Alaknanda Hostel Snet Report

8/3/2019 Alaknanda Hostel Snet Report

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Introduction

Solar energy has been a part of peoples lives for thousands of years. It has been

used for drying clothes, food and other such things. The sun is also the life giver of

the world; the solar energy radiated through the atmosphere provides earth with

the energy necessary for survival. This energy is now used in a modern invention

called photovoltaic cells, which convert the suns energy into relative power. The

earth is rich in natural resources; however the earths natural resources are being

consumed at a tremendous rate. It will only be a matter of time before those

resources are depleted and the population is forced to consider otheralternatives. People can wait until every resource has been consumed and go

back to living the way mankind did over a century ago, or people can continue to

move forward and explore the possibilities of utilizing the power of something

that remains constantthe sun.

Solar water heating, where heat from the Sun is used to heat water in glass

panels on your roof. Water is pumped through pipes in the panel. The pipes are

painted black, so they get hotter when the Sun shines on them. The water is

pumped in at the bottom so that convection helps the flow of hot water out of

the top.

Photovoltaics are the direct conversion of light into electricity at the atomic level.

Some materials exhibit a property known as the photoelectric effect that causes

them to absorb photons of light and release electrons. When these free electrons

are captured, an electric current results that can be used as electricity. A number

of solar cells electrically connected to each other and mounted in a support

structure or frame is called a photovoltaic module. Modules are designed to

supply electricity at a certain voltage, such as a common 12 volts system. The

current produced is directly dependent on how much light strikes the module.


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Multiple modules can be wired together to form an array. In general, the larger

the area of a module or array, the more electricity that will be produced.

Photovoltaic modules and arrays produce direct-current (dc) electricity. They can

be connected in both series and parallel electrical arrangements to produce any

required voltage and current combination.

Activities Undertaken so far

1. Installation of LED lights in the hostel corridors.2. Proposal of a competition to motivate people to participate in sustainability

activities.

3. Survey undertaken to study the energy consumption in the hostel.Types of Solar Generation setups

1. Captive Photovoltaic2. Non-Captive Photovoltaic3. Concentrated solar thermal systems.For the purpose of generation of electrical requirements of a student hostel,

we have to use captive photovoltaic systems. The reason for this decision being

the large consumption of energy at nights.


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Captive Photovoltaic Systems

SCHEMATIC

The suns radiation generates electricity via the solar panels (photoelectric

effect) and a current constitutes and the voltages of the several panels get

added up in the combiner bus.The combiner bus is connected via a fuse (F)(to prevent damage due to

over-current) to the charge controller, which controls the flow of charge to

the battery while it charges. It is placed in order to ensure that the battery

doesnt over-charge, nor over-discharge and gets charged in the minimum

possible time, which in turn helps increase battery life by 2-3 years.


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The charge controller is connected to the battery again via a fuse and also ashunt (in the negative terminal) which just ensures minimal current is being

drawn for metering purposes. Now, the battery stores the energy

generated by the solar panels.

As most of the appliances or instruments nowadays are AC powered we

need to convert the DC current from the battery to the required AC voltage

and power ,and so the battery is connected to an inverter via a circuit

breaker(which is similar to a fuse ,except in the fact that it can be just

switched back to bring into use rather than replacing it).The inverter

converts the DC voltage to AC(~230 V) which is then given out to the AC

breaker panel or the appliances directly after ensuring all safety measures

have been covered.

NOTE : As Captive Solar PV systems are mostly off-grid, it is preferable to

have a back-up DC generator in case the PV system needs to be shut down

for maintenance. The connections linking it to the PV system are as shown

in the schematic. However, for our hostel design, we dont need the

generator as we have a grid connected system.


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Solar Modules:

A solar cell (also c

converts the energ

effect. Assemblies

solar panels.

Types of solar module

There are two type

Sizing of Solar Modul

The size of the

maximum. To esti

The number of

The insolation

Single Crys

lled photovoltaic cell) is a solid state

y of sunlight directly into electricity b

of cells are used to make solar modul

:

s of solar modules;

es:

anel generally determines the wattag

ate the size of your solar array, you'll

att-hours (wh) you plan to produce

alue at your location.

Solar Modules

Crystalline SiliconSolar Modules

talline Poly Crystalline

Thin Film

Solar Modules

device that

the photovoltaic

s, also known as

e it will put out at

need to know:

in one day.


