Radiation over a Period
The solar energy each sensor receives over a period of a weather file, in kWh/m², from the Perez all-weather sky and the sun hour by hour.
Preview implementation — live Rhino verification pending. The engine is built and tested headless, and its sky is checked against Radiance. The weather-file dialog, the run and the panel have not yet been used in a live Rhino session, and the GPU kernels have been compiled and checked against CPU stand-ins but not yet run on a GPU.
Part of Wrengler Pro, with Solar Radiation. On Free, the panel shows an upgrade message instead of running.
Radiation over a period sums the solar energy that reaches your geometry across the hours you choose from a weather file: a year, a season, or a range of dates and hours of the day. For each sensor it reports direct, diffuse and total energy in kWh/m², and paints the total across your geometry.
Every number here is energy summed over the period. For the power arriving at one moment, use Solar Radiation.
The Weather File
Choose an EnergyPlus weather file (.epw), the format TMY3, IWEC and most typical-year datasets ship
in. Rhino reads it on your machine; it is never uploaded. The panel shows the station's place, its
coordinates and how many hours it holds.
An hour whose direct or diffuse irradiance is marked missing is left out and counted, never read as zero. The result says how many hours of the period were missing.
The Sky and the Sun
- The diffuse sky is the Perez all-weather model, evaluated for each hour and scaled so its patches give that hour's diffuse horizontal irradiance exactly. It is divided into Tregenza's 145 patches, or Reinhart's 577 when you choose the finer sky.
- The sun is traced at its true position at the middle of each hour, carrying that hour's direct normal irradiance, so shadows stay as sharp as the sunlight study's.
- The ground is black: nothing reflected from it is counted.
- North is the document's north angle, applied to the sky and the suns together, as the sunlight study applies it.
Checked Against Radiance
The sky is compared with Radiance's gendaymtx, the reference implementation, on the NREL Golden,
Colorado TMY3 file. Hour by hour, every patch matches to within 2×10⁻⁵; over the whole year, every
patch's energy agrees within 1.1%. Over that year, an open horizontal plate receives 1,619.2 kWh/m²,
and the weather file's own global horizontal column sums to 1,619.9 kWh/m².
The Period
- Dates are a month and a day, both ends included. A range from a later month to an earlier one runs across the new year: November to February is one winter.
- Hours of the day are the file's local standard time. An hour counts when its middle falls in the range, so 9 to 17 is eight hours.
Assumptions
They travel with the numbers, in the panel and in every export.
| Assumption | Value |
|---|---|
| Weather file | the station's place and dataset |
| Period | the dates and hours, in words |
| Hours used, hours missing | from the file |
| Sky model | Perez all-weather, 145 or 577 patches |
| Suns | one per hour with the sun up and direct light |
| Ground reflection | not modelled — the ground is black |
| North angle | the document's, in degrees |
| Open total | what an unobstructed horizontal sensor receives over the period, kWh/m² |
| Accumulation | period |
| Units | kWh/m2 |
How to Run
In the radiation panel, set Mode to Weather file, choose the file, and set the dates, the hours of the day and the sky. The analysis surfaces, cell size and display choices are the same as for Solar Radiation. The study runs automatically when an input changes, and the surface table reports each surface's mean, minimum and maximum over the period.
The default legend runs from 0 to what an open horizontal plate receives over the period, or to the brightest sensor when a tilted one receives more.
A year is about four thousand suns and a sky of 145 or 577 patches per sensor. On four CPU cores, ten thousand sensors take about four seconds; a GPU is faster.