A Coordinated Electric System Interconnection Review—the utility’s deep-dive on technical and cost impacts of your project.

Challenge: Frequent false tripping using conventional electromechanical relays
Solution: SEL-487E integration with multi-terminal differential protection and dynamic inrush restraint
Result: 90% reduction in false trips, saving over $250,000 in downtime

The three operating regions you have to design to

Device	Output vs voltage	Response	Best suited to	Main limitations
Mechanically switched capacitor or reactor	Proportional to voltage squared	Seconds; discrete steps; limited switching operations per day	Steady-state reactive supply, voltage profile, loss reduction	No dynamic capability; step voltage change on switching; capability collapses when most needed
Static var compensator	Capacitive branches proportional to voltage squared	A few cycles; continuously controllable	Continuous control where cost matters and deep voltage support is not the driver	Square-law capability loss; harmonic filters are part of the plant and interact with the network
STATCOM	Approximately proportional to voltage — constant current capability	One to two cycles closed loop; converter response faster still	Voltage stability margin, weak interconnections, fast disturbance recovery, flicker and unbalance compensation	Higher capital cost; converter losses; adds a converter and its control dynamics to the network
Synchronous condenser	Governed by machine capability and excitation	Excitation response in the hundreds of milliseconds; inherent inertial response instantaneous	System strength and inertia, short-circuit contribution, black start support	Rotating plant with maintenance and losses; slower controlled response than a converter
STATCOM with energy storage	Reactive as a STATCOM, plus real power within the storage rating	As STATCOM for reactive; real power limited by storage	Where a real power deficiency is part of the problem	Cost and complexity of the storage; different failure and maintenance profile

Stage	Keentel scope	Outcome
Screening	Series-compensation proximity, radial contingency review, UIF and short-circuit ratio screening, frequency scans	Early identification of which SSO types apply
Detailed studies	PSCAD/EMTDC EMT studies with vendor real-code models, impedance-based and frequency-scan analysis	Clear evidence of stability margins or risk
Model quality	EMT model review, benchmarking against positive-sequence models, model acceptance support	Models that system operators accept
Mitigation	Control retuning recommendations with vendors, SSDC and bypass logic requirements, protection and monitoring specifications	Practical, coordinated solutions
Interconnection support	SSR and SSO study reports for ISO and utility requirements, response to reviewer comments	Fewer delays in the interconnection process

Parameter	Definition	What it tells you
Isc	Short-circuit current, at V = 0	Total current; driven by irradiance, reduced by soiling, shading and weak modules
Voc	Open-circuit voltage, at I = 0	Total voltage; affected by temperature, module count, open or shorted cells and bypass diodes
Imp	Current at the maximum power point	Current delivered at the operating point
Vmp	Voltage at the maximum power point	Voltage at the operating point; sensitive to series resistance
Pmax	Maximum power, Imp × Vmp	Overall string health
FF	Fill factor, Pmax ÷ (Isc × Voc)	How "square" the curve is; falls with resistive and mismatch losses

Fault	Isc	Voc	Curve shape
Uniform soiling or dust	Reduced	About normal	Normal shape, scaled down in current
Partial shading	Reduced on part of the curve	About normal	Steps or multiple knees where bypass diodes conduct
Module mismatch	Slightly reduced	About normal	Step-like or rounded knee
Weak or degraded module	Reduced	Reduced	Lower, smaller curve overall
Open or shorted cell, failed bypass diode	Normal or reduced	Reduced by about one substring	Voltage step; irregular curve
High series resistance (loose or poor connectors)	Normal	Normal	Softer slope near Voc, lower Vmp and fill factor
Low shunt resistance (cracked cells, PID)	Normal	Often reduced	Sloping plateau near Isc, lower fill factor

A utility-scale plant may have thousands of strings feeding a few dozen inverters. Plant SCADA typically sees inverter or combiner-level data, where a 20% loss on a few strings disappears into the average. Even string-level current monitoring reports only the operating point the inverter's MPPT chose, not why that point moved.

An I-V curve tracer sweeps the string from short circuit to open circuit and records the entire characteristic. Each type of fault distorts that curve in a recognisable way. That is what makes the I-V curve the most diagnostic single test available at string level.

