Step 1: Within the Project Design Environment, Click Electrical on the left Navigation Bar.
Step 2: Enter Site Interconnection data.
|Max Interconnection AC Power (at POD)||Maximum AC power that can be delivered to the point to delivery. All power generated above this value will be curtailed. This is typically limited by the electric service provider (utility) and dictated within the interconnection agreement.||100||[0 – 999]|
|Interconnection Voltage (kV)||Utility interconnection voltage. If voltage is greater than 34.5kV, additional high voltage transformer and gen-tie line losses may be estimated.||34.5||[0 – 500]|
|Point of Common Coupling (PCC) Coincident with Point of Delivery (POD)?||The PCC is the point at which generator owned facilities connect to the electric service provider (utility) owned facilities. The PCC is generally located within the site boundary. The POD is the point at which electric power is delivered to the electric service provider (utility). The POD may or may not be located within the site boundary. If the PCC and POD are not coincident, then a gen-tie line is required and losses will be estimated and included within the performance model.||Yes||[Yes, No]|
|Gen-Tie Line Length (mi)||Transmission or Distribution line that connects the system with the Utility. This is only used where the PCC is not coincident with the POD. This length is used to estimate line losses that occur between the PCC and POD.||0||[0 – 100]|
|Min Interconnection AC Power (at POD)||Enter the minimum AC power that the plant must be able to deliver to the grid measured at the point of delivery. Any designs tested that are not capable of delivering this minimum power level will be considered infeasible. Set this parameter to 0 if there are no minimum AC power requirements at the point of delivery that must be met. The minimum AC power level includes all AC losses except the availability loss.||0||[0 – 999]|
|Power Factor Requirement at POD (Leading)||The power factor requirement that the plant must be able to meet at full power at the Point of Delivery (POD). This requirement is typically specified within an interconnection agreement. Power Factor is defined as the ratio of Real Power (in kW) to Apparent Power (in kVA). A leading power factor defines the condition where the current leads the voltage. Note that the Plant Control Mode must be placed in “Real and Reative Power Control” and the Capacitor Bank Modeling must be set to “Automatically Size” in order for the software to automatically size the capacitor bank to meet this leading power factor requirement. The leading power factor capability of the plant will be specified in the output report.||0.95||[0.5 – 1]|
|Power Factor Requirement at POD (Lagging)||The lagging power factor requirement that the plant must be able to meet at full power at the Point of Delivery (POD). This requirement is typically specified within an interconnection agreement. Power Factor is defined as the ratio of Real Power (in kW) to Apparent Power (in kVA). A lagging power factor defines the condition where the current lags the voltage. Note that the Plant Control Mode must be placed in “Real and Reative Power Control” in order for the software to determine if the inverters alone can meet the lagging power factor requirement. This will be specified in the output report. Unlike the leading power factor requirement (in which a capacitor bank may be sized to meet the requirment), the software will only use the inverter reactive power capabilities to attempt to meet the lagging power factor requirement and will not add inductive reactors or other compensation devices.||0.95||[0.5 – 1]|
Step 3: Enter System Design data.
|Max String Circuit Loss (%)||Maximum power loss allowed per DC String Circuit at full power. This is used in the plant layout to limit individual circuit distance.||2||>0|
|Max DC Feeder Circuit Loss (Central Inverters Only) (%)||Maximum power loss allowed per DC Feeder Circuit at full power. This is used in the plant layout to limit individual circuit distance. This parameter is only used for central inverter designs.||4||>0|
|Max LV AC Feeder Circuit Loss (String Inverters Only) (%)||Maximum power loss allowed per LV AC Feeder Circuit at full power. This is used in the plant layout to limit individual circuit distance. This parameter is only used for string inverter designs.||4||>0|
|Maximum Number Combiner Box Inputs (# Inputs)||Maximum number of inputs per combiner box that is allowed. This will limit the size of the PV sub-block. A sub-block is defined as the PV that is electrically connected to a single combiner box.||36||–|
|String Monitoring?||Include additional costs for string monitoring within combiner boxes. Not Applicable for String Inverter Systems.||No||[Yes, No]|
|Pre-Parallel Strings?||Strings can be wired in parallel prior to connecting to the combiner box input. This reduces the number of connections made to the combiner box and increases the current in each string home run circuit. This is useful for low-current technologies like thin-film modules. Note that this field really functions as a control to reduce processing time when you are sure that you do not want to pre-parallel strings. If you are sure you do not want strings to be pre-paralleled, choose “No”. If you are unsure or if you are comparing modules with different technologies such as multi-crystalline and thin film in the same optimization run, choose “Yes”. This will result in the application looking at different numbers of strings pre-paralleled including just one string. Where strings are pre-paralleled,an additional positive and negative parallel wiring harness and in-line fusing will be added to the BOM based on the number of strings per harness.||No||[Yes, No]|
Step 4: Enter Energy Modeling Preferences and Data.
