Photovoltaic Training - Session 4 - Plant Maintenance

Photovoltaic Systems Training

Session 4 ‐ Plant Maintenance

Javier Relancio & Luis Recuero
Generalia Group

September 28th 2010

http://www.leonardo-energy.org/training-pv-systems-design-
construction-operation-and-maintenance

PHOTOVOLTAIC SYSTEM
Design, Execution, Operation & Maintenance

PLANT MAINTENANCE

Javier Relancio. Generalia Group. 28/09/2010
www.generalia.es
2
http://www.leonardo-energy.org/training-pv-systems-design-construction-operation-and-maintenance

INDEX

Importance of the plant maintenance during the
operation

Components to maintain

Types of maintenance

Spare parts & stock management

3

INDEX

operation




4

Operation & Maintenance Options (I)

Predictive:
It tries to predict the plant performance in the future, to prevent possible
malfunctions by certain actions. It is only used in plants with suntracking
systems
I.E: If an element life time is supposed to be X years, it can be programmed
to be substituted the year X-1, in order to avoid a serious failure
Preventive:
It tries to set periodical tasks to guarantee the plant lifetime
I.E.: Although the suntracker oil could last for 25 years, we can decide to
change it every 5 years
Corrective:
It tries to repair incidences which have already happened and try to avoid
their repetition.
IE.: Atmospheric phenomenon (such us wind, storms, etc) can damage any
element in the plant. Also, manufacturing defects.

5

Operation & Maintenance Options(II)

Influence of the in-force legislation

Every country can define within its own legislation any type of compulsory
maintenance or control task for PV facilities
If this is the case, this must be integrated in the plant maintenance program.

If there is no legislation for PV facilities, the criteria to implement the maintenance
program will be done according to our decisions, depending on the most important
factors for each plant

6

Operation & Maintenance Options(III)

There are many options to define how the plant maintenance should be done:
It will depend on the plant size

Key points

Issue Options

Maintenance The promoter or installer
Responsible A specialized maintenance company

Continuous presence
Plant staff Intermittent presence
Presence only if an incidence happens

Control & Advanced monitoring system
Supervision Simple monitoring system
System Only inverter monitoring system

Personal
Surveillance
Remote Surveillance System
System
Combination

7

Operation & Maintenance Options (IV)

Depending on the plant size and technology, we should answer the following questions:

Who? How? With which tools?

POWER MW WITH SUNTRACKER WITHOUT SUNTRACKER

0,1‐0,5 MW 1 PERSON. INTERMITTENT INFORMATION FROM THE INVERTERS

0,5‐1 MW 1 PERSON. HALF‐TIME INFORMATION FROM THE INVERTERS

1 PERSON. FULL TIME
1‐2 MW 1 PERSON. HALF‐TIME
WITH MONITORING SYSTEM

2 PERSONS. FULL TIME 1 PERSON. FULL TIME
2‐5 MW
WITH MONITORING SYSTEM WITH MONITORING SYSTEM

FOR EACH 5 MW ADDED .+ 2 PERSON. FULL TIME .+ 1 PERSON. FULL TIME

8

Operation & Maintenance Costs (I)

1. Plant operation & maintenance staff

The training of the maintenance supervisor is essential:
The reparation of possible breakdowns must be done as efficient as
possible
The maintenance responsible must be independent
In a functional level: enough skills to manage the maintenance of one
or several plants by himself
In a documentary level: skills to create and update the records of
maintenance, records of incidents, etc; and to treat the information
Its cost will depend fundamentally on the number of persons (half-
NOTE:
time/full-time) and their skills It is essential for
2. Spare Parts stock management the personnel's
efficiency a
A bad management of supplies can mean complete days of stop of an correct
management of
installation
the spare parts
It is essential to have an updated list of all the spare parts in the plant and consumables
and to assure there is enough quantity
3. Consumable stock management: oil, paint, etc

9

Operation & Maintenance Costs(II)

4. Surveillance system

The reparation, substitution of equipments and other possible defects in the
plant due to thefts, can mean a high cost
Even if we have an insurance: lost production, labor cost for
reinstatements, etc
This reverberates in the need to reduce to 0, as far as possible, this type of
incidents
Options: physical vigilance, TV - vigilance or combination of both

5. Monitoring system

A well implemented supervision of the plant can mean huge savings in the
corrective maintenance
It is important to detect any possible incident before it causes a serious
breakdown

