Why Diode used in Solar Panel, Relay and Soldering Iron?

The diode is used in Solar panels for two reasons, one is to bypass the current, another is to block the reverse current flow to the solar panel from the battery. The diode is used in Relay to provide a path for discharging the stored energy in the relay magnetic coil when the power supply is removed from the relay coil. The diode is used in Soldering Iron to reduce the input power flow to the soldering iron heating element to prevent overheating.

There is a huge application of diode. There are some devices which use diodes for some important reasons. There are some important frequently asked questions i.e. Why Diode used in Solar Panel, Why Diode Used in Relay, Why Diode used in Soldering Iron. So in this article, you will find the answers to those questions in detail.

Why Diode used in Solar Panel?

There are two reasons to use diodes in a solar panel. Generally, the PN Junction diodes are used in solar panels. The first reason is to bypass the current. The diode used in solar panels to bypass the current is called the Bypass Diode. The Bypass Diode is connected in parallel and reverse bias with an individual solar panel when we use a no of solar panels together.

In case, if any panel is damaged or sun rays do not properly reach that solar panel then the bypass diode works and bypasses the current. You can see in the above figure the solar panel A is damaged, so in this case, the bypass diode connected with the solar panel A will bypass the current.

The Blocking Diode is used in Solar Panels to block the reverse power flow. Suppose we connect a solar panel to a battery for charging. When the solar panel gets proper sun rays it creates sufficient voltage to charge the battery and in this case, the current will flow from the solar panel to the battery. But when the sun rays decrease, then the solar panel will create lower voltage than the battery and current will flow from the battery to the solar panel.

So the Blocking Diode prevents the current flow from the battery to the solar panel. The Blocking Diode also prevents the current flow from one string of panels to another string.

Why Diode Used in Relay?

You may notice a PN Junction Diode is always connected with the magnetic coil of the relay in parallel and reverse bias. So you may think why the diode is connected in parallel with the relay coil.

The diode used in the relay is called the freewheeling diode. We know that the inductive coil has the property that when a current flows through a coil it stores electrical energy in the form of a magnetic field and when we stop the flow of current, the coil will discharge the stored energy to the external circuit connected with it. When we use a relay in a circuit, we need to give a power supply to the magnetic coil of the relay for its operation.

When the power supply to the relay is turned OFF, it will discharge energy to the circuit and may damage the circuit. But when a diode is connected with the coil of the relay, it creates a path for discharging current. So when the power supply to the Relay is turned OFF, the coil discharges its stored energy through the diode, therefore the circuit will be safe from damage.

Why Diode used in Soldering Iron?

A PN Junction Diode is used in Soldering Iron to reduce the power input to the soldering iron. The diode is always connected in series with the heating element. If the heating element is connected directly to the power supply it will overheat. But when a diode is connected in series with it the heating will be maintained.

The diode in soldering iron acts as a half-wave rectifier. During the positive half cycle, it will conduct current, and the heating element will get the power supply. During the negative half cycle, the diode blocks the power supply to the heating element. So the diode continuously ON/OFF the power supply to the soldering iron and prevent overheating. Actually, the diode reduces the power to 50% of the actual power input.

In some soldering irons, LED(Light Emitting Diode) is used which provides two facilities, one is reducing power and another is an indication that says the soldering iron is ON or OFF.

Read Also

• Why NPN Transistors are mostly used than PNP Transistors?
• What is Vcc, Vss, Vdd, Vee in Electronics?
• Why PIV rating is very IMPORTANT when purchasing a Diode?
• What is Power Diode? Applications, Use, Working Principle, Types
• Main Difference Between PN Junction Diode and Zener Diode
• Difference between NMOS, PMOS, CMOS Transistor with Symbols

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