The document presents a report on the design calculations for a solar water heating system for domestic use, submitted as part of a mechanical engineering course. It includes sections on site surveys, solar resource estimation, load requirements, absorber area calculations, market surveys, and an economic analysis with payback periods for different solar systems. The conclusion outlines the best-suited systems available in the market, their costs, and potential annual electricity savings.

1. Report
on
Design Calculations for Solar Water Heating
System for Domestic Application
This report is submitted in fulfilment of the requirements of the Seventh
semester B.E. in Mechanical Engineering.
Submitted By
Roll No. Name of Student
60 Sangeet Khule
Under the guidance of
Dr. Sandeep S. Joshi
(Dept. of Mechanical Engg.)
DEPARTMENT OF MECHANICAL ENGINEERING
SHRI RAMDEOBABA COLLEGE OF ENGINEERING &
MANAGEMENT, KATOL ROAD, NAGPUR, INDIA-440013
2020-2021

2. CONTENTS
Chapter Topic Page No.
LINK OF EXCEL i
Chapter 1 City of Residence 1
Chapter 2 Estimation of Available Solar Resources 2
Chapter 3 Site Survey 4
Chapter 4 Load Estimation 6
Chapter 5 Estimation of Required Absorber Area 8
Chapter 6 Market Survey & Estimation of No. of Tubes for ETC 11
Chapter 7 Economical Analysis & Estimation of Payback Period 15
Chapter 8 Conclusion 18

3. i
LINK OF EXCEL
(https://onedrive.live.com/edit.aspx?cid=8c4817d6aab2fed0&page=view&r
esid=8C4817D6AAB2FED0!8767&parId=8C4817D6AAB2FED0!103&app
=Excel)
 Arrangement in excel is rough.
 Proper presentation is in the below report.

4. 1
CHAPTER 1
CITY OF RESIDENCE
Fig 1.1. Location
Address:
Hindustan Colony, Amravati Road, Nagpur, 440033
Latitude: 21 ° 08’ 47.4’’ N ( 21.14639° )
Longitude: 79 ° 02’ 46.0’’E ( 79.04611° )
(Location was found out using Google Maps)

5. 2
CHAPTER 2
ESTIMATION OFAVAILABLE SOLAR RESOURCES
Visited the following website for estimation of All-Sky Surface Shortwave
Downward (https://power.larc.nasa.gov/data-access-viewer/)
Fig 2.1. Step 1
Fig 2.2. Step 2

6. 3
Fig 2.3. Step 3
After the completion of steps 1, 2, and 3 we got the excel. With help of it, the
following average value of solar radiation and its graph throughout the year
2020 was generated.
AVERAGE VALUE: 4.908634 kW-hr/m2
/day
Fig 2.4. Graph of solar energy

7. 4
CHAPTER 3
SITE SURVEY
Now we will see the following
Available shade-free area in m2
(With actual photographs, shading analysis,
shade-free area)
As there is very little shade-free area, we will assume that the following area is
a shade-free area
Total Area = 80.321 + 80.321 + 55.741 m2
Total Area = 216.383 m2
6.096 X 13.176 m
80.321 m2
(a) Terrace 1

8. 5
6.096 X 13.176 m
80.321 m2
(b) Terrace 2
55.741 m2
(C) Garden
Fig 3.1. Site survey at 4:00 pm

9. 6
CHAPTER 4
LOAD ESTIMATION
Now we will see the following
( All the calculations and graphs is done using excel )
 Hot water requirement in Liters/day. (150 LPD)
 Hot water consumption pattern for a typical day.
 Required temperature. (49°C)
Table 4.1 Hot water requirement in Liters/day
MEMBERS REQUIREMENT TOTAL
1 20 1 20
2 40 1 40
3 30 1 30
4 30 2 60
150 LPD
LPD = Litres Per Day
Table 4.2 Hot water consumption pattern for a typical day
TIME REQUIREMENT IN LITRES
6:00 AM 0
7:00 AM 0
8:00 AM 40
9:00 AM 30
10:00 AM 20
11:00 AM 0
12:00 PM 30
1:00 PM 0
2:00 PM 0

