Gaiergy Grid Studio · New York feeder screening

How big a battery fits on a New York circuit, and what it takes.

Grid Studio is Gaiergy's own feeder study tool: it runs EPRI's OpenDSS power flow engine on National Grid's public circuit data to find the equipment and upgrades a battery needs to charge and discharge at a chosen point on a chosen circuit.

EPRI OpenDSS engine National Grid public portal data NY SIR screens A to I Screening tool: the utility sets the real answer in its study (CESIR)

real connection points near Minoa and Mexico, New York (National Grid)

210

engine runs behind this page: 5 points, 3 project types, 14 sizes

0 to 25 MW

size sweep in every run, a full power flow at each step

0.135%

worst bus voltage error on the IEEE 13 node test feeder

The answer up front

The voltage of the line you connect to decides how big a battery fits.

Goal: compare five real connection points near Minoa and Mexico, New York, on National Grid circuits, and show how large a battery each one can take before the wires reach a physical limit or the utility's screens send it to study.

The 4.8 kV feeders fit well under 1 MW. Minoa: physical limit 0.70 MW, set by the MINOA TB 1 bank loading while charging at night. Mexico A: 0.10 MW, set by the Mexico bank loading while charging at night.
The 34.5 kV line fits about 5 MW. Mexico B, on line 22: physical limit 5.10 MW, and no utility study trigger up to 3.80 MW (SIR Screen F at 3.90 MW, on an ESTIMATE 100 MVA source strength).
What is already on the line sets what is left. Both Butternut points sit on 13.2 kV feeder 36_11_25555, which already carries 9.2 MW of generation (National Grid portal). At its far end (Clemons Road) the voltage reaches 1.05 pu at 0.20 MW: physical limit 0.15 MW. Nearer the substation, at the wastewater treatment plant, the limit is 1.60 MW; at 1.70 MW the far end of the same feeder goes above 1.05 pu.
Most points go to utility study at any size. Mexico A (portal 3V0 threshold 0 MW) and both Butternut points (SIR Screen E, a condition of the whole feeder) fail a screen before any project. Minoa passes every screen only up to 0.20 MW.

Largest battery that fits, by connection point

Physical limitNo utility study (passes every screen and trigger test)

Physical limit: the largest size the circuit can carry as built. Checks: line and bank loading above 100%, voltage outside ANSI C84.1 Range A (0.95 to 1.05 per unit), and a voltage change above 3% when the battery switches on or off (NYSERDA 19-45, PDF p.22).

No utility study: the largest size that also passes every New York SIR screen and National Grid trigger test. Above it the battery still connects, but the utility studies it further and usually asks for equipment. 0 MW means the site already fails a screen before any project.

Source: Grid Studio engine runs, 2026-09-28 (Butternut WWTP 2026-09-29), default settings; every input that is not public is an ESTIMATE (list in "How it works"). Circuit data: National Grid NY System Data Portal, pulled 2026-09-26. Screening results, not utility decisions.

Try it

Pick a point, a size and a project type.

Every result below is a real Grid Studio run, computed ahead of time. The verdict word, the limits, the utility study list and the equipment list come straight from the engine.

2.50 MW

Discharge study at minimum load (25% of peak, ESTIMATE). The daily cycle also charges at full nameplate at night, against the highest 2026 National Grid forecast night hour. Charge only runs at minimum load.

Physical limit (what the circuit can carry)

Largest size with no utility study

Equipment (typical)

Loading under 80%80 to 100%Over 100% Flow back toward the substationMoving dashes: flow direction Bus above 1.05 puBus below 0.95 pu34.5 kV line (portal geometry) Treatment plant (OpenStreetMap)

How it works

Public data in, a power flow at every size, a verdict and an equipment list out.

STEP 1

Public circuit dataFeeder sections, bank ratings and hosting capacity from the National Grid portal

STEP 2

OpenDSS networkSections become a radial three-phase model; missing values are ESTIMATE

STEP 3

Size sweep0 to 25 MW: 50 kW steps to 1 MW, then 100 kW; a power flow at each step

STEP 4

Limits and screensPhysical limits first, then the SIR screens and utility trigger tests

STEP 5

Verdict and equipmentEach failed check maps to likely equipment and a screening price

The engine: EPRI OpenDSS

Grid Studio drives the Electric Power Research Institute (EPRI) Open Distribution System Simulator (OpenDSS) through DSS-Extensions (OpenDSSDirect.py 0.9.4 on DSS C-API 0.14.5). Each run solves a full three-phase power flow at every size step, then a fault study for the short-circuit and flicker screens.

Sources: EPRI OpenDSS repository; DSS-Extensions OpenDSSDirect.py (links below).

The data: National Grid's public portal

Feeder line sections with their real geometry, bank ratings, backfeed and 3V0 fields, hosting capacity and the 2026 hourly load forecast per feeder. The models hold 327 line sections at Mexico, 181 at Minoa and 823 at Butternut.

