Intelligent Energy Storage Reveals Market Demand

JuiceBox Energy's first residential solar energy storage system has been installed in a Californian home.
Published: Thu 28 May 2015

With all the hype around Tesla’s new battery announcement, one may be forgiven for thinking they are a first when it comes to home energy storage. In fact several companies are already active with similar products in the United States, and one of these, JuiceBox Energy, has just installed its first residential energy storage system in a California home.

JuiceBox Energy’s solution, which became available in April, is an 8.6kWh lithium-ion battery system. [Engerati-Home Energy Storage Is Here] Aimed primarily at residential users, the Korean-manufactured batteries utilize the same lithium-ion cells that are used in electric vehicles and laptop computers. The system also comes complete with an in-house developed battery management and control system and has out-of-the-box integration with a Schneider Electric XW+ inverter/charger.

Installation in California

The JuiceBox storage system installation, which was financed through the national PACE (Property Assessed Clean Energy) energy efficiency finance programme, is on an exterior wall with a 5.9kW roof mounted solar PV array. With the system, the customer is now able to shift excess solar from day to evening hours, minimize the peak load drawn from the grid during the day and has back-up capability to power up to 5.5kW of continuous household load.

“This production model is the culmination of our vision to deliver high quality, automotive grade energy storage systems to the residential markets,” Neil Maguire, CEO of JuiceBox Energy, told Engerati in an interview.

With the option for an AC or DC coupled configuration, the system is designed for both new and existing solar installations. With web connection it is also adaptable to shifting energy markets and rate structures, and requires little or no customer intervention.

Costs of home energy storage

Inevitably comparisons will be made between the various home storage systems and in particular with Tesla’s. [Engerati’s Week In Energy – Powerwall For All]

The JuiceBox system is available to certified installers at a price of US$9,900, with the inverter/charger purchased separately. For comparison, the Tesla system is priced at US$3,000 for the 7kWh system and US$3,500 for the 10kWh system, also excluding the inverter and any other items that might be required.

“There’s not a lot of definition of what else is needed with the Tesla system as the details of the inverter and other external components haven’t been announced yet,” Maguire comments.

He also notes that while the JuiceBox system has a 5.5kW discharge, the Tesla batteries have a 2kW discharge, severely limiting the loads that can be run with an individual unit.

“We achieve this rating with a combination of the inverter and the component selection,” Maguire says, adding that the JuiceBox battery is rated for 4,000 cycles, corresponding to a more than 10-year lifetime with a daily discharge.

Thereafter, the battery can be fully recycled.

Potential for home energy storage

Maguire says there has been a lot of interest in home storage and the company is currently working with around 30 installers.

“Feedback from these installers suggests that between 10-20% of existing solar customers are a good match for energy storage. There are several reasons – they either don’t want brown electrons in the evening, or they want some amount of resiliency or have critical loads to back up.”

With approximately 1 million residential solar PV installations in the US, that corresponds to up to 200,000 potential storage installations – in addition to a potentially higher proportion of new solar installations.

In addition to the US – and so far primarily in California, Arizona, Hawaii, New York and New Jersey – Maguire says there has also been interest from Australia, South Africa and Europe.

Utility participation in home energy storage

Maguire also comments on a growing interest in home energy storage from utilities, saying that one of the design features in the JuiceBox system from the outset was to enable utilities to participate in demand response and other aggregated storage programmes.

“Several utilities are asking for systems so they can see how it operates, and have expressed interest in doing a perhaps 100-home project to test charge and discharge in response to real-time pricing signals.”

Notwithstanding the potential of home energy storage, Maguire reminds that it is a premium product and as such, comes with a cost – and one that consumers are clearly prepared to pay for self-consumption and back-up power, over and above the savings from a reduction in their electricity bills. Clearly how these costs will pan out will be influenced in no small measure by Tesla and the extent to which its solutions live up to the hype.