I_L is the light-generated current, proportional to irradiance.
I_0 and n describe the diode; N_s is the number of cells in series and V_t is the thermal voltage.
R_s is series resistance: cell metallisation, ribbons, connectors and cables.
R_sh is shunt resistance: leakage paths through cell defects and cracks.

Two simple slope rules make field interpretation much easier:

Near Isc, the slope of the curve is set mainly by shunt resistance. A plateau that tilts downward signals low R_sh.
Near Voc, the slope is set mainly by series resistance. A curve that leans over instead of dropping steeply signals high R_s.

The fill factor summarises how square the curve is:

Isc rises almost linearly with irradiance. Voc falls as cell temperature rises, typically by about 0.25–0.30% per °C for modern crystalline modules, and Pmax falls by about 0.29–0.40% per °C, depending on technology. Use the module datasheet coefficients.

A string measured at 820 W/m² and 52 °C cell temperature cannot be compared directly with its datasheet values at STC (1,000 W/m², 25 °C). Measurements must be translated to a common reference. IEC 60891 gives standard translation procedures. In simplified form:

Item	Requirement or good practice
Irradiance level	At least 400 W/m² of stable irradiance in the plane of the array; at least 700 W/m² when results will be translated to STC
Irradiance stability	Clear sky; avoid moving cloud; repeat any curve taken during a change
Temperature sensor	Flat sensor on the module backsheet, mid-module, at least 10 cm from the junction box
Time of day	Within a few hours of solar noon to limit angle-of-incidence and spectral effects
Trackers	Hold the tracker at a fixed angle during the sweep, and align the sensor with it
Bifacial modules	Measure or estimate rear-side irradiance; front-only translation overstates the loss
Instrument rating	Tracer rated for the string's maximum DC voltage (1,000 V or 1,500 V) and current
Baseline	Record curves for every string at commissioning; they become the reference for O&M

Soiling and dust

Uniform soiling reduces the light reaching every cell, so Isc and Imp fall together while the curve keeps its normal shape. Voc changes very little because it depends on irradiance only logarithmically. The test: compare the Isc ratio (measured ÷ expected, after translation) across strings. A plant-wide drop suggests soiling or a sensor problem; a localised drop suggests site-specific soiling such as dust from an access road.

Partial shading

When some cells are shaded, their current falls below the rest of the string. Bypass diodes then conduct around the shaded substrings, and the curve develops steps, or "multiple knees". The inverter's MPPT may settle on a local maximum and leave further energy behind. Typical causes are vegetation, structures, row-to-row shading at low sun angles, and tracker backtracking errors.

Module mismatch

Modules with different current capability in the same string force the string to operate at a compromise. The curve shows a rounded knee or small steps. Mismatch grows with uneven degradation, mixed module bins after replacements, and uneven soiling.

Weak or degraded modules

General degradation, from light-induced or thermal ageing, reduces both current and voltage. The whole curve shrinks. Comparing with the commissioning baseline shows the rate of degradation, which can then be checked against the module warranty.

Open or shorted cells and bypass diode failures

A typical module has three bypass-diode substrings. A shorted bypass diode removes one substring permanently, so the string Voc drops by about one-third of a module's Voc. An open-circuit or cracked cell can force a substring into bypass. Either way, a clean voltage step from the expected Voc is the signature. A shorted diode is also a fire-safety concern, because it can overheat under reverse conditions.

High series resistance

Loose, corroded or cross-mated connectors, damaged cables and poor crimps add series resistance. Isc and Voc stay close to normal, but the curve leans over near Voc, Vmp drops and the fill factor falls. High-resistance joints are also hot spots: an infrared scan of the suspect string usually finds them quickly, and they should be treated as a fire risk.

Low shunt resistance and PID

Cracked cells and potential-induced degradation (PID) create leakage paths. The plateau near Isc tilts downward and the fill factor drops. PID typically affects modules at the negative end of the string first, so per-module testing or electroluminescence imaging along the string shows a characteristic pattern.

