Wind direction can boost solar panel efficiency

Industrial solar panels of a solar farm sit among grass and flowers beneath a blue sky, with two wind turbine in the distance

A southerly wind can increase the output of solar panels by up to 43%, according to newly published research by a Lancaster University masters student.

The cooling effect of the wind on panels can counteract the negative impact of solar panel overheating on warm sunny days, according to a study published in Solar Energy last week.

Damon Waterworth, lead author of the study, was a taught masters’ student at Lancaster University when he carried out the research for his dissertation project.

“The impact of wind speed and direction on solar panel efficiency has been very much overlooked in the research to date. There are also only limited field studies that investigate the impact of different weather conditions on solar panels: most research is laboratory based, carried out under controlled conditions not the chaotic ones that exist in the real environment.”

Developing understanding of the effect of different weather conditions is important as it helps to make more accurate predictions of electricity generation. This will become increasingly important as the proportion of renewables in our energy mix increase, which makes the electricity grid harder to manage because their output varies with the weather.

Damon was given access to a year’s worth of data from three logging stations set up at the Westmill Solar park in Oxfordshire by Lancaster University’s Dr Alona Armstrong as part of her research into the impacts of solar parks on local climate, vegetation and greenhouse gas emissions.

The first part of Damon’s study looked at what meteorological conditions had the most significant impact on electricity output.

“We found that after solar radiation - the intensity of the sunlight - relative humidity had the greatest impact, with these two factors explaining most of the variation in output: wind speed and direction appeared to have fairly limited impact,” Damon says.

However, the results were very different when the effects of wind direction were isolated. The second part of the study investigated the impact of wind direction when all other variables are equal. Wind direction was categorised by the angle of approach as either ‘northerly’ or ‘southerly’. When isolated, it became clear that wind direction had a significant influence on electricity output, especially when the solar radiation and electricity output were high.

“When electricity output was low, wind direction had a limited effect but as the electricity output grew due to increased sunlight the output of the panels under northerly and southerly winds diverged. When there was a southerly wind the panels produced between 20 per cent and 43 per cent more electricity,” Damon said.

Damon believes that this difference can be explained by more effective cooling on the southern side of the solar panels.

“As solar radiation hits a solar panel, electricity is generated. However, the sun and the energy conversion process cause the panels to heat up, reducing their efficiency. In the northern hemisphere, solar parks face south with panels facing skyward: so a southerly wind passes over the face of the panels, cooling them more”.

“If wind direction has this effect in the south of England, it could have a much bigger impact in solar belt areas like Spain, China, and India which have high solar radiation. These areas are often also very hot and so panel overheating is a much bigger problem.

“If we can find ways of cooling the panels, they will be more efficient, making more energy and money. A lot of research has looked at water cooling systems and other technological solutions to address the problem, but these create additional costs, and water is often scare in these regions. It may be better to first look at more natural ways to cool the panels and boost electricity output. Reduced panel heating could also increase the lifespan of the solar panels and so may save the developer money in the long term.”

Damon hopes that his research will help to both improve the prediction of solar park electricity generation, helping to manage the grid, and influence the design of solar parks, particularly in the solar belt. He believes similar field research is needed in these areas to provide detailed evidence of the potential of wind to boost panel efficiency.

Dr Alona Armstrong, who was Damon’s supervisor for his masters research and a co-author on the paper, says: “Damon has done a fantastic job - not many students manage to produce research within the time frame of a taught masters dissertation that goes on to be published in an international peer-reviewed journal and furthers scientific understanding. You also have to have the dedication and motivation to convert your dissertation into paper format and go through the submission and review process – it’s very impressive!”

Damon, who was the first in his family to go to University, won the prize for the top performing graduate of 2018 at the Lancaster Environment Centre. He is now working as a Sustainability Consultant for the Yordas Group, where he interned while studying at Lancaster. Within Yordas Damon is helping to bridge the gap between business and academia, enabling businesses to better manage operational risk, overcome regulatory challenges, and improve the sustainability performance of their organisations and products.

Read the full paper: Southerly winds increase the electricity generated by solar photovoltaic systems

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