Final brick in the wall

Powerwall makes truly green future a reality with solar energy storage

Efforts by the billionnaire Elon Musk to turn consumers onto sustainable energy took a step forward last week with the first ever UK installation of a Tesla Powerwall, in a home in Wales.

Powerwall has been heralded by Tesla, for which Musk is the CEO, as the ‘missing link’ in solar energy production. The system enables homeowners to store solar energy that has built up during the day for use when they come home in the evening.

The 7kWh system in Wales was installed in the utility room of a modest terraced house in Cardiff, hooked up to 16 solar panels on the roof. A high capacity lithium-ion battery stores electricity, generated by the photovoltaic panels during the day, for use later for lighting, heating, powering electronic devices and so on.

Mark Kerr, electrician and self-confessed techie – and the homeowner – told the Guardian: ‘This is the future. For me this is the logical next step. We have solar panels but we need a way to make best use of the power they produce. My family and I are all out in the day, and we are not making use of the enormous amount of clean energy that our solar panels produce. The battery will allow us to store the energy to use it in the evenings.’

A high capacity lithium-ion battery stores electricity, generated by the photovoltaic panels during the day, for use later

Kerr says his existing solar panels have reduced his electricity bills by 20% and the addition of Powerwall could lead to a total 80% reduction. The system cost Kerr nothing and was installed by Solar Plants of south Wales as a trail before offering the system to more customers.

However, the eco credentials of Powerwall could be held back by its current high cost. At the launch event in May, Musk said it costs $3,500, but that does not take into account the cost of the inverter switchgear needed to make it work and installation. Some experts have suggested it could be more than a decade, the length of a Powerwall warranty, before it can pay for itself.

Powerwall is available as a 7kWh daily cycle unit – most suitable for hooking up to solar – or a 10kWh weekly cycle unit, which is optimized to provide backup power when the grid goes down.