17 Sep 2014

UK’s First Domestic Grid Connected PV System – 20 Years On

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Wind & Sun is celebrating the 20th anniversary of the UK’s first domestic solar power generated to the national grid.

Following installation of a solar photovoltaic array at ‘The Autonomous House’ in Southwell, Nottinghamshire, the first electricity from a private solar system was generated to the UK grid on 27th July 1994. This was a major achievement for Wind & Sun and the birth of a whole solar energy sector and demonstrated the feasibility and potential of harnessing the power of the sun.

In the twenty years that have followed that milestone, Wind & Sun has continued to lead the sector, notching up a string of further UK & world firsts.

Solar panels on roofs have since become a common sight around the country. A whole industry has grown up to service them, with installers in almost every town and costs are now almost a tenth of 1994 prices with payback times in the region of 5 years.

The Autonomous House’s solar panels have generated over 33MWh of electricity (enough to make a million cups of tea!), converting daylight into electrical power, and have worked faultlessly for 20 years.

On the 20th anniversary Wind & Sun re-visited the system to test performance.

The system was tested using a Solmetric PV Analyzer. This measures solar irradiance and back of cell temperature whilst performing a full I-V curve test from open-circuit voltage to short circuit current. From this a comparison in performance can be made against the original panel flash test data when it left the factory.

Testing Robert Vale's Solar PV Panels The Autonomous House


According to the manufacturer’s warranty, at this point in their life the panels should be putting out 80% of their initial value.

Robert Vale - PV Module IV Curve Test

We were astounded to find the first panel tested producing up to almost 95% of it’s original rated power!

Even the entire array, tested as a whole with some inevitable dirt accumulation, panel mis-matching and some slight localised shading (from an unpruned apple tree) scored almost exactly 80%!

The house was designed and built by and for Brenda & Robert Vale along principles outlined in their book 'The Autonomous House' first published in 1975. The aim was to be self-sufficient in energy and water so it incorporates high levels of insulation combined with thermal mass to eliminate heating requirement; rainwater collection for water supply; a compost sewage system and solar photovoltaic panels to produce electricity.

Wind & Sun were at first approached to supply an off-grid system using battery storage to power the house. However, providing reliable power throughout the year would have been difficult and expensive to achieve.

At the time grid connected PV was being developed in Germany as part of their ‘1000 roofs programme. Steve Wade from Wind & Sun had met SMA at a trade fair in Amsterdam where they were exhibiting ‘grid connected PV inverters’. He suggested to the Vales trying this for their house using a PV system sized to generate the equivalent of their annual electricity requirement and using the grid as virtual storage.

SMA agreed to supply Wind & Sun and the local grid company (EMEB) were approached. They were supportive of the idea and agreed that if the inverter was good enough for Germany it was probably good enough for the UK and allowed the connection.

 The PV system used a 2.16kWp array sited on a south facing oak frame garden pergola comprising 36x Solarex 60Wp polycrystalline modules and a SMA PV WR-1800 inverter – the first SMA inverter installed in the UK.

The house cost £155,000 including the PV system whose installed cost was ~ £6900/kWp with a module cost price of ~ £4.40/Wp. This equated to a 200 year payback time!

Robert Vale said at the time: “ with an initial cost of ~ £15,000 and an output of approximately 1800kWh per annum it does not ‘pay’ for itself in a commercial sense”, however, it was installed not for income generation but as part of an environmentally friendly building.

The inverter was replaced in 2009 with a more modern version (Sunny Boy SB-2500), but with this exception the system has worked faultlessly now for 20 years.

Steve Wade, Wind & Sun’s managing director said: “The progress we have made in the last 20 years has been exceptional and it is amazing to see more and more solar systems appearing everywhere thanks to the vision of some pioneering individuals. We expect that this system could be producing for at least another 20 years!

“Important lessons have been learned to ensure long term energy production:

  • Use good system design;
  • Use robust quality products that will last;
  • Install well for reliability;
  • Choose manufacturers and suppliers who will still be around to honour warranties and provide service!

“Solar is now firmly established as a mainstream energy source and we can now look forward with confidence to a sustainable future.” 

We expect that this system could be producing for at least another 20 years! 


As the PV system was switched on and the UK’s first domestic solar power entered the grid, becoming the smallest power station in the country Robert quipped: “Now it’s only me and Sizewell B!”

[Sizewell B is the only pressurised water reactor (PWR) in EDF Energy's fleet. It has been operating since 1995 and is not scheduled to close until 2035. (EDF website)]

From our measurements it could be expected that in another 20 years this PV system could still be generating ~ 60% of it’s original capacity.  Thereby out-lasting Sizewell B.

Even better, if needed the PV system could be safely de-commissioned and re-cycled - there will be no need to protect it’s waste for thousands of years.

Solar power is the future!

Wind & Sun will be exhibiting the PV Analyzer at Solar Energy UK – Visit us on Stand D30.