Detailed engineering
Detailed Engineering: SLDs, Protection Philosophy & Grid Studies, Procurement-Ready
Once sizing and revenue-stack logic are locked, we convert the concept into a bankable engineering package: single-line diagrams, equipment layouts, protection and control philosophy, and grid-connection studies compliant with CEA, CERC/SERC and STU/CTU codes. The output is a procurement-ready specification set that EPC bidders, lenders and utility technical committees can evaluate without ambiguity.
Typical duration · 10-14 weeks, sequenced with STU/CTU connectivity application milestones
Samples generated 05 Sept 2026, 11:26 pm ISTWhat happens in this step
- 01Develop electrical SLDs for AC/DC architecture, PCS/inverter blocks, MV collection, and interconnection switchyard
- 02Prepare general arrangement and cable/trench layouts for BESS containers, PCS skids, transformers and control room
- 03Define protection philosophy: relay coordination, arc-flash study, differential/distance protection settings
- 04Run grid studies — load flow, short-circuit, transient stability, harmonic and voltage-ride-through per CEA/STU requirements
- 05Draft technical specifications and BoQ for PCS, batteries/modules, transformers, switchgear, SCADA and civil works
- 06Coordinate with STU/CTU and DISCOM for connectivity/LTA approval and interconnection agreement inputs
- 07Compile a bid-ready procurement dossier with drawings, specs and evaluation criteria for EPC tendering
What we need from you
- Approved sizing report and RTC/FDRE dispatch model from prior stage
- Site survey data, soil investigation and topographic layout
- Substation single-line and short-circuit data from the interconnecting utility
- Applicable grid code, CEA regulations and state-specific connectivity guidelines
- Preferred equipment vendor shortlist or open specification approach
- Land parcel boundary and statutory clearance status
Worked example (anonymised, illustrative)
Example: Standalone BESS Detailed Engineering · 150 MW / 300 MWh, LFP-based, 33 kV collection · Western India
Illustrative intra-state open-access BESS project requiring 132 kV interconnection studies, protection philosophy and procurement-ready EPC tender documents.
Sample deliverables from this step
Every sample below is analyst-written and anonymised for illustration — structure and depth mirror our real deliverables; figures and names are not from any client engagement.
Illustrative · Growthifye-preparedSingle Line Diagrams & Plant Layout Drawings
AC/DC architecture SLDs, PCS-to-transformer block diagrams, container/skid general arrangement and cable routing layouts.
Sample excerpt · SLD Equipment Schedule (Extract) — illustrative figures
| Tag | Equipment | Rating | Qty | Remarks |
| PCS-01 to 30 | Power Conversion System | 3.5 MVA, 33 kV | 30 | Grouped in 5 blocks |
| TX-01 to 05 | Step-up Transformer | 21 MVA, 33/132 kV | 5 | ONAN/ONAF |
| SWG-132 | 132 kV GIS Switchgear | 132 kV, 2000 A | 1 bay set | Bus coupler incl. |
| BESS-CONT | Battery Container | 3.72 MWh LFP | 84 | 20 ft, IP54 |
| SCADA-01 | Plant SCADA/EMS | N/A | 1 | Redundant servers |
- Drawings issued in AutoCAD/PDF with IEC symbology for EPC bid packages
- Layout accounts for fire-safety separation per applicable battery storage guidelines
Illustrative · Growthifye-preparedProtection & Relay Coordination Philosophy
Defines relay schemes, coordination curves, arc-flash boundaries and settings for BESS, transformer and interconnection protection.
Sample excerpt · Protection Scheme Summary (Extract) — illustrative figures
| Zone | Protection Function | Relay Type | Setting Basis | Coordination Time |
| PCS Block | Overcurrent (50/51) | Numerical IED | 1.25x rated current | 0.2 s |
| Transformer | Differential (87T) | Numerical IED | Slope 25-40% | Instantaneous |
| 132 kV Line | Distance (21) | Numerical IED | Zone 1: 80% line | 0-0.1 s |
| Battery DC Bus | Ground Fault (64) | DC monitor | 5 mA sensitivity | Alarm + trip |
| Busbar | Differential (87B) | Numerical IED | Restrained diff. | Instantaneous |
- Arc-flash study included per applicable IEEE/IS practice for O&M safety labelling
- Settings validated against short-circuit study results before EPC issuance
Grid-Connection Study Report
Load flow, short-circuit, transient stability and voltage-ride-through studies supporting STU/CTU connectivity approval.
Sample excerpt · Study Scope & Compliance Checklist (Extract) — illustrative figures
| Study | Standard/Code | Base Case | Result Summary | Status |
| Load Flow | CEA Grid Code | N-1 peak load | Voltage within ±5% | Compliant |
| Short Circuit | IEC 60909 | 3-phase fault, 132 kV bus | 31.5 kA breaking capacity | Compliant |
| Transient Stability | CERC LVRT/HVRT norms | Grid disturbance event | Ride-through confirmed | Compliant |
| Harmonics | IEEE 519 | Full PCS output | THD < 3% | Compliant |
| Reactive Power | STU technical standard | 0.95 lag-lead range | Within droop capability | Compliant |
- Studies submitted alongside connectivity application to the state transmission utility
- Sensitivity cases included for future capacity addition at the same interconnection point
Procurement Specification & BoQ Package
Technical specifications, bill of quantities and evaluation criteria for PCS, batteries, transformers, switchgear and civil works, ready for EPC tendering.
Sample excerpt · BoQ Summary (Extract) — illustrative figures
| Package | Item | Unit | Quantity | Spec Reference |
| Electrical | PCS, 3.5 MVA | Nos | 30 | Spec Sec. 4.2 |
| Electrical | Battery Container, 3.72 MWh | Nos | 84 | Spec Sec. 4.5 |
| Electrical | 132/33 kV Transformer, 21 MVA | Nos | 5 | Spec Sec. 5.1 |
| Civil | RCC Foundation, container pad | Cum | 1,850 | Spec Sec. 7.3 |
| Civil | Internal Roads & Drainage | Sqm | 12,400 | Spec Sec. 7.6 |
- Issued as a single procurement dossier for EPC bid invitation
- Cross-referenced with SLDs and layout drawings for bidder consistency checks
Outcomes
- A procurement-ready engineering package accepted by EPC bidders and lenders without major clarification rounds
- Grid-connection studies aligned with STU/CTU requirements, reducing connectivity approval delays
- Protection and safety philosophy validated ahead of equipment ordering, minimising rework risk
- Clear BoQ and specifications enabling like-for-like EPC bid comparison and faster contract award
Questions clients ask
Do you work with our chosen EPC contractor or independently?
We prepare vendor-agnostic drawings and specifications so any qualified EPC contractor can bid on equal terms; we can also review contractor-submitted designs if you have already shortlisted one.
Will this package satisfy STU/CTU connectivity requirements?
Yes, grid studies are scoped and formatted to match the applicable state or central transmission utility's technical standards and application checklist.
Can this stage proceed before land and clearances are finalised?
Preliminary SLDs and study assumptions can start in parallel, but final layouts and BoQ quantities are locked once survey and clearance data are confirmed.
