The Annual amount of energy that will be produced by a PV system depends on various conditions. There are some factors which are beyond the control of Human efforts but certainly there are other factors too which can be insured to have optimum out put of energy. A Good design and operation practices save us from huge losses. At "EnvironmentFirst" we help you in selecting good design practices. We guide you for a best practices during pre-installation as well as installation period to achieve a best possible output/PLF from the given resources. We also do performance evaluation of already installed Solar Power Projects therefore if you own a Solar Power project and want to know whether plant is harnessing full available potential then our technical team will do an onsite visit to evaluate the IV and other output test so that to help you in evaluation of O&M and other onsite faults and suggest corrective actions to have optimum level of power from the Installed Power Project.

1. FACTORS AFFECTING
PERFORMANCE OF A SOLAR PV
PROJECTS
EnvironmentFirst Energy Services (P) Ltd.
“Privileged to Impart Knowledge”

2. There some factors which are beyond the control of Human efforts but certainly
there are other factors too which can be insured to have optimum out put of
energy. A Good design and operation practices save us from huge losses
The Annual amount of energy that will be produced by
a PV system depends on various conditions

3. IMPORTANT FACTORS
Solar radiation available at the
site
The orientation (azimuth) and
tilt (elevation) of PV arrays
The peak power rating of the
arrays
Energy Conversion Efficiency of
PV modules
Variation in the efficiency of
the Modules with Temperature
Power reducing effects of array
shading by trees, nearby
buildings
Accumulation of Dirt/Smog etc
The Efficiency of Inverter
Cable Thickness
System Design
Grid Operation & Reliability

4. The annual total quantity of solar
radiation available at the site
• This can be estimated from
meteorological data givng
the measured number of
kWh (or Gj) per square
meter per year incident on
the horizontal surface at the
nearest meteorological
station. In very sunny
conditions it can rise to well
over 2000 kWh m-2y-1.

5. The orientation (azimuth) and tilt
(elevation) of PV arrays
• For maximum energy
output, the arrays should
be oriented close to south
and with an elevation
roughly equal to latitude
of the site – although
deviation from these
optima does not have a
marked effect, and the
choice of tilt angle can be
varied according to the
seasonal output profile
desired.

6. The peak power rating of the arrays
• This alternatively can be
termed as area of the
arrays in square meters.
Each manufacturer of
PV panels provides a
data sheet, which will
specify the kWP or
"rated" amount of
power the solar panel
will produce.

7. Term "Peak Power" is a figure giving
the accuracy
• Many manufacturers
have a + or - of 10%
variation which
suggests a greater
variability in
performance.
• EnvironmentFirst
perform the onsite
analysis of actual power

8. Performance Warranty
• The second thing to look at … which is not
usually found on the manufacturer's data
sheet is the performance warranty. Typically,
the manufacturer will guarantee that the kWp
output of the panels will not be less than 90%
of the rated peak value (under standard
testing conditions) for the first 10 years, and
not less than 80% for the next 15 years.

9. Performance Guarantees
• performance guarantees are important to you
(and they certainly are if you are using bank
financing to pay for your installation), then
having re-insurance gives you a bit of extra
comfort on the performance side, and should
be something you should ask about.

10. The energy Conversion
Efficiency of PV modules:
Different modules have
different kind of materials,
doping type, doping
composition, impurities
etc. due to which their
efficiency varies. Therefore
it is recommended to use
high efficiency modules for
commercial operation so
that to have optimum
results.

11. The Variation in the efficiency of the
Modules with Temperature
• Solar cells work best at low temperatures, as
determined by their material properties. All
cell materials lose efficiency as the operating
temperature rises. Much of the light energy
shining on cells becomes heat, so it is good to
either match the cell material to the operation
temperature or continually cool the cell.

12. The Power reducing effects of array
shading by trees, nearby buildings

13. Accumulation of Dirt/Smog

14. The Efficiency of Inverter
• The Efficiency of Inverter used to convert the
DC power from the PV arrays into AC, and any
losses that occur in the wiring between PV
system and the final consumer of metering
point can amount to about 10% of the
electricity generated.

15. Natural Resistance
• The natural resistance to electron flow in a cell
decreases cell efficiency. These losses
predominantly occur in three places: in the
bulk of the primary solar material, in the thin
top layer typical of many devices, and at the
interface between the cell and the electrical
contacts leading to an external circuit.

