Service stations go solar
by K Chernyshov, BP Amoco, UK

Two hundred of BP Amocoís retail service stations in nine countries are now powered by solar energy.

The PV service station in Perivale, London
Introduction

Grid-connected PV systems have been incorporated into the routine schedule for BP Amocoís new and rebuilt service stations in the UK, the Netherlands, Germany, Austria, Switzerland, Spain, Portugal, Australia and Japan. These countries were selected on the basis of:

  • solar energy availability;
  • significant environmental awareness in the community;
  • ease of connection to the grid;
  • presence of a de-regulated electricity market;
  • potential solar markets;
  • presence of BPís service station network.

Pilot projects are also being conducted in the USA, Malaysia, New Zealand and France.

The work is part of BP Amocoís $50 million (where $ is the US dollar), 3.5 MW Plug in the Sun programme. The programme aims to demonstrate that the company is committed to addressing climate change, develop the solar business by driving down costs and raising awareness of solar energy in urban applications, and complement BP Oilís Clean Fuels, Clean Cities programme.

Pilot phase

The feasibility of designing, building and installing PV systems for service stations was undertaken during a one-year pilot phase. A standardised design was determined and a comprehensive design guide was produced for subcontractors, covering technical requirements for design, safety, obtaining the necessary permits, construction, grid connection and monitoring.

Figure 1: Power generation and consumption at a retail service station in Seville, on a typical July day
Implementation

In April 1999, the global programme was launched at Londonís first PV service station in Perivale. Since implementing the programme: installation costs have been cut by more than one third; electricity generation of the installations is meeting predictions; regular subcontractors have been able to expand their knowledge and experience of PV systems; and many utilities have been given their first experience of handling a grid-connected PV installation.

The systems

The size of each installation depends on the size of the canopy on which it is constructed. An average, 220 panel installation generates up to 25,000 kWh/year of electricity, enough to power the fuel pumps and lights under the canopy. Each system uses BP 585 solar laminates, which utilise high-efficiency solar cell technology. The modular design concept uses 12 laminates connected in series on a support frame mounted on the service station canopy. Each laminate is inclined at a shallow angle, typically 5Ė10o, which enables the array density to be greatly increased and reduces installation costs with only a minor impact on solar performance. Inverters (dc to ac) are mounted on each array of 12 laminates. This cost-saving design has the following advantages:

  • the design is standardised, regardless of canopy size or orientation;
  • there is a high density layout with very little shading;
  • there is a 60% reduction in wiring cost;
  • frameless PV laminates are used instead of more expensive framed PV modules.
Grid connection

The PV installation is designed for connection to a three-phase system operating at a nominal supply of 230/400 V at 50 Hz. The local utilityís permission is always sought before the PV system is installed; local regulations vary between utilities and some have requested that additional protection devices are installed to ensure that their network and personnel are protected in the event of a fault.

Monitoring and Maintenance

Each installation has a fault-finding system that can detect a problem occurring in any of the inverters; to date, the observed failure rate is less than 1%. The system can also store key operating parameters, such as energy generated, operating hours etc, for later analysis. In some cases, the monitoring system is fitted with a modem to enable it to be interrogated remotely.

A PV monitoring system is mounted in the service stationís shop to inform staff of system performance. A customer display sign provides information on the total cumulative energy generation and explains the aims of the programme to the estimated 0.5 million people that visit a typical service station in a year.

The PV installations are virtually maintenance-free and the solar module output is guaranteed for 20 years. The angle of the panels means they are washed by rainwater; practice shows that cleaning the panels at regular intervals does not affect performance significantly.

Energy generation

The energy generation of an installation depends on available radiation, ambient temperature and orientation of the canopy.

Table 1 shows the specific electricity generation values for 12 x 85 W (peak) laminates for the systems in different locations. Figure 1 (page 17) shows the electricity generated by the PV installation and the electricity consumed at a service station at Seville in Spain, on a typical day in July. Annually, around 15% of the total electricity is generated by the PV system.

Table 1: Comparison of energy generated in different countries

Country

City

Energy generated
(kWh/year/array)

Austria

Graz
Innsbruck
Vienna

992
1075
958

Germany

Berlin
Bonn
Hamburg
Munich

642
825
608
1008

Luxembourg

Luxembourg

892

Netherlands

Amsterdam

917

Portugal

Lisbon
Porto

1583
1433

Spain

Barcelona
Madrid
Seville
Valencia

1108
1425
1475
1392

Switzerland

Bern
Geneva
ZŁrich

975
1042
933

UK

Birmingham
Edinburgh
Liverpool
London

792
767
825
758

Japan

Kagoshima
Osaka
Sapporo
Tokyo

1192
1017
1100
1108

Australia

Adelaide
Brisbane
Darwin
Melbourne
Perth
Sydney

1375
1300
1525
1208
1508
1250

Conclusion

The pilot phase and implementation programme have provided valuable lessons for both suppliers and users of solar energy.

For more information contact Clive Sinnott, BP Solarex, Chertsey Road, Sunbury on Thames, Middlesex TW16 7XA, UK. Tel: +44 1932 764800; Fax: +44 1932 763414; e-mail: sinnotcc@bp.com

The CADDET Renewable Energy Newsletter is a quarterly magazine published by  the CADDET Centre for Renewable Energy at ETSU, UK.

The articles published in the Newsletter reflect the opinions of the authors.  They do not necessarily reflect the official view of CADDET.

Enquiries concerning the Newsletter should be addressed to Pauline Toole, Editor, CADDET Centre for Renewable Energy, ETSU, Harwell, Oxfordshire OX11 0RA, United Kingdom. Tel: +44  1235 432968, Fax: +44 1235 433595.