What a simulation includes
What the engine models, and what stays outside a single run.
Reviewed
What this is for
One pairing: this design, this condition set, one non-leap 8,760-hour year. Same inputs, same outputs. The year is local standard time, with no daylight saving. Solar geometry is sampled at the hour midpoint.
It models generation. It does not see a kilowatt-hour of load. Consumption, tariffs, batteries and the grid-code verdict are later pairings that read a run. Folding them into the year would mean a new 8,760 for every load profile, which is why dispatch and pricing happen after.
The engine is bounded against a synthesised clear-sky year and a PVGIS run. It is not validated against a measured year. Treat production as modelled.
Steps
- What goes in: the design (geometry, modules, and the wiring, regenerated before the run if the array has moved since it was generated), the condition set (weather file, horizon, soiling and the other losses, the models, mismatch, which characterisation), nothing else.
- What comes out: hourly production, the loss waterfall (why the year is not the nameplate times 8,760), specific yield, performance ratio, annual energy. Those three are the cell on the matrix. The waterfall is a report of the solved year, not a chain of derates applied to a guess.
- What stays outside this run:
- Site consumption. Edited on Consumption. Used by storage and by the bill.
- The tariff. Set on the site. Used by Financials.
- Storage and outages. Storage, against a run and a load.
- Grid-code checks. Compliance, against a design.
- A proposal. Generated afterwards, frozen.
- The engine is queued. It does not run in the browser session. Cancel is honoured at hour boundaries. Progress is the matrix cell.
- Performance ratio is AC over in-plane irradiance times nameplate (
AC ÷ (POA × kWp)). Dividing by a later optical step would make a dirtier array look better.
Nothing is queued until the design has modules, its modules and inverters carry the datasheet figures the model divides by, and the condition set has weather. The matrix cell says Not ready. A missing figure is refused rather than filled with an assumed value, because a year run on a guess reads exactly like a modelled one.
Tips and common mistakes
- A year of production is not a bill. The bill is two computed years of the tariff, with and without generation.
- Changing soiling stales every cell in that condition set's column; changing a tilt or swapping an inverter stales every cell in that design's row. Re-running writes a new run of the same pairing, and the old one stays in the matrix's run history.
- Do not expect storage to move the production cell. Dispatch reads the run; it does not rewrite it.