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Photovoltaic systems

A PV system converts sunlight directly into electrical energyIt produces direct currentA PV system consists of:Photovoltaic cells connected into modules and encapsulatedModules grouped into panelsPanels groups into arraysA power conditioning unitBatteries. What is a Photovoltaic system? .

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Photovoltaic systems

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    1. Photovoltaic systems

    2. A PV system converts sunlight directly into electrical energy It produces direct current A PV system consists of: Photovoltaic cells connected into modules and encapsulated Modules grouped into panels Panels groups into arrays A power conditioning unit Batteries What is a Photovoltaic system?

    3. …but production is significantly smaller when cloudy. Also functions without direct sunlight

    4. What can be expected from PV systems?

    5. Advantages Environmental performance: emission-free in use “Fuel” delivered free, by nature Easy to install, modular technology install as small or as large as needed More modules can be added later on Low maintenance Long life span Disadvantages Off-grid system needs to be combined with a back-up or storage system to secure supply High initial investment cost Substantial surface required

    6. Off-grid systems For modest consumption or where connection to the grid is difficult Battery needed for storage Over 80% of PV systems in Mexico, Norway, Israel, Canada, Sweden, Australia, … Also used for calculators, emergency telephones, space technology,… Grid coupled system: Surplus electricity is put on the grid Converter is needed to transform direct current into 230V alternating current Over 80% of systems in Germany, Japan, UK, Netherlands, Denmark, … Two current practices

    7. Two main installation methods Mounted systems E.g. Stand-off mounted, roof-top Ground-mounted, rack or pole Patio cover Advantages for lower cost, more flexibility in modules and easier to replace Integrated systems E.g. Roof integrated PV products or roof slates Façade integrated Low visual impact

    8. Two main technologies Silicon Higher efficiency Expensive raw material Energy intensive process 93% of today’s market

    9. Operating principle of the silicon system (1/2) PV arrays are made out of coupled solar cells small sheets of silicon with metal contact strips protected by vacuum behind glass When sunlight strikes, light particles (“photons”) knock electrons free from silicon atoms Internal electrical field pushes electrons out of the cell one surface becomes negatively charged, opposite surface becomes positive An electrical current is created by connecting the positive and negative sides

    10. Operating principle of the silicon system (2/2)

    11. Efficiency… … is determined by percentage of solar energy converted into electrical energy. Depends on the type of silicon: Mono-crystalline: 12 – 16% most expensive, life span > 20 years Polycrystalline: 11 – 15% easier to produce, life span > 20 years Amorphous: 6 – 8% shorter life span, used for watches and calculators Cell efficiency also depends on temperature Further losses occur in wires, inverter and storage systems

    12. Some typical figures Annual horizontal irradiation: 1000-2000 kWh/m2 per year Annual PV electricity production: 100-200 kWh/m2 panel surface Annual electricity consumption: 3500 to 4000 kWh per family Just a family’s domestic electric demand already requires a surface of 17 to 40 m2 But: PV produces about 30 times more energy per square meter than bioenergy (source)

    13. Current potential for installers PV systems have large potential Sales increase by approximately 35% each year Strong incentives promote PV deployment Not yet widely adopted

    14. Prospects Investment costs have reduced by a factor 2 during past 10 years (due to decreasing manufacturing costs through volume production) Increasing performance of silicon cells European Technology Platform has ambitious objectives for 2030 Significant investment in thin film R&D

    15. Requirements for PV system of the future According to PV-TRAC (Photovoltaic Technology Research Advisory Council of the European Commission): Efficiency of 25% Life span of 40 years Pay back period of less than one year Build with abundantly available, non-toxic materials Since silicon is scarce, research on thin film technology is the best option (but silicon cells are growing thinner as well, and new production methods for silicon are being explored)

    16. Round-up Converts sunlight into electrical energy Produces direct current Surplus electricity can be put on the grid for the time being Investment cost is still high Strong incentives are available High potential, provided technology development can significantly reduce costs

    17. Further information PV Technology Platform http://www.eupvplatform.org/ IEA Photovoltaics Power Systems Programme http://www.iea-pvps.org/ DTI Good Practice Guide http://www.dti.gov.uk/files/file29238.pdf?pubpdfdload=06/795

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