Electricity created by residential solar panels can now be more easily stored for later use, such as when the sun goes down or during a power outage.

A new generation of lithium-ion batteries that are totally sealed and wall mounted in a similar fashion to a flatscreen television, are being introduced to Bermuda.

While it has always been possible for householders to store excess electricity from their solar system using old-style lead-acid batteries, they faced drawbacks in doing so, such as the amount of space needed, concerns about fumes and ventilation, and relatively short battery life.

But now residents can install cleaner and longer-lasting lithium-ion batteries at their home and immediately begin storing spare electricity to be used when required. The batteries are available from Bermuda Alternative Energy.

Nick Duffy, divisional manager of BAE, which is part of the BAC Group, pointed out that while the capabilities of the batteries is impressive, they are not able to meet the entire energy demands of a household.

However, they allow some energy to be stored and used for a limited number of home appliances during the hours of darkness to supplement the home’s mains electricity.

And during power outages, such as after a hurricane, it would be possible to run a number of key appliances, such as a water pump, LED lightning and a refrigerator, using solar panel electricity stored in the batteries during the day.

“Say you lost power for three days, you could subsist on this. You could take enough energy from the battery for basic necessities,” Mr Dufy said, liking it to having a 6kW emergency generator.

“But it’s not there to run your whole house,” he said, explaining the batteries were designed so that a householder can save unused kilowatt hours generated by their solar system during the day, then use that power in the evening as an addition to their supply from the Bermuda Electric Light Company.

Financially it can prove to be beneficial, because selling excess solar energy back to Belco during the day attracts a lower price per kilowatt hour than the price Belco charges customers who buy its electricity.

Therefore, having some of your own daytime-generated electricity stored for later use means buying a little less from Belco when night falls.

The storage battery is marketed as a “new age home appliance” and can be installed in various locations, such as a kitchen wall, inside a closet or garage, or outdoors providing it is protected from direct sunlight and rain. The 10 kWh storage units are 29 inches wide, 36 inches tall, and eight inches thick. They weigh 214lbs — hence the need for them to be securely mounted.

A SolarEdge invertor acts as the control unit of the home solar system. For example, it can ensure electricity from solar panels that is not used in the home during the day is diverted to the storage battery, then, when the storage capacity is reached it directs excess electricity from the panels to be exported for sale to Belco.

Explaining why BAE held off on providing a storage option using older style lead-acid batteries, Mr Duffy said: “We made the decision to say we would not involve ourselves in lead-acid batteries, because being involved in greener energy choices, the two things do not go together.”

Instead, the company waited for the arrival of the new lithium-ion batteries, and crucially the introduction of warranties that would cover customers in Bermuda. The batteries come with a 10-year warranty.

BAC has a longstanding relationship with the companies involved in the compatible technologies. The solar modules, or panels, it sells are made by Panasonic and LG, while the control unit, or inverter, for the solar systems are made by SolarEdge.

The batteries are made by LG Chem, which is a subsidiary of LG, and the SolarEdge control unit is the only one certified to work with batteries.

“Because of our business with SolarEdge and LG we have been able to get the batteries and put the warranties together,” said Mr Duffy.

He added: “We are excited to have this. It’s not a panacea to run your house, but it gives you a nice back-up.”

BAE has a website at www.bae.bm