Now that utility providers have implemented time-of-use billing with expensive peak and inexpensive off-peak times, many homeowners are exploring the possibility of using solar batteries to store power in off-peak times to offset the cost of electric usage at night during peak demand times. Since more states are also opting to end net metering (which allowed you to sell your solar-generated power back to the grid) the popularity of home battery backup systems will only continue to grow. Now the amount of electricity your home uses will determine the size of the battery needed to power your home in the event of a power outage or during peak electric demand, the type of batteries solutions available vary. 

A home battery backup system was traditionally a lead-acid battery bank connected to an off-grid solar battery charger and battery inverter, with all of these components being separate. There were wet-cell lead-acid solar batteries and there were sealed gel lead-acid solar batteries, both well known for their reliability (as long as their depth of discharge is limited to 40-50% of the battery' capacity)  and for being bulky and quite heavy.

Recent advancements in Lithium-ion (Li-ion) technology have made this the dominant option for most solar battery systems. This is the same battery chemistry that exists in cell phone batteries and computer batteries. The biggest advantage of Li-ion batteries is that they can be discharged to almost 100% of their total storage capacity with a greater energy density per square foot and per pound of weight.

However, a safe, non-toxic lithium-ion solar battery chemistry called lithium iron phosphate battery (LiFePO4) is gaining popularity as an ideal solution for solar backup power. This technology is more expensive, but this new shift is occurring as more homeowners consider the advantages behind this type of storage system. Unlike other battery technology, LiFePO4 batteries can operate in a partial charge state without any degradation to performance or life. But the main benefit of using a LiFePO4 technology for your solar or back up system is the total number of cycles they provide. These batteries are designed to provide between 7,000 - 8,000 cycles, even up to 80% depth of discharge each cycle. This can equate to over 20 years of use even if they are deeply cycled every single day!

Solar battery systems can either be AC or DC-coupled. With AC coupling, the power generated from your solar panels is converted through a grid connect inverter from DC to AC and is then converted by the battery inverter and then stored in the battery as DC power. When power is needed, the battery inverter converts the DC power from the battery back into AC power and supplies it to your home. 

With a DC-coupled solar battery, the power generated from the solar panels is directly fed into the battery through a solar battery charger that regulates the charging of the battery. Conversion isn't necessary because solar panels natively produce DC power