NOTE: for further information about these points: “Webinar 3: Plant Operation”

10

Operation & Maintenance Costs(III)

6. Insurance

It is important to have an insurance that covers from all the effects of
meteorological conditions
it can suppose an important saving
Also the risks of theft or possible damages due to vandalism
There are insurances that they even cover the losses of production

7. Land renting contract

It must clearly specify:
The surface
The terms
The cost*

8. Supplies: Water, light, internet…
* Including the increases
9. Taxes during the years

Depending on each country, we have to consider the cost of the
different taxes
11

Operation & Maintenance Costs(IV)

Conclusion

The annual maintenance & operation costs, referred to the plant cost
can be considered:

Solar plant without suntracker – 1 %

Solar plant with suntracker – 1,3 %

Solar Roof– 0,7 %

Notes:
It has not been taken into account the cost of physical surveillance, which can raise the operation costs,
except for large plants where the unitary repercussion on the production is not so important.
As a rough estimation, the cost per hour of a guard from an outsourcing company is around 11 € per
hour in Spain

12

INDEX

operation




13

Components to be maintained:
The PV module (I)

It is the most massive element within the facility
It has a guarantee for manufacturing defects during its first period of life
Usually, from 3 to 5 years
It has a guarantee for producing with a minimal performance during 25 years

Due to these reasons, this element should never be repaired.
We analyze the panel, if it has any defect, it is replaced by the manufacturer

Panel Analysis: Manufacturing defects

They should be detected visually
Defective frames
Yellowing (The panel becomes yellow)
Defective connection boxes
Broken glass

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The PV module(II)

Panel Analysis: Production defects (I)

They are harder to be detected, as other components may be involved
It is important to isolate the defect, and confirm it has been produced in the panels

Testing mechanisms

1. To detect which array has the issue

a. Within large facilities: The monitoring system
could control each array separately

b. Within small facilities: we have to do a manual
testing for each array

15

The PV module (III)

Panel Analysis: Production defects (II)

2. To detect the defective panels within the array:

a. Test both the voltage and the current for each panel:
The voltage may be reduced if a cell has any defects

b. The hot spots may produce a voltage
reduction:

They can be detected visually, but a
thermographic camera can help to find
them out

16

The inverter (I)

Type of inverter

The maintenance strategy may vary depending on the type of inverter
Small inverters: to be placed on the wall
Big inverters: to be placed on the ground

Small inverters maintenance

We should have a number of inverters in stock, ready to replace
any defective one
When a malfunction is detected:
The inverter is replaced by one in stock
And it is sent to the factory for its reparation

NOTE: This operation can be done really fast, so that we can avoid
production losses, as if we have a stock we do not depend on third
parties

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The inverter (II)

Big inverter maintenance
We can find two options:

Manufacturer maintenance Maintenance by our own company
Pros

No need of qualified personnel in the plant The reparation might be done faster

Third party dependence when any incidence happens Need of qualified personnel in the plant,
Cons

It might be profitable from a certain installed
power
Try to avoid sending the inverter to be repaired in the In this case, the spare parts stock
factory management is really important
For large inverters, the cost of the spare parts
It may take more than a week to be repaired can be important
Observaciones

In the contract, it is essential to add a clause for indemnity
in case of production losses
If the reparation takes more than a certain period, the
indemnity may be executed
This period should be less than 48 hours (weekends
included)

NOTE: in any case, if we want to guarantee a fast
reparation we must have spare parts in the plant
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Components to maintain:
The suntracker

The suntracker has software, mechanical & electrical devices

Mechanical:

Its preventive maintenance is very important:
Motor lubrication
Sensor state supervision
Any corrective measure will be more expensive

Control

The software must be always updated to the last version
The possibility to remotely update the software can reduce the
time to update it locally

NOTE: As in the inverters case, depending on the amount of units, it can be
interesting either to outsource the maintenance of the suntrackers, or to
employ qualified personnel to do it ourselves.

19

Control cabinets, protections & cables (I)

Control cabinets

Preventive: Visual inspection is very important to know
their state.

Punctual: if they are in the open air, if it is important to
check their state after bad weather conditions

For example, after a hard storm, water could have
gone inside the cabinet

If the control cabinet has lost its capabilities, it must be
replaced as soon as possible

20

Control cabinets, protections & cables (II)

Protections

Preventive:

Periodical tests to the protections that allow them will be
done.