Ratio	Healthy range (indicative)	Deviation suggests
Isc measured ÷ Isc expected	0.97–1.03	Soiling, shading, sensor error, current mismatch
Voc measured ÷ Voc expected	0.98–1.02	Missing module, bypass diode, PID, temperature error
Fill factor	≈ 0.75–0.82 for crystalline silicon	Series or shunt resistance, mismatch
Imp ÷ Isc	≈ 0.92–0.96	Values outside the range indicate measurement or curve errors
Vmp ÷ Voc	≈ 0.78–0.86	Low values point to series resistance or shading
Pmax measured ÷ Pmax expected	≥ 0.95 after allowing for degradation	Any significant shortfall needs root-cause analysis

Parameter	Expected (STC)	Measured (translated)	Change
Isc	9.50 A	8.10 A	−14.7%
Voc	490 V	482 V	−1.6%
Imp	9.00 A	7.60 A	−15.6%
Vmp	410 V	360 V	−12.2%
Pmax	3.69 kW	2.74 kW	−25.8%
Fill factor	0.79	0.70	−0.09

Reading the curve.

Isc is down about 15% while Voc is almost unchanged. That is a current-type loss: soiling and shading, not a missing module.
Vmp is down about 12% and the fill factor has fallen from 0.79 to 0.70. The curve leans over near Voc, pointing to added series resistance.
A small notch in the curve suggests one substring is in bypass during part of the sweep: partial shading.

Inspection findings. Heavy dust on the modules, two loose connectors and slight shading from an adjacent structure.

Actions. Clean the modules, re-make and torque-check the connectors (replacing any cross-mated pairs with matched connectors), and remove the shading source.

After repair. Re-testing gives Isc 9.40 A, Imp 8.95 A, Vmp 405 V and Pmax 3.62 kW, about 98% of expected. The remaining gap is consistent with normal module degradation.

What it is worth. About 0.88 kW is recovered on this one string. At a specific yield of around 1,700 kWh per kW per year, that is roughly 1,500 kWh per year. Across a few hundred affected strings on a utility-scale plant, the recovered generation becomes material, before counting the fire risk removed with the loose connectors.

Method	Best at finding	How it complements I-V testing

Infrared thermography (IEC TS 62446-3)	Hot spots, hot connectors, bypass diodes in conduction, string outages	Locates the fault the I-V curve has identified

Electroluminescence (EL) imaging	Cracked cells, PID patterns, inactive cell areas	Confirms the cause of shunt or mismatch losses

Insulation resistance testing	Ground faults, damaged cables	Detects safety faults that may not affect the curve

String current monitoring and SCADA analytics	Persistent under-performance trends	Tells you which strings to trace first

Drone inspection	Large-area visual and thermal survey	Narrows the sample for I-V testing on big plants

Use the right PPE. Insulated gloves, eye and face protection, arc-rated clothing appropriate to the hazard assessment, and safety footwear.
Treat every string as live. PV strings generate voltage whenever light falls on them. They cannot be switched off at the source.
Never open a connector under load. Break the circuit with the designated DC disconnect, string fuse holder or combiner switch first. Opening an MC4-type connector under load can draw a sustained DC arc.
Isolate DC and AC sides before connecting the tracer, following the site's lockout/tagout procedure and the manufacturer's test procedure.
Check earthing and insulation first. A ground fault can make exposed metalwork live.
Use a tracer rated for the system voltage. On 1,500 V plants, confirm the instrument, leads and adapters carry the right voltage and measurement-category rating.
Follow the applicable electrical safety standard, such as NFPA 70E in the United States, including DC arc-flash and shock risk assessment.

Sampling strategy. Test 100% of strings at commissioning to set the baseline. In operation, test a statistically meaningful sample plus every string that analytics flag.
Contractual acceptance. I-V results support EPC punch lists, capacity tests and module warranty claims, but only if test conditions, translation method and instrument calibration are documented.
1,500 V and long strings. Higher string voltages magnify the energy in a DC arc and demand instruments and adapters rated for the voltage.
Trackers and bifacial modules. Tracker angle, backtracking and rear-side irradiance all affect the curve and must be controlled or measured.
Data management. Store curves with string IDs, timestamps and conditions so trends can be tracked over the life of the plant.

Stage	Keentel scope	Outcome
Design review	String sizing, voltage and temperature checks, connector and cable specification, protection and grounding review	Fewer latent faults built into the plant
Commissioning	IEC 62446-1 test planning, witnessing and data review; baseline I-V dataset requirements	A defensible baseline and a clean punch list
Performance assessment	Analysis of I-V, IR and SCADA data; translation and loss quantification	Losses ranked by cause and by value
Root cause and remediation	Fault investigation, remediation scope, warranty claim technical support	Energy recovered and risks closed out
Owner's engineer	Independent oversight of EPC and O&M contractors, acceptance and capacity testing	Delivered performance matches the contract

Situation. A 100 MWac single-axis tracker plant reports one inverter block producing about 4% less energy than its neighbours. Inverter and transformer data show nothing abnormal.

Analysis. SCADA string-current analytics identify about 60 strings in the block running below their peers. I-V curves on those strings show normal Isc and Voc but a reduced fill factor and a curve that leans over near Voc, the classic series-resistance signature. Thermography finds hot connectors on most of the affected strings, and inspection traces them to field-installed connectors from a different manufacturer mated to the module leads.

Engineered solution. Replace every cross-mated connector pair with matched connectors from a single manufacturer, re-crimp suspect field terminations, and add connector compatibility to the plant's spare-parts and installation procedures.

Outcome. Re-tested strings return to within normal fill factor range, the block's energy deficit closes, and a latent fire risk is removed across the block.

Situation. A 2 MW commercial rooftop plant with transformerless string inverters shows output falling faster than the module warranty allows, worst in humid summer months.

Analysis. I-V curves show reduced Voc and fill factor, with a tilted plateau near Isc. Per-module testing along affected strings, confirmed by electroluminescence imaging, shows the worst damage at the negative end of each string, the characteristic pattern of potential-induced degradation.

Engineered solution. Install PID recovery and prevention equipment compatible with the inverters, verify inverter grounding configuration, replace the most severely affected modules, and support a warranty claim with the documented I-V and EL evidence.

Outcome. Voc and fill factor recover over the following months on most affected modules, the degradation rate returns to warranty limits, and the claim is supported by translated, documented test data.

Situation. A 50 MWac bifacial plant is approaching substantial completion. The owner's contract requires I-V testing of 100% of strings before acceptance.

Analysis. The commissioning test plan sets irradiance, sensor alignment, rear-side irradiance measurement and translation requirements before testing begins. The data review flags a small percentage of strings with Voc about one-third of a module low, indicating shorted bypass diodes, plus several strings with one module fewer than designed, and a few strings whose labels do not match the as-built drawings.

Engineered solution. The EPC replaces the affected modules, corrects the string count and labelling, and re-tests every flagged string. The final dataset, with conditions and translation method documented, is handed to the owner as the plant's performance baseline.

Outcome. The plant is accepted with a closed punch list, and O&M starts with a complete, trustworthy baseline for every string for future comparison and warranty claims.

