Q&A session of photovoltaic training http://www.leonardo-energy.org/node/5948...
PV TRAINING – DESIGN, CONSTRUCTION, OPERATION AND MAINTENANCE
Q&A SESSION 3 September – October 2010 http://www.leonardo-energy.org/node/5948
chokechai chongsiriratanakul 2:
The losses due to dispersion of parameters,
What happens if we installed
increase. It is not recommended that different
different type of panels to the
types of panel (crystalline, thin film, CIS, ….)
same
considering
share the same inverter. The suitable solution
same panel type in same string
is that every type of panel is connected to a
with same Voc among each
different inverter
string ? CHANAN:
string
The String Controller is a new technology and
monitor can alarm a cut of
the manufacturers do not specify how they
cable during night?
detect the cable cut. For further information,
inverter,
how
the
a manufacturer of this kind of devices would
be Carlo Gavazzi.
Bouaziz: Do you recommend
Yes, it is recommended the measure of the I-
measuring the I-V curve in the
V curve of the whole photovoltaic system (not
life of the facility to monitor
every panel). With this, we have results for
performance degradation?
the annual degradation of the facility and we
Aitor
can improve the diagnosis of breakdowns First, you need to verify whether the
Amezua: Regarding to
inverter
maintenance,
it
manufacturer has service of assistance in
common to that manufacturers
your country. If this service is not available,
offer this service or is it done
you need to trust companies of maintenance
via
companies?
or to make it yourself supported by own staff
Are there different practices
and in addition you need to have spare parts
depending on the size of the PV
in the plant. You should assess the possibility
plant? Maybe depending on the
of having many small inverters, thus, with a
inverter size?
minimum
maintenance
is
own
staff,
you
can
do
the
substitution in case of breakdown and then, to send the equipment to be repaired by the manufacturer. The operation of replacement in case of inverters of 5-10 kW could last only 10
minutes
and
you
will
not
lose
any
Ed Servello: How can I get
production. In the practice, it is not easy to have this
information about a real plant
information because usually the operators
in operation today?
reserve
this
information.
The
most
trustworthy data are the ones given by laboratories as CENER in Spain, beacuse they do real measurements in plants. But it is not easy that they give information reserved
[email protected]: How can
without the authorization of their clients To get a calibrated cell, contact
a cell be calibrated? When is
manufacturer. The calibrated cells must be
calibrated?
sent to the manufacturer or to the laboratory
the
in order that they issues a new certificate of
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calibration, once every 3 years (maximum)
Martin Gieler: In case of larger
If the plant has a large size, it is desirable to
facilities: is there any need to
have staff for maintenance and / or security.
have staff onsite?
For facilities over 2 Mw you can consider at least one person, who could solve simple electrical
Raj:
can
i
inverters
use and
combiner
problems
or
substitute
certain
different
elements of the facility. Yes, usually the inverter manufacturers use
different
standard
box
for
communication?
communication
buses,
such
us
RS485 or Ethernet, so they are usually compatible with different converter brands. By the other side, it is important to choose a software
which
is
compatible
with
the
inverters we are choosing, and it might be difficult finding a commercial solution that supports several brands of inverters for a Jonny Huck: In the equation for
good price. The length, d, measured on the horizontal
the distance you should leave
plane, between 2 rows of modules, of height
between panels (d=h/k), what
h, that could produce shades on the facility
did the parameter 'k' refer to?
will have to guarantee a minimum of 4 hours of the Sun concerning the midday of the winter
solstice
(summer
in
southern
hemisphere). This d will be superior to the value obtained by the formula: d = h/tangent (61 °-latitude) where 1/tangent (61 °-latitude) frigitar: Are monitoring systems
is a coefficient dimensionless called k. Normally the monitoring systems
continuously
by
designed to be automatic, so that they do not
there
need personnel to be operated. This is the
can
reason why they usually need calibrated cells
e.g.
and weather stations, in order to have a
power loss is due to decrease
reference. A good monitoring system should
personnel algorithms automatically
manned or
are that detect
if
3
are
in irradiance... etc.
consider all these parameters and give us all the information, just sending an alarm if the plant
is
really
producing
with
a
low
performance. Amr: For 40deg and above, is
40 º is a maximum value for many inverters.
electronic inverters safe to use
If the inverters is placed in a closed room, it is necessary to design a system of ventilation to
Thomas Witt: What would be
reduce this temperature Minimal size does not
the
photovoltaic technology. This is concretely
smallest
plant size?
recommendable
one
of
its
important
exist
in
the
advantages.
Nevertheless, the plants must have minimal profitability. For the minimal profitability it is necessary to contemplate on the one hand the incomes and on the other hand the expenses including amortization and financial costs. It is possible that the part of the installation necessary for the evacuation of energy (connection to the electrical grid) has a cost that forces us to a bigger size of the plant if we want to reach the desirable profitability
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