Stationary Storage: Time shifting solar energy to meet peak demand

Stationary Storage

Posted 5.19.2016 in Articles

Like all product purchase decisions, the higher initial costs for a quality product may be offset by lower operating costs or longer life, so be careful to calculate and discuss total cost of ownership with your system designer

 

Not all solar systems need batteries, but when they do, two types of batteries are used: lead acid and lithium-ion.
 Lead acid batteries are less expensive, but usually don’t last as long as the more expensive lithium-ion. Number of charge cycles, maintenance, physical dimesions and placement location are some of the other issues to be considered when weighing the trade off of up-front cost versus total cost of ownership (TCO).

 

Lead Acid Batteries

Lead acid batteries can be divided into two categories: flooded and sealed/valve regulated. The two types are both made from lead plates and sulfuric acid. Sealed batteries are divided into two types: gel and absorbed glass mat (AGM). In gel batteries, a thickening agent is added to turn the electrolyte from liquid to gel. In AGM cells, a glass matrix is used to contain the liquid electrolyte. While charging, they put out hydrogen and oxygen gas, so they need proper ventilation. Lead acid batteries require maintenance. Their tops and connections must be periodically cleaned. Flooded lead-acid batteries must also be routinely topped off with distilled water. Most lead acid batteries have a cycle life of between 300-500 cycles.

 

Lithium Ion batteries

Lithium ion batteries usually have a much longer cycle life than lead acid batteries. Homeowners can expect between 2,000-5,000 cycles. Lithium ion batteries can be stored upright or on their sides and don’t need to be housed in a vented compartment. Working with a knowledgable system designer and installer will help you make sense of the available options and technologies, and a less complicated buying decision.

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