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

Barometer (BMP 280) Interface with Arduino

The BMP280 is an absolute barometric pressure sensor by BOSCH. Its small dimensions and its low power consumption allow for the implementation in battery-powered devices as mobile phones, GPS modules, or watches. We can interface this sensor with Arduino using SPI or I2C communication.

Items required:

• Arduino Nano
• BMP280
• Jumper Wire

Circuit Diagram:

https://drive.google.com/file/d/1lNnCiqnRWaTVyms3n30e6uSTXWHIA9IF/view?usp=sharing

Video Example:
                Coming Soon

Software:

https://drive.google.com/file/d/1G5sSDW8o3C2-xGOmycm4BjZhKVSpgN__/view?usp=sharing

Updated Library:

https://drive.google.com/file/d/1PMnp-uYyExyOVUsh4ou9veD_lk4TCpPE/view?usp=sharing

PIR Sensor Interfacing with Arduino

PIR stands for Passive Infrared Radiation. PIR sensors are more complicated than many of the other sensors explained in these tutorials because there are multiple variables that affect the sensor's input and output. To begin explaining how a basic sensor works, we'll use this rather nice diagram.

PIRs are basically made of a pyroelectric sensor (which you can see below as the round metal can with a rectangular crystal in the center),
which can detect levels of infrared radiation. Everything emits some low-level radiation, and the hotter something is, the more radiation is emitted. The sensor in a motion detector is actually split into two halves. The reason for that is that we are looking to detect motion (change), not average IR levels. The two halves are wired up so that they cancel each other out. If one half sees more or less IR radiation than the other, the output will swing high or low.
The second important thing is the lens of the sensor. PIR sensors are rather generic and for the most part, vary only in price and sensitivity. Most of the real magic happens with the optics. This is a pretty good idea for manufacturing: the PIR sensor and circuitry is fixed and costs a few dollars. The lens costs only a few cents and can change the breadth, range, sensing pattern, very easily. In the diagram up top, the lens is just a piece of plastic, but that means that the detection area is just two rectangles. Usually, we'd like to have a detection area that is much larger. To do that, we use a simple lens such as those found in a camera: they condense a large area (such as a landscape) into a small one (on film or a CCD sensor). For reasons that will be apparent soon, we would like to make the PIR lenses small and thin and moldable from cheap plastic, even though it may add distortion. For this reason, the sensors are actually Fresnel lenses:

OK, so now we have a much larger range. However, remember that we actually have two sensors, and more importantly, we don't want two really big sensing-area rectangles, but rather a scattering of multiple small areas. So what we do is split up the lens into multiple sections, each section of which is a fresnel lens.

To interface, this module all you have to do is to read the OUT pin signal with Aduino's digital pin using the digitalRead(DataPin) function frequently and if there is any signal keep the output high.

Pinout:

• VCC supplies power for the module. You can directly connect it to the 5V pin on the Arduino.
• DATA pin logical voltage changes from 0 or 5 Volt with the pH value.
• GND is the Ground Pin and needs to be connected to the GND pin on the Arduino.

Connecting This device with Arduino is very easy. VCC pin goes to Arduino 5v pin GND pin goes to Arduino Ground Pin and the OUT pin goes to Arduino D2 pin.

Circuit Diagram:

Video Example:

Software:

Interfacing part Only

Introduction to ESP-01

ESP-01 Module is basically a low-cost esp8266 module, with built-in WIFI. It was created as an Arduino WIFI module but it can also be programmed to work as standalone. Although this module is cheap but working with it is a little difficult. As it is not a breadboard-friendly module it would be a bad choice for a beginner.

Less I/O pins make it a little difficult to use in standalone mode in projects. It has 8 pins.

• Pin1: Ground Pin
• Pin2: GPIO2 Pin 
• Pin3: GPIO0 Pin
• Pin4: RXD is UART data receive pin.
• Pin5: Vcc is for powering the Module. Only 3.3V power is required.
• Pin6: RST is for external reset. It's active Low in nature.
• Pin7: CH_PD is an active-high pin for Chip enable.
• Pin8: TXD is UART data send pin.

Programming this module is a little difficult as it does not have any type of connector. Although programming can be done using Jumper Wires, NodeMCU and Arduino IDE.

Get the Datasheet from the link below:

https://drive.google.com/file/d/1bc6EK2miatXNN_usuPb_G5GgVX3EIL-P/view?usp=sharing

pH Sensor Interface With Arduino

In chemistry, pH is a scale used to specify how acidic or basic a water-based solution is. Acidic solutions have a lower pH, while basic solutions have a higher pH. At room temperature (25°C or 77°F), pure water is neither acidic nor basic and has a pH of 7.

Here is a chart of different pH of different items.

This tutorial is about the interfacing of the Analog pH sensor with Arduino Nano. Then we display the data using a serial terminal.

What is an analog pH sensor?
Analog pH meter is specifically designed to measure the pH of the solution and reflect the acidity or alkalinity. It is commonly used in various applications such as aquaponics, aquaculture, and environmental water testing.
The sensor signal from the sensor goes to a circuit board that converts the signal to a (0-5) V analog signal easily readable from the Arduino board. All we have to do is to put the analog signal to any Analog pin of the Arduino (Arduino Nano in my case) and read the voltage using ADC.

Pinout:

• VCC supplies power for the module. You can directly connect it to the 5V pin on the Arduino.
• Data pin voltage varies from (0-5) Volt with the pH value.
• GND is the Ground Pin and needs to be connected to the GND pin on the Arduino.

Connecting This device with Arduino is very easy. VCC pin goes to Arduino 5v pin GND pin goes to Arduino Ground Pin and the OUT pin goes to Arduino A0 pin.

Circuit Diagram:

Coming Soon

Output:
https://drive.google.com/open?id=1bTpREIrALVdqaLZ9LMlf_zeGo6dNBSzf

Software: