Assessing solar asset operational risks

kWh Analytics, a climate insurance provider, released its 6th annual Solar Risk Assessment report, providing a data-driven overview of risks to solar assets. The report included contributions from solar industry leaders in technology, financing, and insurance. 

“To meet renewable energy deployment goals, the focus needs to be on smart growth – relying on data to inform decisions and utilizing resilience measures to protect assets,” said kWh Analytics chief executive officer Jason Kaminsky. 

The report identified 14 risks to be aware of in the solar industry, including risks related to extreme weather and operational risks. For the first time this year, battery energy storage related risks were included. This news covers the extreme weather risks, with subsequent articles reviewing operational and storage related risks. 

Find coverage of the weather-related risks to solar assets here. This report will focus on solar asset operational risks, with a subsequent article focusing on energy storage risk assessment. 

Aggregating portfolios of 4 or more projects cuts extreme risk scenarios 

kWh Analytics found a trend that most financial forecasts underestimate the risk of extreme downside scenarios, known as P99 level events. These events are expected to occur once every 100 years, but the company’s data has shown that catastrophic damage P99 events have occurred as frequently as every 6 years. 

“One possible way to mitigate the risk of extreme downside scenarios is to aggregate portfolios of projects for financing – the distribution of risk increases the likelihood that a poorly performing site will be balanced by a better one in the portfolio,” said kWh Analytics. 

The company found that median performance across 301 utility-scale solar sites, covering 935 years of production for 2017 to 2022. It found that by aggregating at least four projects into a portfolio, the risk of all assets performing below 80% of initial forecasts is cut in half. 

However, kWh Analytics said that benefit of portfolio aggregation is dwarfed compared to using more accurate production and risk forecasts. It said that improving P50 forecast accuracy with realistic, data-driven availability estimates has the potential to decrease the occurrence of extreme downside scenarios by as much as a factor of 10.

Voltage collapse can reduce production by more than 20% 

Voltage collapse is a significant decline in voltage levels within the DC field. Solarlytics said that voltage collapse is a fast-growing problem in solar assets. 

“As voltage the voltage collapses below the inverter operating range, it hinders the inverter’s ability to match DC field voltage, resulting in energy losses. In advanced cases, the collapse causes the inverters to frequently trip, leading to energy losses that exceed 20%,” said Solarlytics. 

Voltage collapse can be caused by a variety of factors. For example, projects designed for cold weather climates require shorter strings to perform on cold days. When these systems faces warmer weather in the summer, the string voltage can drop below the inverter range. 

Solarlytics estimates that more than 30% of all utility-scale solar plants suffer from voltage collapse. The company recommends using advanced string-level monitoring and optimization, proper inverter sizing and configuration, and continuous monitoring for early detection of voltage sagging to take corrective actions. 

Operations and maintenance corrective actions on the rise 

Solar Advanced Analytics, Univers found that operation and maintenance (O&M) corrective actions continue to rise as more solar assets go online. This past winter, the firm found a 14% increase in corrective actions taken when compared to summer 2023. It analyzed data from over 11 GW of assets across over 300 sites. 

It found that 50% of corrective actions were attributed to the health of DC-level components in the system. This was followed by inverter corrective actions and repairs, which represented 15% of all corrective actions. Data availability actions ranked third, representing 13% of actions taken. 

About 43% of DC corrective actions occur during winter, said Solar Advanced Analytics, indicating the influence of winter conditions like low temperatures, reduced irradiance, and snow cover on DC inputs and strings. Conversely, inverters are prone to corrective action in warmer seasons, as elevated system temperatures can lead to cooling system failures and decreased inverter efficiency. 

The seasonal differences highlight the need for O&M operators to strategize seasonally, planning for DC issues in the winter and inverter issues in the summer. By targeting O&M schedules, providers can limit truck rolls and properly allocate inventory resources and workforce. 

Safety problems require partial or total de-energization in 11% audited systems 

SolarGrade found that critical issues were found in 11% of U.S. solar projects in a series of inspections conducted from January 2023 to March 2024. This critical level designation is placed on assets likely to have catastrophic failure before the next maintenance event. 

About 11% of U.S. solar assets analyzed were found to have critical issues that require the system to be partially or totally de-energized until the problem is fixed. 

The most common critical issue by a large margin was problems with PV connectors, which was the cause of 46% of projects in need of de-energization. Unsafe connectors are often due to complex installation requirements and cooling, pervasive myths about MC4 compatibility, and a lack of field training, said SolarGrade. The company provides a solar connector safety guide. 

Unmitigated soiling can reduce annual production by up to 50% 

Soiling is the accumulation of dust, dirt, and particulates on solar panels. According to data from the National Renewable Energy Laboratory, soiling can cause up to 50% production losses in soiling-prone regions. 

Clean Power Research provides modeling to understand regional differences for soiling risk, which vary widely based on location. The risk is particularly high in regions with low annual rainfall totals, highlighting a need for regularly scheduled soiling cleaning in these regions. 

“By employing various soiling loss models, coupled with accurate model inputs and reliable irradiance data from SolarAnywhere, industry experts can establish effective strategies to minimize performance uncertainty when modeling PV systems in complex climate conditions,” said Clean Power Research. 

Inverters cause 59% of lost energy 

While PV systems are designed to last for 35 years or more, various components fail much sooner. An analysis of O&M logs revealed that the most frequent cause of corrective maintenance issues in response to a significant loss were caused by inverters (51%). This was followed by DC distribution equipment maintenance, including connectors, combiners, and wiring, which represented 21% of actions taken. 

kWh Analytics found that inverter failures cause the highest time-to-resolution and lead to the highest energy lost, about 59% of energy lost due to corrective actions. The most common inverter O&M tickets were related to issues with the controller, fan, and logic board. This data may be useful when determining procurement priorities for spare parts, said kWh Analytics.

The upcoming third article on kWh Analytics Solar Risk Assessment will focus on battery energy storage systems operational risks, marking the first time storage was included in its annual report. For more energy storage news, check out pv magazine’s new Energy Storage News website.