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Automatic Solar Charged Emergency Lighting System

Image of Automatic Solar Charged Emergency Lighting System

Hello!  As I have promised in my previous blog, I will be explaining how my automatic solar charged emergency lighting system works. 

This system is very simple that it only requires few components, wired together for it to work.

However, correctly wiring all the components is needed to ensure that system runs safely and avoid accidental injuries that can be caused by electricity.

WORD OF CAUTION: This system needs to be connected to the AC mains to detect the presence of AC voltage.  Care must be taken when doing the wiring to ensure safety and avoid accidental electric shock. 

Circuit Configuration Brief Description

The system is composed of two different circuits.  One is the solar charging system, and the other is the automatic emergency lighting system. 

The solar charging system circuit is composed of 1) the 70w Solar panels wired in parallel configuration; 2) the Solar Charged Controller, (SCC); 3) and the Lithium-ion battery packs that I will also be sharing to you in my next blog post. 

The next circuit is composed of 1) the Direct Current Solid State Relay, (DC-SSR); 2) the AC Circuit Sensor; and 3) the LED Lighting system.

How The System Works

As you can see in the circuit, the DC-SSR simply acts as a switch that can turn on the emergency lighting system, while the AC sensor is the trigger that switches the DC-SSR when the AC power is missing. 

Physical Wiring diagram

Fig 1. Emergency Lighting System
The image in the left shows the actual wiring connection of the system, enclosed in a PVC Square Box.

It is necessary to separate this system from the other circuits to ensure that safety is maintained. 

Which the image clearly says why. (The connection for the AC mains can actually be seen in the image.) 

Also seen is the presence of an AC fuse, connected in series to one of the AC lines of the AC sensor to act as protection in cases of accidental short circuit.

The green component is the AC sensor, and the bigger blue square component is the DC-SSR.

AC Sensor Schematic Diagram

The AC sensor that I have used is actually a one channel 220v AC opto isolator module that can be bought from local online shopping sites. 

Fig 2. One channel 220v opto isolator circuit

How The Sensor Works!

Fig 2 is the schematic diagram of the opto-isolator circuit.  As one can see, the circuit has a Hot and a cold side.  The "hot side" is referred to as the circuit components that are directly connected to the AC mains, while the "cold side" is the part of the circuit that is already isolated form the AC mains.

The hot side is the circuit from the AC mains up to the input of the opto-isolator component, while the cold side is the circuit that starts from the output of the opto-isolator.

Circuit Description

The 220v AC input voltage is dropped by resistor R1 before being rectified by the Bridge rectifier Circuit D1, after the rectification process, the output voltage is filtered by capacitor C1, while D2, regulates the DC output voltage to around 5V.  D3 is an LED indicator, while opto 1 is the circuit that isolates the "Hot side" from the " cold side" of the circuit.

The output of the opto-isolator is a transistor circuit that is configured as a class A Common Emitter Amplifier that has a 180 degrees phase difference from the input, which means that when the base voltage is zero, full potential can be measured at the output of the isolator which then switches on the DC-SSR.  

CAUTION: Although the AC voltage has been dropped to a much lower voltage, any portion of the "hot side" is dangerous and can be the cause of accidental electric shock.  NEVER touch this side of the circuit when the device is connected to the AC mains as indicated by the LED indicator when it is lit. 

Wiring Diagram

Wiring Diagram of the Automatic Solar Charged Lighting Sytem
Fig 3. Automatic solar Charged Emergency Lighting System

Fig 3 shows how the different modules that forms the circuit is wired.  Care should be observed when doing the wiring to ensure safety. 

TIP: To ensure safety, a plug can be used at the other end of the AC line so that the AC sensor can be easily plugged into an AC outlet instead of wiring it directly to the AC receptacle. 

In Closing

The brief explanation on how the AC Sensor module works has been provided for the reader to easily grasp how the entire circuit works. 

Although it is crude and simple to assemble since everything can be easily brought in an online store, proper care and safety should always be observed when wiring the circuit.

Well, that's its folks, for my next blog post I will be writing about Batteries.  See yahh...


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