Battery Guide for Small Stand Alone PV Systems. IEA PVPS Task III

991223

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Lead-Acid Battery Guide for Stand-Alone Photovoltaic Systems

IEA Task III Report IEA-PVPS 3-06:1999 December 1999

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Battery Guide for Small Stand Alone PV Systems. IEA PVPS Task III991223

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CONTENTS FOREWORD ……………………………………………………………………………………………………………………. 5 SUMMARY ………………………………………………………………………………………………………………………. 6 1. INTRODUCTION…………………………………………………………………………………………………………… 6 1.1 Solar energy ……………………………………………………………………………………………………………………………. 7 1.2 Sun power into electricity…………………………………………………………………………………………………………. 7 1.3 Lead-acidbatteries all over the world ……………………………………………………………………………………….. 7 2. THE BATTERY – A ”CONTAINER” FOR ELECTRICITY …………………………………………………….. 9 3. A CLOSER LOOK INSIDE A LEAD-ACID BATTERY ……………………………………………………… 10 3.1 Positive electrodedesign…………………………………………………………………………………………………………. 10 3.2 Negative electrode designs………………………………………………………………………………………………………. 10 3.3Electrolyte…………………………………………………………………………………………………………………………….. 11 3.4 Cell cases made of moulded plastics…………………………………………………………………………………………. 12 3.5 Battery boxes for small systems……………………………………………………………………………………………….. 12 3.5 Standardised terminals and connectors……………………………………………………………………………………. 12 4. WHAT TYPE OF BATTERY SHOULD BE CHOSEN? ………………………………………………………. 13 5. BATTERY VOLTAGE CHARACTERISTICS …………………………………………………………………… 15 5.1 The higher the discharge rate – the lower the battery voltage…………………………………………………….. 15 5.2 Higher voltage with series connection………………………………………………………………………………………. 15 6. BATTERY CAPACITY – THE AMOUNT OF ELECTRICITY STORED………………………………….. 16 6.1 Capacity can differ from battery to battery ……………………………………………………………………………… 166.2 Design your system based on 80% of nominal battery capacity…………………………………………………… 16 6.3 How to size the battery for a certain system and load………………………………………………………………… 17 6.3 Higher capacity with parallel connection…………………………………………………………………………………. 18 6.4 Capacity will increase slightly in the beginning of operation………………………………………………………. 18 6.5 Temperature effect on capacity……………………………………………………………………………………………….. 18 7. CHARGING FILLS YOUR ENERGY STORAGE ………………………………………………………………….