DC Fuse and DC MCB

A fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Its essential component is a metal wire or strip that melts when too much current flows through it, thereby stopping or interrupting the current. It is a sacrificial device; once a fuse has operated it is an open circuit, and must be replaced or rewired, depending on its type.

DC Miniature Circuit Breaker (DC MCB) is particularly designed for DC over-current and short-circuit protection in an electrical circuit. DC MCB and the AC MCB have the same functions. Only application scenarios are different. DC MCB is mainly used for direct current (DC) systems applications, line Solar Photovoltaic (PV) and Solar Battery Energy Storage Systems (BESS). The voltage state of DC MCB is generally DC 12V-1500V.

Reference:
[1] https://en.wikipedia.org/wiki/Fuse_(electrical)

Array and Array Junction Box

We commonly use 72 Cell panels or 144 Half-Cut Cell Panels. A 72-cell panel produces 46-50 Volts while not under load. At maximum power point, it drops around 37-42 Volts. A standard On-grid Inverter requires a much higher voltage than this. Sometimes off-grid inverters also require multiple modules in series. 
A solar photovoltaic array is formed by a series/parallel combination of SPV modules to attain the desired voltage and current level. Usually in an Array modules are kept in series to obtain a certain voltage. Arrays are kept in parallel to increase the current.
Before connecting to the inverter sometimes protection is required (if it is not built in the inverter). Like DC Fuse, DC MCB, DC SPD and Current Measurement Unit. These are installed in an Array Junction Box or String Combiner Box. 

Reference:
[1] https://creativestudio1973.blogspot.com/2021/06/introduction-to-solar-panel.html
[2] https://creativestudio1973.blogspot.com/2021/06/on-grid-systems.html
[3] https://creativestudio1973.blogspot.com/2021/09/surge-protection-device.html
[4] https://creativestudio1973.blogspot.com/2023/11/dc-fuse-and-dc-mcb.html

Hydrometer

 A Hydrometer is a device for measuring some characteristics of a liquid, such as its density (weight per unit volume) or specific gravity (weight per unit volume compared with water). 

A hydrometer usually consists of a sealed hollow glass tube with a wider bottom portion for buoyancy, a ballast such as lead or mercury for stability, and a narrow stem with graduations for measuring. The liquid to test is poured into a tall container, often a graduated cylinder, and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer correlates to relative density. Hydrometers can contain any number of scales along the stem corresponding to properties correlating to the density.

A simple hydrometer consists of a glass float inside a glass tube, as shown above.

The hydrometer float is weighted at one end and sealed at both ends. A scale calibrated in specific gravity is positioned lengthwise along the body of the float. The float is placed inside the glass tube, and the fluid to be tested is drawn into the tube.

As the fluid is drawn into the tube, the hydrometer float will sink to a certain level in the fluid. The extent to which the hydrometer float protrudes above the level of the fluid depends on the specific gravity of the fluid. The reading on the float scale at the surface of the fluid is the specific gravity of the fluid.

The point at which the surface of the liquid touches the stem of the hydrometer correlates to relative density.

Hydrometers are calibrated for different uses, such as a lactometer for measuring the density (creaminess) of milk, a saccharometer for measuring the density of sugar in a liquid, or an alcoholometer for measuring higher levels of alcohol in spirits. In our application, we measure the Specific Gravity of Battery Acid.

Reference:
[1] https://en.wikipedia.org/wiki/Hydrometer
[2] https://www.britannica.com/technology/hydrometer
[3] https://instrumentationtools.com/how-to-measure-specific-gravity-of-battery/
[4] https://www.batteriesinaflash.com/how-to-measure-specific-gravity

How to use Sun Path Finder

Sun path diagrams can tell you a lot about how the sun will impact your site and building throughout the year. Stereographic sun path diagrams can be used to read the solar azimuth and altitude for a given location. Sun path finder is a device that helps you to read the Stereographic Sun Path Diagrams ans shading analysis.

Azimuth Lines - Azimuth angles run around the edge of the diagram.

Altitude Lines - Altitude angles are represented as concentric circular dotted lines that run from the centre of the diagram out.

