Thursday, 26 December 2013

Types of Solar Power System

The solar power system which has three types and these types are in terms of usage.The solar power system which has mainly three components Solar Panel,battery,Inverter.The solar panels for producing DC electricity, Batteries for Storage and inverter for conversion of Dc power to AC power and these components with other BOS(Balance of Systems) called Solar Power System.

1.Off-Grid Solar Power System

2.On-Grid System(captive use)

3.On-Grid System(Power selling)

1.Off-Grid solar power system

The off grid system which are used for the individual homes,offices,stores,where power requirement was minimal up to 10KW,As the system includes Solar Panels,Charge controllers,Batteries,Inverter,BOS (other components),The off grid system means that there is no grid supply for the system,the battery act as a backup when the grid is off.The solar panel produce power supply say from morning7:00AM till evening 4:00PM,for the remaining hours batteries can able to supply power and acting as a backup generator.The batteries should be rightly designed and it should be properly maintained.Especially for solar, Deep cycle tubular batteries are used. 

offgrid solar power system

Note: The difference between car batteries (Lead acid Batteries) and deep cycle batteries is the way their lead plates are structured and designed. These plates determine the function of the batteries. The Deep cycle batteries have thick, solid lead plates to handle deep discharge so the battery can provide power for a long time but at low ampere (A),Lead-Acid batteries have thin plates that provide greater surface area to generate big amps for short periods for cranking application.

2.On grid(Captive use)

gridtied solar power system

The on grid solar power system is same as off-grid solar power system except batteries,The system utilize Grid as a backup generator.When the system is in working condition the solar panels produce dc power fro sunlight and the inverter converts that dc power to ac and supply to the household or commercial needs,during night the on grid system utilize the grid as a source or generator,it bypass the grid power to your home or office and its only for captive use.These system ranges upto 100KW.These systems are mainly used in Commercial sectors like Malls,Hospitals,Colleges.The On grid systems has more advantages than offgrid due to the absence of batteries,The cost of the entire system reduces and the maintenance costs reduces and the replacement cost of the batteries was eliminated as the batteries must be replaced every 3-5 years.

3.ON Grid(Power Selling).

Power Selling

The other type of on grid system in which the construction of components are same as On grid(Captive) except the usage,Here the solar system produces power from morning till evening was sold to the electricity board or to the consumer of any industrial type.The Power selling has different types  and the system ranged fro few 100KW to MW.The selling of electricity can be majorly done by Net-metering, PPA, RAC ,Solar Power Lease.

Wednesday, 25 December 2013

What is VFD Control?Why it is used in Solar Water Pumping System?

VFD(Variable frequency Drive), an old technology but most efficient one for solar power water pumping system,It is also known as Variable Speed Drive(VSD).Almost 65% of the electrical energy utilized in America which are from Pumps,Compressors,Fans,Blowers etc..,which are driven by constant speed motors or synchronous motors where the speed of the motors are constant till the end and in which the option to control the running speed will be using resistive devices which will dissipate more heat ,the efficiency of the system is low due to the wastage of power through dissipation of heat.

vfd circuit


In the early days of VFD technology, it was used for some typical application in process control for manufacturing synthetic fiber,steel bars,and aluminum foil. Because it improves process performance and reduces maintenance costs, they replaced motor generator sets and DC drives. When the energy crisis occurred in the early 1970s, saving energy became a critical goal, and the use of VFDs quickly spread into large pump applications.

What is VFD Control?.
Variable frequency control of AC induction motors provides an economically sound and operationally effective solution for speed control and reduced power consumption,the converter develops a voltage 
directly proportional to the frequency, which produces a constant magnetic flux in the motor.This electronic control can match the motor speed to the load requirement. This eliminates a number of costly and energy inefficient ancillaries to throttle the speed of the motor.

Types of Variable Frequency Drives(VFD).

VFD types

Why VFD used in Solar Pumping System?.
The principle of this method of VFD is to supply DC from the PV array directly into the DC bus inside the VFD. The normal AC input is not used. As the sun rises,the PV voltage and current will increase,when the power is high enough, it will start the pump. The PV array must be large enough to provide enough power to start the pump with including the head of water. The size of the PV array required for this method can be very expensive.

vfd drives for motors and pumpsA VFD reduces the actual motor speed, which reduces the amps drawn by the motor,This reduces the amount of energy used and saves you energy costs. By ramping up the motor speed slowly, VFDs also help customers save energy by reducing the in-rush and mechanical issues associated with starting of motors.

The first and most obvious way a VFD can save you money is through increasing the efficiency of your AC motors and decreasing electricity use. The amount of energy that a VFD can save depends on the average load of the motor and the number of hours per day it is turned on. While average energy savings varies, it’s safe to say that most AC motors do not need to be running at full capacity for most hours of their use. Furthermore, the initial cost of a motor or VFD is generally only a fraction of the cost of operating the motor over its life span. This means that a VFD system usually pays for itself in a matter of months or years.

Advantages of VFD:
  1. A VFD may be used for control of process temperature, pressure, or flow without the use of a separate controller. Suitable sensors and electronics are used to interface the driven equipment with the VFD.
  2. Lower maintenance costs, as lower operating speeds result in longer life for bearings and motors.
  3. The motor does not require a starter.
  4. The ability of a VFD to limit torque to a user-selected level ,protects driven equipment that cannot tolerate excessive torque.
  5. Users can utilize multi-motor applications, such as pumps or fans, with one control unit.
  6. High-speed applications for the wood-finishing industry ,approx 30-40% energy is saved

Tuesday, 24 December 2013

Solar Pumping System

solar pumping system
The sun not only helps the plants to grow directly but also indirectly,Solar pump is one of the agricultural innovation that utilizes suns energy to convert solar power to mechanical power to draw water from wells etc..,The system has solar panels,charge controller,pump controller,batteries(Optional),Pump set,Pressure tank.