Periodical inspections will be done, specially in the
connections

If any defect is detected, the device will be immediately
replaced. The spare part stock is important

NOTE: A bad connection can produce an electrical arc, that may raise
the temperature and cause the device breakdown

21

Control cabinets, protections & cables (III)

Cable

Preventive
To check the connections between the different
equipments
To check those parts where the cable cover can
be damaged

Facilities without suntracker: once the cable installation
has been verified, and its voltage and connection have
been checked, the cable shouldn’t have any problems
Facilities with suntracker: it is important to periodically
check the cable route and test if there are any important
mechanical tensions at any point, which may cause a
serious problem in the future

22

The meter

The meters are solid devices

They have a critical function

Once they are installed and the plant has been commissioned,
the electric company seals them to avoid being operated

Anyway, a preventive maintenance should be done:

To check if the data being sent by the meter is logical, and is the same as the one
we can read at the display

When handling any incidence, we must contact the electric company:

They can send their own personnel

They can allow us to operate the meter

23

INDEX

operation




24

Preventive Maintenance (I)

The preventive maintenance must:
Go as far as possible and as structured as possible.
Be present in all steps: design, execution & operation

Before the plant operation, the preventive maintenance must be taken into
account:

In the plant design In the components provisioning

In the equipment guarantees In the components reception

In the insurance contracting

We cannot think about the plant maintenance
as: “A man with his tools”
25

Preventive Maintenance (II)

During the plant design (I):

Have the parameters of radiation and tilt of the modules been
well studied?

Are we sure that we are not demanding to the plant
operator a performance over the real capabilities of the
plant, due to an optimistic study?

Has the shadowing study been done properly, especially on those plants with suntracking
systems?

We always have to take into account a balance between the losses for shading versus
the optimization of the plot

Has a study of the wind been developed in the zone, in order to properly determine the
suntracker specs?

Have we taken into account the salinity and humidity of the local atmosphere that could
influence the structure and screws?
26

Preventive Maintenance (III)

During the plant design (II):

Has the quality of the soil been studied to verify the
absence of materials that attack the concrete and
may debilitate the fixation to the soil?

Have we checked that all the equipments have the minimal protection level, IP65, to be
installed outdoor?

Are the important components protected by voltage dischargers?

In case of control cabinets or control rooms which contain various devices, such us
inverter or transformers... Do they have an appropriate cooling system?

27

Preventive Maintenance (IV)

During the plant design(III):

Do the electrical cabinets have the enough dimensions to
dissipate the heat of their components, specially during
summer?

Is the section of the cables adapted to avoid voltage drops below the
desirable 0.5 - 1%?

Have we tried to distribute the main elements in several isolated rooms, to
avoid losing the whole production in case of fire or flood?

28

Preventive Maintenance (V)

In the supply of components:
The chosen modules …

Are they certified by a certified laboratory?

Do they fulfill the standard EN 61.215?

Or the one applicable for each country?

Are they a “class II”?

The inverters …

Do they a have reasonable European efficiency, between 94 and 96 %?

Do they a have suitable galvanic protection?

Are the structures galvanized with a minimum thickness of 80 microns
(or equivalent treatment)?

29

Preventive Maintenance (VI)

In the required guarantees for the devices (I)

Nearly all the modules manufacturers guarantee a degradation of
less than 20 % after 25 years, but …

What guarantees does the chosen manufacturer offer for
manufacturing defects?

Is it over 2 years? Is it close to 5 years?

Does the manufacturer guarantee a degradation of less than 10% after 10 years?

NOTE: this point should be specially verified for thin-film modules:

They do not always guarantee it

They can suffer a strong initial degradation

30

Preventive Maintenance (VII)

In the required guarantees for the devices (II)

Is it either the manufacturer or the distributor the one who offers the
guarantee?

If it is the distributor … is he established in our country?

If he is not… does he have the right to sell out of his country?

Is it “guaranteed” the “chain of guarantees"?

Does the contract detail all the guarantees adequately?

For the inverters, have the guarantees been extended to the maximum number of
years (at a reasonable cost)?

Does the manufacturer offer a replacement service, within 24-48 hours?

Does he have a hotline service?

31

Preventive Maintenance (VIII)

At the component reception

Have we done a visual inspection of the modules?

Have we done a selection of the modules by power?

