The studies ETAP offers, and what ELAP does with the grid
July 202612 min read
Two lists, face to face. On one side, ETAP's families of analysis modules. On the other, the 33 studies ELAP computes on its own network model, each with its boundary declared: which are owned outright, which are screening, and who has the version that gets signed.
Every electrical design tool gets compared against ETAP sooner or later, and the comparison is almost always done badly: modules are listed on one side, ticks are marked on the other, and parity is declared. This guide does the opposite. It enumerates ETAP's catalogue module by module, says what ELAP does with the same network in each case, and explicitly names where its own scope ends.
The split is this: of the 33 studies in the catalogue, 12 are owned outright and 21 are declared screening. Of those 21, nine delegate to ETAP by name, three to PSCAD or PSS/E, and nine to detail engineering or to the manufacturer's certified model.
How to read the boundary
“Screening” does not mean incomplete. It means the study runs, delivers a number and a verdict, and additionally declares who has the certified version. The rule that holds the catalogue together is that when a datum is missing, the study degrades to screening and says so — it never issues a favourable result by omission.
ETAP's catalogue, module by module
The analysis families ETAP publishes, against what ELAP does today with the same network. The rows marked “Out” are not holes left by oversight: they are scope decisions with the reason on record.
Solved. The method is chosen by topology: radial sweep on a tree, loop compensation, or nodal admittance when there are rings. It delivers voltage and angle per bus, and flow and loss per branch.
Own
Contingency AnalysisN-1 / N-1-1
Screening: every transformer and AC cable out of service one at a time, with a ranking of thermal, voltage and withstand violations.
ScreeningFull N-1 → ETAP / PSS/E
Unbalanced and single-phase Load Flow
Not covered: the plant's power path is balanced three-phase. Asymmetries are resolved inside the IEC 60909 short-circuit calculation, which does treat single-phase and two-phase-to-ground faults.
Out
Optimal Power Flow and optimal capacitor placement
Not a design decision of a PV plant. What is resolved is the reactive requirement at the point of connection and its achievable envelope.
Out
Voltage stabilityP-V / Q-V curves
Not covered. The voltage check goes as far as the variation band at the point of connection and the series profile per section, not as far as the collapse margin.
They do not apply to a plant: the power is known, dispatchable generation, not demand to be estimated.
Out
Switching Sequence and interlocks
Operations territory, not design. The medium-voltage switchgear and metering do exist as data derived from the topology.
Out
Short circuit and arc flash
ETAP module
What ELAP does with the network
Scope
Short-Circuit IECIEC 60909-0
Screening: initial symmetrical current and peak current per bus, to specify switchgear. On a tree it accumulates radially; with rings it uses the bus impedance matrix by sequences. Radial mode opens the rings and delivers a lower bound, declared as such.
Fast screening of maximum and minimum fault current per bus, the one that feeds early sizing before the full nodal model exists.
ScreeningFull IEC 60909 → ETAP
Short-Circuit ANSI/IEEEIEEE C37
No: the catalogue works in the IEC branch end to end.
Out
DC Short-CircuitIEC 61660
Solved outright: fault current of the battery bank on the DC side.
Own
Arc FlashIEEE 1584-2018 · NFPA 70E
Owned, and with the 2018 edition's coefficient model: incident energy and arc-flash boundary. It refuses to calculate outside the standard's validity range instead of extrapolating.
Own
Protections
ETAP module
What ELAP does with the network
Scope
Star — curve coordinationIEC 60255-151 · IEEE 242
Screening: coordination margin per series pair, instantaneous setting, transformer inrush current and curve crossings over the radial tree, with automatic adjustment and every finding coded.
ScreeningRigorous plotting and fine grading of the instantaneous → ETAP
Ring coordination
N-1 screening: grades the overcurrent in every radial configuration of the ring — the base plus each tie opening — and flags the pairs that reverse orientation, that is, where the design demands directional protection.