1. What is an I-V curve test?
It is a measurement that sweeps a PV string, module or cell from short circuit to open circuit while recording current and voltage. The result is the full current–voltage characteristic, from which Isc, Voc, Imp, Vmp, Pmax and fill factor are extracted. Because each fault distorts the curve differently, it is a diagnostic test as well as a performance test.
2. How is I-V testing different from what SCADA shows?
SCADA and string monitors record the operating point chosen by the inverter's MPPT, usually aggregated across many strings. The I-V curve shows the whole characteristic of one string at one moment. It reveals why a string is under-performing, not just that it is.
3. What irradiance is needed for valid I-V testing?
At least 400 W/m² of stable irradiance in the plane of the array is a common minimum. When results will be translated to STC, IEC 61829 recommends at least 700 W/m². Higher, stable irradiance gives more accurate translation.
4. Why must results be translated to STC?
Isc depends on irradiance and Voc depends on cell temperature, so raw readings change through the day. Translating to STC (1,000 W/m², 25 °C cell temperature) using IEC 60891 methods lets strings, days and datasheet values be compared fairly.
5. How should the irradiance and temperature sensors be installed?
The irradiance reference cell should be in the plane of the array within ±2° and matched to the module technology. The temperature sensor should be a flat sensor on the module backsheet, mid-module, at least 10 cm from the junction box. Poor sensor placement is the most common cause of false readings.
6. What is fill factor and what is a good value?
Fill factor is Pmax divided by Isc × Voc. It measures how square the curve is. Healthy crystalline silicon strings typically sit around 0.75–0.82; a lower value with normal Isc and Voc points to resistive or mismatch losses.
7. How does soiling appear on the curve?
Uniform soiling lowers Isc and Imp in proportion while the shape stays normal and Voc barely changes. Non-uniform soiling, such as heavy dirt along the bottom edge of modules, behaves more like partial shading and can create steps.
8. Why does shading create steps in the curve?
Shaded cells produce less current than the rest of the string. Bypass diodes switch in around the shaded substrings, so the string effectively has two or more operating regions. Each transition appears as a step, or knee, in the curve.
9. What does a voltage step of about one-third of a module mean?
Most modules have three bypass-diode substrings. A Voc deficit of about one-third of a module Voc usually means one substring is permanently bypassed, typically because of a shorted bypass diode or an open cell circuit. It should be located and repaired, because a shorted diode can overheat.
10. How can I tell series resistance from shunt resistance problems?
Look at the slopes. High series resistance makes the curve lean over near Voc and reduces Vmp. Low shunt resistance makes the plateau near Isc slope downward. Both reduce fill factor, but they point to different causes: connections and cabling for series, cell damage or PID for shunt.
11. What is potential-induced degradation and how does I-V testing reveal it?
PID is a leakage-driven degradation caused by high voltage between cells and the grounded frame, aggravated by heat and humidity. It reduces Voc and fill factor and tilts the curve near Isc. It typically affects modules at the negative end of the string first, a pattern confirmed by per-module testing or EL imaging.
12. How many strings should be tested?
At commissioning, 100% testing sets a complete baseline and is increasingly specified in EPC contracts. In operation, test a representative sample on a regular cycle, plus every string flagged by SCADA analytics, thermography or inspections.
13. Can I-V testing be done on 1,500 V systems?
Yes, with a curve tracer, leads and adapters rated for 1,500 V DC and the string's current. Higher voltage raises the shock and arc-flash hazard, so procedures, PPE and isolation must be appropriate to the system.
14. How do bifacial modules affect I-V testing?
Rear-side irradiance adds current that a front-facing sensor does not see. Without measuring or estimating rear irradiance, translation overstates the string's performance. Test plans for bifacial plants should specify rear-side sensors or a documented bifaciality correction.
15. How do trackers affect testing?
The module angle changes continuously, which alters plane-of-array irradiance and angle of incidence. Hold the tracker at a fixed position during testing, align the irradiance sensor with it, and avoid times when backtracking may shade rows.
16. Is it safe to disconnect an MC4 connector to test a string?
Only when no current is flowing. Open the string fuse, DC disconnect or combiner switch first, verify zero current, then separate the connectors. Opening a connector under load can draw a sustained DC arc that damages equipment and injures people.
17. What other tests should accompany I-V curves?
Infrared thermography to locate hot spots and hot connectors, insulation resistance testing for ground faults, electroluminescence imaging for cracked cells and PID, and SCADA analytics to target the testing. Together they move from detection to diagnosis to location.
18. Can I-V data support a module warranty claim?
Yes, if it is collected properly. Claims need translated results, documented test conditions, calibrated instruments, sensor details and the translation method used. Commissioning baselines make the evidence much stronger because they show the change over time.
19. How much energy can I-V-guided maintenance recover?
It depends on the faults found. Individual strings can recover 10–30% when connectors, bypass diodes or shading are corrected. Across a large plant, even a small percentage of under-performing strings can add up to a meaningful share of annual generation and revenue.
20. What should an I-V test report include?
String identification and location, date and time, plane-of-array irradiance and cell temperature, instrument and calibration details, raw and translated curves, the extracted parameters, comparison with expected and baseline values, the diagnosed fault type, and the corrective action and re-test result.

Links were current at publication (October 2026).

IEC 62446-1, Photovoltaic (PV) systems — Requirements for testing, documentation and maintenance — Part 1: Grid connected systems. International Electrotechnical Commission.
IEC 61829:2015, Photovoltaic (PV) array — On-site measurement of current-voltage characteristics. International Electrotechnical Commission.
IEC 60891, Photovoltaic devices — Procedures for temperature and irradiance corrections to measured I-V characteristics. International Electrotechnical Commission.
IEC TS 62446-3, Photovoltaic modules and plants — Outdoor infrared thermography. International Electrotechnical Commission.
NFPA 70E, Standard for Electrical Safety in the Workplace. National Fire Protection Association.
Curve Tracing FAQs (summary of IEC 61829 irradiance and sensor guidance). Seaward. https://www.seaward.com/gb/support/solar/faqs/29495-curve-tracing-faq-s/

This article is general technical information for educational purposes. It is not engineering advice for any specific project and does not create a professional relationship. Temperature coefficients, fill factor ranges, diagnostic ratios and recovery figures are indicative; project-specific values depend on module technology, site conditions and test methods, and must be confirmed against manufacturer data and measurement. Field testing of energised PV systems must be carried out by qualified personnel under the site's safety procedures. Verify the current edition of any standard before relying on a requirement quoted here.

