Photovoltaic Training - Session 4 - Plant Maintenance

Photovoltaic Systems Training

Session 4 ‐ Plant Maintenance

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

Javier Relancio & Luis RecueroGeneralia Group

September 28th 2010

PHOTOVOLTAIC SYSTEM

Design, Execution, Operation & Maintenance

PLANT MAINTENANCE

Javier Relancio. Generalia Group. 28/09/2010www.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


INDEX






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 (I)



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

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Operation & Maintenance Options(II)


There are many options to define how the plant maintenance should be done:

It will depend on the plant size

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Operation & Maintenance Options(III)

Key points

Issue Options

MaintenanceResponsible

The promoter or installer

A specialized maintenance company

Plant staff

Continuous presence

Intermittent presence

Presence only if an incidence happens

Control & SupervisionSystem

Advanced monitoring system

Simple monitoring system

Only inverter monitoring system

SurveillanceSystem

Personal

Remote Surveillance System

Combination


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

1‐2 MW1 PERSON. FULL TIME

WITH MONITORING SYSTEM1 PERSON. HALF‐TIME

2‐5 MW2 PERSONS. FULL TIME

WITH MONITORING SYSTEM

1 PERSON. FULL TIME

WITH MONITORING SYSTEM

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

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

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Operation & Maintenance Options (IV)

Who? How? With which tools?


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-

time/full-time) and their skills

2. Spare Parts stock management

A bad management of supplies can mean complete days of stop of an

installation

It is essential to have an updated list of all the spare parts in the plant

and to assure there is enough quantity

3. Consumable stock management: oil, paint, etc

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Operation & Maintenance Costs (I)

NOTE: It is essential for the personnel's

efficiency a correct

management of the spare parts

and consumables


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

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Operation & Maintenance Costs(II)

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


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…

9. Taxes

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

different taxes 11

Operation & Maintenance Costs(III)

* Including the increases during the years


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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 %

Operation & Maintenance Costs(IV)

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


INDEX






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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

They should be detected visually

Defective frames

Yellowing (The panel becomes yellow)

Defective connection boxes

Broken glass

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


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Components to be maintained:The PV module(II)

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

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

Panel Analysis: Production defects (I)


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Components to be maintained:The PV module (III)

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

Panel Analysis: Production defects (II)

b. The hot spots may produce a voltage

reduction:

They can be detected visually, but a

thermographic camera can help to find

them out


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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

Components to be maintained: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


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Components to be maintained: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

Cons

Third party dependence when any incidence happens Need of qualified personnel in the plant, It might be profitable from a certain installed power

Observacion

es

Try to avoid sending the inverter to be repaired in the factory

It may take more than a week to be repaired

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)

In this case, the spare parts stock management is really importantFor large inverters, the cost of the spare parts can be important

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

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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

Components to maintain:The suntracker

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.


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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

Components to maintain:Control cabinets, protections & cables (I)


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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

Components to maintain:Control cabinets, protections & cables (II)


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Components to maintain:Control cabinets, protections & cables (III)

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

Cable


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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

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

Components to maintain:The meter

Anyway, a preventive maintenance should be done:


INDEX






25

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:

Preventive Maintenance (I)

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”


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?

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Preventive Maintenance (II)

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?


27

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?

Preventive Maintenance (III)

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?


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During the plant design(III):

Do the electrical cabinets have the enough dimensions to

dissipate the heat of their components, specially during

summer?

Preventive Maintenance (IV)

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?


29

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)?

Preventive Maintenance (V)


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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?

Preventive Maintenance (VI)

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


31

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?

Preventive Maintenance (VII)

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?


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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?

Preventive Maintenance (VIII)


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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

Preventive Maintenance (IX)


Key points:

Preventive maintenance Spare parts in the plant

Training Meteorological predictions

Incidence detection Grid connection breakdown(Electrical company side)

Physical/Remote Surveillance

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Preventive Maintenance (X)

Preventive maintenance during the plant operation (I)


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 (XI)

Preventive maintenance during the plant operation (II)


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 *

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Preventive Maintenance (XII)

Preventive maintenance during the plant operation (III)

* It is usually outsourced to the installer of the center

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DATE TASK OBSERVATIONS

15/02/2010 Cable checking Routine

06/03/2010 Suntracker lubrication Routine

… … …

Preventive Maintenance (XIII)

Maintenance tasks follow-up

Preventive maintenance during the plant operation (IV)

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

Example: Suntracker record


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Preventive Maintenance (XIV)

Meteorological predictions

Preventive maintenance during the plant operation (V)

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

Training

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


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Preventive Maintenance (XV)

Grid breakdown detection (From the company side)

Preventive maintenance during the plant operation (VI)

As the detection of a fire in any building:

Incidence detection mechanisms

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

Transformation center

Grid isolating center

Meter room

Control & Supervision Room

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

INDEX






Spare parts in the plantIf 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)

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Stock & Spare Part Management

ELEMENT CRITICALMALFUNCTION

PROBABILITY

DELIVERY

TIMETOTAL

INVERTER 5 1 3 15

MAGNETOTHERMIC 5 2 1 10

GEAR MOTOR 5 1 4 20

TRANSFORMER 3 1 3 9

… … … …


Depending on:

Each element evaluation

Each element price

A percentage of

elements in stock is

determined

Between 0,5 to 2%

Note: It can reach a 3% if

the element price is very

low

42

Sto

ckTime

SUPP

LIER

SOLA

R PLAN

T

Material Input

Material Output

Devolution

Reparation

Management

Stock & Spare Part Management


43

End of Session 4


Thank you for attending

Technology

Photovoltaic Training - Session 4 - Plant Maintenance