Losses may be either manually entered by the user or may be calculated within SAM or View. The following table gives an overview of how each loss category can be specified and/or determined:
| Loss Category | Determined via | Description |
| Long-Term Module Degradation | User Input | Annual degradation rate of module output power due to long-term degradation of module performance. Note: This is currently applied to the annual AC output of the system for each year after Year 1 and is not modeled as a true DC degradation. |
| Light Induced Module Degradation | User Input | Short-term degradation of module output power due to initial exposure to irradiation. Typically occurs over initial days to months of plant operation. This loss should be lumped within the Non-Ohmic DC Loss input field on the Electrical Inputs page. Non-Ohmic DC losses are applied as a DC loss within the model. |
| Self-Shading | SAM | Row-to-row shading of modules within an array. SAM uses a non-linear shading calculation for crystaline modules and a linear shading calculation method for thin film modules. |
| External Shading | Not Calculated | Shading from near and far objects such as trees and mountains is currently not considered unless they are integrated by the user into the TMY weather data to simulate a horizon obstruction. Note: Some weather data software such as Meteonorm can automatically integrate the effects of far-shading horizon effects into TMY weather data. |
| Soiling | User Input | Users may input either average annual soiling losses or monthly soiling losses. The total losses due to soiling as a percentage will be reported in the HST report. |
| Snow | Not Calculated | The effect of snow accumulation is not currently considered |
| Module Cover / Incident Angle Modification (IAM) | SAM | Optical losses that occur when the solar angle of incidence on the array surface is greater than zero. This represents energy that is lost to reflection from the module surface materials. |
| Bifacial Gain | SAM | Energy generation gain due to module rear-side contribution. This is only reported when the module is bifacial. |
| Module Thermal (Cell Temperature Correction) | SAM | The mounting specific heat transfer model is used to determine losses due to off-nominal cell temperatures for modules selected from the CEC database. Alternatively, the NOCT temperature correction method is utilized for cell operating temperature correction when user defined modules are selected. |
| Module Nameplate | User Input | Nameplate losses or gains stem from variances in actual module power ratings versus nameplate power ratings. This should be accounted for in the Non-Ohmic DC Loss input field on the Electrical Inputs page |
| Module Mismatch | User Input | Module Mismatch losses stem from variances in module IV characteristics for series connected modules in a string. This should be accounted for in the Non-Ohmic DC Loss input field on the Electrical Inputs page |
| MPPT Clipping | SAM | Losses due to operating outside of the Maximum Power Point Tracking (MPPT) voltage window of the inverter |
| DC Connections | User Input | Thermal losses due to increased resistance across connection points and through fuses and diodes. This should be accounted for in the Non-Ohmic DC Loss input field on the Electrical Inputs page |
| DC Wiring | View | Thermal losses due to DC resistance of wires. Calculated using length and size of all DC circuits. The loss percentage used is calculated at the maximum DC current flowing through the circuit. DC String and DC Feeder (where designed) wiring are both calculated and reported separately. |
| DC Wire Mismatch | User Input | Losses due to differences in voltage drop between multiple DC circuits on the same inverter Maximum Power Point Tracker (MPPT). This should be accounted for in the Non-Ohmic DC Loss input field on the Electrical Inputs page |
| Inverter Clipping | SAM | Power lost due to DC input power exceeding inverter input power limit. |
| Inverter Internal Power Consumption (Day/Night) | SAM | Normal active and standby power consumed by the inverter. |
| Inverter Efficiency | SAM | Energy lost due to DC/AC conversion efficiency of the inverter. |
| Inverter Ambient Temperature Derate | View | Energy clipped by the inverter to prevent thermal damage to inverter components as a function of ambient temperature. |
| Medium Voltage Transformers | View | Winding and core losses due based on typical transformer characteristics for the voltage and power ratings of the transformers used. Note that the core losses reported are for a single transformer only. |
| AC Wiring | View | Thermal losses due to AC resistance of wires. Calculated using length and size of all AC circuits (Low Voltage/ Medium Voltage/High Voltage). The loss percentage used is calculated at the maximum AC current flowing through the circuit. LV AC Feeder (where designed), MV AC Feeder and Gen-Tie Line (where designed) wiring are all calculated and reported separately. |
| High Voltage Transformer | View | Winding and core losses due based on typical transformer characteristics for the voltage and power ratings of the transformers used |
| Station Losses | User Input | Energy lost to supply normal station loads such as station lighting and security, O&M building loads, relay house loads, etc. |
| Reactive Power Compensation | View | Real Power lost due to power factor control at the and reactive power compensation. |
| Generation Curtailment | View | Energy lost due to intentional power curtailment when AC power generated exceeds Max AC Power limit at the Point of Delivery |
| System Availability | User Input | Lost energy production due to system outages, planned maintenance and/or grid availability being less than 100% |