Components of solar systems

1. A few components of Solar PV system:-
i. Solar modules
A module is a group of cells connected electrically and packaged into a
frame (more commonly known as a solar panel), which can then be grouped
into larger solar arrays.
There are two types of solar modules:
 Crystalline silicon
o Monocrystalline
o Polycrystalline
 Thin-film

5. ii. Mounting structures
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 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.

6. iii. Charge controllers
There are basically two types of charge controllers existing today in terms of
functionality:
PWM charge controllers: These kinds of charge controller operate by sending
out pulses of charge which helps in uniform distribution of the charges on
the plates of battery. These are modulating the pulse widths and slopes of
the voltage and current levels and also their rate of change. They operate in
three phases:
Bulk phase: During the Bulk phase of the charge cycle, the voltage gradually
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.
Absorption phase: During this phase the voltage is maintained at bulk
voltage level for specified times (usually an hour) while the current gradually
tapers off as the batteries charge up.
Float phase: After the absorption time passes the voltage is lowered to float
level (usually 13.4 to 13.7 volts) and the batteries draw a small maintenance
current until the next cycle.
Relationship between the Current and the Voltage during the 3 Phases of the
Charge Cycle
Source: http://www.solardropshipping.com/charge_controller.php

7. 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).
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 the 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:
Parameters 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; Almost thrice that of PWM
Efficiency 60-80%(approx. 68%)
Increases charging efficiency to up
to 30%
Peak efficiency:99%
Physical Size
Larger in size
Ex:- Xantrex XW Solar Charge
Controller368 × 146 × 138 mm
Flexibility for
system growth
Low;
Input voltage should be equal to
battery nominal voltage
High;
Arrays having higher output
voltage than battery nominal
voltage can be used

8. Warranty and
life Low Much higher than PWM
Operating
Power
consumption 4.5W 2.5 W
With ‘Edge of
Cloud’ effect
Without
iv. Batteries
Batteries chemically store electrical energy in renewable energy systems.
They come in several voltages, but the most common varieties are 6 Volt and
12 Volt.
The following types of batteries are commonly used in PV systems:
 Lead-acid batteries
o Liquid vetted or flooded
o Sealed (VRLA – Valve Regulated Lead Acid)
 Gel Cell
 Absorbed Glass Mat (AGM)
 Alkaline batteries
o Nickle-cadmium
o Nickle-iron
Lead-acid Batteries: in the United States, the battery most commonly used
for residential scale PV application is the lead-acid battery. This chapter
primarily discusses the lead-acid battery system, since these batteries are
rechargeable, widely available, relatively inexpensive and available in a
variety of sizes and options. They are also commonly used, easily
maintained, and reasonably long lived.

9. Flooded lead-acid batteries are the most cost-effective variety. They require
maintenance that involves monitoring voltage, adding water, and occasional.
Additionally, FLA batteries vent hydrogen under heavy charging so they
must be stored in a ventilated enclosure. Because of the maintenance issues
of FLAs, some people prefer sealed batteries, which don’t require
maintenance. Since they are sealed, they do not require watering, nor do
they typically vent any gasses. AGM batteries cost more and are more
sensitive to overcharging than FLAs. Gel Cell batteries are similar to AGMs
in that they are also sealed and therefore do not require maintenance, but
tend to be the most expensive of the three types. The useful life of all battery
types is measured in rather than units of time. is directly related to number
of charge cycles possible: the deeper you drain batteries each time you use
them, the fewer charge cycles you will get from them. Sealed batteries tend
not to last as long as flooded batteries. Well-maintained FLAs can last as
long as ten years, with sealed batteries lasting closer to five years. Other
factors to keep in mind are that some of these batteries weigh over 200
pounds and, depending upon capacity, can cost anywhere from $20 to
$1200 each. So, given the maintenance issues, weight and expense,
consider your energy storage needs very carefully.
Types of Batteries:
Parameters Flooded Sealed
AGM Gel
Cost
Cost-effectiveness,
least cost per amp hour
Nearly three
times the cost
of flooded
batteries
2-3 times the cost
of flooded batteries
Maintenance Require maintenance
No/negligible maintenance
required
Size and
placement
Need ventilation; Mostly need to
be kept outdoors which hinders
working at ambient temperature
Sealed batteries conform to
situations with space constraints
that require you to store your

10. batteries in unusual orientations
or where venting is not possible
Transportation
classed under “hazardous
materials” rules, which restrict
shipping options increased ease of transportation
Life
Longest life
less than a 2% self-discharge rate
during transport and storage
3-7 years
Industrial(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
Alkaline Batteries
Alkaline batteries, such as nickel-cadmium and nickel-iron batteries, also
have positive and negative plates in an electrolyte. These plates are made of
nickel and cadmium or nickel and iron and the electrolyte is potassium
hydroxide. Each cell has a nominal voltage of 1.2 volts and charge
termination point is 1.65-1.8 volts per cell. These batteries are often
expensive and may have voltage window compatibility issues with certain
inverters and charge controls. An advantage is that they are not affected by
temperatures as other types of batteries. For this reason, alkaline batteries
are usually only recommended for commercial and industrial applications in
locations where extremely cold temperatures (-50oF or less) are anticipated.
In residential PV systems, typically liquid lead-acid batteries are the wisest
choice. They usually constitute a significant part of the total system cost.
The majority of PV systems and components are designed to use lead-acid
batteries.

11. v. 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:
ParameterType
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 of
same capacity,
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 also make a
buzzing sound.)
It produces an AC
waveform somewhere
between a square wave
and a pure sine wave
Capacity
500 watts or less.
Appropriate for small
resistive heating
loads, some small
appliances and
incandescent lights.
They have high surge
capabilities and can
start many types of
motors easily.
Usability
Not suitable forThis style of inverterThey are the most

12. captive systems;
cabin systems or
mobile applications
is more appropriate
for operating a wide
variety of loads,
including motors,
lights, standard
electronic equipments
like TV and stereos.
However, some
electronic devices may
pick up inverter noise.
common inverters
today in residential
application. It will run
practically any type of
AC equipment. For grid
tied applications one
may use a sine wave
inverter
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.