10. 7
3:00 PM 0
4:00 PM 0
5:00 PM 0
6:00 PM 0
7:00 PM 30
8:00 PM 0
9:00 PM 0
10:00 PM 0
11:00 PM 0
12:00 AM 0
1:00 AM 0
2:00 AM 0
3:00 AM 0
4:00 AM 0
5:00 AM 0
6:00 AM 0
150
Fig 4.1. Graph of hot water consumption pattern for a typical day
Required Temperature of Hot Water = 49°C

11. 8
CHAPTER 5
ESTIMATION OF REQUIRED ABSORBER AREA
Now we will see the following
Estimation of required absorber area for (FPC and ETC)
Energy balance equation:
m * Cp * (Th-Ta) = Efficiency * Average Radiation * Area of collector
Ab = m x Cp x dt
η x Rad
Symbol Meaning Values Unit
Ab Absorber Area ? m2
M Mass of Water 150 Kg
Cp Specific Heat Capacity 4186 J/Kg°C
Δt Temperature Difference 23 °C
η Efficiency 0.4[FPC(40%)]
0.6[ETC(40%)]
-
Rad Solar Energy 4.908634 kW-hr/m2
/day
So, let us assume Hot water temperature to be 49 degrees Celsius as it is the
ideal hot water temperature for the human body and normal tap water
temperature to be 26 degrees Celsius. As the temperature difference is 23
degrees Celsius which means the increase in the temperature generated by the
solar water heater should be 23 °C.
Hot water temperature = 49 °C
Normal tap water temperature = 26 °C
Change in temperature (Δt) = 23 °C
Solar Energy - Rad - kW-hr/m2
/day should be converted into the W-Sec/m2
So, kW-hr/m2
= 1000 x 3600 W-Sec/m2
After all the unit conversions and then putting the value in the above equation.

12. 9
We get the following,
Absorber area for flat plate collector solar water heater and evacuated tube
collector solar water heater.
FPC Ab = 14441700 FPC 2.043126119 m2
7068432.96
ETC Ab = 14441700 ETC 1.362084079 m2
10602649.44
Absorber area for flat plate collector solar water heater = 2.043126119 m2
Absorber area for evacuated tube collector solar water heater = 1.362084079 m2
EXTRA
Optimum Tilt angle in Nagpur ( According to each month )
Table 5.1 Optimum Tilt angle in Nagpur
January February March April May June
37 ° 29 ° 21 ° 13 ° 5 ° 180 °
July August September October November December
5 ° 13 ° 21 ° 29 ° 37 ° 44 °
β = 21.1666 °
As the optimum tilt angle for the application of the solar water heater should be
taken in the winter months as this will ensure the proper utilization of the solar
water heater.
The value is being as follow
βwinter = 35.2 °
Assumed winter months consist of October, November, December, January &
February.
Both the above value of optimum tilt angle satisfies the thumb rule of
calculation of optimum tilt angle, as well.

13. 10
Fig 5.1. 36 ° of flat plate solar collector
The above photo shows the existing flat plate solar water heater in my building.
The angle is equal to 36 °.
But the optimum tilt angle for my system is 35.2 degrees which are optimized in
such a way that it is more useful in the winter months.

14. 11
CHAPTER 6
MARKET SURVEY & ESTIMATION OF NO. OF TUBES FOR ETC
Now we will see the following
 Market survey for available solutions
 Estimation of no. of tubes required for ETC collectors
First, we will see the estimation of the number of tubes required for ETC
collectors.
From we got the evacuated tube having the following product description
( https://www.tradeindia.com/products/1500mm-solar-vacuum-tube-
557997.html )
Fig 6.1. 1500 mm Solar vacuum tube with product description
PRODUCT DESCRIPTION
Length(nominal): 1500mm
Inner tube diameter: 47mm