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IMPORTANT NOTE:

We analyzed all the possibilities ( Mono and poly crystalline and thin film cells ) ,it was found that :

1>When we consider only cost, thin films are the most economical, for givenpower requirement.

2>On considering, other factors, such as installation cost, payback period andconstrained installation area, mono crystalline performs exceedingly well

compared to thin film and polycrystalline modules.

Solar panels mounting:

Solar panels are mounted on iron fixtures so that it can withstand wind and

weight of panels. The direction of panel is south facing for maximum power

tracking. The tilt angle of panels will be 13 to 25 from horizontal. This angle is

called axis tracking angle. You can set 40 degree tracking angle in the month of

December and 10 degree in the month of June. In the month of September &

March it will be 25 degree.


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CHARGE CONTROLLERS

There are basically two types of charge controllers existing today in terms offunctionality:

1.) PWM charge controllers:

These kind of charge controllers operate by sending out pulses of charge

which helps in uniform distribution of the charges on the plates of battery.

These modulate the pulse widths and slopes of the voltage and current levels

and also their rate of change. They operate in three phases :

i. Bulk phase: During the Bulk phase of the charge cycle, the voltagegradually rises to the Bulk level (usually 14.4 to 14.6 volts) while the

batteries draw maximum current. When Bulk level voltage is reached the

absorption stage begins.

ii. Absorption phase: During this phase the voltage is maintained at Bulkvoltage level for specified times (usually an hour) while the current

gradually tapers off as the batteries charge up.

iii. Float phase: After the absorption time passes the voltage is lowered tofloat level (usually 13.4 to 13.7 volts) and the batteries draw a small

maintenance current until the next cycle.

2.) MPPT charge controllers: They constantly track and maintain the

optimum voltage and current to charge the battery. They match the output of

the solar panels to the battery voltage to insure maximum charge (amps).


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For example: even though your solar panel is rated at 100 watts, you won't get

the full 100 watts unless the battery is at optimum voltage.

If your batteries are low at say 12.4 volts, then your 100 watt solar panel rated at

6 amps at 16.5 volts (6 amps times 16.5 volts = 100 watts) will only charge at 6

amps times 12.4 volts or just 75 watts. You just lost 25% of your capacity!

The MPPT controller compensates for the lower battery voltage by delivering

closer to 8 amps into the 12.4 volt battery maintaining the full power of the 100

watt solar panel! 100 watts = 12.4 volts times 8 amps

Comparison of PWM and MPPT charge controllers:

PWM MPPT

Capacity a)Available only up to 60 Amps

only

b)Can take only certain input

voltages :12V,24V,48V

c)Limits solar panel output

voltage

a) Available up to 80 Amps

b) Can take a varying range of

input voltages and hence,

reduces losses in transmission

and provides flexibility in solar

module configuration.

Cost Inexpensive;


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outperform PWM charge controllers in terms of the operating efficiency and

range of operation.

If Wp is the peak power of the solar modules that the MPPT chargecontroller handles, then the input current to the MPPT controller would be

Wp divided by nominal voltage of battery bank. Then, the MPPT charge

controller should have at least 1.2 times this value as its current input

capacity.

The input voltage of the MPPT controller should be big enough to handlethe open circuit voltages of the modules in series.

MPPT charge controllers(Major companies)

Company I Cost 12 V 24V 48 V

Morning star 60 A 565.50 $ 800 W 1600 W 3200 W

Outback 60 A 597.72 $ 900 W 1800 W 3600 W

Solar converters 60 A 581.45 $ 48 W 96 W 192 W

Xantrex 60 A 537.00 $ 720 W 1440 W 2280 W

Maximum Battery current = I; Nominal maximum solar input = V; Capacity = C

For a sample analysis ,let us consider an MPPT and a PWM charge controller from

xantrex:

For P power output from the solar panels,

No.of MPPT charge controllers=P/(110*60) {values from datasheet Xantrex

XW Solar Charge Controller MPPT 865-1030 }

Total cost =Cmppt=P*537/(110*60)=0.081*P


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BATTERIES

Types of Batteries:

