New-Class-Assignment-4-SCIE-3006 (1)
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Humber College *
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3006
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Aerospace Engineering
Date
Feb 20, 2024
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Assignment 4: Off-Grid PV and Solar Water Heater
Sub: SCIE 3006
RE and Sustainable Future Student Name(s): Nguyen Ngan__________________________
Date: ----------------------
Note:
Please understand all the terminology/steps carefully, discuss it with your classmate (or with me, if
you have doubts), then calculate each empty box and write appropriate explanation in the given space. Off-Grid System (designed usually for isolated electricity demands, such as cottage
)
Fig. 2. A schematic of off-grid PV system for a typical home (away from the grid supply)
Off-grid PV system major components (it is assumed all the electricity is going to the house demand/load,
no grid support): The off-grid system components and the design steps:
✔
Estimation of house/building/application electricity demand (load) (kWh)
✔
Inverter efficiency (convert DC power into AC power), estimate actual DC load ✔
Solar modules (convert solar into DC electricity)
✔
Battery Bank (number of batteries at one place for electricity storage)
✔
Charge controller or Charger (to protect the battery system)
✔
Assumptions about the depth-of-discharge (DOD), days of autonomy (F), and battery efficiency (
η
), and battery bank system voltage (V
n
)
Depth of Discharge (DOD): DOD is the fraction or percentage of the capacity removed from the fully charged battery.
Days of Autonomy: Days of autonomy is a term used in off-grid system design to describe how many days you expect to run your loads (house demand) directly off your batteries before they need to be recharged by the solar modules.
Battery Efficiency
: It's important to remember that no battery is 100% efficient. Energy is lost during storage, charging, and discharging processes. The efficiency of a battery is a measure of the amount of energy that is lost during the entire discharge/recharge cycle. Lead acid batteries typically have 80-90% efficiencies, but this efficiency decreases with usage, age, and surrounding temperature. On the other hand, Lithium-ion batteries have typical efficiencies of over 95%.
Estimation of battery bank size and PV modules of a typical off-grid system:
Estimation of the battery bank size Calculate the size of battery bank requires to support the electrical loads of Table 3. Assume battery bank voltage is 60 volts, efficiency of batteries is 90%, depth of discharge is 80%, and the days of autonomy (how many days it supports load without recharging) are 2. Estimate the number of batteries in the battery
bank (Table 4) and solar modules in the system (Table 5).
Note: The rated parameters for the selected battery for this project are 12 V and 50 Ah
. The efficiency of inverter (DC to AC conversion) is 95%.
Table 3
: House Load (demand)
Load
Watts
(h)
Wh
Coffee Maker
600
0.5
300
Lights
100
4
400
Dish washer
1600
1.25 2000
Microwave 1800
0.25
450
Entertainment 300
2
600
Washing Machine 1200
1.5
1800
Total AC Load
5550
Total DC Load (AC Load/0.95)
5842
Equation to calculate the capacity of battery bank:
Capacity of battery Bank C
n
=
W x F
ηx DOD xV
n
Where,
W= Total DC load in a day (W-h) (you will get from the Table 3)
F= days of autonomy (day) (this value is given in the text)
𝛈
= Efficiency of battery (this value is given in the text)
DOD = depth of discharge (this value is given in the text)
V
n
= Battery System voltage (this value is also given in the text)
Table 4
: Total batteries
Batteries in series (in line)
(A) (=Battery system voltage/selected battery Batteries in parallel (no. of lines) (B) (=Battery system capacity (C
n
)/selected battery capacity), Total batteries (A x B)
voltage)
round this number to higher value
60/12=5
270.46/50=6
5*6=30
Equation to estimate solar modules:
Total number of module
¿
supportthe load
=
Total DC Load
Net DC energyoutput of onemodule
Table 5
: Estimation the number of solar modules Module size
Temp. de-rate=5%
Wire and other de-
rates=2
%
PSH
Energy from one module
Estimated modules required
Actual number of modules (round estimated number to the higher value)
200 W
200-200*5%=190
186.2
4 h
744.8
7.8
8
200 W
200-200*5%=190
186.2
8 h
1489.6
3.9
4
150 W
150-150*5%=142.5
186.2
4 h
558.6
10.4
11
150 W
150-150*5%=142.5
186.2
2 h
279.3
20.9
21
Question:
What do you understand by the numbers of Tables 4 such as battery capacity, battery in series
and parallel, and Table 5 such as the effect of module size and PSH on the module numbers? Please
discuss your results.
Solar Water Heater
How can you justify an investment in solar water heaters? Discuss it in detail based on the posted
information and slides on the blackboard. Please write some of the ideal applications for solar
water heaters in Canada.
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Solar water heaters work by capturing sunlight and converting it into heat energy, which is then
used to heat water. This process can significantly reduce the amount of electricity or gas needed
to heat water, leading to cost savings. The exact amount of savings will depend on factors like
the amount of sunlight in your location and the efficiency of the solar water heater system. In
terms of environmental benefits, solar water heaters can help reduce greenhouse gas emissions.
Traditional water heaters that use electricity or gas produce emissions during operation, while
solar water heaters do not. This makes them a more sustainable choice. Finally, solar water
heaters can contribute to energy independence. By generating your own heat energy from the
sun, you reduce your reliance on the grid and fossil fuels. This can be particularly beneficial in
areas with high energy costs or unreliable grid supply. In Canada, solar water heaters can be
particularly effective in regions with high levels of sunlight. However, even in less sunny areas,
they can still provide significant benefits when used in combination with other heating systems.
The ideal application will depend on the specific needs and circumstances of the user.