Core partner

Angelo Baggini*, Franco Bua**, Francesco Buratti*** * angelo.baggini@unibg.it - Università degli Studi di Bergamo** franco.bua@ecd.it – ECD, Pavia, Italy*** francesco.buratti@ecd.it – ECD, Pavia, Italy

Webinar - 9 May 2008

Case Study - Photovoltaics

Index

Site Design criteria PV system components Tests and inspections Bill of materials Investment analysis Summary

Site > Where

Site > Global horizontal irradiation (kWh/m2 year)

Source: PVGIS © European Communities, 2001-2007http://re.jrc.ec.europa.eu/pvgis/

1300 kWh/m2 per year

Site > Electricity from PV systems

Source: PVGIS © European Communities, 2001-2007http://re.jrc.ec.europa.eu/pvgis/

(1100 kWh/kWp year)

Site > The house

Site > The house

Area: 356 m2

Electricity consumption:

5.500 kWh/year

Site > The house

Orientation

Roof area (South): 95 m2

Site > Area for installation

Orientation: South

Area: 45 m2

Slope: 19°

Design criteria

Available surface

Feed-in tariff maximization– 2005 – Ministerial Decree referred to in Art. 7, para. 1 of

Legislative Decree no. 387 of 29 Dec. 2003. Criteria for incentivising electricity generation by photovoltaic solar plants

– 2005 - AEEG - electricity & gas regulator adopted its Decision 188/05, which identifies GRTN (now GSE) as “implementing body” in charge of granting incentivising tariffs

– 2006 - second decree on photovoltaic solar generation, extending and supplementing the Ministerial Decree of 2005, was enacted

– Incentive scheme applies to photovoltaic (PV) solar plants or systems which have a capacity of 1 to 1,000 kW and which have become operational after 30 Sept. 2005

Design criteria > Incentivising tariffs

PV SystemCapacity (kWp)

Incentivising Tariffs (€/kWh)

Not integrated

Partially integrated

Integrated

1 kW ≤ P ≤ 3 kW 0,4 0,44 0,49

3 kW < P ≤ 20 kW 0,38 0,42 0,46

P > 20 kW 0,36 0,4 0,44

Design criteria > Contract Type and Energy usage

PV energy ContractType

No sale

Partial sale

Complete sale

Net Metering

Energy sale

Design criteria > Contract Type and Rated Power

PV system

Net metering

≤ 20kW

Sale contract

> 20kW

Design criteria > Contract Type and PV energy value

PV energy

Used

Net metering

Used

Sale contract

To grid To grid

Energy Energy

0,4 €/kWh

0,12-0,18 €/kWh 0 €/kWh 0,12-0,18 €/kWh 0,1 €/kWh

Design criteria > PV System size

2,94 kWp

PV system components (PV SC)

PV Generator Inverter DC & AC Cables AC & DC disconnecting switch AC & DC overcurrent protection Metering Earthing Overvoltage protection Grid connection

PV SC > System overviewGrid

Energy measurement

Coupling pointMain Switch

Load

InterfaceInt. Protection

PV energy measurement

PV Systemswitch

Inverter

PV modules

PV SC > PV Generator, module features

PV SC > PV Generator, module features

800

G20NOCTTT MAXMAX

aMAXCELL

STDa

MINCELL

STDOC

MAXOC T.T

dT

dVVV

MINa

MINCELL TT

STDa

MAXCELL

STDMPP

MINMPP T.T

dT

dVVV

STDa

MINCELL

STDMPP

MAXMPP T.T

dT

dVVV

PV SC > PV Generator

Modules 14

Arrays 1

System rated peak power (W) 2940

Voc, max @ Ta, min (V) 562,94

Vmpp @ STC (V) 407,40

Vmpp, min @ Ta, max (V) 344,73

Vmpp, max @ Ta, min (V) 460,74

Isc, max (A) 9,91

Module

Diode

PV SC > PV Generator > constructive aspects

PV module

Roof underlay

Tiles

Orientation: -5° (South 0, East -90, West 90)