Sl. No. Flooded Sealed

AGM Gel

1.Cost cost-effectiveness,

least cost per amp hour

Nearly three

times the cost

of flooded

batteries

2-3 times the

cost of

flooded

batteries

2.Maintenance require maintenance No/negligible maintenance

required

3.Size and placement Need ventilation ;

Mostly need to be keptoutdoors which hinders

working at ambient

temperature

sealed batteries conform to

situations with spaceconstraints that require you to

store your batteries in unusual

orientations or where venting

is not possible

4.Transportation classed under hazardous

materials rules, which restrict

shipping options

increased ease of

transportation

5.Life longest life less than a 2% self-discharge

rate during transport and

storage

3-7 yearsIndustrial(Traction):20 years

Industrial(Stationary):20 years

10 years 8 years

% of electrical power lost

as heat

15-20% 4% 10-16%

http://www.vonwentzel.net/Battery/01.Type/index.html


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INVERTERS:

An inverter is used in the system where AC power output is needed.

There are basically three types of inverters on the basis of the output that they

give :

Parameter\Type Square Wave Power

Inverter

Modified Sine Wave

Power Inverters

True Sine Wave Power

Inverters

Cost Least Expensive Most popular and

economical type of

power inverter

Most expensive and

best quality;

Twice the price of

modified sine wave

power inverters ofsame capcity

,generally.

Output quality The square wave it

produces is inefficient

and is hard on many

types of equipment.

It produces an AC

waveform somewhere

between a square

wave and a pure sine

wave.(Some

instruments like

motors consume more

than 30% their normal

consumption and alsomake a buzzing sound.)

It produces an AC

waveform somewhere

between a square

wave and a pure sine

wave

Capacity 500 watts or less

Usability Not suitable for

captive systems;

Cabin systems or

mobile applications

Work well in all but the

most demanding

applications and even

most computers work

well;

appliances that use

motor speed controls

or that use timers may

not work quite right

It will run practically

any type of AC

equipment

Merits Very economical and

reliable

Most appliances run

more efficiently and

use less power with a

True Sine Wave

inverter as opposed to

a Modified Sine Wave

power inverter.

Life 6 months-1 year 1-2 years 1-2 years

.


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Roof top area analysis:-

Total available area available (aftertaking out the shadowed regions)

Region Area

A 93 x 5

B 93 x 5

C 30.36 x 8

AERIAL VIEW OF ALAKANANDA HOSTEL

A

C

B

SOLAR PANELS


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Compiled data from s

The data from the survey

TYPE

SINGLE ROOMS

TRIPLE ROOMS

LED LIGHTS

DISPENSER

PC

WASHING MASHINE

TOTAL

3

Ene

urvey conducted in the hostel

has been compiled into a table :

ENERGY CONSUMPTION

639010

81645

9720

28800

3750

7000

769925

15%

51%

%

2%

gy Consumption by various

Appliances

TubeLight Fan Comp Other Devices


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3D VIEW OF THE HOSTEL

SOLAR PANELBATTERY


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Design of system:

1. Solar Panels

Model: Canadian Solar CSI CS6P-235

Peak Wattage =235 W

Module Area =1.61 m2

Therefore, No. of modules that can be installed = (2 x 93x 5 + 30.36 x

8)/1.61=728

Total Power generated = 728*235=171.08 kW

Taking output efficiency to be 95%,

Actual power generated=0.95*171.08=163 kW

Cost of each module = Rs. 28440

Total cost of modules =28440 x 728 =Rs.20,704,320.


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Power Conditioning Unit Sizing

It was observed that instead of having separately installed chargecontrollers and inverters, it was more economical and more robust in

design to have a Power conditioning unit .

It also allows the battery to charge from the grid power even when there isless power generation from the PV modules than required.

Amongst the power conditioning units that we analyzed we found, the 6KW Su-

KAM PCU 6K96 model to be best suited for our purpose. The sizing for the same

has been given below:

The PCU has a charge controller (PWM) which chargers and maintains the health

of the battery. It also has a pure sine wave inverter, which converts the DC output

of the batteries to grid A/C voltage (239 VAC). It also has a grid charger, which

provides the facility of directly utilizing the DC power generated by the solar

panels directly by converting it into 230 VAC and combining with grid supply. It

also has the required safety instrumentations, making them an ideal choice for

the required charge.

