Simulation variables: Grid system
The following variables are calculated during the simulation process, and available as results:
Weather data and irradiation variables: see previous page.
PV array behaviour
| PNomArray | Nominal Installed Power | Nb. PV modules * nameplate PNom |
| EArrRef | Array reference energy for PR calculation (as defined in the IEC EN 61724 norm) | GlobInc * PNomArray |
| EArrNom | Array nominal energy at STC, according to the one-diode model. Starting point of the array energy evaluation in the loss diagram | GlobEff * Pmpp (STC) |
| GIncLoss | PV loss due to irradiance level | low-light efficiency |
| TempLoss | PV loss due to temperature | see Uc and UV parameters |
| SpctCor | Spectral correction | for amorphous modules, CdTe, Sandia model |
| LigSoak | Light soaking for CIS/CIGS modules | |
| ShdElec | Electrical loss for mismatch due to shadings | calculation "according to module strings" or "ModuleLayout" |
| ModQual | Module quality loss | users choice concerning real performance of the modules |
| LIDLoss | Light Induced degradation | for mono-crystalline modules, p-type wafer only |
| MisLoss | Module array mismatch loss | |
| OP_Oper | Optimizers Loss during operation | efficiency curve |
| OP_Pmin | Optimizers Loss due to power threshold | |
| OP_Pmax | Optimizers Loss due to power overload | |
| OP_Vmin | Optimizers Loss due to low voltage MPP window | |
| OP_Vmax | Optimizers Loss due to upper voltage MPP window | |
| OhmLoss | Ohmic wiring loss in the DC array | |
| EArrMPP | Array MPP energy after all array losses | on the loss diagram |
| EArray | Effective energy at the array output | taking inverter operating point displacements into account - not represented on the Loss diagram |
| Iarray | Array current | taking inverter operating point displacements into account |
| Uarray | Array voltage | taking inverter operating point displacements into account |
Inverter behaviour
(see also Inverter operating limits)
| InvLoss | Global inverter loss | |
| IL_Oper | Inverter Loss during operation | efficiency curve |
| IL_Pmin | Inverter Loss due to power threshold | |
| IL_Pmax | Inverter Loss due to power overload | |
| IL_Vmin | Inverter Loss due to low voltage MPP window | |
| IL_Vmax | Inverter Loss due to upper voltage MPP window | |
| IL_Night | Inverter night energy | |
| Syst_ON | System operating duration | |
| EOutInv | Available Energy at Inverter Output | may be larger than EArray if grid limitation is accounted as separate loss |
Energy output and use
| Aux_Lss | Auxiliaries consumption | Fans, other... |
| EacOhmL | AC ohmic loss | wiring up to injection point |
| ETrfLss | External transfo loss | iron loss and ohmic contribution |
| UnavLss | System Unavailability loss | Specified or random periods of shutdown |
| E_Solar | Energy supplied to the user from solar | if load is defined (Netmetering) |
| E_User | Energy need of the user | if load is defined (Netmetering) |
| E_Avail | Energy available from the sun | = EOutInv - losses after inverter (Wiring, night losses) |
| E_Grid | Energy injected into the grid | |
| EApGrid | Apparent energy into the grid | when Power factor defined |
| ERegrid | Reactive energy into grid | when Power factor defined |
| EGrdLim | Grid limitation loss | when Grid limitation is accounted as separate loss |
| SolFrac | Solar fraction | ESolar / EUser |
Efficiencies
| EffArrR | Array Efficiency | EArray / rough area |
| EffArrC | Array Efficiency | EArray / cells area (=0 when cells area not defined) |
| EffSyR | System efficiency | EOutInv / rough area |
| EffSyC | System efficiency | EOutInv / cells area. |
| EffInvB | Inverter efficiency | Threshold loss included |
| EffInvR | Inverter efficiency | When operating |
Normalised performance index (cf IEC EN 61724, usually expressed and plotted as values per day)
| Yr or | Reference Incident Energy in collector plane | = GlobInc [kWh/m²] (kWh irradiance) |
| Yr | Normalized Reference nominal energy at STC | = EArrRef / PNomArray [kWh/kWp] (kWh electrical) |
| Ya | Normalized Array Production | = EArray / PNomArray [kWh/kWp] |
| Yf | Normalized System Production | = EGrid or EAvail / PNomArray [kWh/kWp] |
| Lc | Normalized Array Losses | = Yr - Ya |
| Ls | Normalized System Losses | = Ya - Yf |
| PR | Performance Ratio | = Yf / Yr = E_Grid / (GlobInc * PNomArray) |
NB: The Normalized Reference nominal energy at STC Yr [kWh/kWp] is the electrical energy which would be produced by the Reference incident energy on the collector plane under STC conditions (1 kWirrad/m2, 25°C). This explains that the values are identical.