Date Lines - Date lines start on the eastern side of the graph and run to the western side and represent the path of the sun on one particular day of the year.

Hour Lines - Hour lines are shown as figure-eight-type lines that intersect the date lines and represent the position of the sun at a specific hour of the day. The intersection points between date and hour lines give the position of the sun.

Step by Step Guide to use Sun Path Finder:

1. Locate the required hour line on the diagram. 

2. Locate the required date line, remembering that solid are used for Jan-June and dotted lines for July-Dec. 

3. Find the intersection point of the hour and date lines. Remember to intersect solid with solid and dotted with dotted lines. 

4. Draw a line from the very centre of the diagram, through the intersection point, out to the perimeter of the diagram. 

5. Read the azimuth as an angle taken clockwise from north. In this case, the value is about 62°. 

6. Trace a concentric circle around from the intersection point to the vertical north axis, on which is displayed the altitude angles. 

7. Interpolate between the concentric circle lines to find the altitude. In this case the intersection point sits exactly on the 30° line. 

8. This gives the position of the sun, fully defined as an azimuth and altitude.

Surge Protection Device

A voltage spike is a transient event, typically lasting 1 to 30 microseconds, that may reach over 1,000 volts. Lightning that hits a power line can give a spike of over 100,000 volts and can burn through wiring insulation and cause fires, but even modest spikes can destroy a wide variety of electronic devices, computers, battery chargers, modems and TVs etc, that happen to be plugged in at the time. However, lightning and utility power anomalies only account for 20% of transient surges. The remaining 80% of surge activity is produced internally. Although these surges may be smaller in magnitude, they occur more frequently and with continuous exposure can degrade sensitive electronic equipment within the facility.

A Surge Protector or a spike suppressor, surge suppressor, surge diverter, Surge Protection Device (SPD) or transient voltage surge suppressor (TVSS) is an appliance or device intended to protect electrical devices from voltage spikes in alternating current (AC) circuits. 

Typically the surge device will trigger at a set voltage, around 3 to 4 times the mains voltage, and divert the current to earth. Some devices may absorb the spike and release it as heat. They are generally rated according to the amount of energy in joules they can absorb.

There are three types of power surge protectors:

• Type I: This Power surge protector is installed at the origin such as the main distribution board.

• Type II: It is installed sub-distribution boards.

• Type III: This power surge protector is installed at the protection load.

Reference:
[1] https://en.wikipedia.org/wiki/Surge_protector
[2] https://new.abb.com/low-voltage/products/surge-protective-devices
[3] https://www.se.com/in/en/product-subcategory/1615-acti-9-surge-protection-devices-spds/

Solar Energy Trainer Kit

Effect of Series
Effect of Parallal
IV Curve 
Video

Solar Pumping Systems

    Pumps are devices that use energy to raise, transport, or compress fluids. Pumps are divided into two main categories, Positive Displacement Pumps and Dynamic Pumps. They also have many types.

1. Positive Displacement Pump: Pumps in which displacement is accomplished mechanically are called positive displacement pumps. There are many types of Displacement Pumps.
   a. Diaphragm pumps
   b. Gear pumps
   c. Peristaltic pumps
   d. Cam pumps
   e. Piston pumps
2. Dynamic Pump: Kinetic pumps impart kinetic energy to the fluid using a rapidly rotating impeller. There are many types of Dynamic Pumps.
   a. Centrifugal pumps
   b. Vertical Pumps

    All these types of pumps have their specific pumping fluid nature (i.e. viscosity, density), fluid pressure, and flow rate. Hence their application is also different.

    Depending upon the installation locations pumps are of two types, pumps that are installed on the surface and pumps that are submerged under fluid.

1. Surface Pumps: Surface water pumps A surface water pump helps in pumping out water from a water body, like a well, or a river, and transports it to different destinations.
   
   
   
   
   

1. Submersible Pumps: A submersible pump, also known as an electrical submersible pump, is a water pump that is completely submerged in the water and can be used for a variety of applications. The electric motor used in the process is hermetically sealed and also close-coupled to the pump. One of the major advantages of a submersible pump is that it does not require priming because it has already been submerged in the liquid.
   
