Circuit Diagram for 5kW Off-Grid Solar PV System

Circuit Diagram for 5kW Off-Grid (Hybrid) Solar PV System

Precautions:

• Use common ground.
• Do not touch DC cables or DC breakers while ON.
• Do not overload the system.
• Use appropriate size of cable.
• In case of any warning on Sunny boy or Sunny island display, contact the installer.

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5kW Off-Grid Solar PV System Design - Hybrid

Project Requirements:

• Total load = 5kW
• Battery backup time = 1 hour
• Primary source = Solar PV
• Secondary source = Grid
• Tertiary source = Battery Bank

System Design:

1. Solar Panels:

Wattage of single panel = 235Wp

No. of solar panels = (Total load x 1.4) / 235

                                = (5000 x 1.4) / 235
                                = 30 (rounded value)
     2.  Inverters:
Company = SMA
Two types of inverters (built in charge controllers) will be used.
a). Sunny Boy     b). Sunny Island

a) Sunny Boy:
Requirement for sunny boy = 7000W*
* 5000W x 1.4 = 7000Wp
Suitable sunny boy (according to the requirement) = SMC 7000 TL

SMC 7000 TL

b). Sunny Island
Requirement for sunny island = 5000W*
* Sunny island runs the load, so its rating depends upon total load.
Suitable sunny island (according to the requirement) = SI 5048

SI 5048

     3. Solar PV array design:
According to the data sheet of SMC 7000 TL, the input DC voltage capacity of SMC 7000 TL is 750V. It has four inputs of solar PV arrays. The input voltage of one array must not be greater than 90 % of 750V. 
Since the open circuit voltage of one solar PV panel is around 34V. Connecting 15 solar panels in series will give us (15*34) 510V DC which is smaller than 675V (90% of 750V).
So we can make two solar PV arrays, having 15 panels each. All the 15 solar panels will be connected in series in one array.

     4. Battery Bank:
Battery rating is defined in terms of Ampere Hours (Ah). We can find out the Ah for battery bank according to the load and backup time.
Ah = (Load x backup time) / (DOD x PF x System Voltage)
Now
   load = 5000
   backup time = 1 hour
   DOD (depth of discharge) = 0.6
   PF (power factor) = 0.8
   System voltage = 48V
So
Ah = (5000 x 1) / (0.6 x 0.8 x 48)
      =  217.01
So now we need 217Ah @ 48V for battery bank.
Rating of single battery = 200Ah @ 12 V
Connecting four batteries of above rating, in series, will give us 200Ah @ 48V.

System Topology:

Circuit Diagram:

You may also know:
a) HOW TO DESIGN AN OFF-GRID (HYBRID) SOLAR PV SYSTEM USING SMA SOLAR INVERTERS
b) CIRCUIT DIAGRAM FOR 5KW OFF-GRID SOLAR PV SYSTEM

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Terms Used In Renewable Energy (Solar PV)

Global Horizontal Irradiation (GHI):

The total solar energy received on a unit area of horizontal surface.

Capacity Factor (CF):

Capacity factor (usually expressed as a percentage) is the ratio of the actual output over a period of a year to theoretical output if the plant had operated at nominal power for the entire year.

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Major Components of Solar PV systems

The major components for solar PV system are PV module，solar charge controller, inverter, battery bank, and auxiliary energy sources.

PV module – converts sunlight(photons) into DC electricity.

Solar charge controller – regulates the voltage and current coming from the PV panels going to battery and prevents battery overcharging and prolongs the battery life.

Inverter – converts DC output of PV panels  into a clean AC current for AC appliances or fed back into grid line.

Battery – stores energy for supplying to electrical appliances when there is a demand.

Auxiliary energy sources - is diesel generator or other renewable energy sources.

Below is a general block diagram of solar PV system.

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Interview Questions Regarding Instrumentation and Process Control

Q1: Which are the basic elements used for temperature measurements in industry?

Bi Metal Strip, Liquid Filled Thermometer, Liquid Filled Thermo Bulbs, Thermocouples, RTD (Resistance Temperate Dependent), Optical Pyro Meter and Infrared Pyrometer. 

Q2: Which are the basic elements used for pressure measurements in industry?

Diaphragm, Bellow, Bourdon Tube (Spiral or Helical), U Type Monometer (Water Filled or Mercury Filled).

Q3: Which are the basic elements used for flow measurements in industry?

Orifice Plate, Venture Tube, Flow Nozzle, Elbow, Pitot tube (Anubar) Ultrasonic, Magnetic Flow Meter, Thermal Flow Meter.

Q4: Which are the basic elements for Level Measurements in industry?

Diaphragm, Bellow, Bourdon Tube It May Be Spiral Or Helical Type, U Type Monometer Water Filled Or Mercury Filled, Capacitance, Ultrasonic, Radar Meter, Radiation Meter, Displacer, Float.

