraction of a second, and can damage the electronic switching component that caused the planned interruption (say timer switch)
The diode lets current pass in one direction, and wiring it into the circuit conducts this surge of "back-voltage" harmlessly away.
We install solar systems in Northern NSW and Southern QLD.
QLD: Gold Coast (from Coolangatta to Southport), Nerang and Hinterland (Beaudesert) and out West (Warwick, Stanthorpe, Killarney)
NSW: Northern NSW (Tweed Heads to Yamba, including Evans Head, Byron Bay and Ballina); the Far North Coast Hinterland (Grafton via Lismore to Murwillumbah) and out West (Casino to Tenterfield, including Drake and Tabulam, as well as Woodenbong and Bonalbo)
For larger system we also go up to Brisbane or down to Coffs Harbour and even Glen Innes. Other places by arrangement.