Summary of the Solar Charger

23:31 21 Comments

Summary of the Solar Charger

A better future with the solar charger application

Solar energy is a viable source of renewable energy that generates no pollution and no hydrocarbons which is very good to our environment surroundings. It can provide energy for a very long time as fossil fuels is rapidly depleting. Therefore, the solar charger application can reduce the dependency on fossil fuels and is also seen as a potential solution to the imminent energy shortages in the future. It can also reduces the greenhouse effect and global warming which causes rises in Earth's temperature and rising of sea level. In short, the solar charger application bring lots of benefits not only to the consumers but also to the environment in long term.

Read More

Solar Panel

23:12 5 Comments

Solar Panel is collection of solar cells interconnected together either in series or parallel to give the desired output voltage and current rating. They convert sunlight energy into electrical energy. Solar cell is made up of different materials such as monocrystalline silicon, polycrystalline silicon, cadmium telluride, amorphous silicon and copper indium selenide. Most of the solar cells in the market are composed of monocrystalline silicon and polycrytalline silicon. Monocrystalline silicon is more expensive to produce but it is more efficient. Polycrystalline silicon is less expensive to produce but it is less efficient. Therefore, types of solar cells selected depends on the application of the solar cells. How does solar cell work? The photons from the sunlight once hit the solar panel, they will are absorbed by the silicon. Electrons are broken from their bonds creating a potential difference. To cancel this potential difference, current starts flowing through the material and this electrical energy is captured. The electrons are only allowed to flow in one direction due to the special composition of the materials. 

In order to get the maximum output energy from the sun, the sunlight rays should hit directly or perpendicular to the solar panel. As the sun moves from east to west from day to day, the position of the solar panel has to be adjusted or the tilt angle of the solar panel is varied in order to maximize the energy capture from the sun. A device called solar tracker is invented for this purpose which constantly moves the solar panel in desired angle according to the sun position. However, solar tracker is too expensive to be implemented than installing extra solar panel to compensate for the loss of energy capture. Particularly in solar charger for mobile phones, a solar tracker is not needed. This is because the mobile phone will start charging even under low light condition. Solar tracker however is useful for the solar panels installed on the roof top used for supplying electricity to the house in certain countries. 

Read More

Principle of Operation

21:34 1 Comment

Basic Principle of Operation

·         45 turns on the primary windings and 15 turns on the feedback winding.

·         When current flows through the primary windings of the coil, magnetic flux will be produced. This flux cuts the feedback windings and causes voltage to be induced in the coils.

·         The polarity of induced voltage in the primary windings is the opposite of the feedback windings. This causes the voltage from the feedback windings to be coupled with the base of the transistor. This effect turns the transistor on more.

·         As the current increases and reaches steady-state, there will be zero induced voltage and causes an instant collapse of magnetic flux, causing the voltage in the feedback winding reversed, turning off the transistor even more. The cycle ends when the transistor is completely off.

·         the transient pulse is generated when transistor is fully off. The collapsing magnetic flux produces a voltage in the primary winding.

·         Since the transistor no longer functions, the energy from the windings is transferred to the high-speed diode. A high voltage spike is produced and this energy is used to charge up the battery. 

·         A whole new cycle will begin when the resistor on the base turns the transistor on again.

Physic Laws Involved

The theory of induction and inductance explains it all. When current flows through a long straight wire, magnetic field is produced.  The Biot-Savart law states that the current flowing through the conductor and the perpendicular distance of the point R from the wire affect the magnitude of magnetic field produced.

                                     Diagram 1: Magnetic field due to current carrying conductor

The same phenomenon happens when the wire is wound up into a helical coil of wire. This is also known as solenoid. However, due to the placing of circular wires which are adjacent to each other, there is an increase in the complexity of the flux produced.

                                                  Diagram 2 : Magnetic field in a solenoid

As shown in Diagram 4, there are circular magnetic field lines being produced surrounding the wires. The magnetic fields in between each turn is cancelled out as they are in the opposite direction. Due to this effect, the magnetic fields outside the solenoid are weak and widely spaced. On the other hand, the magnetic fields which are in the same direction combines and a stronger resultant field is produced. This happens in the region of the central axis of the solenoid.

