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

Pyrheliometer

Direct beam solar irradiance is the solar irradiance coming directly from the sun. A pyrheliometer is an instrument that can measure direct beam solar irradiance. Sunlight enters the instrument through a window and is directed onto a thermopile which converts heat to an electrical signal that can be recorded.

    The signal voltage is then converted via the ADC of a microcontroller. Then, it results in irradiance value. The SI units of irradiance are watts per square metre (W/m²).

    A Sun Tracker is used to keep the pyranometer aligned with the sun during the entire day. The Pyrheliometer is mounted on the Sun Tracker.

    Traditionally pyrheliometers were mainly used for climatological research and weather monitoring purposes. Traditionally pyrheliometers were mainly used for climatological research and weather monitoring purposes

Reference

1. https://en.wikipedia.org/wiki/Pyrheliometer
2. https://www.hukseflux.com/applications/solar-energy-pv-system-performance-monitoring/what-is-a-pyrheliometer

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.