   
   
   
   

    Solar Pumping Systems are nowadays very common. SPV modules are used to run pumps to get water. Depending on  These systems come in two types. one with Submersible pumps and one with surface pumps. 

    Most of the time pumps run with AC power. On the other hand, SPV modules provide us with DC. To integrate them together one VFD-based pump controller is used. Sometimes these controller comes with AC power input terminals, and they can be run using AC Power at night also. They also can be equipped with a float switch so that the pump can be turned on and off depending on the water level of the reserver, tank or borewell.

    Variable Frequency Drive: A variable-frequency drive (VFD) is a type of motor drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and, depending on the topology, to control associated voltage or current variation.

There are mainly two types of applications for solar pumping systems.

Solar Pumping for Irrigation where is taken from a borewell by a submersible pump or from a river, lake or pond-like waterbody by a surface pump and used for irrigation.

Solar Pumping System for Drinking Water Project. Where a submersible pump is used to pump groundwater and store it in a tank. Then after filtering the water, it can be used locally. Or using a surface pump it can be pumped to water distribution networks.

Reference:

1. https://en.wikipedia.org/wiki/Pump
2. https://www.britannica.com/technology/pump
3. https://www.haoshpump.com/different-types-of-pumps/
4. https://multiphase-corp.com/articles/types-of-pumps-and-their-working-principles/
5. https://www.cgglobal.com/our_business/Industrial/Drives-and-Automation/Industrial-Drives/Emotron-VSR-Solar-Drive
6. https://www.crompton.co.in/blogs/pumps/what-is-a-submersible-pump-understanding-its-working-and-applications
7. https://www.crigroups.com/pump/surface-water-pumps/

Pyranometer

 A pyranometer is a type of actinometer used for measuring solar irradiance on a planar surface and it is designed to measure the solar radiation flux density (W/m2) from the hemisphere above within a wavelength range of 400 nm to 1000 nm(range may vary upon application).

Types of Pyranometer:
Pyranometers can be recognized and grouped into two different technologies: Thermopile Technology and Silicon Semiconductor Technology.

Thermopile Pyranometers:
It has a thermopile detector (a device that converts thermal energy into electrical energy) with strongly light-absorbing black paint that equally consumes all sun radiation. This creates a temperature difference between the black surface of the sensors and the body of the instrument and results in a small voltage at the sensor that can be measured and translated into W/m2.
Thermopile pyranometers follow the ISO 9060 standard, also adopted by the World Meteorological Organization (WMO). This standard discriminates between three classes. The latest version of ISO 9060, from 2018 uses the following classification: Class A for the best performing, followed by Class B and Class C, while the older ISO 9060 standard from 1990 used ambiguous terms such as "secondary standard", "first-class", and "second-class".

Semiconductor Pyranometers:
A semiconductor or silicon pyranometer uses a photodiode (a device that converts light into current) to create an electrical signal from the incoming solar radiation. It can detect the portion of the solar spectrum between 400 nm and 1100 nm.

    The device measures radiation from the sun and the sky on a horizontal surface. When exposed to radiation, the silicon cell produces a voltage, and the current output is proportional to the radiation energy received. 

    Now, this signal is sent to a device that converts this signal to a human-readable format. This device can be a data logger or a display unit.

To know more about data loggers follow the link below.
https://creativestudio1973.blogspot.com/2020/09/datalogger.html

Reference:

1. https://en.wikipedia.org/wiki/Pyranometer
2. https://www.eko-instruments.com/us/categories/products/pyranometers

Datalogger

A data logger is an electronic device that records data over time with a built-in or via external sensors.

Weather Monitoring Station

Weather Monitoring Systems are used to keep track of the ever-changing weather conditions. The information obtained by such sensors is used to report weather and maintain track of environmental changes in a given location. Such information is particularly useful in the study of the earth as well as the analysis of changing climatic and environmental conditions in a given location. Furthermore, the collected data and analytics can be used in a range of applications, including agriculture, geology, mining, and building weather forecasting models.

