Solar PV System - Key Asset Management Considerations
Solar PV system – Key Asset
management considerations
Last decade has seen a
consistent growth in new capacity addition in Solar PV systems in almost every
part of the world. This growth has been achieved through new installations of
both small and large size solar PV systems by retail and corporate segments.
However the growth in
new capacity addition has not resulted in proportionate growth in energy availability
from installed capacity due to number of factors of which one of the most important
is the deficiency in the operations and management of the installed solar plants.
A Solar PV system, which apparently has no moving parts seems like a silent machine which might require only little attention but in reality, a solar PV systems employs dangerous levels of DC current and voltages and has its own design and Engineering complexities thus require prudent care and attention by all solar PV assets owners and manpower working on them to ensure optimum energy generation, overall plant reliability, safety, and long life.
In order to achieve the maximum possible usable life and optimized plant efficiency in terms of
generation output and plant availability, carefully planned operations and maintenance
procedures can be a source of extended life and faster payback. We will deliberate on various factors that play a crucial role in determining the performance of a solar PV system, along with an evaluation of prudent O& M approaches to achieve optimum performance in terms of energy generation and ROI.
A) Design Stage Considerations
Factoring O&M
requirements before construction
When the design and the engineering team is working on the initial project concept due to consideration should
also, be given to various requirements by the operations and maintenance team .Wherever
required ,sufficient tolerances should be made in the design to facilitate operation and maintenance of the
Solar PV system. Due consideration to operation and maintenance requirements
before construction will also minimize unforeseen costs arising out of unplanned
modifications post-commissioning.eg. provisions must be made for walkways and safety lines so that modules and workmen safety can be facilitated for Rooftop installations.
Due consideration to
standards and benchmarks
Plant performance and
safety of operations are interlinked. A good performance can only be achieved
if proper consideration has been given to safety and security of the assets , manpower
power and environment. It is imperative that
design and Engineering be entrusted with the agencies that have proper
qualification and adequate experience of working with standardized practices
and procedures for Solar PV system design and construction in accordance with
standardized norms and specifications.
Lifelong costs of
operations and maintenance to be factored
Investment decision
for solar PV system return on investment
is generally made on the basis of upfront capital investment without serious consideration
on future recurring O&M costs. There can be a sizeable cost in the form of
component replacement, repairs, obsolescence, breakdowns and unpredictable
failures. Additionally, there can be unforeseen influences due to changes in
business scenario, manpower cost, and nonavailability of human resources in
later years of plant life. We should factor in such cost while evaluating a project
from returns perspective and only invest if ROI is good even with all costs
factored in.
B)During Projects Execution, Considerations
Supervision by the
owner during construction
It is advisable that
owner of the Solar PV system engages his manpower for general supervision when
the plant is still being constructed , this will facilitate his team to
understand and learn the typical demands and challenges which might arise in
future due to the complex working of components in the plant itself. This proactive
approach should be preferred because during construction face it is easier to
grasp the complexities of.
Preparation, handover
and maintenance of Technical records
The solar PV system is warranted
to work for around 25 years; it is important that it’s all necessary records
are maintained and handed over to the Asset owner once the plant has been
commissioned. If in the later years there is any component breakdown then
warranties can only be availed when there is proper documentation available and
records can be verified for the proper execution of the project. After receiving
the records from the execution team onus is on the owner to maintain these records
on a regular basis so that faults diagnosed in future can be traced back and
proper corrective actions can be taken with the help of good documentation.
Clarity over the scope for
parties
A solar system requires coordinated
efforts by different parties for supplies, execution, and post-commissioning
performance. It is highly desirable that there are clearly defined
responsibilities for parties participating in the execution, operation, and
maintenance of the Solar PV system. This will help to avoid any misunderstanding
related to handling the responsibilities during various phases of project
life cycle.
C) Post Commissioning Considerations
Post commissioning
technical due diligence
Once the plant
construction has been completed it is prudent on the part of the owner to
ensure that plant has been commissioned in line with the contracted
requirements by the EPC contractor.
In general asset owners are not qualified to evaluate a commissioned plant regarding
these requirements. A competent technical Agency may be employed who can inspect and certify that EPC
activities have been completed by the contractor in line with the contractual
agreements and in case there is any deviation they have to be corrected or the owner has to be compensated in line with the scale of such deviation.
Ensuring safety
management post-commissioning
The EPC contractor is
required to fulfill all the regulatory requirements related to safety
procedures and compliances during construction phase but once construction has
been completed it becomes the responsibility of the Asset owner to comply with
any safety norms and provide for any resources which are required to comply
with regulatory requirements for safety of the operations, assets and men
power. So it is advisable that owner deputes a qualified person to evaluate the
work till commissioning and decide what kind of safety requirements have to be
met by the owner and necessary arrangements should be done plant has been handed over to the owner and
plant operations and manpower safety becomes the responsibility of the Asset
owner.
Independent evaluation of O and M activities
Generally O&M activities are contracted out to third party companies which only visit the Solar PV system for scheduled maintenance purpose as per their contracted schedule. In most such cases, the Solar PV system owner is not technically qualified or competent to evaluate the work done by a third party agency. In a worst-case scenario, even the third party agency which is doing O&M might be employing unskilled manpower to cut costs. It is suggested that an independent, qualified expert is brought in to supervise and evaluate the quality of work done by the third party agency so that there are enough checks in the system to identify a big potential breakdown.
