Is charging batteries using DC from the solar array ‘smart’?

Enphase AC Batteries

There are batteries on the market that use Direct Current (DC) from a solar array to charge them, but is this ‘smart’?    The problem with this approach is that dangerous unprotected DC cabling is required from the solar array on the roof, through the building, to the battery.  This unprotected DC cabling and DC isolators have been a source of fire and shock with hundreds of homes and businesses across Australia.

AC solar systems and AC batteries have been developed to eliminate dangerous DC cabling making solar systems and energy storage significantly safer, more reliable, more flexible and provide greater performance.

It is believed by some that converting DC from the solar array to AC and back to DC at the battery is inefficient because of the losses in the inverter.  However, this is not necessarily true.  Inverter efficiency is approximately 97% with only 3% of energy lost converting from DC to AC.  This lost energy is easily made up with the improved Round Trip Efficiency (RTF) of AC Batteries by having a modular approach and multiple Battery Management Systems.

Large DC batteries commonly have a large number of cells within the battery enclosure managed by one large Battery Management System (BMS).  Cells in the battery that underperform, over time, can negatively affect the performance of the whole battery.

The Enphase AC battery storage system consists of a number of batteries that are physically small in size, very powerful, modular and operate independently.  They are wired directly into the switchboard  (230V AC) with multiple batteries being added to meet the energy storage needs of the specific location.

Each AC battery has a small number of cells managed by their own Battery Management System (BMS) therefore operating independently at their highest efficiency over the life of the batteries.   Having multiple separate BMS systems allows the total energy storage system to be more efficient than a large single battery with only one BMS.  This efficiency improvement eclipses the 3% lost due to conversion from DC to AC and there are no dangerous DC voltages in the system.  The result is better performance over the life of the batteries and safer with no dangerous DC voltages.

To read more about the Enphase AC Battery click here


  • Email

  • info@acsolarwarehouse.com

  • Phone

  • Australia 07 4028 3979

  • New Zealand 09 222 2262

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  • PO Box 408, Cairns

  • Queensland 4870

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  • 310 Spence Street, Bungalow

  • Queensland 4870

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