It is not practical a “module by module” electrical measurement

But the classification of the manufacturer " flash list “ can be very useful.

NOTE: For module tolerances of around 5 %, two classifications can be enough

Are the components stored in the suitable conditions during the period of assembly?

Are this same conditions applied for the storage of the spare parts?

32

Preventive Maintenance (IX)

At the insurance contract signature

Has the insurance been contracted with the suitable coverage …?

Atmospheric phenomena

Electrical damages

Thefts

Production Losses

Civil responsibility

With reasonable excess

33

Preventive Maintenance (X)

Preventive maintenance during the plant operation (I)

Key points:

Preventive maintenance Spare parts in the plant

Training Meteorological predictions

Incidence detection Grid connection breakdown
(Electrical company side)

Physical/Remote Surveillance

34

Preventive Maintenance (XI)

Preventive maintenance during the plant operation (II)

It is necessary to define the maintenance tasks and their periodicity
And then create a record of preventive maintenance on every element, with the
date of accomplishment.

Example: Preventive maintenance calendar 20XX

TASK PERIODICITY DATE

Checking the cables state Yearly dd/mm/yyyy

Retightening of the electrical connections Yearly dd/mm/yyyy

… … …

35

Preventive Maintenance (XII)

Preventive maintenance during the plant operation (III)

List of tasks that generally require preventive maintenance:

Earthing system checking in transformers and rest of the facility

Retightening of the electrical connections in the control-cabinets

Voltage dischargers checking

Cable state checking

Module dirtiness checking

Suntrackers deviation according to the position of the sun

Lubrication of the components of the suntrackers

Retightening of the suntrackers screws

Maintenance required by the electrical Companies in the Transformation Center *

36
* It is usually outsourced to the installer of the center

Preventive Maintenance (XIII)

Preventive maintenance during the plant operation (IV)

Maintenance tasks follow-up

Every maintenance task must be logged in individual records for
every device or component

Example: Suntracker record

DATE TASK OBSERVATIONS

15/02/2010 Cable checking Routine

06/03/2010 Suntracker lubrication Routine

… … …

37

Preventive Maintenance (XIV)

Preventive maintenance during the plant operation (V)

Training

This is really important specially if the final client has decided to do the plant
maintenance by his own

The person in charge of the plant maintenance must have an important electrical
formation and reasonable knowledge on solar power.

If the plant is with suntracker, he must also have electromechanical formation

Meteorological predictions

It is really important in plants with suntrackers.

The wind may cause serious damages to the suntrackers

It is a requirement for the suntracker to have protections against the wind:

It can automatically be positioned horizontally when receiving a signal
from the central anemometer

It is recommended that each suntracker has its own wind sensor

38

Preventive Maintenance (XV)

Preventive maintenance during the plant operation (VI)

Incidence detection mechanisms

As the detection of a fire in any building:

Transformation center Meter room

Grid isolating center Control & Supervision Room

Grid breakdown detection (From the company side)

Certain issues from the electrical company can cause the plant disconnection from the
grid

It is important to notify it to the responsible as soon as possible

By an acoustic alarm

By SMS. Specially important during the weekends

NOTE: All these breakdowns could be unnoticed for the electrical company
or, sometimes ignored, and if they are not demonstrable they might not be
recognized or compensated
39

INDEX

operation




40

Stock & Spare Part Management

Spare parts in the plant
If the plant is larger than 500 kW, we have to store spare parts in situ

The “List of Spare parts” must be done evaluating:
If the element is critical (1 - 5)
Malfunction probability (1 - 5)
Delivery time (1 - 5)

MALFUNCTION DELIVERY
ELEMENT CRITICAL TOTAL
PROBABILITY TIME

INVERTER 5 1 3 15

MAGNETOTHERMIC 5 2 1 10
GEAR MOTOR 5 1 4 20
TRANSFORMER 3 1 3 9
… … … …

41

Stock & Spare Part Management

Depending on: Material Material
Each element evaluation Input Output

SOLAR PLANT
Each element price

SUPPLIER
A percentage of Devolution
elements in stock is
Reparation
determined

Between 0,5 to 2%
Management
Note: It can reach a 3% if
the element price is very

Stock
low

Time

42

End of Session 4

Thank you for attending

http://www.leonardo-energy.org/training-pv-systems-design-
construction-operation-and-maintenance

43

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