|Average Annual Soiling Losses (%) **||Irradiance blocked by soiling or other material buildup on module surfaces||5||real >= 0 or array of real >= 0 (length 12)|
|Energy Availability (%)||Amount of time that it is able to produce electricity over a certain period, divided by the amount of the time in the period||100||[75 – 100]|
|Simulate True DC Module Degradation?||Module Degradation reduces the DC output of the system annualy. To accurately simulate this within the energy model, the simulation must be performed separately for every year of the project lifespan which increases processing time by approximately 1 second per design iteration. Alternatively, the module degradation may be applied to the AC output of the system which simply reduces the first year annual generation by the compounded module degradation rate for years 2 through the project lifespan and thus only requires hourly simulation of a single year. By selecting ‘Yes’, you are choosing to more accurately apply the module degradation rate to the DC generation for each year in the project lifespan. By selecting ‘No’, you are choosing to apply the module degradation rate to the annual AC generation for each year. Note: This selection will not affect the Year 1 energy production or losses. It will only affect the annual energy production.||Yes||[Yes, No]|
|Non-Ohmic DC Losses (%)||DC electrical losses not due to heat loss in wiring. This includes, e.g., mismatch losses and connector losses.||0||–|
|Station Constant Power Loss (kW)||The Station Power Loss is a constant loss that is subtracted at each hour time step and can be used to represent station loads such as lighting, HVAC, relay house loads, security system, O&M computer networks, etc.||0||>=0|
|Plant Control Mode||Under Real Power Control Only mode, the effects of reactive power and reactive power compensation are not modeled and only the real power may be curtailed at the point of delivery to meet the “Max AC Power” interconnection limit. Under Real and Reactive Power Control mode, both real and reactive power are simulated and the effects of reactive power compensation to meet power factor requirements are factored into the energy simulation and real power losses. In this mode, the inverter power factor is controlled (within the limits specified within the inverter profile) at each hour time step of the simulation to meet the average power factor requirement specified at the point of delivery, inclusive of AC network impedances from cables and transformers. Additionally, cap bank stages (if incorporated in the design) may be switched in at each hour time step to reduce real power losses. Finally, the real power is curtailed if necessary to meet the “Max AC Power” interconnection limit.||Real Power Control Only||[Real Power Control Only, Real and Reactive Power Control]|
|Capacitor Bank Modeling||Choose how you would like to size the capacitor bank. Automatically sized cap banks will be sized to meet the Leading Power Factor Requirement at the POD. But the size will be selected to either: 1) minimize the cap bank size or 2) minimize the AC losses.||No Cap Bank||[No Cap Bank, User Defined Size, Automatically Sized (Min Cap Bank), Automatically Sized (Min Losses)]|
|Capacitor Bank Size (kVAR)||The total capacitor bank size in kVAR for the user specified capacitor bank
|Number of Capacitor Bank Stages||The total number of capacitor bank stages. Stages can be used to break the total capacitor bank up into smaller banks for the purpose of more granular reactive power control. Each stage may be switched into the system independently. For example, a 4.5MVAR capacitor bank with 3 stages will be modeled as 3 x 1.5MVAR cap banks which can be switched into the system as 1.5MVAR, 3MVAR or 4.5MVAR.||2||>0|
|Average Operating Power Factor at POD||This is the average operating power factor that should be modeled. The plant controller will attempt to meet this power factor for each hour of the day using both the inverter capabilities as well as cap banks (if included in design). Typically, this should be fairly close to 1 and not as extreme as the power factor requirements specified within the interconnection agreement. Power Factor is defined as the ratio of Real Power (in kW) to Apparent Power (in kVA). A leading power factor defines the condition where the current leads the voltage while a lagging power factor defines the condition where the current lags the voltage.||0.98||[0.7 – 1]|
|Average Operating Power Factor at POD Leading or Lagging||A leading power factor defines the condition where the current leads the voltage while a lagging power factor defines the condition where the current lags the voltage. Typically the average power factor will be leading as the plant will be called on to support a lagging grid||Leading||[Leading, Lagging]|
** To enter Monthly Soiling Losses in lieu of entering an Average Annual Soiling Loss, click Edit Monthly. In the window that pops up enter the soiling loss percentages for each month. Note – once monthly losses have been entered, the average of the 12 monthly loss values will be displayed in the annual loss field in the user interface. The system will not use this average value and will instead use the monthly loss values entered. Therefore, the annual soiling loss reported in the optimization report after hourly energy simulation will typically not match the average annual soiling loss in the user interface due to monthly variations in weather.
Step 5: Enter Soil Thermal Resistivity. This is typically obtained from a geotechnical study.
|Soil Thermal Resistivity (°C-cm/W)||Site soil thermal resistivity (typically obtained from geotechnical study). This is used to calculate cable ampacity for underground circuits.||90||[20 – 500]|
Step 6: Click Save.