Denowatts

Model Management

Simulations vs. Models

Simulations are model chains (Models) run with synthesized datasets, often in hourly .csv formats referred to as “P50” or “8760” files. The purpose of Simulations is to produce the Predicted Energy used to underwrite sites. Every Simulation is mapped to a corresponding Model. Models consist of Blocks, sometimes referred to as “subarrays”, and shade scenes.

Simulations and Models are managed within Denowatts’ framework for Benchmark computation. Each Simulation and Model has a start date, and prior versions have end dates. Denowatts supports multiple versions of each, including model Use classification. For example, a Site may have a single Investor Model, with 20 Predicted Simulations—one for each Year 1-20.

Simulations may also be set to Predicted, Capacity Test, or N/A (deprecated), depending on the purpose. In the portal’s Simulation tab, this is the “Use as” column, where the options are Predicted, Capacity Test, and Not in Use. For example, the Predicted mark indicates the Simulation will be used for Energy Accounting and long-term reporting. However, the Capacity Test mark indicates the simulation will be used for the ASTM E2848 Capacity Test.

In the Deno Portal, the Energy Model page has a Model tab and a Simulation tab, and the Model Type is chosen as Owner’s (Expected) or Operator’s. An Operator’s Model is linked to an Owner’s Model.

See Models & Benchmarks for Model Types (Investor’s and Operator’s) and the benchmarks they produce.

Proxy Model

Denowatts accepts any Investor model format. Users upload model files to the Deno Portal during the onboarding process, and Denowatts reconstructs a Proxy Model that is used for day-to-day benchmarking and reporting. Denowatts uses physics-based model chains to replicate the Investor’s model, including any post-processing steps that the original modeling software may not capture. Models are organized by Blocks, a Shade Scene, Degradation schedule, and Site-level Parameters.

  • Blocks are the input parameters, containing information about the physical model, including PV modules, inverters, string sizing, mismatch and ohmic loss assumptions, mounting type and characteristics, etc. In some modeling software, Blocks are known as “subarrays”. A Model always describes a discrete Site, containing one or more Blocks.
  • A Shade Scene consists of a table of factors that quantify the impacts of modeled shade on a Site. Investor’s Model Shade Scenes may be imported into the Model page as Irradiance and Mismatch Shade Scenes, often exported with a PVsyst.prj folder.
  • The Degradation Schedule includes the project’s Commercial Operation Date (COD), the start of the degradation, as well as annual degradation and unavailability assumptions.
  • The Site Parameters consist of factors that apply to the Site level rather than Block level, for example, sub-interval clipping, soiling, snow, power factor, curtailment, and other dispatch assumptions.

In the Model tab, the Degradation Schedule is edited under Degradation (“Degradation & Availability by Year”), the Site Parameters under Site Assumption, and the Shade Scene under Shade (“Load Shade Data”, with Linear Shade Table and Strings Shade Table).

Proxy Model Pipeline

Simulation Management

Predicted Energy assumptions are often a combination of model pipeline software (e.g., PVsyst) and post-processing impacts. This format provides Year 0 detail, but does not allow for adequate Year N simulation detail to perform Energy Accounting. To address this, Denowatts reconstructs the Investor Simulation, including Post Processing impacts, using the Proxy Model and the Investor Model Resource file. Combined with the Degradation Schedule, Year N Simulations are produced, each accurately reflecting the Investor’s assumptions about future years. In summary, all Predicted Energy accounting is reported against reconstructed Proxy Model Simulations, not the original Investor’s Model, though the Predicted Energy values should be very closely aligned.

Denowatts prefers original Investor Simulations be uploaded to Denowatts as PVsyst.prj .zip folders, along with Post-Processing impacts, if any. Denowatts prefers to maintain the project source files whenever possible, including a full (all-parameter) 8760 file. Detailed simulations, including all loss parameters, are necessary for Energy Accounting analysis and reporting to baseline assumptions. Simulations are uploaded to Denowatts as .csv files, often from PVsyst.

Denowatts requires two simulations to be uploaded: With and without soiling/snow effects. The “clean” variant represents the deterministic model steps. The “soiled” variant includes non-deterministic losses, often set as losses by month, in modeling software.

Post-processing impacts are part of the Proxy model chain reconstruction. Post-processing steps are generally Point of Interconnection (POI) impacts of loss drivers that are not captured by the Investor Model software. Instead, users often add these losses in a spreadsheet. During the Proxy model setup, users quantify Post-Processing losses. This allows Investor Post-Processing loss drivers and impact values to be natively transformed into the Proxy Model in proper sequential transformation steps.

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