Designing for a large continuous load (ductless mini split)

This Zomeworks 9 top passive tracker follows the suns path throughout the day to gain the modules full potential current from sun up to sundown.  It was incorporated in an existing off grid system when the owners decided to add a ductless mini split system for heating and cooling.  We also replaced a large forklift lead acid battery(FLA) with Aquion sodium-ion batteries.  The Aquion batteries are the most eco friendly on the planet and can tolerate long periods of discharge without damage, something that will drastically shorten the life of a typical lead acid battery.  This relieves a lot of anxiety of living off the grid and eliminates the need for long emergency generator run times which typically are needed to de-sulfate an FLA battery bank.  They can be cycled to 100% depth of discharge(DOD) without damage, and have five times the cycles of a typical L-16 lead acid battery. And when considering the loss of life of lead acid batteries due to sulfating plates from lack of a constant float charge and maintenance, the life expectancy is even longer.  

When sizing an FLA battery, it is recommended to size it to 50% DOD.  With Aquion batteries, because you can cycle them so low, the size of the bank is around half of the size of an FLA.  

 

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Secure Power Supply and room for backup additions

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We finished up this 54 module grid tie system on The Bansley's Berkshire Ridge Farms in Harrison, Arkansas back in February.  We were delighted to provide affordable green energy to this free range, non-GMO hog farm.

The two SMA SB6.0-US inverters pictured have a unique feature of providing power in the daytime when the power goes out without the need for batteries. This feature can be used to run lights or charge batteries for power tools, or may be used to power a larger battery charger for a separate UPS system.

This system can also be upgraded to a fully functioning off grid system with additional components later on down the road, leaving all options on the table.  Other grid tie brands offer the same, but currently the full potential output power, battery selection and size is limited.