30th March 2016

​The high-tech battery that benefits fans of solar energy


You’d be forgiven for assuming Mark Kerr was the proud owner of a sought-after piece of art, judging by the impressed sounds from visitors to his home.

Instead, he’s the proud owner of state-of-the-art battery technology, installed in his home to further benefit from the energy generated via the solar panels on his roof.

In a nutshell, it’s a slick home energy system that increases self-consumption.

Mark, who has been an electrician for nearly 30 years, was one of the first people recently selected to have a Tesla Powerwall installed in his four-bedroom detached house in Cardiff, after having solar panels fitted in 2010.

Thanks to an advance in battery technology, the installation means the Powerwall will store the energy generated from his solar panels while Mark and his family are out of the house all day and they will benefit when they get home in the evenings.

Otherwise, without this clever battery, the energy generated during the working day is merely fed back into the grid if the house is empty. Which seems a bit of a waste.

SolarEdge is the inverter technology which controls the DC power from the Photovoltaic (PV) panels on a householder’s roof into the home. There is a power optimisation unit under each panel, allowing each panel to be tracked and monitored online.


Mark told Acre: “Energy can be costly in the evening so harnessing our solar PV is essential to bringing our electricity bill down.

“The Tesla battery can only be switched using a SolarEdge system in the UK at the minute, hence the importance of having SolarEdge. The coupling is DC to DC to minimise loss of energy. The battery itself can be monitored online by Tesla, SolarEdge and the user.”

Current generation home batteries tend to be more bulky, expensive to install and maintain. However, the Powerwall battery technology can power a home safely and economically.

The sleek design, which utilises powerful lithium ion technology, sits neatly on the wall of Mark’s study. It’s bigger – but less bulky – than a boiler, and quietly stores the energy generated from the sun.

And Mark couldn’t be happier since he got his.


“I often get asked ‘how much money does the battery make you’? It’s not about what it makes you, in my opinion its more about enhancing your installation to maximise on your savings based on what you will store and use later which you would have exported. Also it’s a lifestyle and very eco friendly for the environment.

“I also get asked if there was a power cut in the evening could we use the power from the batteries and the answer is no. It is for storage only and not back up on grid failure,” he said.

In the daytime it accumulates any unused solar PV generation and makes it available to the home in the evening, solving the problem of peak solar production and peak demand being at different times of the day/night.

It claims to be less reliant on the national grid and allows householders to use up almost all of their generated energy which in turn brings in cheaper energy bills.

“When the Powerwall came out, no one knew how successful it was going to be. You have the solar panels and the battery topping up. You can tap into the battery at any time, not just at night. And the SolarEdge system is monitored 24 hours a day so you can see what you are importing.

“It’s ergonomic and slick due to the shape. It’s a nice piece of structure and all my friends, male and female, say it looks amazing. It’s revolutionary!” he added.

“Why has it taken so long to develop this market? Batteries I suppose have always been expensive so maybe mining the minerals has got cheaper using machines etc, then there is the technology to control and maximise efficiency. A safe system to operate it and the cost to the consumer. All major contributors I would think.

“I have now had the Tesla installed for over a month. It has been very beneficial to our home, supplying it in the evening with power that we would have normally exported to the national grid. It is reducing our bills. It is a bit early to give stats on this though as it is still only new to our home. I am hoping however that I will start to use 90 per cent generation from my solar now and reduce my electricity bill by 80 per cent.”

The Powerwall, provided by Solar Plants, is guaranteed for 10 years.

How it works

A typical Powerwall system includes solar panels, an inverter for converting electricity between direct and alternating current, a meter for measuring battery charge, and in backup applications, a secondary circuit that powers key appliances.

Solar panels convert sunlight into electricity that charges the Powerwall and powers your home during the day. Without solar the Powerwall can strategically shift energy consumption.

The home battery is then changed with electricity generated by solar or from the grid.

The inverter converts direct current electricity from solar panels, the grid and Powerwall into the alternating current used by your home’s lights, appliances and devices.

All Powerwall installations require a compatible inverter. To maximize solar consumption, a meter is also installed to measure solar production and home energy use.

Electricity from the inverter is sent to your home’s electrical panel. For applications without solar, and night time, electricity generated by the power company is sent from the electrical panel to the inverter to charge the Powerwall.

Some backup installations may require a secondary electrical panel containing the critical appliances and outlets you wish to back up. An electrical switch automatically activates the backup panel during a power cut. When installed with solar, this switch can keep your solar producing during a power cut.