Introduction
For many years, solar asset performance has been measured using a familiar set of indicators, including generation, availability, and performance ratio (PR). While these metrics remain important, the rapid growth of solar + storage portfolios is changing how performance should be evaluated. As storage introduces new operational, financial, and commercial considerations, asset managers increasingly need to understand not only how assets are performing, but how effectively they are creating value.
Asset managers must also understand battery behaviour, hidden sources of value loss, revenue performance, curtailment impacts, and portfolio-level priorities.
In this article, we explore the operational, financial, and portfolio-level KPIs that asset managers should be tracking beyond traditional solar metrics. This includes battery health indicators, measures of value creation, sources of hidden loss, and the performance insights needed to prioritize actions across increasingly complex solar + storage portfolios.
Are traditional solar KPIs still enough?
As portfolios grow, the challenge is not only measuring performance accurately but understanding where value is being lost. A traditional performance metric, such as Performance Ratio (PR) can be difficult to interpret because expected values depend on plant, location, and seasonal context.
As a result, metrics such as the Energy Performance Index (EPI), which compares actual production against expected production, can complement PR by providing a more direct view of whether an asset is producing in line with expectations under the conditions experienced.
At the same time, aggregated KPIs can mask underperformance at individual asset level, creating a risk that issues go unnoticed. While a portfolio may appear to be performing well overall, problems at specific assets can be overlooked without the ability to drill down into detail.
Measuring performance for hybrid portfolios
As portfolios become increasingly hybrid, however, asset managers also need to understand how operational decisions influence commercial outcomes and long-term value creation.
In hybrid portfolios, performance can no longer be evaluated purely in terms of energy production. Storage introduces flexibility, allowing energy to be moved, timed, and monetized differently depending on market conditions.
As a result, the objective is to maximize the value created from that energy. Lower output at a given moment does not necessarily indicate underperformance; in some cases, it may reflect a deliberate decision to store energy and capture greater value later.
Traditional measures such as generation, availability, and efficiency must be considered alongside indicators that reflect revenue, market participation, and value creation.
Which financial KPIs should asset managers be tracking for hybrid portfolios?
If the focus is moving to value creation, the next question becomes: what should asset managers actually be measuring to evaluate financial performance?
Financial KPIs help operators understand whether operational decisions are translating into commercial value.
Key financial indicators include:
- Captured price: how effectively generation is being sold into the market.
- Value from energy shifting: the incremental value created by charging during lower-value periods and dispatching energy when market value is higher.
- Curtailment avoided: the extent to which storage or operational decisions reduce lost generation.
- Forecast and imbalance costs: the financial impact of deviations between forecast and actual generation or dispatch, including resulting imbalance costs where applicable.
The storage metrics of key importance for tracking operations
While these financial indicators help quantify value creation, they must be supported by a strong understanding of battery performance and operational health.
Effective storage management also depends on tracking core operational metrics. SoH, SoC, energy throughput, cycling and round-trip efficiency provide visibility into how the battery is being utilized, how efficiently it is operating, and how its operation may affect degradation and long-term value.
Even small deviations in storage performance can have a significant financial impact. DNV estimates that for a 100 MW storage asset, a 2% availability shortfall can represent around €240,000 per year in recoverable value, provided operators have the data and analytics needed to identify and substantiate the loss.
- State of Health (SoH) determines how much usable capacity the battery retains over time. Lower SoH reduces the amount of energy that can be stored and discharged, directly impacting value.
- State of Charge (SoC) determines how much energy is available at a given moment. Poor visibility into SoC can lead to underutilization or missed revenue opportunities.
- Cycling behaviour influences degradation and asset lifetime. Excessive or aggressive cycling can accelerate degradation and reduce long-term value.
- Round-trip efficiency affects how much energy can be recovered from storage, influencing overall portfolio performance.
- Availability and alarms provide early indicators of operational issues, helping teams identify risks before they affect performance, safety, or warranties.
Hidden losses in solar and hybrid portfolios
However, even when the right financial and operational KPIs are in place, significant value can still be lost if underlying issues remain hidden within the portfolio.
Even with strong monitoring, losses can still be missed when data is fragmented or difficult to interpret. Common sources of solar performance loss include soiling, tracker losses, string and combiner losses, shading, and inverter underperformance or derating.
Organizations increasingly need a connected view of performance in order to be able to identify the source of the losses. Managing solar and storage separately can also result in missed opportunities to optimize energy flows and maximize value across the portfolio.
Organizations increasingly need to move beyond detecting underperformance to quantifying and attributing its causes. A structured view of losses helps distinguish between factors such as weather, curtailment, equipment availability and component underperformance, and understand their contribution to the overall performance gap.
Prioritizing performance actions across larger portfolios with fewer resources
Identifying losses is only the first step. As portfolios grow, asset managers must also decide which issues should be addressed first and where resources will have the greatest impact.
As portfolios grow, asset managers must decide how to prioritize actions based on factors such as financial impact, performance gaps, operational risk, and the urgency of intervention.
Teams therefore need tools that help them focus attention effectively. In practice, this means highlighting the issues that are causing the greatest value loss, presenting performance in a clear portfolio context, and providing asset managers with a prioritized set of actions. Effective decision-making depends on accurate information, clear prioritization, and the ability to understand both operational and financial impacts.
As portfolios become larger and more complex, maintaining visibility across assets, technologies, and performance metrics becomes increasingly challenging. Platforms such as GPM Horizon for multi-tech portfolios help asset managers identify underperformance earlier, prioritize corrective actions, and better understand the operational and financial impact of issues across the portfolio.
Read more in our recent article about Maximizing ROI through BESS energy storage optimization and smart monitoring.
Download DNV’s report ‘Improving performance and maximizing value: solar + storage’ as an opportunity to dive deeper into this topic.
Conclusion
Ultimately, the challenge is not collecting more data but turning information into action. The organizations that will be most successful in the next generation of solar + storage portfolios are unlikely to be those with the most data. They will be those that can identify where value is being lost, prioritize the actions that matter most, and translate insight into better operational and commercial decisions.
Contact our renewable energy experts to book a meeting today
If you’re looking to find ways to reduce revenue leakage, identify losses earlier, and better understand portfolio performance, through the metrics that matter most, fill in the form to request a meeting with our renewable energy experts who will be available to answer your questions and offer insights on best practices.
