Twenty years’ ago, Professor Sue Roaf had an ambition to power her home from the energy generated by the sun.

Sceptics dismissed her, scoffing that solar photovoltaic and solar thermal technologies couldn’t possibly work in the UK – you’d need the sun to shine. Nevertheless Roaf pressed on, adamant that solar would sit at the heart of her visionary Oxford Ecohouse.

The design of the Oxford Ecohouse was innovative from the beginning. The entire form, orientation and structural shading of the home was designed so that the house stayed warm in the winter and cool in the summer. However, it’s the roof-integrated 4kWp solar array that marked the most radical break with tradition.

In 1995, the 4kWp BP Saturn 585 PV modules alone cost £18,000, with the aluminium support structure costing an additional £10,000. All in all, the rooftop array was expected to payback in 66 years.

Thankfully, Roaf was not dissuaded by the high cost and long payback times of the UK’s first (and probably still one of the best looking) residential solar installation. Instead, Roaf lit the fuse for the modern explosion of solar PV.

The UK now has over one million roofs generating their own carbon-free electricity thanks to solar PV – cost declines and government support mean that the payback time of a modern solar array is around 10 years.

“It was hard to believe then that solar was going to be the thing that drives changes in the energy system in the way that, I don’t think anyone was expecting – certainly not 10 years’ ago,” explained Doug Parr, chief scientist for Greenpeace UK, who was on hand to paint the attic of the Oxford Ecohouse 20 years earlier.

Doug Parr addresses attendees at a party to market 20 years since solar was installed at the Oxford Ecohouse

Parr continued: “And yet, as we look around the world, more and more places are finding solar power as something that isn’t ‘nice to have’, it’s something that just makes sense. It’s always made sense from the point of view of fighting climate change and fighting air pollution. But now it starts to make sense as part of an energy system where investment should logically be doing something else.

“Last year, private bank UBS told its client that all centralised power stations were going to be redundant in 10-20 years, and that the smart money would be on decentralised power like solar – combined with storage and an electric car and in Southern Europe before 2020 it will make economic sense to do it.

“There is hope for the future that the combination of solar, storage and smart technologies, stand to catalyse the change in our energy system that we so badly need to tackle climate change.

“Solar is absolutely central to making this happen. And when it does, it’s worth remembering that the energy revolution that is going to happen started here, at the Oxford Ecohouse.”

Looking ahead, Roaf is excited about the next chapter of UK solar. Having taken 20 years to get from one to one million, the Oxford Ecohouse is once again looking to set the agenda for the next generation: storage. The designers of the Oxford Ecohouse understood that to operate on 100% renewable electricity storage was essential. That’s why the house has high mass walls and floors to store heat, while a 300-litre hot water storage tank holds the product of the 5m2 AES Solar thermal panels. Storing the PV electricity was always out of reach, until now.

Roaf is installing a 2kWh SMA inverter/storage combination to help ensure that all of the energy generated from the 20-year old modules is captured and used by the house. In addition, the Oxford Ecohouse is having low-consumption white goods installed that will automatically run when the PV system is at peak generation. Rounding out the next stage of the Oxford Ecohouse’s makeover is an LED refit, which will ensure that lighting costs are kept to a minimum.

With the UK now Europe’s most prominent solar market, those of us who make a living out of it will forever be indebted to the foresight, conviction and tenacity of Sue Roaf – a solar pioneer.

Here’s to the next stage of the solar revolution.