Photo voltaic Photovoltaic vitality is obtainable all through the day whereas the Solar shines. Nevertheless, this vitality is very fluctuating in nature. Additionally, lighting is principally required throughout night time when photo voltaic vitality isn’t accessible. Due to this fact, there’s a want for vitality storage units. The plain selection is Lithium-ion battery. Regardless that Li-ion battery is the best choice, there are some limitations:
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Value of Li-ion Battery is rising yr after yr. Therefore, these batteries might be primarily used for automobiles and mobiles. For stationary purposes we’ve got to seek out options.
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Li-ion Batteries can deal with few thousand cost/discharge cycles. This means the battery must be changed after about 5 years
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Re-cycling of Li-ion batteries is difficult and costly.
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India doesn’t have Lithium mines. We’re utterly depending on imports. Therefore it turns into crucial to discover different units for vitality storage.
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Li-ion Batteries additionally use different metals akin to Nickle and Cobalt and many others. Due to this fact, these batteries will not be atmosphere pleasant. Lot of mining is required to get these metals.
Proposed Different
Right here we are going to discover use of Supercapacitors for vitality storage for low energy however widespread purposes. Supercapacitors (or Extremely Capacitors) are additionally known as as Electrical Double-Layer Capacitors. They use porous carbon electrodes and retailer vitality within the type of electrical discipline. In contrast to batteries which retailer vitality in electrochemical type. These supply very massive values of capacitance, measured in Farads. Typical working voltage of those capacitors is low (2.7 V). Following are their benefits:
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May be charged and discharged 100,000 occasions with out dropping storage capability. Therefore, they’ve lengthy lifetime of > 15 years.
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Quick charging and discharging
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Safer than batteries
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Use simply accessible uncooked supplies (eg carbon), therefore atmosphere pleasant. No dependency on imports for costly uncooked supplies.
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Straightforward to recycle
Limitations:
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Low particular vitality and decrease working voltage
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Linear discharge voltage
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Barely larger self-discharge
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Greater price. A 500 F capacitor presently prices about Rs 400 and 100 F capacitor prices about 175 rupees.
As of at this time, the price of supercapacitors is considerably larger. Only for storing few Watt-Hours of vitality we’ve got to make use of a number of capacitors. Therefore the price of even small low energy programs is pretty excessive. Some solutions are given beneath for decreasing the fee:
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Mass Manufacturing: As mentioned earlier, supercapacitors don’t want costly uncooked materials. So, the excessive price could be primarily attributed to low volumes of manufacturing. Due to this fact, there’s a must establish many purposes which may generate huge demand. Because the manufacturing scales up, robotically the manufacturing price will come down.
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Redesign for gradual cost/ discharge purposes: Most supercapacitors accessible out there are designed for dealing with excessive (in amps) cost/ discharge currents. Due to this fact, these Supercapacitors have thick terminals and huge electrodes. Nevertheless, in small photo voltaic purposes the capacitor cost/ discharge currents are low (in milliamps). Therefore, for such purposes capacitor design could be optimized to cut back price and dimension.
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Greater worth of capacitance for a given dimension and price: By optimizing capacitor design for decrease present purposes, it might be attainable to get larger capacitance in the identical dimension and price. This may improve the vitality storage capability for given dimension and price.
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Many of the Supercapacitors accessible out there are imported. Stimulating the demand will entice Indian firms for native manufacture. The price of domestically produced capacitors might be a lot decrease.
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Authorities Subsidy to the producers: Firms who need to manufacture supercapacitors, our authorities ought to present some monetary help for organising manufacturing strains and for getting the most recent design understand how from established producers.
Supercapacitor based mostly Clock:
This is without doubt one of the finest suited purposes. Wall clocks want very low energy. Wall clocks use one AA major battery per yr. Each home has few such clocks. So, we’re consuming large variety of batteries yearly containing hazardous chemical compounds. Additional, these batteries will not be correctly disposed, therefore pose huge risk to the atmosphere and well being. Right here, clock energy provide design is proposed which makes use of photo voltaic vitality and Supercapacitors. The goal right here is to run the clock nonstop for at the least 15 years beneath all climate circumstances. This may remove the usage of 15 AA cells and cut back hazardous chemical waste.
