Batteries
Battery considerations include the type of technology, cost, preferred voltage system, ambient temperature, maintenance requirements and battery location. Almost all home bank batteries are deep lead acid batteries, which can be regularly and deeply discharged. For lead-acid batteries, the first decision is whether to use a flooded battery that requires regular distilled water to be added, or a lead-acid battery with sealed regulating valve that may require no watering. Sealed batteries are more expensive and have a shorter life than flooded full size batteries, but this compensation may be worth it in cases where battery maintenance can not or does not want to be done.
Modern benchless battery packs are typically 24 or 48 V, which allows the use of smaller caliber cable from 12V systems, which have higher current for the same power level. Choosing a higher voltage battery also means wiring more batteries in series to increase the voltage, thus reducing the number of parallel battery strings needed for the same available power. This, in turn, helps reduce imbalances through the battery bank. If there are 12 V on loads that need to be driven, a DC to DC converter can be used to supply the correct voltage.
It is important to keep leaded batteries out of living spaces and all batteries should be protected from unauthorized access as they contain caustic chemicals and pose a shock and risk of burn if not handled properly. Choosing a place with moderate temperatures is critical to the longevity of the battery. For every 18 ° F increase in temperature of battery experiences, the number of cycles available reduces by half.
For example, if the battery has a power of 3,600 cycles at 77 ° F, it would then be expected to last 1,800 cycles, or about five years, if it is installed in a 95 ° F climate. At lower temperatures, a battery will win Lifetime, but its available capacity will decrease.
Maintenance requirements for all batteries include keeping the terminals and battery lids free from corrosion, dirt and debris. This helps keep electricity flowing through the entire battery bank. The battery must be charged at 100% once a week, keeping the batteries in discharged state can shorten their life. The electrolyte level should not expose lead plates to air. Flooded batteries also have to be matched, a controlled overload that is commonly done every few months.
Equalization helps to rebalance cell voltage and improves battery health by mixing the electrolyte, which can stratify over time. Ventilating explosive hydrogen gases from a battery case into the open air is very important. Passive ventilation can be achieved by the intake air vents installed in the bottom of a battery box that is combined with the highest outlet vents at the top. This allows the lighter hydrogen gases to rise up and out. Active ventilation by a DC fan can also be used.
Dimensioning a battery bank starts with load analysis. The battery needs to store the amount of energy needed for the daily loads. If loads have to work on some days where there is no sun available, then the battery bank has to be larger, known as days off. Beyond that, the batteries will yield more cycles the less they are extracted from them on a daily basis. For example, a battery that is discharged 20% can provide 3,300 cycles; If 80% is discharged, it can only provide 675 cycles.
Battery considerations include the type of technology, cost, preferred voltage system, ambient temperature, maintenance requirements and battery location. Almost all home bank batteries are deep lead acid batteries, which can be regularly and deeply discharged. For lead-acid batteries, the first decision is whether to use a flooded battery that requires regular distilled water to be added, or a lead-acid battery with sealed regulating valve that may require no watering. Sealed batteries are more expensive and have a shorter life than flooded full size batteries, but this compensation may be worth it in cases where battery maintenance can not or does not want to be done.
Modern benchless battery packs are typically 24 or 48 V, which allows the use of smaller caliber cable from 12V systems, which have higher current for the same power level. Choosing a higher voltage battery also means wiring more batteries in series to increase the voltage, thus reducing the number of parallel battery strings needed for the same available power. This, in turn, helps reduce imbalances through the battery bank. If there are 12 V on loads that need to be driven, a DC to DC converter can be used to supply the correct voltage.
It is important to keep leaded batteries out of living spaces and all batteries should be protected from unauthorized access as they contain caustic chemicals and pose a shock and risk of burn if not handled properly. Choosing a place with moderate temperatures is critical to the longevity of the battery. For every 18 ° F increase in temperature of battery experiences, the number of cycles available reduces by half.
For example, if the battery has a power of 3,600 cycles at 77 ° F, it would then be expected to last 1,800 cycles, or about five years, if it is installed in a 95 ° F climate. At lower temperatures, a battery will win Lifetime, but its available capacity will decrease.
Maintenance requirements for all batteries include keeping the terminals and battery lids free from corrosion, dirt and debris. This helps keep electricity flowing through the entire battery bank. The battery must be charged at 100% once a week, keeping the batteries in discharged state can shorten their life. The electrolyte level should not expose lead plates to air. Flooded batteries also have to be matched, a controlled overload that is commonly done every few months.
Equalization helps to rebalance cell voltage and improves battery health by mixing the electrolyte, which can stratify over time. Ventilating explosive hydrogen gases from a battery case into the open air is very important. Passive ventilation can be achieved by the intake air vents installed in the bottom of a battery box that is combined with the highest outlet vents at the top. This allows the lighter hydrogen gases to rise up and out. Active ventilation by a DC fan can also be used.
Dimensioning a battery bank starts with load analysis. The battery needs to store the amount of energy needed for the daily loads. If loads have to work on some days where there is no sun available, then the battery bank has to be larger, known as days off. Beyond that, the batteries will yield more cycles the less they are extracted from them on a daily basis. For example, a battery that is discharged 20% can provide 3,300 cycles; If 80% is discharged, it can only provide 675 cycles.
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