Off-Grid Solar Power system
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| Solar panels |
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| Cover page |
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| IV and PV CURVE |
Introduction
Off Grid
Off Grid solar power System is which system that generates power not feeds to any Grid.
On Grid
On Grid solar power system is which system that generates power feeds a Grid.Some smart devices used in modern off-grid solar power system, which makes the solar power system much more efficient.
Because of the arrangement used in domestic modern solar power systems, the initial cost is comparatively low and the output power is regulated. The conventional old solar power system is not in these facilities therefore uneconomical.
Modern Solar Power Arrangements
Let's talk about how modern solar power systems have improved so much. This modern system is capable of using battery power as well as the power of the service main, capable of tracking the maximum power from PV panel output and efficiently regulating battery charging .
Mainly two smart devices used in this modern system: the first one is a maximum power point tracker with voltage regulator and another one smart inverter with charge sharing technique.
Let's discuss the first smart maximum power point tracker. Basically this one is a modern charge controller.First of all we will try to understand current voltage curve and power voltage curve in PV modules.
Photovoltaic cells
We give just brief information about photovoltaic cells. Photovoltaic cells work like bipolar junction diodes. In a PV cell made by two types of material P type material and another is N type material .
P type material Dropped by Trivalent impurity and N type material Dropped by Pentavalent impurity. In between two materials make a junction .
P type materials belongs positive charge electrons or Holes and N type material belongs negative charge electrons . So we know the heating effect of semiconductors And we need to know the definition of semiconductors , when such conditions make a conductor which is called a semi conductor.
The such condition is the heat from the sun 🌞. The density of electrons is huge in N type material, it helps to heat the electron flow through the circuit and neutralize in P type material . The flow of electrons through a circuit called current.
Types of PV module available in market
There are many PV module available in market but most three PV module is used commonly
1) Mono crystalline
2) Poly crystalline
3) thin film
Charge Controller
In the figure we see the IV curve over the PV curve in the PV module. In PV curve a maximum point is shown this is called maximum power point .The charge controller tracker is a microprocessor based module.
The tracker tracks the maximum power point of the PV panel as well as identifies the output of the PV panel and battery charge. Then sends a signal to the PWM module .
In the PWM module generate a pulse for control dc to dc converter or buck boost converter. The battery input voltage Maintained by the voltage regulator.
When the battery charging is full, the tracking device sends a signal to the breaker and the breaker will cut the supply. The function of the tracking in the microprocessor module will be done by algorithm. Most algorithms are used for tracking the maximum power.
The maximum power point in the PV panel depends on weather. When the weather is poor proportionally the output power is poor.
Then buck boost converter boost to the power and regulate output is provided for battery charging. This is the main advantage of this type of charge controller.
Inverter
Another, advanced inverter Generally inverter works to change the supply DC to AC. But this type of advanced inverter is mainly from battery and PV cell DC supply to AC supply.
But there is also another feature in inverter supply power to load with help of service main AC power; this is called smart charge sharing technique. How it works, let's see. When power from a PV cells or batteries is not enough to drive the load.
The rest of the inverter takes power from the service main. On other hand PV cell output power is not enough for battery charging then the inverter takes remaining power from the supply main.
If the user wants to drive total load by PV call at that time inverter charging the battery by service main till full charge but does not overcharge under any circumstances. This inverter makes the solar power system as uninterruptible as possible .
Economical view
Mono crystalline pv module is popular in the market for Efficiency .This type of PV module speciality is this module Generate electricity not depends on weather . It can give electricity Maximum of any weather. Due to this reason this module price is more than the polycrystalline pv module.
Polycrystalline pv module is less Efficient then mono .It can generate electricity depending on weather . It is most popular in domestic application for reducing the total installation cost .
Price low then other type of pv module available in market.Thin film it is efficient and it is transferable. It is most popular in E-bikes, E-van ,E-cars,Buses etc. It is looks like a paper.
Calculation of Install Off-Grid Solar Power system
Before the estimation we need the to know what is the approximate load when Off-Grid Solar Power system Install . Number of Pv module need and need to know range of battery and charge controller and other safety Equipments.
Load Calculation
Working Load is needed for Estimation . Load is directly proportional to Total cost. If you want to reduce your price . You must select the selective loads Or on the other hand you want an Off-Grid Solar Power system that can drive all loads that can reflect your total cost..
At first I added all the Loads . For proper understanding we use a example
Ceiling fan - 3nos ×75 watts =225 watts
LED LAMP - 2 nos×18 watts =36 watts
LED TUBE - 2 nos × 20 watts =40 watts
LED TV - 2 nos × 20 watts. =50 watts
Total load =400 watts
Inverter Selection
Our total load is 400 watts
For safety Reason selected inverter is 300% above the total load. It can depends upon the what Inverter available in market . But This case we choose inverter between 800 watts -1 kw.
Required Current
Total. Load is 400 kw
And battery voltage is 12 v
Required Current is =400/12= 33 A
Battery AH Selection
For 400 watt load and backup time 6 hours and battery volt 12 v
The Required AH is = (400×6 )/12 = 200 AH
But the market Available Amp-hour battery is 150 AH and 220 AH . So here this case 220 AH battery is preferable.
But here you backup more than you need to another battery which is connected with a series with the present battery.
Normal Battery charging current
Well and safe battery charging current 10% of total capacity of battery. Here in this case 200AH battery capacity and the charging current is 20 A.
Here you will set the inverter 20 A as an output.
PV module required
Various types of Pv module is available in the market . They are different wattage and voltage . Our battery voltage is 12 volt . We recommend using a 150 watt PV module or 180 Watt PV module Mono crystalline.
Our total current requirement is total battery charging current and total required load current is about 53 A
And total wattage required is 12×53= 636 watt.
This wattage helps to choose solar panels. If you use 150 watt Solar panel then required 636/150= 4.24 or 5
If you use 180 then the required solar panels are 4 .
Minimum Estimation of Solar Power If Install at Home
In this point we give an example for installing a pv module at home . If you calculate this way you can find your estimation.
This Estimation is our Example load (400 watt)
5 solar panel price is =5500 Rs ×5 =27500/-
( 5500 is approx value for 1 solar panels ,it will varies manufacturing companies)
Inverter 1000 watts = 5100/- (approx)
battery 220AH = 15700/- (approx)
12 volt charge controller =700/- (approx)
Required wires= 4000/- (approx)
Installation Frame = 7000/- (approx)
Total Expenditure = 53,000/- ( maximum)
Conclusion
If the user wants to reduce installation cost then the user can install a solar panel with a lower power rating than the rated power required for driving load.
such advanced solar power systems have become widely popular in homes, offices, schools and colleges.
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