Sensors:

1. Weather Temperature Sensors: Measures the Temperature the the environment. 
2. Humidity Sensor: Measures the relative humidity of ambient air.
3. Barometer: It is mainly an Air Pressure Sensor. 
4. Anemometer: It is used to measure Wind Speed.
5. Wind Vain: Wind Direction is detected by Wind Vain
6. Rain Gauge: A rain gauge is used to measure the rainfall of an area.

Reference

1. Mondal, S., Mondal, A., Bhattacharya, S. (2021). Smart Data Logger for Solar and Wind Power Generation. In: Nath, V., Mandal, J.K. (eds) Proceedings of the Fourth International Conference on Microelectronics, Computing and Communication Systems. Lecture Notes in Electrical Engineering, vol 673. Springer, Singapore. https://doi.org/10.1007/978-981-15-5546-6_49
2. Mishra, S., Bera, A. Behera, J.K. (2022). Weather Monitoring System. Dogo Rangsang Research Journal, vol 12, issue 5, pp 582-586

On Grid Systems

The on-grid solar power system is a solar power generation system that is connected to the utility grid. The electricity produced by the system is routed to the grid. The installation of this type of system is very easy to install and easy to maintain. Solar Array produces Direct Current (DC). This DC passes through the Array Junction Box (AJB) to the Inverter. Inverter Consumes DC to produce Alternative Current (AC).

When an inverter starts first it samples different parameters of the grid, like Voltage Frequency and Phase. Then the inverter starts producing power which is synchronized to the grid. This synchronized power flows to the grid through the Net Metering system that measures power export to the grid. In the absence of the sun (e.g. Night, Cloudy Day) loads consume power from the grid. The net meter calculates the net consumption/export of power.

SPV Array: 
A solar photovoltaic array is formed by a series/parallel combination of SPV modules to attain the desired voltage and current level.

Array Junction Box (AJB): 

Typically the surge device will trigger at a set voltage, around 3 to 4 times the mains voltage, and divert the current to earth. Some devices may absorb the spike and release it as heat. They are generally rated according to the amount of energy in joules they can absorb.

Inverter:
A grid-tie inverter converts direct current into an alternating current suitable for injecting into an electrical power grid. To inject electrical power efficiently and safely into the grid, grid-tie inverters must accurately match the voltage and phase of the grid sine wave AC waveform.

Inverter Interfacing Panel (IIP):
The Inverter Interfacing Panel usually contains one MCB and one AC Surge Protection Device(SPD). It is mainly used to isolate the while maintenance.

Reference:
[1] https://creativestudio1973.blogspot.com/2021/06/introduction-to-solar-panel.html
[1] https://en.wikipedia.org/wiki/Surge_protector
[2] https://creativestudio1973.blogspot.com/2021/09/surge-protection-device.html
[3] https://creativestudio1973.blogspot.com/2023/10/array-and-array-junction-box.html

 

Off Grid Systems

Off-grid systems are widely used domestically when sending power to the grid is not an option for consumers. An off-grid system can be used in two ways. You can use it as an uninterrupted power supply or you can use it as a regular power supply. Depending upon the application there are two types of the inverter.

 

    Solar UPS Inverter: Solar UPS inverters are the same as our home inverter that supplies power when the grid supply is out. The only difference is that Solar inverters charge the battery primarily from solar energy and power the load during the grid outage. During grid outages, if sufficient solar energy is available, the load runs from solar power only.

    

    Solar PCU: On the other hand solar power conditioning units continuously run the load primarily from solar energy as well as charge the battery from solar energy irrespective of a grid outage. 

Nowadays almost all solar inverters have both modes. We can select the mode required as per our needs. All Off-grid inverters have three basic building blocks. 

1. One MPPT/PWM-based charge controller unit that protects the battery from over-charging or deep-discharging.
2. One Battery Charger unit that charges the battery from the mains. Which is only used if solar panels fail to charge the batteries completely.
3. One Sine Wave Inverter Unit
4. Other than that one control system and display/indicators are there

 Apart from this, Sometimes a battery balancing unit is also there. Some of the inverters come with IoT-based remote monitoring or data logging-like features this depends upon the manufacturer and model of the device.

MPPT: Maximum Power Point Trackers are used to capture maximum output from solar panels. An MPPT is an electronic DC-to-DC converter that optimizes the match between the solar array (PV panels), and the battery bank.