Q5: Which are the commonly Pressure units used?

Psi, Kg, Bar, Milli Bar, Kilo Pascal, Inches of Water, Inches of Mercury Column

Q6: What Is Pt 100 Sensor?

It Is Platinum Wire Temperature Sensor which have 100 Ohms Resistance at 0 Degree Centigrade

Q7: What is the need of third wire of RTD?

Third Wire is use to compensate lead wire resistance (Due to this wire, cable length Resistance is not added in actual resistance)

Q8: Which equipment is used to calibrate pressure instruments?

Pneumatic Calibrator for Low Pressure Range and Dead Weight for High Pressure, 24 Volts Power Supply for Pressure Transmitters, Digital Multy Meter for Checking milli Amperes

Q9: Can DP Transmitter be used for Level Measurements?

Yes it can be used with open or closed tank

Q10: What is suppression of Differential Pressure Level Transmitter?

 To Zero the Effect of Head Pressure At Low Side of Level Transmitter

Q11: Which are the types of Control Valve Cages?

Quick open, Linear and Equal Percentage.

Q12: Which parts include Sin Control Valve Trim?

Plug, Cage and Seat.

Q13: What is Hart Communicator?

It is a Device by which smart instruments can be configure and calibrate .

Q14: What is the Split Range Control Loop?

It is a loop in which one controller is controlling 2 valves in series that is one complete open or close at 0% to 50 % and second open or close at 50 %To 100% Signal

Q15: What Is Buoyancy Type Level Transmitter?

This Transmitter consist of Cage, Displacer and Torque Tube, when liquid rise in cage, Displacer loose his weight and Torque Tube move and change signal output

Q16: Which Type of Cable Are Used In Industry?

For Instruments Signal and Thermocouple Single and Multi Pair Cables Are Used

What Is Color of J and K Type Cables

For J type: Outer cable color is black and inner is red and white For K type: Outer cable is yellow and inner is red and yellow.

Q17: What Is Valve Positioner?

It is used for quick response of control valve by getting feed back when valve open and close.

Q18: What Is I / P Convertor

I/P converter convert the standard 4-20 mA input signal to standard 3-5 Psi signal at its output.

Q19: What is Dead Band of Pressure Switch?

It is the difference of Pressure between Alarm and Normal Conditions.

Q20: What Is Controller PID?

P = Proportional, I = Integral, D = Derivative Every controller used in the industry has these basic functions. P factor controls the overall gain or shoot, I factor controls the change while D factor tells that whether the process value is going to shoot the Set point or decay off before reaching it.

Q21: Which types of drawings are used in Plants

PID (Process Identification Drawing) Instrument Hook up Drawings Control Loop Drawings

Q22: What is square root Extractor?

This instrument is used to convert Non Linear Signal in to Linear Form

Q23: What is the three Element Control?

This Loop Is Normally Used For Boiler Steam Drum Level Control Which Includes Level, Steam Flow and Feed Water Flow

Q24: What is the Cascade Control Loop?

In this control loop one controller is master and other controller is slave These Set Points are controlled by Master Controller which is known as remote set point

Q25: What do you know about PLC and DCS systems and at which you had worked

PLC = Programmable Logic Controller, DCS = Distributed Control System Make Abb, Honey Well, Foxboro.

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Vectors

Q1:    What is resolution of vector?

Ans:  To resolve a vector into its components is called resolution of vectors. A vector can be resolved in to two components.

Q2:    What is head to tail rule?

Ans:  Two or more vectors can be added by using head to tail rule. According to this rule the head of first vector is joined with the tail of second vector and heat of second vector joins with the tail of third and so on. The resultant vector is directed from the tail of first vector to the head of last vector as shown in fig.

Q3:     Define negative vector?

Ans:   The negative vector (-A) of a vector A is such that it has the same magnitude as that of A but opposite direction.

Q4:     What are rectangular components of a vector?

Ans:    The components of a vector which are perpendicular to each other. The magnitude of the components are 

Fx = Fcos (theeta)               Fy = Fsin (theeta)

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Atomic And Nuclear Physics

Q:   What is half life time?
Ans:  The half life of an element is that time during which the number of atoms of that element are reduced to one half. i.e half life of uranium is 4.5 x 10⁹ years.


Q:   Define fission reaction.
Ans:  Breaking of a nucleus into two parts with the release of large amount of energy is called fission reaction. i.e 

Q:   What is Atomic Mass Number?
The sum of neutrons and protons present in a nucleus is called its Atomic Mass number. It is denoted by the letter A. i.e where 16 14 and 12 are atomic mass numbers of oxygen, nitrogen and carbon respectively.

Q:   What is natural radioactivity?
Ans:  The elements whose atomic number is greater than 82 naturally break and emit alpha, beta and gamma particles. The natural process of breaking of the elements is called natural radioactivity. i.e Uranium

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