ScreeningDirectional coordination with the ring closed → ETAP
Corridor verification
Screening: every proposed curve is verified against the corridor of damage, inrush, load, minimum fault and coordination margin, with screening-grade damage curves.
ScreeningCertified plotting and rigorous damage curves → ETAP
Distance, differential and directionalfunctions 21 · 87 · 67
Not at settings level. What is answered is the design question: where the ring demands a directional function. The setting is detail engineering.
Out
Sequence-of-Operation
Not issued as a sequence. The equivalent input comes out of the coordination and the protection sizing.
Out
Grounding, cables and insulation
ETAP module
What ELAP does with the network
Scope
Ground Grid SystemsIEEE Std 80 · finite elements
Analytical screening over a regular grid and uniform or two-layer soil: grid resistance, ground potential rise and tolerable step and touch voltages. Against a finite-element calculation the band is ±15 to 20% — it is a band, not an equality, and it is declared as such.
ScreeningGrid design with mesh and step voltages → detail engineering
System earthingsolid, resistive or isolated neutral
Screening: target ground-fault current, earth-fault factor and the arrester's continuous and temporary operating voltage.
ScreeningThermal sizing of the neutral resistor → detail engineering
Screening, and the nuance matters: the reduced thermal chain is solved, and dielectric losses and screen and armour factors are omitted. Those omissions are not conservative — they raise the calculated ampacity. That is why it appears as screening and not as a closed calculation.
ScreeningFull IEC 60287, with the real thermal chain and grouping
Cable Pulling and cable thermal transient
Not covered. Derating for grouping, soil resistivity and depth does come in before the conductor is chosen.
Out
Insulation coordinationIEC 60071
Screening: arrester rated voltage and standardized basic insulation level derived from the earth-fault factor. The protection level is taken from a representative residual ratio, not from the published value of the chosen arrester — it is a proposal to verify against the datasheet.
ScreeningVerification against the selected arrester and the margins of IEC 60071-2
Power quality and dynamics
ETAP module
What ELAP does with the network
Scope
Harmonic Load FlowIEEE 519 · IEC 61000-3-6
Screening: total demand distortion and voltage distortion at the point of common coupling against the standard's limits, with diversification of N inverters. The default spectrum is generic and labelled as an assumption; it is replaced by the manufacturer's.
ScreeningHarmonic study with the manufacturer's spectrum
Frequency Scan — resonance
Screening: nodal impedance sweep order by order up to the 50th, flagging parallel resonance near a characteristic order.
ScreeningHarmonic penetration with the manufacturer's model → ETAP / PSCAD
Harmonic filter design
Not covered.
Out
Transient Stability and RMS or EMT dynamicsIEC 61400-27 · grid code
Pre-verification only: the grid code envelopes — sag support and voltage, frequency and rate-of-change windows — are compared against the protection scheme's settings. The inverter's dynamic model is a black box under NDA at all fourteen manufacturers surveyed, so this boundary is permanent, not transitional.
ScreeningManufacturer's certified model → the operator's PSCAD / PSS/E
Motor Acceleration and startingIEEE 399
There are no large motors in the power path of a PV plant.
Out
DC, storage, reliability and real time
ETAP module
What ELAP does with the network
Scope
Battery Sizing & DischargeIEEE 485
Owned: section-by-section sizing of the substation DC bank, plus charger and autonomy hours.
Own
DC Load Flow
Partial: the series voltage profile includes the DC stretch — accumulated drop from string to combiner box to inverter — but it is not a nodal DC flow.
Partial
Reliability / RAMIEEE 493
Not a design decision of the plant.
Out
Panel Systems
Outside the product.
Out
Real timeSCADA · energy management · load shedding · digital twin
ELAP is design, not operation. The entire real-time family stays out.
Out
ELAP's 33 studies
The complete catalogue, grouped by the view that consumes it. The scope column is the same one printed on the report's cover page: whoever reviews the file sees the boundary before the number.
Network — 9 studies
Study
What it resolves
Scope
Load flow
Voltage and angle per bus, flow and loss per branch; the method is chosen by topology.