 

PWM: Maximum power points could also be achieved by using PWM-based DC-DC converters. PWM converters are very much used in lower voltage systems. Especially for 12V systems and less as they are cheap and reliable.

To learn more about Solar Panels follow the links below:
https://creativestudio1973.blogspot.com/2021/06/introduction-to-solar-panel.html

To learn more about PWM/MPPT Controllers follow the link below:
https://creativestudio1973.blogspot.com/2020/09/solar-charge-controller-unit.html

To learn more about Batteries follow the link below:

https://creativestudio1973.blogspot.com/2020/09/battery.html

Solar DC System

Solar panels produce DC power. The most common type of solar system is DC System. It is simple, reliable, easy to install, and easy to maintain. When sunlight hits the panel it produces electricity that we get access through the terminals connected to the solar panel. We can use this power directly during the daytime but there is one issue with that. Sun intensity varies for different reasons. Shadows of cloud trees or birds could create disruption in the power supply. Even during the night, we need power as well. 

    Here comes the application of the Battery. A battery is a device that stores electricity in form of chemical energy. Batteries help us to store the power and use it whenever we need it as per our requirement. Batteries are sensitive devices too. To get the long life of a battery we must not do some things. Like over-charging a battery or over-discharging a battery.

    This is what a Charge Controller does. A Solar Charge Controller is a device that controlles the charging and discharging process of a battery. It aslo gives protection against over-charging and deep-discharging of the battery. There are some other optional features of a charge controller like Dusk to Dawn. With this feature charge controller automatically turns on the light during the dusk and turs the light back off at dawn. Some charge controller comes with MPPT or PWM algorithm for getting maximum power from the solar panel. Some of them comes with Trickle Charging to keep the battery fully charged.

There are mainly two terminals of a solar panel Positive and Negative. A charge controller unit has six terminals. One pair of positive and negative is for solar, one pair is for battery and the last pair is for the load. The connection is very simple Positive of the solar panel goes to the Solar Positive(S+) terminal of the charge controller and negative from the solar panel goes to Solar Negative(S-) of the charge controller. Battery positive goes to charge controllers Battery Positive(B+) terminal and battery negative goes to the Battery Negative(B-) terminal of the charge controller. Now finally we can connect the load to the Load Positive(L+) and Load Negative(L-) of the charge controller.

These Types of system are sometimes called Home Lighting System. In remote areas we use these system to provide power to small houses.

Battery

A Cell is a device that stores electricity in form of chemical energy. It is the smallest unit of a battery. We combine multiple cells mostly in series and call it a Battery. Inside a cell, a reversible chemical reaction occurs. When we charge a battery inside the cell the reaction goes forward then when we discharge the battery the reaction goes backward. Although it is a reversible chemical reaction, with every cycle a small percentage becomes irreversible. This is how batteries die after a period of time.

To prevent this scenario we need to handle batteries very carefully. There are certain things that need to be maintained while using a battery.

• Temperature: Temperature is the worst enemy of a battery. It not just reduce battery life also reduces battery performence. 

• Deep Discharging: While discharging a battery we must never fully discharge a battery. If we fully discharge a battery the chemical reaction inside it becomes irriversible. Repetative deep discharging might kill the battery after a certain time.

• Over Charging: Just like Over Discharing, Overcharging also damages a battery in the same way. Deruced capacity, bad peformence might occur due to overcharging.

• Ventilation: Lead Acid batteries produces Hydrogen and Oxygen. Without proper ventilation during charging causes corotion in battery terminals.

•  Moisture: Moisture causes corotion in battery terminals.

Lead Acid Batteries:

 Depending upon the chemistry there are different types of cells. Among all of them, Lead-Acid is the most popular and widely used everywhere. 12 Volt Lead Acid batteries are made by combining 6 Nos Lead-Acid Cells together. Every Cell has multiple negative and positive plates. One disadvantage is that these have low energy density and the advantage is robustness. Depending upon the construction of the plates there are two types of Lead Acid Batteries.

• Tubuler Battery

•  Flat Plate Battery

Although the plate construction is different the chemical process remains the same. Typical construction is shown below.