Source: National Grid NY System Data Portal, pulled 2026-09-26.

Physical limits and utility study triggers

Physical limits say what the wires and the bank can carry. Utility study triggers are the New York Standardized Interconnection Requirements (SIR) Appendix G screens A to I and National Grid's own tests: the 3V0 test (generation above 67% of minimum load with the largest feeder open), the portal 3V0 threshold and the anti-islanding limit.

Sources: NY SIR effective 2026-02-09, App. G (PDF pp.97 to 101); National Grid Technical Review of Pterra R149-16 (2017-01-31), section V p.7; National Grid ESB 756B-2024; National Grid portal pop-up definitions.

Equipment and screening prices

Each failed check maps to the equipment it most likely leads to, for example 3V0 protection (three high-side voltage transformers and a 59N relay) or direct transfer trip. Prices come from the Joint Utilities of New York Upgrade Cost Matrix (May 2026, National Grid column) and National Grid's studied upgrade estimates, with no contingency or tax. They are screening estimates. ESTIMATE

Sources: JU Upgrade Cost Matrix, May 2026; National Grid Cost-Sharing 2.0 semi-annual report (Oct 2025 to Mar 2026); National Grid Cost Sharing Monthly Report.

Validation: the IEEE 13 node test feeder

The same engine path runs the IEEE Power and Energy Society 13 node test feeder with its published regulator taps (10, 8, 11) and matches the published answer.

Worst bus voltage error 0.135%

Substation input 3,578.0 kW vs 3,577.2 kW published (0.02%)

1,722.5 kvar vs 1,724.8 kvar (0.13%)

Sources: IEEE PES Distribution Test Feeders, feeder13.zip (published results); EPRI IEEE13Nodeckt.dss. Result: pass.

Why screen before applying, and what the tool cannot see

Of 1,665 National Grid CESIRs in its public CESIR Pass/Fail Report, 36 (2.2%) passed all 18 criteria. A screen shows early which of them a site will most likely fail.

Grid Studio cannot check fault duty against device ratings (not public, UNCONFIRMED), protection settings, or the real conductors and regulators. Where the portal hosting capacity is lower than the model, treat the portal number as National Grid's position. The utility sets the real answer in its study.

Source: National Grid CESIR Pass/Fail Report (National Grid NY System Data Portal).

The ESTIMATE inputs

These values are not public. Each one is an engineering ESTIMATE, the same default for every run on this page. The utility gives the real values in its study.

Input	Minoa	Mexico (A and B)	Butternut (both points)	Why it is an ESTIMATE
Supply strength (three-phase fault level)	150 MVA; 34.5 kV assumed (voltage UNCONFIRMED)	100 MVA at 34.5 kV	1,500 MVA; 115 kV assumed (UNCONFIRMED)	Not public. It drives SIR Screen F, flicker and every fault current.
Supply X/R ratio	3.5	3	8	Not public; typical for the line type.
Bank impedance	7%, X/R 10	7%, X/R 10	9%, X/R 20	Nameplate not public; typical for the bank size.
Bank winding	Delta high side, grounded wye low side			The portal gives STA_CONFIG only; which winding it describes is UNCONFIRMED.
Load tap changer (LTC) setpoint	122 V on a 120 V base, 2 V band			Not public; a common setting.
Mainline conductor	336.4 ACSR, 530 A	336.4 ACSR, 530 A; line 22 also 530 A	477 AAC, 650 A	The portal gives only the feeder rating.
Lateral conductor	1/0 ACSR, 230 A, all three-phase			Not public; real laterals may be single-phase.
Minimum load	25% of peak, spread along each feeder by line length			National Grid rule for stations without metering (Joint Utilities of New York ITWG Technical Guide Matrix, 2016-12-13, p.2); customer locations are not public.
Existing generation	0.03 MW per feeder, at the feeder midpoint	0.11 and 0.03 MW, at the feeder midpoint	Clemons Road Solar 2.8 MW AC at its EIA-860M point; the rest at each feeder midpoint	The portal gives the amount per feeder, not the location. Output at the daytime minimum hour: 0.6 x nameplate (for SIR Screen E).
Inverter	Unity power factor; fault current 1.2 x rated; flicker factor 7.8			Typical inverter behavior; 7.8 is the SIR Screen H value for solar plants, used here for batteries too.