Design particulars:
Determine 1 exhibits the circuit diagram of proposed energy provide. It consists of two small photo voltaic panels PV1 and PV2. Following are the specs of those panels:
- Voltage at most energy = Vmp = 5 V (Relies upon upon daylight depth)
- Present at most energy = Imp = 100 mA
- Open circuit voltage = Voc = 6 V
- Dimension = 70 mm X 70 mm
These panels are related in parallel utilizing two diodes D1 and D2 (1N5819). These Schottky diodes block present from one panel getting into the opposite panel. The panel output voltage Vpv is fed to the Supercapacitor C1 (100F 2.7V) via present limiting resistor R1 (330Ω 1W). Voltage regulator IC1 (TL431) is related throughout C1. It regulates the capacitor voltage to 2.5 V. IC1 ensures that the capacitor voltage by no means exceeds rated voltage of two.7 V. Word that, diodes D1 and D2 additionally cease C1 from discharging into the panels, when there is no such thing as a daylight.
The output of capacitor C1 is related to the clock terminals via present limiting resistor R2 (220Ω). Throughout these terminals three diodes D2, D3 and D4 (1N4007) are related in sequence.
Complete Ahead voltage of D2, D3, D4 = 0.65 X 3 = 1.95 V
The clock motion operates within the vary from 2 V right down to 1V. Thus, the three diodes restrict the voltage Vclock to lower than 2V. C2 is used to cut back voltage dip every time the motion attracts pulse present. Fig 2 exhibits the assembled PCB.
The working of the above circuit might be clearer after numerous waveforms proven in Figs 3, 4 and 5.
Determine 3 exhibits capacitor voltage (C1) and +Vclock voltage. These waveforms have been captured with out mounting the filter capacitor C2. Additionally, worth of resistor R2 was modified to 100Ω. As seen within the determine, the capacitor voltage is steady at 1.99 V. We see dip in +Vclock voltage each second when the clock motion attracts pulse present. Utilizing math operate of the oscilloscope, hint M (crimson) has been plotted which supplies distinction between Ch1 and Ch2. This waveform is the voltage throughout R2. Determine 4 exhibits the identical waveform expanded.
From the crimson hint of Fig 4 we will calculate present via R2.
- Regular present via R2 and D3, D4, D5 = 0.2 V/ 100Ω = 2 mA
- Common pulse present = 0.6V / 100Ω = 6 mA
- Precise pulse present drawn by the clock motion = 6 – 2 = 4 mA
- Pulse period = 30 msec
- Common present drawn by clock motion = 4 mA * 30 msec / 1000 msec = 0.12 mA.
- Common Energy drawn by the clock motion = 0.12 * 1.71 = 0.2 mW
- Power Consumed throughout 24 hours = 0.2 mW * 24 = 4.8 mWh
- Power saved within the capacitor = 0.5 * C1 * V * V = 0.5 * 100 * 1.99 * 1.99 = 198 joules
- Power saved = (198 / 3600) * 1000 = 55 mWh
From above calculations it’s seen that, we’ve got virtually 11 occasions vitality accessible within the capacitors on per day foundation (beneath supreme circumstances). Nevertheless, there are self-discharge loss within the capacitor and losses in R2 and Diodes and residual voltage within the capacitor. Contemplating all of the losses we will safely assume that the saved energy within the capacitor might be ample for about 2 or 3 days. This issue helps in continuous working of clock on wet days when the daylight could be very much less.
Determine 5 exhibits the filtered voltage waveform +Vclock. With C2 (4700 µF) related on the output, the heart beat peak voltage drops to lower than 200 mV. Additionally, the worth of resistance has been elevated to 220Ω to cut back present via the diodes. These waveforms have been captured when the C1 voltage was 1.08 V. Thus, it’s clear that the clock works right down to 1 V.
Interface:
Determine 6 exhibits proposed AA dimension dummy cell made out of plastic materials. It has metallic +ve and -ve terminals. Two wires are related to those terminals and introduced out via the holes offered. These wires are related to +Vclock and -Vclock. Person can merely insert this dummy cell within the clock second.
Utilization of the system:
Wall clocks are mounted contained in the buildings therefore they don’t obtain direct daylight. Due to this fact, two PV panels have been used in order that the circuit works on the subtle ambient mild accessible contained in the rooms. There isn’t a must mount the panels within the direct daylight. The panels could possibly be mounted on the identical wall on which the clock is current. We’ve got to make sure that all through the day, the panels get good ambient mild. If this mild isn’t ample then we will mount the panels close to the home windows the place mild depth is larger. Two PV panels additionally be sure that throughout wet season the circuit works correctly. {Photograph} of built-in system is proven in Fig. 7.
Fig.7 {Photograph} of system exhibiting PV panels and clock interconnections.
Costing:
Assuming one cell is required per yr, in 15 years of lifespan, we spend about 150 rupees on these cells.