Li Based Batteries:

 Now on the other hand Lithium Batteries are popular for high energy density, hence small size. Almost no maintenance. Due to these two features, these are widely used in mobile phones, laptops, drill machines, power banks, airplanes, spaceships, nowadays there are inverters that come with inbuilt Lithium batteries.

Depending upon chemical composition there are types of Lithium Based batteries:

• Li-Ion: Lithium-ion batteries are most popular for Mobile Phones. Their typical voltage is 3.7V. 
• Li-Po: Lithium Polymer batteries are mostly used in health monitoring gadgets, mobile phones.
• LiFePO4: Lithium Ferro Phosphate batteries are becoming more and more popular every day. Due to similar voltage parameters, Lead Acid batteries could be easily replaced by LIFePO4 Batteries.

Every Li-Ion cell comes with a number marking, Capacity(mAh) and Voltage printed on its body. The number marking states the dimension of the cell. Like 18650 means it has a dia of 18mm and height is 62mm.

Battery Management System:

 Battery Management System (BMS) is a device that charges and discharges Li Based batteries in a proper manner. All Li Cells of the same capacity are not identical. Hence while charging, one cell in series might get fully charged, while the others are not fully charged. The full-charged cell then stops the current to flow and due to that others, won't get charged. BMS balances all the cell so that all of them gets fully charged. BMS also provides High Temperature, Short Circuit, Deep-discharge, and Overcharge protection for each cell in a battery.

Battery Operating Voltages:

Solar Charge Controller Unit

 Solar Charge Controller Unit is a device that controls the charging process of the battery, monitors the status of the battery also generates alarms when required. Before microcontrollers, analogue charge controllers were used. Nowadays microcontroller-based solar charge controllers are quite popular. The benefit of these CCUs is that we can use MPPT or PWM algorithms for controlling the charging process. These algorithms help to harness maximum power from the PV panel. Even nowadays displays can be interfaced to show the Battery Voltage, Current, and Load Parameters.

Maximum Power Point:
The maximum power point (MPP) represents the bias potential at which the solar cell outputs the maximum net power. The MPP voltage can drift depending on a wide range of variables including the irradiance intensity, device temperature, and device degradation [1].


For a detailed connection diagram please follow the link to our blog Solar DC System
https://creativestudio1973.blogspot.com/2020/09/solar-dc-system.html

Specification of 6A Charge Controller Unit:

Specification of 10A Charge Controller Unit:


Protection Features of the Charge Controller Unit:

Indicator function:


Dusk to Dawn Feature:
The dusk to Dawn (D2D) feature enables the CCU to automatically turn on the load during low-light situations. Dusk to Dawn Charge controller turns the light on during the evening and then turns it back off during dawn. This feature is widely used in Solar Powered Street Lights, as it saves electricity and manpower. 

Reference:

1. Roger Jiang, Hannes Michaels, Nick Vlachopoulos, Marina Freitag, Chapter 8 - Beyond the Limitations of Dye-Sensitized Solar Cells, Editor(s): Masoud Soroush, Kenneth K.S. Lau, Dye-Sensitized Solar Cells, Academic Press, 2019, Pages 285-323, ISBN 9780128145418, https://doi.org/10.1016/B978-0-12-814541-8.00008-2.

Solar Thermal Systems

 The easiest way of harvesting solar energy is converting it into heat energy.  It mostly uses the greenhouse effect to convert the sunlight into heat and store the heat in a closed chamber. The best things are that no pollution and no fuel required. The most common items that we use are mentioned below along with their working process.

Solar Cooker:

Three types of solar cooker explained below.

Box Type Solar Cooker:
It is a well-insulated box that has a double glass door and a mirror to reflect some extra light towards it. The light goes in through the double glass door and falls on the black surface inside. Due to the double glass door and insulated sides heat gets trapped inside. Thus the temperature rises inside the cooker.

ETC Tube Solar Cooker:

Evacuated Tube is used as the collector to contain the heat. Stainless steel or Aluminium reflector is used for focusing the light towards the tube. This parabolic reflector concentrates the light on a point or on an axis. By this method approx. 300 deg C temperature could be generated very easily. Evacuated Tube gives it extra heat collection capacity and due to the vacuum layer heat loss becomes very less.

