Seite - 127 - in Clean Water Using Solar and Wind - Outside the Power Grid

Handling variable production 127 are carefully managed their lifetime may be only three years, which is much shorter than other components in the energy system. If the capacity of discharge is limited to 20% then the batteries may last five years. There are three main types of lead-acid batteries: flooded, AGM (absorbent glass mat) and gel. In a flooded battery the electrolyte is in liquid form (sulphuric acid diluted in water) while in the AGM and gel the electrolyte cannot flow. The liquid in the flooded battery must be maintained, while the latter two do not need maintenance. They can also be used in any orientation. Traditional car lead-acid batteries are usually not the best option for solar energy storage. Unfortunately, they are the type of batteries most commonly used in the developing world as they are cheap and easily available. A car battery is designed to produce a high current over a short time in order to provide power to start an engine. Typical loads powered by solar energy, on the contrary, usually require low currents over an extended period. The problem is not the battery chemistry; it is the design of the batteries. A traditional car battery will not survive for long if it is discharged more than 50%. Deep-cycle batteries are better for solar energy uses as they have larger electrodes than car batteries. All three lead-acid battery types are available for deep cycle. A flooded battery has a price of around 70–80 USD/kWh while AGM and gel batteries are more expensive, around 260–330 USD/kWh. At first glance the use of a car battery for the storage of solar- generated power may look more attractive than other options. However, in the long run this choice will almost certainly turn out to be wrong. 10.3.2 Lithium batteries We use lithium batteries in our mobile telephones. Such batteries use some form of lithium chemical composition. They are lighter and more compact than lead-acid batteries. They can be discharged more, are Traditional car lead-acid batteries are usually not the best option for solar energy storage. Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user