The magnitude of magnetic field of the solenoid can be determined from Ampere’s law.

           

According Faraday’s law of induction, the magnetic field stops expanding when current reaches steady-state. The magnetic field collapses when the applied voltage is removed. This induces an emf and current flow which opposes the polarity of the previous induced emf. This is also known as the counter emf as a result of the collapsing of magnetic field.

                           Diagram 3 : Graphs of voltage and current due to induction

These are the theories behind happening in the primary windings when current flows through. For the feedback windings, the reverse process takes place when the magnetic flux of the primary windings cut through the coils. Current and emf will be induced.

Read More

Solar Charger Prototype

21:33 3 Comments

Solar Charger Prototype

Function of Capacitors

100 uF capacitor – acts as a storage component. The instantaneous current is as high as 300mA. However, solar panel is only capable of delivering average current of 150mA. This capacitor stores the current and delivers the peak to the circuit, thereby remains the low impedance of the circuit.

10 uF capacitor - When current flows out from the feed back winding, it will flow to the end connected to the base of transistor as it will have to charge up the capacitor (time consumption) if the current flows out the other end. This will eventually ensure the cycle of the circuit to be well-operated.

3 capacitors (2200uF, 2200uF and 4700uF) - to smoothen the high spike voltage as it is  too extreme for a mobile phone battery. They smoothened the amplitude of the high voltage spike and also broaden the rise time of the high spike voltage waveform which absorbs the voltage spikes and make it compatible with charging mobile phone battery.

Extra features

1)      AC adapter – in case of low light condition, users can choose to charge their phones with electricity by switching the single pole double throw(SPDT) switch. However, more emphasis is on the solar charger itself.

2)      NMOS and low current LED – to indicate if users should switch to AC adapter. NMOS will only turn on when the input voltage exceeds the turn-on voltage of NMOS which is about 0.8V. If NMOS is turned on, charging current will pass through the NMOS to the battery and a small amount of current as little as 2mA will light up the LED. . A resistor of 10kΩ is used before the LED to restrict the amount of current going to the LED. This is crucial as the more current flowing to the LED, the less charging current flowing to the battery.

All the components for this circuit are simple and cheap. The battery can be charged either by solar circuit or by AC adapter.

Schematics of the Solar Charger

The uniqueness of this solar charger is that it uses low input voltage as low as 4v to generate high voltage spikes of up to 13.6v. This is due to the principle of electromagnetism and inductance.  Besides that, it has another alternative which is the AC adapter when there is too insufficient sunlight.

Input source	Specification	Values
Solar charger	Input  Voltage	4V(max)
	Input Current	1.6(max)
	Output Voltage	5V(max)
	Output Current	8.48mA(max)
AC adapter (Mobile Charger)	Input Voltage	100-240V
	Input Current	0.15A(max)
	Output Voltage	5V
	Output Current	350mA

Read More

Solar Charger In the Market

22:48 2 Comments

Solar Charger In the Market

Solar charger is not a new thing in the market. However, innovation in solar charger has always been improving. For instance, what if the sun goes down? Solar charger nowadays always equipped with extra source of charging the battery apart from charging by the sun alone. This is an user-concerning feature. Apart from that, LED indication is used to determine if the sunlight is enough to start a charging process. This can tell the user when to switch to another source of charging. The recent solar charger in the market are compatible with most USB-powered devices such as camera, smartphone, GPS, E-Readers and so on and of course compatible with popular products such as Iphone, Ipad and Ipod. Solar charger company such as Solio has introduced a wide range of products for many application.  Below shows an example of solar charger called Solio Bolt. 

Solar Bolt solar charger by Solio

As shown in the image above, it is small, light and portable. In fact, it has LED indication when the battery is charging. As you may notice, there is a hole in the center of the solar charger. This allows a pencil to be inserted into the hole. The bolt acts like a sundial and simply point it towards the sun until the pencil cast no shadow. The purpose of this is to capture the maximum energy from the sun. This is related to the optimum tilt of the solar cell. For more information about Solar Bolt, please visit  http://store.solio.com/Solio-Store/Solar-Chargers/Solio-Bolt-Solar-Charger-S620-AH1RW . Apart form that, according to source from the internet, Indian Manufacturer Micromax will soon launch mobile phone with built-in solar charger to target those living in rural areas where electricity supply has been a major concern.