Parabolic Solar Cooker:

Umbrella type parabolic reflector is used to focus the light to the pot. 

Solar Dryer:

Solar Dryer is a well-insulated chamber that has a fan to pull the water vapour out. There are mainly two types of dryer:

• Direct Dryer
• Direct Sun Light is used to dry the items. This type of dryer used outdoor mainly. 
• Indirect Dryer
• Sunlight falls on the collector then air is heated up. This hot air is then used to dry the items.

Solar Water Heater:

Solar water heaters are used to get 24 hrs hot water supply. Heat Collector is used to collecting heat from the sunlight. Puff insulated tank is then used to store the hot water. This tank has no partition between hot and cold water. Hot water stays on the top and cold water rests on the bottom. This is the reason every tank has a cold water intake point at the bottom side. Hot water outlet point and temperature meter connecting point at the top side. Depending upon the type of collector there are two types of water heater present.

• ETC: In Evacuated Tube Collector specially made copper coated glass tubes were used to convert the sunlight into heat and the water gets heated up from there. Every tube has a three-layer coating with a vacuum between the glass to reduce the heat loss.

• FPC: In Flat Plate Collector type system copper fins were used to convert the light into heat. The top side of the collector is made of tougfened glass to let the light in. The light falls on the couper fins that has a large surface area. These fins are specially coated with a mat black colour. As the light falls over the coper fins they gets heated up then this heat gets transferred to the water in the copper tube that is connected with the fins. Hot water goes towards the top and cold water takes its place from the bottom. Every collector has a lightweight aluminium body. The collector directly connected with the tank is called the primary collector. If required there is probation for an extra auxiliary collector. Standard collector size is 1m x 2m. Every collector is properly insulated from the back side to reduce heat loss. 

 

Solar Panel

 Individual solar cell devices are often the electrical building blocks of photovoltaic modules, known colloquially as "solar panels". A PV module consists of several interconnected solar cells encapsulated into a single, long-lasting, stable unit. The key purpose of encapsulating a set of electrically connected solar cells is to protect them and their interconnecting wires from the typically harsh environment in which they are used. For example, solar cells, since they are relatively thin, are prone to mechanical damage (break) unless protected. In addition, the metal grid on the top surface of the solar cell and the wires interconnecting the individual solar cells may be corroded by water or water vapour. The two key functions of encapsulation are to prevent mechanical damage to the solar cells and to prevent water or water vapour from corroding the electrical contacts.

Many different types of PV modules exist and the module structure is often different for different types of solar cells or for different applications. For example, amorphous silicon solar cells are often encapsulated into a flexible array, while bulk silicon solar cells for remote power applications are usually rigid with glass front surfaces.

A Solar Panel has multiple layers from top to bottom they are -

Front Glass:
The front glass protects the Solar Cells from the weather and impact from hail or dust. The glass is typically low Iron high-strength tempered glass which is 3.0 to 4.0mm thick and is designed to resist mechanical loads and extreme temperature changes. The IEC minimum standard impact test requires solar panels to withstand an impact of hail stones of 1 inch (25 mm) diameter travelling up to 60 mph (27 m/s). In the event of an impact tempered glass is also much safer than standard glass as it shatters into tiny fragments rather than sharp jagged sections.

Upper EVA Layer:
EVA stands for ‘ethylene vinyl acetate’ which is a specially designed polymer highly transparent (plastic) layer used to encapsulate the cells and hold them in position during manufacture. It is extremely durable and tolerant of extreme temperatures and humidity, it plays an important part in long-term performance by preventing moisture and dirt ingress. EVA comes in thin sheets. Two layrs of EVA are used to make a sandwitch like arrangement where the cell assembly stays in middle. This sandwich is then heated to 150 °C to polymerize the EVA and bond the module together.

Solar Cell:
Solar Cell is mainly the optoelectronic device that converts the light to electricity.

Lower EVA Layer:
The lamination on either side of the PV cells provides some shock absorption and helps protect the cells and interconnecting wires from vibrations and sudden impact from hail stones and other objects. During manufacture the cells are first encapsulated with the EVA before being assembled within the glass and back sheet.