16. Electrical Resistance
• Larger electrical contacts can minimize electrical resistance, but
covering a cell with large, opaque metallic contacts would block
too much incident light. Therefore, a trade off must be made
between loss due to resistance and loss due to shading effects.
Typically, top-surface contacts are designed as grids, with many
thin, conductive fingers spread over the cell's surface. However,
it is difficult to produce a grid that maintains good electrical
contact with a cell while also resisting deterioration caused by
changes in temperature or humidity. Generally, the back-surface
contact of a cell is simpler, often being just a layer of metal.
Other designs for electrical contacts include placing everything
on the cell's back surface, or, as in some thin films, depositing a
thin layer of a transparent conducting oxide across the entire
cell.

17. Cable Thickness
While the size and length of
the cables is a matter of
system design and
installation, for the quality of
cables it is utmost important
that cables adhere to IEC
60227 / IS 694 or IEC 60502 /
IS 1554 (Part I & II). It pays to
familiarize what these
specification standards say. It
is important for a project
developer to know that what
quality of cables are being
installed at site as it could
affect the overall generation
of the plant.

18. Cable Thickness
• 20 meter is the length of cable between the panel and the
charge controller. A typical cable with 1.5 sq mm cross section
has resistance of about 0.012 ohms per meter of wire length. So
a 20 meter long wire will offer resistance of 20 x 0.012 = 0.24
ohms.
• If it is a 24V system and a 10 ampere current is flowing through
this wire, then from the Ohm’s law (V = IxR), we can calculate
voltage drop across this wire: 2.4V. It means the voltage at the
charge controller end of the cables will be 2.4V less than the
voltage produced by the panels if a 10 Amp current is flowing.
This 10% voltage drop is clearly unacceptable.

19. Cable Thickness
• What if we use a 6 sq mm cross section cable which has a
resistance of 0.003 ohms per meter. The total resistance for 20
meter long cable will now be 0.06 ohms; and the voltage drop,
10×0.06 or 0.6V. It is 2.5% voltage drop for a 24V system which
might be acceptable. But what about the increased cost of
thicker cable? Likewise, there would be wiring all around and
careful attention must be paid to know the impact on overall
system efficiency. Thus, cable length and size needs careful
attention right at the planning stage.
• Another way to reduce resistance loss is to raise the system
voltage, to say 48V. It will still give the same watt as above (48V x
5A = 240W). Doubling the system voltage reduces the voltage
drop by 1/4th.

20. System Design
Complexity lowers reliability and increases maintenance cost.
KEEPITSIMPLE

21. Determining the Performance
• At “EnvironmentFirst” we measure the
performance of a photovoltaic (PV) device to
predict the power the cell will produce. Current-
voltage (I-V) relationships, which measure the
electrical characteristics of PV devices, are
depicted by I-V curves. These I-V curves are
obtained by exposing the cell to a constant level
of light while maintaining a constant cell
temperature, varying the resistance of the load,
and measuring the current that is produced.

22. Determining the Performance
On an I-V plot, the vertical axis refers to current, and the horizontal axis refers to
voltage. The actual I-V curve typically passes through two significant points:
• The short-circuit current (Isc) is
the current produced when the
positive and negative terminals of
the cell are short-circuited and
the voltage between the
terminals is zero, which
corresponds to a load resistance
of zero.
• The open-circuit voltage (Voc) is
the voltage across the positive
and negative terminals under
open-circuit conditions when the
current is zero, which
corresponds to a load resistance
of infinity.

23. Determining the Performance
• The cell may be operated
over a range of voltages
and currents. By varying
the load resistance from
zero (a short circuit) to
infinity (an open circuit),
researchers can
determine the highest
efficiency as the point at
which the cell delivers
maximum power.

24. Determining the Performance
• Maximum power is
generated at only one
place on the power
curve, at about the
"knee" of the curve.
This point represents
the maximum efficiency
of the solar device at
converting sunlight into
electricity.

25. Grid Operation & Reliability
• This is the factor beyond
control but proper
planning can avoid later
problems. Therefore at
EnvironmentFirst we
collect the data of
nearest Grid at the design
phase itself to insure the
maximum reliability

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