Terms and acronyms

3V0: Ground-fault overvoltage protection at a substation: three high-side voltage transformers wired to a 59N relay that trips the feeder breakers.
ANSI C84.1 Range A: The normal service voltage range of the American National Standards Institute standard: plus or minus 5% (0.95 to 1.05 pu).
CESIR: Coordinated Electric System Interconnection Review: the utility's detailed study of a project under the New York SIR.
CT / VT: Current transformer / voltage transformer (instrument transformers that feed relays and meters).
DER / DG: Distributed energy resource / distributed generation.
DTT: Direct transfer trip: a signal from the substation that disconnects the project when the feeder breaker opens.
EPRI: Electric Power Research Institute.
ESB 756: National Grid Electric System Bulletin 756: requirements for generation connected to its system.
IEEE / PES: Institute of Electrical and Electronics Engineers / its Power and Energy Society.
JU: Joint Utilities of New York.
kV, kW, MW, MVA, kvar: Kilovolt, kilowatt, megawatt, megavolt-ampere, kilovolt-ampere reactive.
LTC: Load tap changer: the voltage regulator built into a substation transformer.
NYSERDA: New York State Energy Research and Development Authority.
OpenDSS: Open Distribution System Simulator, EPRI's open-source power flow engine.
PCC / POI: Point of common coupling / point of interconnection: where the project meets the utility system.
Pst: Short-term flicker severity (SIR Screen H: 0.35 or less passes).
pu: Per unit: a voltage as a fraction of nominal (1.05 pu = 5% above nominal).
RTU / EMS / SCADA: Remote terminal unit / energy management system / supervisory control and data acquisition.
SCE: Southern California Edison.
SIR: New York State Standardized Interconnection Requirements (for projects of 5 MW or less).
WWTP: Wastewater treatment plant.
X/R: Ratio of reactance to resistance of the supply; it shapes fault current and voltage change.

Sources

Public sources behind the numbers

National Grid, New York System Data Portal: feeder and sub-transmission geometry, hosting capacity, bank ratings, backfeed and 3V0 fields, pop-up definitions, Cost Sharing Monthly Report. systemdataportal.nationalgrid.com/NYPulled 2026-09-26.
National Grid, 2026 hourly load forecast per feeder, for example 36_11_4463.csv (same address pattern for 36_11_4430, 36_14_4361, 36_14_4362 and 36_11_25554 to 25556).Pulled 2026-09-26.
National Grid, CESIR Pass/Fail Report. CESIR_Pass_Fail_Report.xlsxAccessed 2026-09-26.
New York State Standardized Interconnection Requirements (SIR), effective 2026-02-09, Appendix G screens A to I. dps.ny.gov (PDF)Accessed 2026-09-26.
Joint Utilities of New York, Upgrade Cost Matrix, Updated and Combined, May 2026 (National Grid column). dps.ny.govAccessed 2026-09-26.
National Grid, ESB 756 (2024), including Appendix B, New York (3V0 in section 6.2.2, DTT in 6.2.1, PCC recloser in 7.6.12). nationalgridus.com (PDF)Accessed 2026-09-26.
National Grid, Cost-Sharing 2.0 semi-annual report, Oct 1 2025 to Mar 31 2026, Case 20-E-0543 (3V0 actual costs). documents.dps.ny.govAccessed 2026-09-26.
NYSERDA 19-45, Mitigation Methods to Increase Feeder Hosting Capacity (EPRI, December 2019): thresholds of 1.05 pu, 3% voltage change and 100% loading (PDF p.22). nyserda.ny.gov (PDF)Accessed 2026-09-26.
PG&E, Voltage Tolerance Boundary (ANSI C84.1 Range A and B). pge.com (PDF)Accessed 2026-09-26.
IEEE PES Distribution Test Feeders, IEEE 13 Node Test Feeder, published results. feeder13.zipDownloaded 2026-09-26.
EPRI OpenDSS repository, IEEE 13 node circuit files. svn.code.sf.net/p/electricdssAccessed 2026-09-26.
DSS-Extensions, OpenDSSDirect.py. github.com/dss-extensionsAccessed 2026-09-28.
U.S. Energy Information Administration, EIA-860M, April 2026 (Clemons Road Solar, plant 67407, 2.8 MW AC). eia.govAccessed 2026-09-26.
OpenStreetMap, way 220583825, Meadowbrook-Limestone Wastewater Treatment Plant (location 43.05407 N, 76.00741 W). openstreetmap.org/way/220583825Accessed 2026-09-26.
National Grid, Technical Review of Pterra report R149-16 (2017-01-31), section V p.7: the 67% N-1 rule for 3V0. Cited by document name.
Joint Utilities of New York, ITWG Technical Guide Matrix (2016-12-13), p.2: minimum load at 25% of peak where a station has no metering. Cited by document name.
Southern California Edison, Unit Cost Guide (2026-03-31): 33 kV recloser and metering, used where National Grid publishes no 35 kV price. Cited by document name.
E. Csanyi, summary of the IEEE PSRC "Schematic Representation of Power System Relaying", electrical-engineering-portal.com (2018): symbol conventions for the engineering one-line. Cited by document name.
Map tiles and base map: OpenStreetMap contributors, drawn with Leaflet 1.9.4.