1>System Capacity = 171. 08 KW.2>Hence number of PCUs required is (171.08/6)= 29 units.3>No of solar panels approximately by each CPU = 728 / 29= 25.

From the data sheet of Canadian Solar CSI CS6P-235 solar module,

Operating Voltage = 36 V

Short Circuit Current = Isc

= 8.46 Amp.

Each of the PCUs can handle a maximum 0f 25V,

Therefore, No. of solar panel parallel module to be connected to a

PCU=1/{36/25}=0.5

This means that 2 PCUs are required for a solar panel array consisting of only

single modules in parallel.

Therefore, No. of solar panels in parallel= 50


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(as two PCUs need to handle 50 panels approximately and there are not more

than 1 solar panel in each parallel branch)

Current generated = 50 * 8.46 = 423A

This is within the maximum value that can be handled by an individual PCU (


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Battery sizing

We have taken the Su-KAM SBT 1800 battery backup as our module for building

the battery banks.

Total energy consumption per day =E =720.66 kWhr.

No. of days of autonomy of the battery=N= 1 day

Depth of discharge of battery =DoD =80%

Derating factor at 27 deg.C= d =1

Therefore, battery bank capacity = (E*N*d)/DoD=901 kWhr

Nominal input voltage for the PCU inverter=Nominal output voltage of battery

bank=Vn=96V

Approximate energy handled by a single PCU =901/29=31.07 kWhr.

Therefore, Amp-hour of battery bank connected to one PCU = 31070/96=

323.65Ahr

The Amp hour capacity of SBT1800 is 150 Ahr , so ,

No. of parallel chains in battery bank = {323.65/180}= 2

Nominal battery voltage of SBT1800 = 12 V

Now,the no. modules in every parallel chain =Vn/12=96/12=8

Total no. of batteries required = 8*2*29 = 46


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SP

SP

SP

SP

SP

SP

SP

P.C.U. P.C.U.

B B B B B B B B

B B B B B B B B

UPTO 50 UNITS

GRID

TOWARDS LOAD

NEARLY 15 SUCHMODULES

SCHEMATIC DIAGRAM OF SYSTEM


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Cost Analysis

Cost of Essential Components

Module Cost of each

module(Rs.)

No. of module Total cost(Rs.)

Solar panel 24,900 728 1,81,27,200

PCU 50,000 29 14,50,000

Battery 17100 464 79,34,400Total 2,75,11,600

Cost of Ancillary Components (based on Projected values per watt of

generated power)

Component Cost per watt(Rs.) Total Cost

Mounting

Structure

12.8 21.99 lakhs

Cables and

Transformers

7.1 12. 19 lakhs

Civil and Technical

Works

5.4 9.23 lakhs

Total 43.41 lakhs

Total cost incurred Rs 3.19 crores

Cost of electricity per unit = Rs.4.1

Savings per day = (4 * 171.08*4.35) = Rs.2976.8


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Savings per year= 2976.8 * 365 = Rs.10,86,530

Break-even time = 3.19 crores/0.108653= 29.31 years

NOTE: This system of cost analysis is inadequate for the given setup, as it doesnt

consider the life of the various components involved nor the efficiency drop over

this period of time. For a Solar Panel, the efficiency of panel drops to 90 % after

10 years and to 80 % after 10 more years. This is not the case for the PCU and the

batteries as they have to be replaced after a period of 10 years.

However, The Ministry of New and Renewable energy , Government of India

pays Rs.7 per unit of power generated by the help of rooftop solar photovoltaic

systems

Quote: a tariff of Rs. 7/- per unit for solar power generation projects with an

annual escalation of 5%. (Rs 8.09/KWh for 2009-10)

with an annual escalation varying from 3% to 5% on yearly basis up to 5years ( Rs 4.10/KWh for 2009-10)Hence the money earned by the hostel from such an arrangement will be equal to

a.)Without considering the annual escalation:

Savings per day = (8.09+4.1)*171.08*4.35=Rs.9146.19

Savings per year=9146.19*365=Rs.33,38,359

Therefore, the payback period =3.19 crores / 33,38,359=9.55 years

b.)After considering the annual escalation:

The payback period turns out to be 7.65 years.