Slope: 19°

PV SC > PV Generator > Final result

PV SC > Inverter, MPPT

I

V

MAXPV,MPP

MAXMPPT II

PV generator

Inverter

MAXPV,OC

MAXINV VV

MAXPV,MPP

MAXMPPT VV MIN

PV,MPPMINMPPT VV

T c

ell,

min

T c

ell,

max

MPP MPP

PV SC > Inverter, efficiency

Inverter n. 1 Inverter n. 2

MPPT adjustment efficiency

Source: Photon Internationalwww.photon-magazine.com

PV SC > Inverter, efficiency

Inverter n. 1 Inverter n. 2

Overall efficiency

Source: Photon Internationalwww.photon-magazine.com

PV SC > Inverter

PV SC > DC & AC Cables

Uo/U

Section– Capacity– Voltage drop

Cross section: 4, 6 mm2

Formation: 1X

0,6/1 kV

os

asaK

0iZ IKI

PV SC > DC & AC Cables

Type– External

installation– Anti-Fraud

PV SC > AC & DC disconnecting switch& overcurrent protection

Inverter

PV modules

Meter

QS 2

QP1

To load

Grid

Existing electrical

installation

QS 1

PV SC > AC & DC disconnecting switch& overcurrent protection

Inverter

PV modules

Meter

QS 2

QP1

To load

Grid

Existing electrical

installation

QS 1

PV SC > AC & DC disconnecting switch& overcurrent protection

QP1 QS2 QS 1

Rated current 16 32 25

Termical release type C Curve

Magnetic release type C Curve

Breaking capacity 6

Residual current type B

Rated residual current 0,3

PV SC > Metering

PV system energy– Produced– To grid– From grid

Measurement system– Installation and maintenance– Recording– Transmission

Location Type of connection

– Direct– Indirect– Semi-direct

On way meter

Two way meter

Near the inverter

PV SC > Earthing

All exposed conductive parts and the whole electrical system

A PV system can be connected to earth only if a transformer separates it from the grid

Without separation, PV system is considered as part of the grid, which already has an earthing connection. PV system is then connected to earth through the grid.

PV SC > Overvoltage protection

Direct lightningstrike Building

LPS ?

PV system increasesstrike frequency?

Class 1 LPS

New risk assessment LPS integration

Risk assessment

No

No

No

Yes

Yes

Yes

PV SC > Overvoltage protection

Indirect lightningstrike

SPD SPD

SPD

PV System

Tests and Inspections

On site (acceptance and periodic) inspections– Shadows– Equipment

Tests– DC side– AC side– At acceptance:

• Array voltage and current• Circuit insulation• Equipotential bonding

Tests and Inspections > On site inspectionsType Acceptance Periodic inspection

Module installation Yes Yes

Modules

Module damage Yes Yes

Frame corrosion No Yes

Earthing conductors damage Yes Yes

Boxes damage No Yes

Plate damage Yes Yes

Cables type and installation Yes No

CablesMechanical and fault stresses No Yes

Circuit identification Yes Yes

Rack proper installation Yes No

Rack

Terminal installation Yes Yes

Water/corrosion No Yes

Fuses No Yes

Earthing conductors damage Yes Yes

Plate damage Yes Yes

Inverter proper installation Yes No

Inverter

Operation and alarm signalling Yes Yes

Connections Yes Yes

Fan Yes Yes

Plate damage Yes Yes

Bill of materials

Modules: 14.200€Inverter: 1.900€Other (cables, accessories, etc…): 7.081€Total: 23.181€

Specific cost: 7.884 €/kW

Investment analysis > Energy cost

Year Electric energy (€/kWh)(VAT excluded)

1 0,1920 0,29

Environment and energy. 2006. (epp.eurostat.ec.europa.eu)

Calculation made on the basis of variation average index for domestic energy cost calculated for 2000-2006 (source Eurostat)

Average: +0,26% / year

Investment analysis > Cash Flows

Year0 1st 12th 20th

Incomes

Energy sale € - € - € -

Energy savings € 676,80 € 760,47 € 796,77

Incentives € 1.524,15 € 1.356,50 € 1.234,57

Total € 2.200,96 € 2.116,97 € 2.031,33

Costs

Operative -€ 100,00 -€ 100,00 -€ 100,00

Maintenance € - -€ 2.781,76 € -

Insurance € - € - € -

Total -€ 23.181,31 -€ 100,00 -€ 2.881,76 -€ 100,00

Balance € 2.100,96 -€ 764,79 € 1.931,33

Cash flows -€ 23.181,31 -€ 21.080,36 -€ 1.220,01 € 14.543,93

Discount rate 2% NPV +7684,4€

Rate of return 5,4%

Investment analysis > Cash Flows

-€ 30.000,00

-€ 25.000,00

-€ 20.000,00

-€ 15.000,00

-€ 10.000,00

-€ 5.000,00

€ 0,00

€ 5.000,00

€ 10.000,00

€ 15.000,00

€ 20.000,00

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Summary

Site location: Northern Italy Irradiation: 1058 kWh/kWp System power capacity: 2,94 kW System installation: roof integrated Investment cost: approx. 23.000€ Specific cost: 7.884 €/kW Incentive: 0,49€/kWh Investment rate of return: 5,4% Energy savings: ~ 3000 kWh/year Emissions savings: 2350 kg CO2/year