Backsheet:
The backsheet is the rearmost layer of standard solar panels which acts as a moisture barrier and final external skin to provide both mechanical protection and electrical insulation. The backsheet material is made of various polymers or plastics including PP, PET and PVF which offer different levels of protection, thermal stability and long-term UV resistance. Nowadays Tedlar is uded as backsheet material. The backsheet layer is typically white in colour but is also available as clear or black, depending on the manufacturer and module.

The most common modules have 36 cells, 60 cells or 72 cells with bypass diodes. A 36-cell produces a maximum open circuit voltage of 17-18 Volts while a 60-cell module produces around 36-38 Volts. A 72-cell panel produces 46-47 Volts. With the Wp (Watt-Peak) of the module increase number of cells increases. Example 10 Wp, 20 Wp, and 40 Wp module comes with 36 cells in series. On the other hand, 325 Wp, 330 Wp, and 335 Wp modules come with 72 cells in series.

Module lifetimes and warranties on bulk silicon PV modules are over 20 years, indicating the robustness of an encapsulated PV module.

Every module comes with some technical specifications written on its back, and also in the Test Report.
The main electrical specifications are:

Peak Power Pmax (Wp): The maximum power that can be drawn from a solar panel while tested with some standards. The Standard Test Condition (STC) is 1000 W/m2 irradiance, 25°C cell temperature, and AM1.5g spectrum.

Maximum Voltage Vmpp (V): This is the voltage available when the panel is connected to a load and is operating at its maximum capacity under standard test conditions.

Maximum Current Impp (A): This current is obtained when the solar panels are producing their maximum power under standard test conditions.

Open Circuit Voltage Voc (V): It is the maximum voltage a solar panel can produce under Standard Test Conditions without any load connected.

Short Circuit Current Isc (A): This is the highest current the solar panel cell can deliver without any damage at Full Load condition or Short Circuit Condition while it is in Standard Test Conditions.
 
Module Efficiency (%): It is defined as the ratio of energy produced by a solar cell to the energy it receives from the sun. The efficiency of solar panels depends on the efficiency of the solar cell. Most solar cells available in the market offer an efficiency of 17-19% and the highest efficiency of a commercial solar panel is about 23%.

The mechanical specifications are:
Length × Width × Height

Weight
Number of Cells

Reference

[1] https://www.pveducation.org/pvcdrom/modules-and-arrays/module-structure
[2] https://en.wikipedia.org/wiki/Solar_panel

[3] https://www.sovasolar.com/upload/media/23102019/Datasheet-23102019.pdf
[4] https://www.vikramsolar.de/download-category/data-sheets/
[5] https://www.renewsysworld.com/post/understanding-open-circuit-voltage-voc-and-short-circuit-current-isc-in-solar-panels
[6] https://www.electronicsforu.com/market-verticals/solar/difference-nominal-voltage-voc-vmp-isc-imp-solar-panels
[7] https://www.cleanenergyreviews.info/blog/solar-panel-components-construction

Solar Photovoltaic Cell

A solar cell or photovoltaic cell (PV cell) is an optoelectronic device that converts the energy of light directly into electricity by means of the photovoltaic effect, which is generally done by a p-n junction. Although solar cell without p-n junction is available. This process requires firstly, a material in which light absorption raises an electron to a higher energy state, and secondly, the movement of this higher energy electron from the solar cell into an external circuit. The electron dissipates energy in the external circuit and returns to the solar cell. Various materials and processes can potentially satisfy the requirements for photovoltaic energy conversion. Still, in practice, nearly all photovoltaic energy conversion uses semiconductor materials in the form of a p-n junction. The common single-junction silicon solar cell can produce a maximum open-circuit voltage of approximately 0.5 to 0.6 volts.

A photoelectric cell is a device whose electrical characteristics (such as current, voltage, or resistance) vary when exposed to light.

Reference
[1] https://en.wikipedia.org/wiki/Solar_cell
[2] https://www.pveducation.org/pvcdrom/solar-cell-operation/solar-cell-structure