Own
Series voltage profile
Accumulated voltage drop per section, from DC to low and medium voltage, up to the point of connection.
Own
Joule losses
Total and per-section losses, and their percentage of delivered energy.
Own
Medium-voltage feeder proposal
Capacity per feeder and grouping of stations by proximity, derived from the plant's real positions.
Own
N-1 contingencies
Every AC transformer and cable out of service one at a time, with a ranking of violations.
ScreeningETAP / PSS/E (full N-1)
Harmonic screeningIEEE 519
Demand and voltage distortion at the point of coupling against the standard's limits.
ScreeningHarmonic study with the manufacturer's spectrum
Harmonic resonance sweep
Nodal impedance order by order up to the 50th; flags parallel resonance near a characteristic order.
ScreeningHarmonic penetration with the manufacturer's model (ETAP / PSCAD)
Cable thermal ratingIEC 60287
Permissible current of the buried cable with the duct bank's real grouping.
ScreeningFull IEC 60287, thermal chain and screen factors included
Retained-voltage profile under fault
Voltage remaining at every bus during a three-phase fault at another, solved on the impedance matrix, with flat pre-fault and positive sequence, without crediting converter contribution.
ScreeningETAP / PSS/E (full sequence)
Protection — 15 studies
Study
What it resolves
Scope
Arc flashIEEE 1584-2018
Incident energy and arc boundary; refuses outside the standard's validity range.
Own
DC short circuitIEC 61660
Fault current of the battery bank on the DC side.
Own
DC ground fault and arc
Insulation monitoring, differential protection and functional earthing per IEC 62109-2 and UL 1741, plus arc detection per UL 1699B.
Own
Short-circuit dutyIEC 60909
Initial and peak current per bus to specify switchgear; radial mode opens the rings and delivers a lower bound.
ScreeningETAP (full IEC 60909)
Radial fault level
Maximum and minimum fault current per bus by Thévenin equivalent, plus inverter contribution.
ScreeningETAP (full IEC 60909)
Protection coordination
Coordination margin per series pair, instantaneous setting and transformer inrush current.
Grid resistance, ground potential rise and step and touch voltages.
ScreeningGrid design with mesh and step voltages (detail engineering)
System earthing
Solid, resistive or isolated neutral, earthing coefficient and arrester voltage.
ScreeningThermal sizing of the neutral resistor (detail engineering)
Insulation coordinationIEC 60071
Arrester rated voltage and minimum standardized basic insulation level.
ScreeningVerification against the selected arrester and the margins of IEC 60071-2
Lightning riskIEC 62305
Expected annual strikes from the collection area and risk of loss of human life against the tolerable risk, with the suggested protection class.
ScreeningFull IEC 62305-2 assessment, with the risk components per zone
Anti-islanding
Voltage, frequency and rate-of-change windows of the grid code against the scheme's settings.
ScreeningManufacturer's certified model
External fault — selectivity towards the grid
Verifies that the interface protections do not disconnect the plant within the sag-support envelope during a fault that is not its own. It does not evaluate current elements, and says so.
ScreeningCertified model + the operator's case
Remote fault impact at the point of connection
Composes depth, duration and the code's envelope: how much voltage remains, whether it must be ridden out, and whether your own interface protection would trip over a fault that is not yours.
ScreeningCertified model + the operator's case
Delivery — 9 studies
Study
What it resolves
Scope
Reactive capability at the point of connection
Envelope of achievable active and reactive power against the connection agreement's target power factor.
Own
Storage sizing
Nominal energy, charge and discharge rate, converter and end-of-life augmentation.
Own
Auxiliary load schedule
Maximum coincident demand of the low-voltage auxiliary services.
Own
Auxiliary services transformer
Selection by standardized power step, loading, impedance and regulation, with a redundancy verdict.
Own
Substation battery bankIEEE 485
Section-by-section sizing, charger and autonomy hours.
Own
Grid connection
Voltage variation at the point of connection when connecting and disconnecting the plant.