Those features included in the solar charger already sold in the market are being included in the sample solar charger prototype. For instance, the prototype has LED indication to indicate when to switch to AC adapter when the sun goes down. Therefore, the solar charger also able to charge when to sun goes down. Apart from that, it only requires a low input voltage to start charging. This is due to the law of induction and magnetism in the circuit that makes this possible. 

Read More

Advantages of Solar Charger

21:27 20 Comments

Advantages of Solar Charger

Source of power of the solar charger: Solar Energy

The solar charger power source comes from the solar energy which is an reliable alternative and renewable energy sources. Besides that, the solar energy comes in free of charge. The energy from the sun is free after giving up a little bit of money, the source of energy is practically free. The solar cells panel on the solar charger does not require much maintenance once they are brought up to its maximum efficiency.Besides that, the solar cells panel is very reliable as it can last longer than other source of energy. The solar charger also does emit zero pollution and is very environmental friendly which helps in reducing global warming and greenhouse effect. It also helps reduces cost such as electric bills as the solar charger source of energy is free. The solar charger also operate quietly and this does not contribute to noise pollution.

Read More

Why Solar Energy?

10:13 7 Comments

        Industrial Revolution has brought many negative impacts on the environment. Generation of electricity using fossil fuels pollutes the environment. The question is why not we make use of something free and easily available??  Naturally, solar energy comes into picture. First, it is renewable source of energy. Second, it is clean and environmental friendly. These two criteria helps to conserve and preserve the environment. We should utilize it to the maximum extent as it is totally free and abundant in tropical countries like Malaysia!!

          Solar heater always comes into our mind when we talk about solar energy. In fact, the application of solar energy has gone way far beyond that. Solar energy can be used to power calculator, serves as electricity supply to house, to power satellite and so on. Ever fancy about going out without having to worry about the mobile phones dying?? Solar energy is one of the potential solution. And solar energy is applied in charging a mobile phone.

        The demand for electricity has always been on the rise from year to year due to the increase in population. Fossil fuel such as coal is burnt to generate electricity to meet the increasing demand. This not only pollutes the environment but also depletes the earth’s natural resources. Therefore, limitation of mobile phones is directly linked to the supply of electricity. In rural areas where there is limited or no supply of electricity, shortage of electricity supply can cause inconvenience to the villagers in remote areas. They can hardly be contacted because their villages do not have electricity supply to charge their mobile phones.

        To overcome the limitation of shortage of electricity supply in remote areas, solar energy could be an alternative. As far as solar energy is concerned, people will think of solar heater. In fact, the application of solar energy is broad and can be implemented in many systems. For instance, solar energy can be implemented in charger for mobile phones via photovoltaic conversion. It is extremely handy in remote areas where electricity supply has been a concern.

         Solar charger is the most suitable choice to replace conventional mobile charger which needs electricity to charge. The reason is simple because solar energy is abundant in tropical countries like Malaysia. Unlike other resources like wind energy, solar energy is more consistent as Malaysia receives more than 7 hours of sunlight a day. In rural areas, though there is no electricity supply, there is an abundance of sunlight. The basic theory of solar charger is to convert the sunlight’s heat into electrical energy by photovoltaic cells. The electrical energy generated is used to charge the rechargeable battery. With solar chargers, they can help reduce environmental pollution. Besides, solar energy is convenient, available in abundant amount and non-depleting renewable source of energy.

          Realizing the energy crisis, more and more renewable sources of energy have been implemented to generate electricity. Solar energy is one of the potential and useful energy source that will help reduce environmental pollution. The project of solar charger for mobile phones makes use of the solar energy. This not only helps reduce pollution but also solves the electricity shortage in rural areas. Therefore, it is crucial to design solar chargers with high efficiency and high voltage output.

Read More