Photovoltaic Performance
You might have followed the sections for solar position and solar irradiance or maybe not. Regardless, this tutorial is both a stand-alone document and a building block in the chain of calculations to estimate photovoltaic power output.
Analysis of Performance¶
We start right away with an analysis of the photovoltaic performance for our sample location behind the ESTI facilities in the JRC, Ispra.
pvgis power broadband \
8.628 45.812 214 180 0.1 \
--start-time '2014-01-01' \
--end-time '2014-12-31' \
--global-horizontal-irradiance data/sample_sarah3_sis_over_esti.nc \
--direct-horizontal-irradiance data/sample_sarah3_sid_over_esti.nc \
--spectral-factor-series data/sample_spectral_effect_cSi_over_esti.nc \
--temperature-series data/sample_era5landplus_t2m_over_esti.nc \
--wind-speed-series data/sample_era5landplus_wind_speed_2m_over_esti.nc \
--neighbor-lookup nearest \
-aou degrees \
--quiet
PVGIS provides a compact overview of the calculations that generate the final power output.
Nonetheless, in order to make better sense of the reported figures, we can go through the algorithmic structure of the power-rating model implemented in PVGIS.
Efficiency¶
Have a look in the following sources:
Photovoltaic power¶
PVGIS uses a modified version of the power-rating model by King.
See also: Huld, 2011
Thomas Huld, Gabi Friesen, Artur Skoczek, Robert P. Kenny, Tony Sample, Michael Field, Ewan D. Dunlop, A power-rating model for crystalline silicon PV modules, Solar Energy Materials and Solar Cells, Volume 95, Issue 12, 2011, Pages 3359-3369, ISSN 0927-0248, doi.org/10.1016/j.solmat.2011.07.026 (https://www.sciencedirect.com/science/article/pii/S0927024811004442)
Abstract
A model for the performance of generic crystalline silicon photovoltaic (PV) modules is proposed. The model represents the output power of the module as a function of module temperature and in-plane irradiance, with a number of coefficients to be determined by fitting to measured performance data from indoor or outdoor measurements. The model has been validated using data from 3 different modules characterized through extensive measurements in outdoor conditions over several seasons. The model was then applied to indoor measurement data for 18 different PV modules to investigate the variability in modeled output from different module types. It was found that for a Central European climate the modeled output of the 18 modules varies with a standard deviation (SD) of 1.22%, but that the between-module variation is higher at low irradiance (SD of 3.8%). The variability between modules of different types is thus smaller than the uncertainty normally found in the total solar irradiation per year for a given site. We conclude that the model can therefore be used for generalized estimates of PV performance with only a relatively small impact on the overall uncertainty of such estimates resulting from different module types.
Keywords Crystalline silicon; PV energy rating; PV performance; Performance rating
We can simulate the photovoltaic power output via
or estimate it by reading external irradiance time series via
pvgis power broadband \
8.628 45.812 214 180 45 \
'2014-01-27 12:00:00' \
--global-horizontal-irradiance data/sample_sarah3_sis_over_esti.nc \
--direct-horizontal-irradiance data/sample_sarah3_sid_over_esti.nc \
--neighbor-lookup nearest
Panel tilt¶
The default tilt angle for a solar surface is 45 degrees.
In order to get the calculations done for a horizontally flat panel,
we need to request this via the fifth positional parameter
with a value close to 0 like 0.0001.
Let's add it to the power commands :
- simulating the photovoltaic power output
- using SARAH-3 data
pvgis power broadband \
8.628 45.812 214 180 0.0001 \
'2014-01-27 12:00:00' \
--global-horizontal-irradiance data/sample_sarah3_sis_over_esti.nc \
--direct-horizontal-irradiance data/sample_sarah3_sid_over_esti.nc \
--neighbor-lookup nearest
We can request more details on the calculations
pvgis power broadband \
8.628 45.812 214 180 0.0001 \
'2014-01-27 12:00:00' \
--global-horizontal-irradiance data/sample_sarah3_sis_over_esti.nc \
--direct-horizontal-irradiance data/sample_sarah3_sid_over_esti.nc \
--neighbor-lookup nearest \
-vvv
PV Power series [W] (1/3)
Time ⌁ Power Technology ⌁ Power without Loss ％ Efficiency
───────────────────────────────────────────────────────────────────────────────────────────────
2014-01-27 12:00:00 173.761 cSi:Free standing 2025 202.048 0.98
⅀ / μ 173.761 202.048 0.98
PV Power series [W] (2/3)
Time % System Efficiency ☂ In shade ☉ ⛰ Sun-Horizon Position
────────────────────────────────────────────────────────────────────────────────────
2014-01-27 12:00:00 0.86 False Above
⅀ / μ 0.86
PV Power series [W] (3/3)
Time Incidence Definition Frequency
───────────────────────────────────────────────────────────────
2014-01-27 12:00:00 Sun-Vector-to-Surface-Plane Single
⅀ / μ
╭──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ Angular units ㎭ radians │
│ Location Longitude, Latitude = 0.151, 0.8 │
│ Position Surface Orientation: 3.142, Surface Tilt: 0.0 │
│ Definitions Azimuth origin : North, Zone : UTC, Sun-Horizon Positions: Above, Low angle, Below, Shading states: │
│ Sunlit, Potentially-sunlit, In-shade, │
│ Algorithms Power model: Huld 2011, Timing : NOAA, Positioning : NOAA, Incidence : Iqbal, │
│ Constants Solar constant : 1360.8, Perigee : 0.048869, Eccentricity : 0.03344 │
╰────────────────────────────────────────────────────────────────────────────────────────────────────────── Reference ─╯
╭──────────────────────────────────────╮
│ ⌁ Power ⅀ N-ary Summation │
│ ％ Percentage μ Mean │
│ ☂ In shade │
│ ☉ Sun │
│ ⛰ Horizon │
│ - Loss │
╰───────────────────────────── Legend ─╯