ScreeningETAP (nodal load flow)
FlickerIEC 61000-3-7
Planning flicker severity at the point of coupling against the network's allocated level.
ScreeningMeasurement per IEC 61000-4-15 (PSCAD)
Sag and overvoltage support
The grid code's envelope against the protection scheme's voltage settings.
ScreeningManufacturer's certified model (the operator's PSS/E)
RMS dynamics
Response to disturbances as a pre-verification of the formal study.
ScreeningCertified model (PSCAD / PSS/E)
What ELAP does that exists as no module
The comparison is not a subset. There are studies that come from having the plant drawn, not from having a solver — and that is why they do not appear in the catalogue of a generic network tool, which analyses the network it was drawn.
Medium-voltage feeder proposal: grouping of stations by proximity and capacity per feeder, derived from the real positions of the equipment on the terrain. The network proposes itself before it is analysed.
Lightning risk per IEC 62305, with the collection area taken from the plant's real geometry.
Flicker and insulation coordination, which are filing requirements and not headline modules of a network analysis tool.
External fault and remote fault impact at the point of connection: three independent answers to the question of whether the plant falls over because of somebody else's fault — and if a datum is missing, the verdict is never a pass.
The substation auxiliary services package — load schedule, services transformer and DC bank — tied to the same model as everything else.
DC-side ground fault and arc detection, which lives in the photovoltaic half of the design.
The loop with ETAP: verifier, not competitor
The relationship with ETAP is not to replace it. It is to export the model to it with stable identifiers, let it run the rigorous study, import the report and compare bus by bus, branch by branch and device by device against a tolerance declared in advance. Every row ends up verified, with deviation, or pending.
Comparison tolerances by quantity
Quantity
Tolerance
Initial short-circuit current
±10%
Voltage magnitude
±0.5 to 2%
Bus angle
±1 to 2° (informative)
Active and reactive flow per branch
±5 to 10%
Reactance-to-resistance ratio
±15%
Losses
±3 to 15%
Grid resistance and ground potential
±20%
Mesh and step voltages
±15 to 20% (analytical against finite elements)
Protection operating time
the greater of one cycle and 10%
Arc incident energy
±10 to 15%, boundary ±15%
DC fault current
±10%
Nor is the differential in the solver. Against thirty years of homologated ETAP and PSS/E, the engine fight is lost in advance and there is no point in fighting it. What ELAP contests is the file: issuing the study numbered, dated and with the scope declared right in the reviewer's face. That is, competing against Word and Excel — which is what the engineer really fights against.
Standards and references cited
IEC 60909-0Short-circuit currents in three-phase AC systems: calculation of currents.
IEEE Std 1584-2018Guide for performing arc-flash incident energy calculations, with the coefficient model's validity range.
IEEE Std 80Safety in AC substation grounding: tolerable step and touch voltages.
IEC 60287Electric cables: calculation of the current rating, including dielectric losses and screen and armour loss factors.
IEEE Std 519Recommended practice and requirements for harmonic control in electric power systems.
IEC 60071-1 / 60071-2Insulation co-ordination: definitions, principles and application guidelines.
IEC 62305-2Protection against lightning: risk assessment by components and by zone.
IEC 61660Short-circuit currents in DC auxiliary installations.
IEEE Std 485Sizing of vented lead-acid batteries for stationary applications.
IEC 61000-3-7 / 61000-4-15Flicker emission limits for disturbing installations and the flickermeter specification.
IEC 61400-27Electrical simulation models for converter-based generation, the basis of certified dynamic studies.
ETAP — analysis module families published by the manufacturerThe basis of the module-by-module comparison. Module names belong to Operation Technology, Inc.; this guide is not affiliated with nor endorsed by ETAP.
Informational content current as of July 2026. It is not legal or regulatory advice: always verify against the standard in force and the requirements of your grid operator.
Ask to see a report with its scope declared
The 33 studies come out of the same plant model and are issued as a numbered file, with each study's boundary printed where the reviewer reads it first. We will show you the entire document, including the rows that say “screening”.