Diodes and Solar Panels
Without diodes solar panels can discharge energy from battery storage at nighttime, and current can flow between solar panels when one or more panel is under shadow which can cause overheating damage to panels. (Typically one bypass diode is fitted for each solar panel although many modern solar panels already have diodes incorporated in their circuitry.) Take a look at our page on diodes and solar panels and another on germanium diodes to find out more about the 1N34A diode which is excellent for this application.
Diodes and Wind Turbines
For wind turbines a diode is also very useful since in periods with little or no wind, the turbine generator can turn in reverse like a motor powered by your battery storage.
Also for wind turbines and other AC generating devices, diodes are used in the rectification of AC voltage to DC voltage for battery charging. See our article Making a Bridge Rectifier from Diodes for information on how diodes can be put together to make a bridge recifier.
The 1N1190A Power Rectifier diode (pictured above) is ideal for typical domestic wind powerapplications in particular since it can cope with a continuous 40 Amps of current (with sufficient heatsinking) and up to 600 Volts.
Using a 1N1190A Diode
The diode is simply connected between the live / positive cable of the renewable energy charging device (solar panel, wind turbine, hydro generator etc) and the battery bank. The threaded end of the diode can be clamped to the positive terminal of the battery, and the looped end connected to the live cable with a nut and bolt and/or some solder.
When large currents are flowing through the diode it will get hot so you must fix a heat sink to the diode (at the threaded end) to dissipate the heat. The bigger the better! Pictured above is an example of a 1N1190A fitted to a heat sink for sale on eBay for around $7. (Click here to search for eBay for1N1190A)
Alternative to the 1N1190A Diode
If you have difficulty finding 1N1190A diodes, then the diode pictured above is an excellent substitute for low voltage systems. Rated at 30 Amps this is a Schottky diode with a forward voltage drop of just310mV (less than one third that of the 1N1190A which has a 1.1 to 1.3V forward voltage drop); but note that the maximum voltage rating of this diode is only 40 Volts. The lower forward voltage drop means that the same current passing through this Schottky diode will generate less than one third of the heat generated in the 1N1190A which makes heat dissipation easier, and of course less power is wasted. We invariably use these diodes on small to medium scale (<300 Watt) battery charging solar systems.
Click here to view the eBay listings for the seller of these 30 Amp Blocking Diodes (sold at around£1.99 each) which at the time of updating this article (Jan 2014) he has been selling to happy customers for more than six years.
The technical specifications of the 1N1190A rectifier can be downloaded by clicking here for the 1N1190A Datasheet.