D) Technical Considerations
Shading of solar panels
Although due care is
taken during design and Engineering stages to ensure that there is no shadow on solar
modules, in later years we have to pay the attention that any vegetation, tree, etc which may cause the shadow on solar panels
has to be trimmed, removed to maintain optimum energy generation from a solar
PV system. The manpower engaged in day-to-day supervision and maintenance has
to be duly instructed and regularly followed up with for this purpose.
Soiling effect on
solar PV systems
In most of the countries
solar PV systems are preferred to be installed at the rooftop or on a
large tract of land which is located far away from populated areas. Ambient air almost always causes some soil and dust particles to be deposited on solar panels
which is further aggravated by the stickiness caused by humidity, dew and
entrapped pollutants.
The soiling on the
Solar PV module can drastically reduce the efficiency and energy generation
from the Solar PV system. If a proper arrangement has not been done to clean the
dust from the Solar modules generation of energy from a solar PV system can
reduce even by 30% due to soiling impact.
As a good industry
practice, it is recommended that solar modules must be cleaned at least twice in
a month so that to keep performance degradation by soiling within bearable
limits. If possible we should prefer modules that come with specially coated
glass for lesser soiling. In certain places ambient air might contain
contaminants and chemical pollutants like cement and limestone dust, acid fumes etc. In
such cases, it is recommended that modules are cleaned with specialized cleaning
agents made to take care of the effect of contamination by soiling.
Due to the critical importance of module cleaning, a dedicated module cleaning system has to be
part of every solar PV system with provisions for supply and storage of clean
water in adequate quantities along with properly designed pumping and piping
arrangements to facilitate the cleaning of solar PV systems.
As module cleaning
requires clean water in ample quantities, we should make provision for
recycling and reuse of water once it has been used for module cleaning. A good
alternative to water-based module cleaning can be robotic cleaning which
employs dry cleaning with the help of cleaning brushes.
Overall any investment
made in a good module cleaning system will result in higher energy generation
and increase in useful plant life for the Solar PV systems.
Array performance
imbalance
Different arrays in a
big solar PV system will tend to perform at different performance levels and
their operating current and voltages will differ from each other. The performance of the system will be impacted by the least generating array hence different
arrays have to be regularly monitored and balanced to maintain optimum energy
generation and module life. We can do this by carefully monitoring the data
from different arrays in the Solar PV system.
Thermal imaging equipped
with drones plays an important role in identifying faulty, underperforming
arrays and specific modules.
Once an imbalance has
been detected among the different arrays proper diagnosis should be done and
underperforming array has to be given due treatment to achieve a balanced
performance for the Solar PV system. For this, we should regularly analyze the
data received by the monitoring system and we should highlight the errors and
specific modules that are underperforming.
Once the
underperforming array and specific module have been highlighted for under
performance we can use a PV analyzer or IV curve tracing instrument to check
the module behavior in comparison to theoretical performance. Depending upon
the specific condition we may like to replace or repair the modules in question
to achieve balance among the performance of different arrays in the Solar PV
system for optimized energy generation and system.
Cabling and connectors
During regular
operation cables are subject to Extreme voltages and current, humidity,
stresses and unforeseen influences. This may cause damages to the conductor or sheath.
Also we should carefully pay attention to watch out for improper cable
bending and cable routing which might be causing inappropriate twisting and
strains in the cable thus might be a potential reason for damage to the cable or
life of the workman maintaining the plant.
Damaged cable can be
reason for both loss of energy and dangerous electrocution to the workmen.
Cables can also be damaged due to biting by rodents and other creatures.
Regular supervision by operations team can avoid a big unattended loss to the Solar PV
system.
Inverters and
accessories
Inverter is like the heart
of a solar PV system. If the inverter is not functioning then simply there will
be no energy generation from the installation. A well maintained, good
performing inverter may be operating at around 98% efficiency level however if
proper O&M is not being done its efficiency
can even drop to 70% which will bring down the efficiency of the complete solar
PV system . For optimum performance, an inverter should be in a clean, well-ventilated environment protected from unnecessary exposure, flooding and
unauthorized access.
Plant condition
monitoring
Regularly collected,
carefully evaluated and duly acted upon condition monitoring data will help us
to plan maintenance activities so that Scheduled shutdown time can be minimized.
Based upon the inferences derived from the condition monitoring data we can
make provisions for stocking required standby components ,consumables and
spares so that minimum time is lost due to troubleshooting.
For utility-scale solar
PV systems it is always advisable to keep spare units of critical components
like modules, connectors, inverters etc. Required
and Scheduled repair, maintenance activities must be sacrosanctly performed
when they are due as per schedule and there should be no exceptions to this rule.
Safety procedures and
vigilance
No unauthorized access
is to be allowed as it may cause a serious damage to the Solar PV system or for the unauthorized
person due to dangerous DC current and voltages in the system or unpredictable
faults occurring due to unskilled person’s intervention. All cleaning, repairing,
supervision must only be performed by well trained, qualified and designated
persons only.