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Carbon Footprint

Carbon dioxide released for one kilowatt-hour of electricity produced from Coal: 909 gm

Carbon dioxide released for one kilowatt-hour of electricity produced from PV: 105 gm

Reduction in carbon dioxide production per kWh: 804 gm

Total reduction in carbon dioxide production per year: (804*171.08*4.35*365) gm

218.392 tonnes of CO2.

Hence we can reduce the emission of carbon-di-oxide significantly.


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OPTIONAL COMPONENTS (suggestions to improve

efficiency and reliability)

TRACKERS AND SENSORS

There are two types of tracking systems:

Single axis tracking system.

Double axis tracking system.

Table 1:

Type Electricity production CostSingle axis tracking system Increases 20-30% relative to

fixed

Only 10-15% higher than fixed

Double axis tracking system Increases 30-40% relative to

fixed

Only 15-20% higher than fixed

systems

Source: http://www.rimlifegreentech.com/products/tracker/why.htm

METERS AND SHUNTS

Having a meter, helps in data-logging and monitoring the state of your system.This helps inclaiming warranties and also early fault detection.

Shunts are introduced if there are chances of electrical interference ,like in grid-connected

or Power generator connected systems, or to introduce an added tier of safety when it

comes to electrical discharges from batteries or other components where it is introduced.

It is basically a low-resistance path which ensures that current only flows through it and no

other crossing wires.

AC GENERATOR (BACK UP)If your system is off-grid, it is wise to have a back up AC generator, in cases of system failure or

shutdown for maintenance. It can be any kind of DC generator, linked to the inverter which then can

be used as a stand-in system for the critical loads.


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BREAKTHROUGHS

Sl.No.

Component PossibleTechnology

breakthrough

Description/Reference

1 Solar Modules 1.)SILICON

BLADES:

1.) Novel silicon micro wires can harvest nearly as much

light as traditional photovoltaic wafers, with just one

percent of the total silicon.

http://www.scientificamerican.com/article.cfm?id=phot

ovoltaic-breakthroughs-brighten-outlook-for-cheap-

solar-power

2 Charge

Controller

1.)SMPC(Switch

ed Mode PowerConversion)

This is a mode of charging being considered for

increasing power quality to batteries in order todecrease fluctuations to it and hence,reduce the

damage to battery

Efforts are being made to increase efficiencies of power

conversion though there doesnt seem to be any more

significant difference from MPPT charge controllers.

3 Batteries 1.)Ceramatec

battery

2.)Electrolysis

Breakthrough

for Solar

Storage

1.) Ceramatec says its new generation of battery would

deliver a continuous flow of 5kW of electricity over four

hours. And these batteries are expected to withstand

daily discharge/recharge cycles over 10 years (3,650

times). The batteries would hopefully sell for around

USD$2,000, which is less than 3c per kWh over the

battery's life. Conventional power from the grid typically

costs around 8c per kWh and continues to rise.

http://solarseeds.blogspot.com/2010/07/battery-

breakthrough-may-trigger-off.html

2.)http://peswiki.com/index.php/Directory:MIT:Daniel_

Nocera:Catalytic_Electrolysis#Company:

4 Inverters 1.)XPX

Technology

1.) The XPX technology, embodied in a printed circuit

board (PCB), extracts significantly more electrical energy

from any PV solar media through a combination of

patent pending design and proprietary algorithms

http://www.eosrenewabletech.com/


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EMERGING TRENDS TO REDUCE OFF-GRID

CAPTIVE SOLAR PV COSTSi. Various subsidies are being given by government in order to promote the use and installation of

captive solar PV plants in India.

ii. Batteries with longer life period are being developed in order to match their life with that ofsolar panels in order to save on replacement and maintenance costs.

iii. Stress is being laid on increased production and usage of Solar PV modules in order to bringdown the costs of the manufacturing processes. It is estimated that these costs can be brought

down by 50% with a 25% increase in solar PV consumption.

iv. The use of thin film is supposed to bring the cost of PV systems (although our analysis showednot much difference and with constrained area , it is always better to use mono crystalline solarpanels).

v. Sealed batteries are being preferred over flooded ones as the transportation costs for these aremuch less than the flooded batteries as they are not hazardous

Implementation

Currently, work is underway to supply the common room , the office, the corridors and the tech

room with electricity from solar power alone. Our hostel warden , Prof. Srinivas Reddy , has attracted

sponsors willing to invest for this issue.

Documents

Alaknanda Hostel Snet Report