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Stage 2 of 13 / Calculation

Build the load profile

Convert a listed load schedule into daily and annual energy, a diversified peak and a critical-load subset for backup.

  • Practitioner
  • 13 stages
  • 12 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
  • Enter a load schedule and read daily, annual and critical energy.
  • Explain why the diversified peak is lower than the sum of nameplate ratings.
  • Decide which loads are critical and defend the autonomy target they imply.

The engineering

The load audit is a ledger: quantity × rated watts × daily hours, with a category template that spreads the load across the day. Refrigeration cycles, motors surge, cooling follows summer and lighting follows winter; the workbench applies those shapes rather than treating every load as a flat block.

The energy total and the peak are different questions. Energy sizes the array and the battery; the coincident, diversified peak sizes the inverter and the backed-up AC load. A schedule with a large energy total but a small peak is a very different design from the reverse.

Mark only the loads that must survive an outage as critical. That subset drives the autonomy requirement, and inflating it silently oversizes the battery. If there is no measured profile, say so in the capstone rather than presenting an estimate as a measurement.

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Inputs and outputs

What this stage owns

You own

  • Quantity, rated watts and daily hours for each load
  • Category and seasonal shape
  • Critical flag, deferrable flag and surge factor
  • Diversity factor and load growth

You produce

  • Daily, annual and critical energy (kWh)
  • Coincident diversified peak (kW)
  • 24-hour shape and monthly energy/peak table

Your deliverable for this stage

Capstone evidence

A load schedule with daily energy, diversified peak and a marked critical subset.

Stage assumptions, limits and sources

Provenance

Assumptions

  • Rated watts are running watts for the hours entered.
  • Category templates are representative shapes, not measured appliance traces.
  • Diversity applies to the coincident peak, not to the energy total.

Constraints

  • The schedule is a single typical day repeated across each month.
  • Load growth is applied to the annual forecast, not to the hourly shape.

Limitations

  • Duty cycles, standby power, low power factor and harmonic currents are not modelled.
  • No weekday/weekend or occupancy variation; no measured demand data.

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: load-audit