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:
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.
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.
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 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 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.
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.
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: email@example.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.
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