The price of proposed system is given beneath:
- Supercapacitor 100 F 2.7 V Rs 175
- Two 6V PV panels Rs 110
- PCB and small parts Rs 35
- Complete Rs 320
Word: These costs are for MOQ of fifty items. For one or two portions costs could also be a lot larger.
Thus, we see that the price of proposed circuit is sort of double as in contrast with the cash we spend on batteries. We’ve got to contemplate few extra factors relating to price comparability that are as follows:
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The lifetime of PV panels is 30 years. Therefore, we’ve got to contemplate solely half of it’s price. As it may be reused for an additional 15 years together with one other clock.
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As of at this time, the manufacturing quantity of supercapacitors is low, therefore its price is larger. If the manufacturing quantity will increase by many folds the fee will come down considerably.
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By utilizing the proposed circuit, we’re eliminating the battery hazardous waste which in any other case goes into landfill. This poses risk to atmosphere and well being. We’ve got to issue this atmosphere price in favor of the proposed design.
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Supercapacitors don’t require imported materials. It principally makes use of carbon; therefore it’ll present vitality independence for our nation.
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Use of proposed circuit additionally eliminates the trouble of changing the batteries. This can be a major benefit for corporates, as they will cut back the manpower and want for holding inventory of batteries.
Optimization:
If there’s some place contained in the room, the place direct daylight is obtainable for few hours then it might be attainable to take away one PV panel. With direct daylight, single panel can totally cost the capacitor shortly. This may assist in decreasing the fee to some extent. This may want long run testing in all seasons to make sure nonstop operation.
Energy provide design for a number of clocks
In lots of firms there are a number of clocks mounted on the identical wall. These clocks are used to indicate native time from completely different nations. Additionally, in wall clock showrooms, retailers and restore retailers there are a number of clocks working on particular person batteries. Due to this fact, massive variety of cells are consumed in these retailers. For such purposes a single energy provide is designed which may cater to many clocks. On this case, the price of the circuit will get divided amongst all of the clocks and the general price of the circuit comes down.
Circuit design for 5 clocks:
Determine 8 exhibits the circuit diagram of energy provide which caters to 5 clocks.
This design consists of two forms of models. One storage unit and 5 filter models for 5 clocks. A 6V 3W photo voltaic PV panel is related to the storage unit. Storage unit consists of a 500 F capacitor which is charged via diode D10 (1N5819) and resistor R10 (68 Ω 2W). Regulator IC10 (TL431) clamps the capacitor voltage to 2.5V. This regulator is rated for 100 mA present. Therefore, further Zener diodes DZ1 and DZ2 (2.5V 1W) are related in parallel with the IC10. These Zener diodes can deal with extra present.
Filter Models 1 to five need to be mounted very close to to their respective clocks. The filter unit consists of filter capacitor of 4700 µF (C11 to C15, one for every filter unit). Additionally, every filter unit has three 1N4007 diodes related in sequence (D11 to D25). The outputs of 5 filter models are related to 5 completely different clocks.
The PV panel is mounted on a roof high or in a spot the place there’s good sunshine. The storage unit is positioned in a location contained in the constructing, the place the cable from PV panel comes contained in the constructing. From storage unit, via present limiting resistors R11 to R15 skinny cables are related to the respective filter models. These wire lengths could possibly be few tens of ft lengthy. The capacitor within the filter unit will compensate for the cable inductance. In Fig 8, crimson wires join R11 to filter unit 1. Equally, blue wires join R15 to filter unit 5.
Costing:
Costing for this design is given beneath:
- Supercapacitor 500 F 2.7 V Rs 400
- 6V 3W PV panel Rs 400
- PCB and small parts Rs 200
- Complete Rs 1000
The fee per clock is 1000 / 5 = 200 rupees. Thus, we will say that a number of clock design will present higher price benefit. Thus, it may be applied by all store keepers in order that demand for supercapacitors will get a lift.
Conclusion
Above design demonstrates use of supercapacitors for storing small quantity of vitality. As crores of clocks are getting used, it presents huge potential for decreasing the usage of chemical batteries. This may assist in decreasing hazardous waste. Additionally, it’ll generate demand for crores of supercapacitors. Many fold improve in manufacturing quantity of those capacitors will deliver down the fee. It should open up many different areas the place these capacitors could possibly be used for vitality storage. Scale back dependence on imported Lithium and different pricey metals. Every home will generate small quantity of solar energy and it’s cumulative impact might be important. Want of the hour is to establish many extra such purposes.
Supercapacitors can contribute in the direction of making Atmanirbhar and Swachh Bharat.