Scots energy conference looks to solar power renaissance with battery storage

21 years after she built it, solar roof of Edinburgh professor’s home is still generating electricity
21 years after she built it, solar roof of Edinburgh professor’s home is still generating electricity

When Heriot Watt University professor Sue Roaf first applied to install solar power panels on the roof of her home, she was told by the bureaucrats that the plan would never work ‘because there isn’t enough sunshine in Britain’.

That was in 1995 and now – 21 years later – the solar panels are still generating sufficient energy for the first home in the UK to have a fully-integrated solar roof, while today there are now more than one million such homes in the UK.

Although the solar PV installation rate has fallen by more than 70% since the UK-Govt. cut the feed-in tariff last year, Professor Roaf says that this can be remedied by greater use of battery storage for solar energy.

She explained: “My solar roof helped light the spark that started the UK solar revolution – now more than 20 years later –  over 1 million people across the country are living in houses powered by solar energy

“My PV roof system cost me £28,000 and to build it I needed to change Local Planning and Building Regulations Guidance on PV roofs and partner with Southern Electric to pioneer the first grid-connection agreement developed by an energy company in Britain. Today you can get a roof with 4Kwp of PV for your home for less than £5,000.  

“The PV system then had a 66-year payback. Today similar PV systems could cost less than £5,000 to install on an existing home and with feed-in tariff support on adjacent homes have a payback of around 6-10 years

“The solar panels are still generating electricity and hot water and generate enough heat and electricity to ensure that my six bedroom home in Oxford still has one of the lowest carbon footprints for any building in Britain. Averaged over the last 20 years the house uses only 13.2 kWhm2 of gas and electricity and produces only 4 kg CO2 m2 each year, a fraction of the impacts of most modern buildings.

Prof. Roaf
Prof. Roaf

“The house was built with an integrated roof including a 4kWp of BP Solar array of Saturn 585 photovoltaic panels; 5m2 of AES Solar, solar hot water panels and two Velux roof lights integrated into the single south facing roof.

“The actual building of that first PV roof required the re-writing of local Planning Laws and Building Regulations Guidance and in partnership with the Southern Electric utility, the pioneering of the first domestic grid-solar connection agreement in Britain.

“The solar panels are still working well, generating both electricity and hot water despite having had no maintenance over their lifetime, save for one pump replacement for the hot water system. 

“Meanwhile, householders have been building the foundations for a sustainable solar future for two decades, under the radar, and against many odds, not least the barriers placed before them by many of the interested vested in Big Energy.

“The UK now has over 8GW of installed PV energy of which around 2.3 GW is in domestic systems. In contrast, the UK has only 9.4GW of installed nuclear capacity much of which is scheduled for decommissioning over the next decade or so.”

Roaf says the full solar dream is to have homes that rely almost 100% on the energy they can harvest from their own environs.

Her house – which she still owns today – was already one of the lowest energy homes in Britain with a passive low energy design has highly efficient white goods and these were manually activated, typically when it is sunniest. Its PV panels have an annual solar yield of around 2200kWh. 

So she has gone the next step and recently installed a Sunny Boy Smart Energy battery system.

Previously the self-consumption rate of electricity from the solar roof was around one third, and on measured outputs that has now risen to around 90% resulting in a CO2 emissions reduction of around 1,200 kg per annum.  

To install this the Sunny Boy PV invertor was upgraded with a Sunny Boy 3600 Smart Energy system with a 2kW capacity lithium-ion battery and a SMA Energy Meter, Sunny Home Manager.

Prof. Roaf added: “The UK solar story shows how popular PV has been amongst ordinary householders.  The addition of battery capacity into the domestic systems may add £2-3,000 to the cost of the basic array and will most likely appeal to particular market demographics. 

“This must include those who are approaching retirement and not only may have available lump sums to invest in reducing their dependence on irrationally and escalating domestic energy costs and establishing for themselves a degree of energy security that no other source of energy offers them. 

“For this demographic it is easy to predict a significant uptake of the addition options for battery inclusions, not least to their own existing solar arrays, particularly at the point of upgrading their existing invertor. 

“A reassuring result of the close monitoring of the Oxford array is that its performance over the last 21 years of operation has been nominal, considering that some predicted a 20-25 year lifespan of PV panels at a time when none had been measured over such periods.

“The rate and scale of the expansion of the UK solar markets has been phenomenal, but as with all renewables that harvest clean free energy from the sun and air they are only intermittently available. Therefore the ability to store their energy and use it when needed represents the next great step towards a 100% renewable energy society.”

Prof Sue Roaf (front, centre) celebrates 21 years of solar power at her house
Prof Sue Roaf (front, centre) celebrates 21 years of solar power at her house

Professor Sue Roaf  is due to speak at a solar power conference being held in Edinburgh next month in association with the Scottish Institute for Solar Energy Research.


Renewable Energy Capacity as at the end of the first Quarter of 2016 

In the first quarter of 2016, 25% of all UK energy generated was from renewable sources.

Renewable electricity capacity was 31.2 GW at the end of 2016 Q1, a 11.8 per cent increase (3.3 GW) on a year earlier, and a 2.4 per cent increase (0.7 GW) on the previous quarter.

Of the 0.7 GW increase in 2016 Q1, over half was due to new, mainly large-scale, solar photovoltaic capacity.  

According to Solar Intelligence analyst Finlay Colville, the UK installed 1.553 GW of new solar PV capacity during the first quarter of 2016.  There are currently around 10 GW of installed solar capacity in the UK as opposed to 9.3 GW nuclear capacity and 9 5 GW onshore wind.

The bulk of the installed solar capacity is in commercial solar plants but a substantial and growing number are on domestic roofs. 

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