Case studies are illustrative scenarios based on typical project conditions, not records of specific client projects. Figures are rounded and indicative.

IEC, NFPA and other standards bodies, and product names such as MC4, are the property of their respective owners. Keentel Engineering is not affiliated with or endorsed by these organisations or any equipment manufacturer.

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In 1995, Sonny Patel earned his Electrical Engineering degree from the University of Illinois. But degrees don't build legacies — action does.

For three decades, he has worked the power industry from every side of the table: 16 years as a utility engineer at Exelon/Commonwealth Edison; generation leadership across hydroelectric, industrial steam turbine, and a 9 GW renewable fleet; NERC Regional Entity Senior Compliance Engineer and Audit Team Lead, auditing some of the nation's largest utilities; and testing and commissioning lead on equipment up to 765 kV — the very top of the North American grid.Utility. Generator. Regulator. Consultant. Few engineers have seen all four seats. Fewer still have sat in them.

His experience spans nuclear, hydro, conventional generation, renewables, oil and gas, mining — and today's data centers, where he is authoring a three-book series on data center design. He is a Licensed Professional Engineer in six states and a Licensed Electrical Contractor in Florida (Unlimited EC) — he doesn't just design the work; he's qualified to stand behind its execution.Today, as Founder and CEO of Keentel Engineering, Sonny leads a nationwide team of engineers delivering substation design, power system studies, NERC compliance, and commissioning — done right, coast to coast.Three decades. Every side of the table. One standard: accountable engineering.

In 1995, Sonny Patel earned his Electrical Engineering degree from the University of Illinois. But degrees don't build legacies — action does.

Utility. Generator. Regulator. Consultant. Few engineers have seen all four seats. Fewer still have sat in them.

Today, as Founder and CEO of Keentel Engineering, Sonny leads a nationwide team of engineers delivering substation design, power system studies, NERC compliance, and commissioning — done right, coast to coast.Three decades. Every side of the table. One standard: accountable engineering.

Keentel Engineering graphic showing damped and undamped subsynchronous oscillations.

The three operating regions you have to design to

PV String I-V Curve Testing: Finding Hidden Performance Losses

Part A — PV String I-V Curve Testing at a Glance

The five parameters that define a string

Common faults and their curve signatures

The six-step field troubleshooting flow

Part B — PV String I-V Curve Testing: Finding Hidden Performance Losses

Why SCADA alone is not enough

The physics behind the curve

Irradiance and temperature: why raw readings mislead

Measuring correctly: conditions and set-up

Reading the curve: diagnostic signatures in detail

Key diagnostic ratios

A worked field example

Combining I-V testing with other diagnostics

Safety: DC is unforgiving

Utility-scale considerations

How Keentel Engineering helps

Part C — Case Studies

Case Study 1 — Single-axis tracker plant with a hidden connector problem

Case Study 2 — Commercial rooftop plant with potential-induced degradation

Case Study 3 — Bifacial plant commissioning baseline

Part D — Technical FAQ: PV String I-V Curve Testing

1. What is an I-V curve test?

2. How is I-V testing different from what SCADA shows?

3. What irradiance is needed for valid I-V testing?

4. Why must results be translated to STC?

5. How should the irradiance and temperature sensors be installed?

6. What is fill factor and what is a good value?

7. How does soiling appear on the curve?

8. Why does shading create steps in the curve?

9. What does a voltage step of about one-third of a module mean?

10. How can I tell series resistance from shunt resistance problems?

11. What is potential-induced degradation and how does I-V testing reveal it?

12. How many strings should be tested?

13. Can I-V testing be done on 1,500 V systems?

14. How do bifacial modules affect I-V testing?

15. How do trackers affect testing?

16. Is it safe to disconnect an MC4 connector to test a string?

17. What other tests should accompany I-V curves?

18. Can I-V data support a module warranty claim?

19. How much energy can I-V-guided maintenance recover?

20. What should an I-V test report include?

References and Further Reading

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About the Author:

Sandip "Sonny" R. Patel, P.E.

IEEE Senior Member · Founder & CEO, Keentel Engineering

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