15. 12
Absorber area for evacuated tube collector solar water heater = 1.362084079 m2
Area of tubes = Length x Inner Tube Diameter = 0.0705 m2
No. of tubes =
Absorbe area for evacuated tube collector solar water heater
Area of tubes
No. of tubes = 19.32034155
No. of tubes required = 20
Now we will see a market survey for available solutions
FLAT PLATE COLLECTOR ( FPC )
Flat Plate Collector (FPC) Stainless Steel 150 Lpd FPC Solar Water Heater
( https://www.indiamart.com/proddetail/150-lpd-fpc-solar-water-heater-
21796743330.html )
( ₹ 15,000 )
Fig 6.2. Flat Plate Collector (FPC) Solar Water Heater
NO. OF TUBE 19.32034155
APPROXIMATE 20

16. 13
Fig 6.3. Flat Plate Collector (FPC) Solar Water Heater Product Specification
EVACUATED TUBE COLLECTOR ( ETC )
SOLERO PRIME 150 L White ETC Solar Water Heater
( https://www.havells.com/en/consumer/water-heater/solar/solar-water-
heater/solero-prime-150-l-white.html )
( ₹ 30,095 )
Fig 6.4. Evacuated Tube Collector (ETC) Solar Water Heater

17. 14
Fig 6.5. Evacuated Tube Collector (ETC) Solar Water Heater Product
Specification
We have seen a flat plate collector solar water heater as well as an evacuated
tube collector tube solar water heater.
The market survey was done in such a way that good quality was the priority.

18. 15
CHAPTER 7
ECONOMICALANALYSIS & ESTIMATION OF PAYBACK PERIOD
Now we will see the following
For economical analysis and estimation of the payback period
 Step 1: Know the expense of the current system.
 Step 2: Know the initial investment in the solar water heater.
STEP 1: ENERGY USAGE
So, the current system for water heating application in my house is the electric
geyser.
Fig 7.1. 2000 W Electric geyser

19. 16
For, accurate calculation of time required for heating the 150 Kg of water the
below link formulae was used.
( https://www.shaalaa.com/question-bank-solutions/calculate-time-required-
heat-20-kg-water-10-c-35-c-using-immersion-heater-rated-1000-w-anomalous-
expansion-of-water_68196 )
ie.
Power rating, P = 2000 W
Specific heat of water, S = 4186 J/Kg°C
Mass of water, M = 150 Kg
Change in temperature, Δt = 23 °C
Q is also equal to Time * Efficiency * Power rating ( P )
Assume, Efficiency = 95 % = 0.95
After substituting the values, we get time equal to
14441700
1900
After calculation
we get Time =
ENERGY USAGE = 2.111359649 * 2000
4222.719298 4.222 Units/Day
Fig 7.1. Electricity Bill’s Unit Cost
7600.894737 SEC
126.6815789 MIN
2.111359649 HRS

20. 17
The expense of electric geyser in rupees
14.52368 /Day
RUPEES 435.7104 /Month
5228.5248 /Year
STEP 2: PAYBACK PERIOD
Now we will calculate the payback period
In this case
The payback period is equal to the initial investment divided by the
expenses of the previous system.
Table 7.1 Payback Period
Initial investment (ETC) 30095 Rupees
Payback Period (ETC) 5.755925648 Years
Initial investment (FPC) 15000 Rupees
Payback Period (FPC) 2.868878044 Years
This concludes the economical analysis and estimation of the payback
period.

21. 18
CHAPTER 8
CONCLUSION
We will now conclude the report with the help of the following table.
Table 8.1 Conclusion Table
Type FPC ETC
Collector Area 2.04 m2
1.36 m2
No of Tubes - 20
Total System Cost ₹ 15000.00 ₹ 30095.00
Best Suitable Systems Available in
Market
150 LPD 150 LPD
Annual Electricity Savings (Yearly
in Rs)
₹ 5228.52 ₹ 5228.52
Payback Period (in Years) 2.87
2 Years 11 Months
5.76
5 Years 9 Months