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Aerial view of rows of photovoltaic modules at a large solar farm

Stage 3 of 13 / Calculation

Build the solar resource and PV yield

Transpose monthly horizontal irradiation onto the array plane and compute hourly-shaped PV yield with explicit loss terms.

  • Practitioner
  • 13 stages
  • 14 min
  • Solar PV and electrical storage
Development preview Solar PV and Battery: Full Engineering Workbench
Development preview. The calculations on this journey run on existing EngiMetric engines, but the journey text and scope have not completed independent engineering review. The route is excluded from search while it remains a preview.
Professional review required.The engines are implemented and unit-tested in this repository, but the journey copy, defaults and boundary still require review by a licensed engineer before publication. The route remains a noindex preview. Current verification state: Needs engineering review.

After this stage you can

Learning objectives
  • Explain the difference between GHI and plane-of-array irradiation.
  • Read monthly yield, performance ratio, capacity factor and clipping loss together.
  • Identify the assumptions that would change the annual total most.

The engineering

Horizontal irradiation is not array irradiation. The workbench splits global horizontal irradiation into beam and diffuse components with an Erbs correlation, then transposes both onto the tilted plane with an isotropic sky model evaluated at mid-month noon. That is a defensible screening step, not a bankable transposition.

Yield applies temperature, soiling, mismatch, DC wiring, AC wiring and availability losses, and clips AC output at the inverter limit. Clipping is reported separately: a high DC/AC ratio can raise energy in weak months while throwing away midday production in strong ones.

Read the monthly table before the annual total. An annual number can look healthy while the shortest month is carried by the battery or the grid. The performance ratio and capacity factor are sanity checks, not guarantees.

EngiMetric / solar workbench

Your project, computed stage by stage

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Inputs and outputs

What this stage owns

You own

  • Latitude, tilt, azimuth and albedo
  • Twelve monthly GHI and ambient-temperature values
  • Module rating, count, efficiency and temperature coefficient
  • Inverter AC limit and loss percentages

You produce

  • Monthly POA irradiation and PV AC energy
  • Annual yield, specific yield, PR and capacity factor
  • Clipping loss, hourly average shape and degradation forecast

Your deliverable for this stage

Capstone evidence

A monthly and annual PV yield table with every loss term and limit stated.

Stage assumptions, limits and sources

Provenance

Assumptions

  • The sky is isotropic and the transposition is evaluated at mid-month noon.
  • Cell temperature follows a NOCT model with the stated ambient temperature.
  • Losses are multiplicative and constant across the year.

Constraints

  • One representative day per month is repeated; no hourly weather file is used.
  • The Erbs correlation is a screening split, not a site calibration.

Limitations

  • No shading, snow, spectral, low-irradiance or thermal-transient model.
  • No measured irradiance, soiling station or module binning.
  • Uncertainty is indicative and is not a bankable P50/P90 analysis.

Review status

  • Needs engineering review
  • Professional review is required before publication or use as a design basis.

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Stage kind: Calculation / Journey: solar-bess-screening / Stage: solar-resource-yield