The system uses a method called VFD(Variable frequency controller),This VFD targeted mainly for irrigation with solar pumping system.The scarcity of the power,Poor quality of pow
er in rural areas and the absence of grid are the main reasons for the usage of alternate power supply for water pumping system.Solar energy which is abundant in nature can be harnessed for this purpose.

Solar Pump

The solar pumping system can be a great boon to the farmers, as the power supply was unlimited and free to use.The system which has batteries are optional and not recommended for the solar pumping system,Off-Grid system without Batteries or On-Grid System Without Batteries can be a better option for solar water pumping system.

The operation of solar pump is more economical mainly due to very low operation and maintenance costs.The maintenance would be cleaning the solar panel twice a week and inverter and the pump controller dust free.The operation is simple,as the motor will start even in the morning 6:00AM and will continue to run till 5:00PM like in India.

The size of the solar pumping system is mainly depends on the amount of water drawn and the amount of sunlight received,The solar pumping system can be of two types AC Operated,Dc Operated.

The DC(Direct Current) operated system which can capable of deliver small quantity of water so that it can be used for small and medium type of irrigation and it can ranged fro from 300W to 3KW of system Capacity.

The AC(Alternating Current) operated system which can be utilized to provide large quantity of water used for Larger irrigation purposes, as the system has inverter which is necessary to convert the DC power from the solar panels to the AC,the system is not that efficient than DC operated system,its ranges from few KW to 50 KW,But the system should be properly designed for higher power systems.

Monday, 9 December 2013

Types of Solar Cells:

Till now as per 'Wikipedia' these are the known Solar cell types where invented.These types of solar cells are differ from its own assembly or the structure wise but the final goal is same,it will produce electricity from the photons of the sun.
  • Buried Contact Solar Cells
  • Cadmium Telluride Solar Cells
  • Copper Indium Gallium Selenide Solar Cell
  • Dye-Sensitized Solar Cell
  • Gallium Arsenide Germanium Solar Cell
  • Hybrid Solar Cell
  • Monocrystalline Solar Cell
  • Multijunction Solar Cell
  • Nanocrystal Solar Cell
  • Organic Solar Cell
  • Plasmonic Solar Cells
  • Plastic Solar Cells
  • Polycrystalline Solar Cell
  • Polymer Solar Cell
  • Quantum dot Solar Cell
  • Solid State Solar Cell
  • Thin Film Solar Cell
  • Wafer Solar Cell

Tuesday, 3 December 2013

About Solar Cell

How Solar Cell Works ?

Solar cells are the one which converts sunlight into electricity,Silicon is a semiconductor material, that has some of the properties of metals and insulator and we will see how this cells convert sun rays into electricity,

Sunlight is composed of pockets of energies called photons, which are radiates from the sun. These photons hits the silicon atoms and transfer its energy to loose an electron from the atom,One photon of energy can eject one electron from the atom of silicon,you can compare this with the white ball in a game of pool,which transfer its energy to the colored ball if its strikes.

solar cell

Creating an electron from the atom of silicon is one of the part and the next part is flow of electron,that needs an electrical imbalance.The internal organisation of the silicon makes it possible,The silicon atoms are tightly bounded by bond structure,There is a technique called doping,which means making silicon spare or missing of electrons,thus we can create two types of silicon,N-Type and P-Type.
Working Princible of PV Cells

As this two types are placed side by side then the electrons which are spare from N-Type silicon jumps to the P-type silicon to fill the gap of missing electrons.When an electron is missing from an atom,a hole is created,HOLE is positively charged,When photon eject an electron from the silicon atom then a hole will be formed at that place.

The circuit was completed by connecting a load which may be a Light,Fan etc...,Once the circuit was complete then electron starts to flow otherwise it won't be created.

What is a Photovoltaic Cell?

The photovoltaic cell is made up of semiconductor material,as the photon of certain frequency hits an electron,the electron absorbs and ejects out from the atom of semiconductor and an external circuit was connected from the (+) and (-) poles thus electrons flows between them.

PV Cell Basic Schema
SiO2: It is the basic element of semiconductor segments. This chemical is used in the making of the transistors and diodes that are used in electronic circuits.
Silicon Wafer: The silicon wafer is responsible for creating a semiconductor environment. The process of separation to the poles occurs with SiO2.
Flow of Electrons: The extra electrons that come out as a result of the photons move from (-) pole to (+) pole and generate electricity.

Working Principle of Photovoltaic Cells.

Figure 1 shows a PV cell in a normal condition without sunlight.As it shows no movement of electron or holes so no current will be generated.
PV Cell without Sun Light
Figure - 1

PV Cell with Sun Light
Figure 2 shows a PV cell which is active,The sunlight falls on the atom of a semiconductror thus increase the number of electrons and resulted in increasing voltage.As long as sunlight falls on the cell,this electron generation will occur.

Note: A silicon surface of a cell does not completely transform the power of the light which falls on it into electricity. The main reason for this is that even though there are many colors in light only the red color is transformed into electricity.Certain frequency of the sunlight was converted into electricity and others are not,The electrons accepts certain frequency and absorbs energy and other are wasted as a heat,or not absorbed.