SOLAR ROOFTOP MODEL

Table of Content
Introduction to Solar Energy
Solar Panels
Solar Panel Systems
Load and Cost Calculations
Maintenance and Lifespan of Solar Panel
Challenges
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2
3
4
5
6

Available throughout the year
during day period
Free renewable source of energy
Solar cells have long life time
Solar Energy
Solar energy is a clean, inexpensive, renewable power source that is harness-
able nearly everywhere in the world
No Maintenance
1
2
4
3

• India being a tropical country receives adequate solar
radiation for 300 days, amounting at least 3000hrs of
sunshine
• Average intensity of solar radiation received on India is
200 MW/km square (megawatt per kilometre square). With
a geographical area of 3.287 million km square, this
amounts to 657.4 million MW
Solar Irradiation in India

Solar Panel
Solar panel type Advantages Disadvantages
Monocrystalline
•High efficiency, performance
•Aesthetics
•Higher costs
Polycrystalline •Low cost
•Lower efficiency,
performance
Thin-film
•Portable and flexible
•Lightweight
•Aesthetics
•Lowest efficiency,
performance
To produce electricity, solar cells are made from a semiconducting material that converts light into electricity.
Three types of solar panels are monocrystalline, polycrystalline, and thin-film panels.

Solar Panel System
On-Grid Solar System
• Generate power when the utility power grid is available
and must connect to the grid to function
• They can send excess power generated back to the grid
when you are overproducing so you credit it for later use
Advantage:
• Most cost effective to install
• Can pay offsetting utility bills in 3-8 years
Disadvantage:
• These do not provide power during a grid outage

Solar Panel System
Off-Grid Solar System
• Solar power can be stored batteries for use when the
power grid goes down or if you are not on the grid.
• Provide power to offset the grid power whenever the sun
is shining and will even send excess power to the grid for
credit for later use.
Benefits:
• Provides power for your loads when the power is down
Downside:
• Cannot be expected to provide power for all your loads
since the cost and volume of batteries would be
prohibitive

Solar Panel Calculations
• Basis of all calculations is polycrystalline off grid solar
panel system
• Sun light available only for 8hrs in a single day
• Cost of solar panel varies consumer to consumer
• Solar Panel used in calculations is 300W
• Battery used in calculations is 200Ah
• Taking 70% efficiency in calculations
• Installation cost is also subjected to consumer
Assumptions

Load Calculations
• Quantity and usage (hrs/day) are variables in
calculations if you change them, automatically all
other calculation will adjust themselves to the
new value
• Efficiency of solar panel system is taken as 30%
• Number of solar panels needed is subjected to
total usage or consumption
Equipment Wattage Quantity Usage(Hrs/day) Watts(Hrs/day)
TV 100 1 6 600
Refrigerator 400 1 8 3200
Fan 75 1 8 600
Tube Light (LED) 10 4 12 480
Laptop 40 1 6 240
Total 625 5120
UTILITIES LOAD CALCULATION
Total Watts/hr 5120
Total Sunlight (Hrs) 8.22
Size of solar panel 622.933
System Inefficiency On Grid 30%
System Inefficiency Off Grid 30%
Required size of solar panel 809.813
Number of solar panels needed 2.70
Calculation for a Single day

Cost Calculations
• Typical 1KW solar panel system produces. 4-5KWh
(Units) of electricity in a single day hence around
1200-1500 units throughout the year
• The average cost of installation of rooftop 1KW off
grid system is around Rs 70,000 - 80,000.
• After leveraging 30% subsidy for on grid system,
people just have to pay Rs 51,000 - 56,000 for
installing a rooftop PV system.
Total Watts(Hrs/Day)
Back up days
Batter Longetivity
Actual Total Watts(Hrs/Day)
Battery Voltage(V)
Batteries Current(Ah)
Watt Hour Capacity
Batteries Needed
Battery Requirement Calculation
5120
1
80%
2.67
6400
12
200
2400
Equipment Quantity Cost(Rs)
Solar Panel Plates 3 9000
Batteries 3 10000
Inverter 1 25000
Installation Cost 1 5000
Approximate Cost Calculation
Total Cost
24294
26667
25000
5000
80961Total Cost in Rs

Maintenance and Lifespan of Solar Panel
Assumptions
• Solar panels have a lifespan of 25 years, do not require
regular maintenance
• Manual cleaning can be done to remove dirt particles
deposited on the surface of panel
• Output of solar panels degrades 0.8% by each passing year
and only 80% power remains at the end of 25 years

Challenges
• Solar energy can not be used in night time
• Government only gives subsidy to on-grid solar panels
systems
• Polycrystalline solar panels are not that efficient and
monocrystalline panels are very costly
• Bad weather and air pollution can hinder the performance
of solar panel system
• Lack of awareness about proper usage and benefits of solar
energy

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