The Waterfall page provides a comprehensive overview of the entire plant’s performance: From the original energy model predictions, highlighting the gaps between the expected and actual losses, to what was generated, and then what actions can be taken to reach an achievable energy goal. At the bottom of the Waterfall page, you'll find the "Comparison of TMY and Actual Weather for P50 Weather Adjustment" plot, which compares the measured data with the Typical Meteorological Year (TMY) data provided by the client or sourced via API. 


Plant and Model Performance Waterfall


Key Definitions

  • P50 Budgeted: The P50 Budgeted Production comes from the Original Energy Model expectations in year 0. P50 means that the original model used TMY weather data as an input.
  • Weather Adjustment: The Weather Adjustment is calculated by Solar AI using a simple physical model similar to NREL’s PVWatts.
    1. First, the actual weather is down-sampled to hourly values to match the frequency of the TMY data onboarded,
    2. The DC nameplate is truncated according to the number of years the site has been in operation using the Budgeted Degradation Rate (described below),
    3. Both the Actual weather and the TMY weather are passed through the model for the equivalent time period of data.
    4. The delta between the two results (Actual model - TMY model) is the weather adjustment.
  • Budgeted Degradation: The Budgeted Degradation is calculated according to:
    1. ((End date - COD) - (Start date - COD))/2 x (Annual Degradation rate)/365
  • Adjusted Budgeted: The Adjusted Budgeted then comes from subtracting the Weather Adjustment and the Budgeted Degradation from the P50 Budgeted.
  • Performance Loss deltas: The expected performance loss quantity from the original budgeted energy model is minus what was actually experienced by the PV plant in each performance loss category.
  • Downtime Loss: The downtime loss experienced by the PV plant is in each downtime loss category.
  • The Other bar represents any unclassified difference between the original budgeted production and the actual production. It may include:
    1. Inconsistencies in the TMY weather data that was used for the P50 budget vs what was used in Solar AI,
    2. Inconsistencies between the original energy model and the simple physical model used in Solar AI
    3. Missed losses due to data availability gaps,
    4. Unaccounted for AC losses in cases where the meter was not onboarded,
    5. Some missed performance and downtime losses were not captured by Solar AI.
  • Metered Production: The total production is measured at the plant’s energy meter if one is configured for a site.
  • Data Quality / AC loss gap: This is the gap between the Metered Production and the Analyzed Inverter Production. The difference can be due to actual AC wiring losses between the two (when the Inverter Production is higher than the Metered Production) or due to data gaps or other data quality issues (when the Inverter Production is lower than the Metered Production).
  • Analyzed Inverter Production: The production is measured at the inverter output after filtering out periods of poor data quality. Depending on the quality of the data flows, this value may be more or less than the metered production. Theoretically, this value shall be greater than metered production due to downstream AC wiring losses, but in practice, this often shows up less than metered production due to varying degrees of data quality problems in the time series data.
  • Achievable Production: The sum of analysed production and recoverable production.
  • Recoverable Production: Production that can be added to the actual production by taking all cost-effective corrective actions.


Budgeted Values

Settings page where the user can update their initial energy model assumptions

If the configuration gets modified on the Waterfall page or any of the loss assumptions on the Settings page and “Save” them, then the page will update what is shown in the Waterfall immediately. To update the TMY used in the Weather Adjustment or update the production budgets, the run of the waterfall algorithm is required for these to take effect, so please get in touch with the delivery team representative with a request to do so.


Comparison TMY and Actual Weather for P50 Weather Adjustment

This time chart provides a visual representation of different Production Metrics (Expected and Budgeted), and also the weather adjustment calculations based on POA and GHI sensors.


At the top-right side, two different point sets are available, including:

  1. Production
  2. Weather Adjustment