KPIs solar operators should be tracking to overcome the data deluge


We’re all aware of the scale of the data challenge in renewables. The sheer volume of data produced is a substantial obstacle facing operators in the sector. In the wind industry alone, more than 400 billion points of data are generated every year. Solar might have fewer variables to measure than wind, but typical solar portfolios contain a far larger number of assets, and so operators still must contend with a mountain of information.

Furthermore, it doesn’t help that the quality and reliability of data are a tremendous problem in the solar industry. This can make it extremely difficult to uncover useful data and garner a holistic view of how solar and wind assets are performing.

Indeed, the ‘data deluge’ poses a particular challenge for solar operators and solar asset managers. Wading through huge amounts of project performance data, while also contending with gaps in solar project data caused by unreliable collection practices, is never ideal and often results in solar operators missing critical information.

The next question is, how can solar asset managers efficiently and effectively uncover the actionable information embedded in their performance data that actually adds value while avoiding sifting through the mass of unusable information? This is an area where the right key performance indicators (KPIs) can add significant value.

KPIs quickly reveal issues with underperformance and enable asset managers to fix them, ultimately providing a multitude of benefits to project owners, including improved asset performance, lifetime, and return on investment, along with reduced downtime and more effective business decision-making.

To ensure that solar operators are supported by informative, valuable data, the industry needs to consider implementing additional KPIs which can enable project owners.

In short, asset managers need:

  • The right KPIs in place that can quickly indicate underperformance that matters and is actionable.
  • KPIs based on reliable and up-to-date data. This has traditionally been done by improving data infrastructure and measurement devices, but today, robust software solutions should also be put in place that can identify faulty data automatically and in real-time and substitute this faulty data with reliable surrogate data.
  • The ability to break down KPIs easily and intuitively, and know what action to take on which assets

As an asset manager, if you can achieve the above, then you have solved the problem of managing complex solar assets at scale using data. In this article, we’ll zero in on the KPIs that you should make sure you are tracking.

  1. Investment Performance Ratio (IPR) or Energy Index

The IPR is a key financial performance metric for solar operators and investors as it can measure the performance of a project’s solar inverters by demonstrating how actual production relates to the energy budget. This enables solar operators to calculate whether the financial expectation for the project is being met, or not as the case may be.

For this, the formula IPR = [Actual energy production (Energy)] / [Reference energy production (Default energy budget)] is used.

The IPR can thus be critical for solar operators seeking to understand whether a solar plant is underperforming, and to then provide the insights needed to rapidly identify the cause of the issue, irrespective of whether the issue is due to a fault with the asset or with the energy budget.

If a solar farm is consistently underperforming – or even overperforming – then adjustments may be necessary to ensure the budget is reflecting real-world conditions, ultimately enhancing budgetary decision-making.

  1. Resource Index (inverter) or Weather Index

This KPI measures the power output of a PV inverter in comparison to the production that was forecast from the expected solar irradiance given current on-site weather conditions. It delivers crucial insight for operators and investors as it allows them to calculate whether lower than expected production was due to low irradiation levels or problems with the project’s inverters.

Removing doubt as to the cause of a solar asset’s underperformance can significantly reduce costs for site managers, reducing the need to bring in expensive ad-hoc operations and maintenance teams.

For this, the equation Resource index = Solar Irradiation Reference / Solar Irradiation Forecast (on device level) is used.

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Weather is a key variable in a solar project’s performance, and a better understanding of on-site climate conditions can help operators and asset managers provide transparency with investors around the causes behind lower-than-expected energy production.

  1. Energy Budget (weather adjusted)

To shed light on the remaining losses that solar operators and asset managers can take action on, rather than issues caused by external factors such as the weather, the Energy Budget KPI can correct a PV inverter’s resource budget with actual irradiance data.

In layman’s terms, this means that the volume of electricity that an inverter generates can be compared to the weather-adjusted Energy Budget, highlighting when the inverters produced more or less energy than the budget predicted – taking into consideration the weather on any given day.

This metric follows the formula: Energy Budget (weather adjusted) = Energy Budget (Default) * RI.

Solar operators and investors need to have their understanding of the financial performance of their assets grounded on real-world conditions. When there is less sun, solar panels will receive less energy, and budgets will either need to be adjusted down to meet those expectations or have the ‘missing’ expected energy removed from them.

Energy budgets can therefore enable operators to calculate the losses caused by the lack of available resources. Without being able to calculate whether inverters are producing 100% of electricity expected in any given weather condition, operators will be unable to confirm to investors whether they are on track to meet their expected returns.

  1. Operating Performance Ratio (OPR) or Weather Adjusted Energy Index

Ensuring that operators and asset managers can measure whether inverters are consistently performing at 100% capacity in all weather conditions is essential. By measuring inverters’ performance in actual weather events, the Operating Performance Ratio can link real-world conditions to inverter performance and highlight where more could have been done to improve the management of those assets during these periods.

This formula compares the actual plant performance ratio to the reference performance ratio: OPR = Energy Actual / Energy Budget (weather adjusted) = IPR / RI.

If a solar inverter is performing at less than 100%, as is the case for the majority of solar farms, the Operating Performance Ratio can therefore support solar operators and asset managers in identifying whether improvements are required with their physical assets or asset management processes – or both.

Another approach that can be highly effective is filtered KPIs designed to highlight specific aspects of asset health.  Solar generators are subject to a wide variety of external performance impairments that do not necessarily represent the health or capability of the asset.  Examples include grid outages, curtailment, shade, and clipping.  The ability to automate the detection and classification of these types of events unlocks additional KPIs such as a Filtered Temperature Corrected Performance Ratio facilitates rapid (and automated) identification of actionable issues, such as tracker stalls, string outages, and soiling.

Information overload is a growing challenge for solar operators and investors and KPIs will become an increasingly essential tool to help pick out important data and enhance a project’s productivity.

Providing transparency and meeting expected return on investment is key to keeping investors happy and having the right KPIs in place which are based on reliable, trustworthy data and can be broken down to identify actionable deviations will enable a holistic overview of a solar project’s performance and support investor reporting.

As solar technology continues to adapt and evolve, greater complexities will undoubtedly follow, but the sector is on the right track to solving the data deluge.

The views and opinions expressed in this article are the author’s own, and do not necessarily reflect those held by pv magazine.

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