Wallingford DCNN 5558- Relocated for a solar farm.

51.60312 -1.11334 Met Office Assessed Class 4 and Good Installed 1/1/1960

This site is in the grounds of UK Centre for Ecology and Hydrology. Until 2011 it was located approximately 50 metres to the east of the above being moved to accommodate the 3,000 panel (700MW) Howbery Solar Farm. Unlike Chertsey Abbey Meads at least the screen was moved and not simply built around. So has relocating the screen only a small distance from the panels avoided any temperature and humidity distortions?

Rather implausibly it was originally assumed that solar farms would likely reduce local average temperatures by absorbing solar insolation. Increasingly, however, new empirical research has revealed the complete opposite, solar farms create their own variant of an urban heat island effect.

The Photovoltaic Heat Island Effect: Larger solar power plants increase local temperatures

As the above research points out, actually taking physical readings and site observations trumps computer modelling every time. Whether or not the Met Office has ever actually tested such sites alongside solar farms is not clear, however, their response to my inquiry regarding the Chertsey site indicates downgrading as follows

“The weather station was originally given a CIMO 2 rating for temperature, however, following the installation of the solar panels this rating was adjusted to CIMO 3 in line with World Meteorological Organisation guidelines for screen temperatures due to the  artificial heat sources and reflective surfaces.” 

In the absence of the solar panels at Wallingford, it would be likely assessed CIMO Class 2 or may possibly even Class 1 instead it is now rated Class 4. This makes any comparison of data post solar farm installation with prior readings unrealistic – apples with oranges.

Notably in the Met Office response, there was no specific reference to heat island effects generated by solar farms. This is of particular importance regarding the ever increasing location of solar panels alongside Met Office sites. Weather stations sites are often on government owned land and should be surrounded by flat open space i.e. ideal locations for solar farms. Wallingford and Chertsey are no longer exceptional and there are several other projects in hand. RAF Leconfield (to be reviewed shortly) has been severely compromised by “Project Prometheus” an initiative to spread to more sites around the country , inevitably in the vicinity of more weather stations.

https://www.army.mod.uk/news-and-events/news/2021/09/dst-leconfield-prometheus-solar-farm-opening/#

Yet again, though, as in the case of Llandwddyn:Cwm Cownwy there is another official Met Office weather station under 2 kilometres away. In this case the CIMO rated Class 1 and Excellent Benson site which has been continuously reporting since 1951. Tim Channon reviewed Benson in the days before the Met Office was obliged to release (but only under FOI request) its CIMO assessments and correctly predicted its Class 1 rating. This raises the same questions as those from the Welsh site, if there is a First Class site so close by why bother to use readings from an unacceptably low rated site known to have a wide error margin and distorted historic record?