Companies like supermarket giant Lidl have been impacted by business rates. Image: Lidl.

As many as 91% of solar arrays are underperforming in the UK, according to a recent survey by independent power and energy consultant Roadnight Taylor.

The company surveyed over 50 10-500kWp solar schemes on non-domestic buildings throughout March, finding that the most common issue was poor photovoltaic output. This affected 40% of those surveyed, while 27% reported impacts from metering and tariff issues and 18% from insurance and maintenance overspend.

“Rooftop arrays are fitted to more than 20,000 non-domestic buildings across the UK,” said Roadnight Taylor CEO Hugh Taylor. “The financial benefits across the UK from optimising these investments could run to hundreds of millions over their feed-in tariff (FIT) life-spans.”

For 6% of sites surveyed, business rates liabilities were singled out as an issue. Lidl made a particularly high-profile case in March, when it announced it had seen its rates grow by 528% due to changes in valuation.

Roadnight Taylor has previously spoken to Solar Power Portal about the controversial rates and their impact on companies interested in pursuing onsite solar power.

“There are many steps that can be taken to avoid paying excessive business rates associated with solar arrays,” said Taylor. “A common example is moving ownership of an installation into a special purpose vehicle, or exporting the electricity generated to another party, but a range of intelligent strategies exist that can achieve this objective.”

The report concluded that low-cost changes to solar arrays could save on average £1,473 in annual financial performance for non-domestic solar owners.