In  Solar

Battery Storage. For when the sun doesnt shine.

By [email protected] | December 22, 2020

A battery stores electrical energy in a reversible chemical reaction. The renewable energy (RE) source (PV, wind, or hydro) produces the energy, and the battery stores it for times of low or no RE production. Most batteries employed in renewable energy systems use the same electro-chemical reactions as the lead-acid battery in your car. But, unlike your car battery, they are specifically designed for deep cycling (the many times that a battery will go from full charge to needing another recharge back to full again).

Most renewable energy systems have batteries which store between ten and hundreds of times more energy than a car battery. This doesn’t guarantee you will have a consistent performance with batteries.

There are many brands and types of batteries available for your solar PV energy system. It is important to find the right battery for your situation and wallet. The two most common batteries are the Lithium Ion and the Gel/AGM batteries. With proper care, Solar PV system batteries have a lifetime of five to ten years, but there are more expensive Lithium Ion batteries that are warranted to last ten to twenty years.

Battery capacity is rated in amp-hours (Ah). This rating is more typical of the Gel/AGM batteries and is used as a method of determining the differences in the batteries. 1 amp-hour is the equivalent of drawing 1 amp steadily for one hour, or 2 amps steadily for half an hour. A typical 12 volt system may have 800 amp-hours of battery capacity. This battery can draw 100 Amps for 8 hours if fully discharged and starting from a fully charged state. This is the equivalent of 1,200 watts for eight hours (watts = amps x volts), or about the same power consumed as running a small hair dryer for eight hours.

Lithium Ion batteries are typically rated using kilowatts as they are packed with much larger storage capacity than Gel/AGM batteries. Importantly, another distinction to take note of is the output voltage on a Lithium Ion battery as this would need to be compatible with the inverter that you choose.

However, completely discharging your battery decreases its longevity, and can ruin it in short order. Most home power users will only tap into a portion of available capacity to keep their batteries alive longer. Opinion varies as to the appropriate depth of discharge, but most agree that 50% (and many say 30%) is the maximum a battery should be routinely discharged. Never go below 80% depth of discharge. 50% means that the above 1200 watt hair dryer would only be used for 4 hours instead of the 8 indicated by the maximum capacity of the batteries.

Batteries typically are encased in plastic and need to be wired together in series and parallel strings by the installer. Some larger batteries are pre-wired and encased in steel containers/cabinets.

Batteries do not belong inside your living space. They have dangerous chemicals in them, so they must be contained to avoid spills. They also put out hydrogen and oxygen gas while being charged, so they should be vented to the outdoors. Their tops and connections must be periodically cleaned to avoid energy losses. Finally, they need to be “equalized” with an occasional controlled overcharge to keep the individual cells at equal states of charge.

Here are a few battery🔋 options from our store that you may want to consider:

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