# FieldWatt: Solar PV Toolkit — Inverter faults & NEC calcs > Offline solar PV toolkit for utility scale technicians with calculators and reference guides. (iPhone/iPad app by Chris Thrasher.) - Source: https://appshunter.io/ios/app/fieldwatt-solar-pv-toolkit/id6787932579 (this page in markdown: same URL + `.md`) - Developer: [Chris Thrasher](https://appshunter.io/developer/1790762521) - Category: Utilities, Productivity - Price: Free with in-app purchases - Rating: 5.00/5 from 1 App Store ratings · 1 written reviews indexed - Age rating: 4+ - Requires: iOS 17.6 · 3 MB - Languages: American English - Released: 2026-07-19 - Data updated: 2026-08-27 - Monetization: freemium - User reviews in markdown: https://appshunter.io/ios/app/fieldwatt-solar-pv-toolkit/id6787932579/reviews.md ## What is FieldWatt? FieldWatt is the offline field toolkit for utility scale solar technicians: commissioning and O&M crews on 1500 volt DC plants with central inverters, single axis trackers, and a controls layer nobody documented in one place. Everything ships inside the app, so it works in the middle of a field with zero cell signal. CALCULATORS THAT SHOW THEIR WORK • Max and min string size with cold and hot temperature corrections (NEC 690.7) • DC conductor sizing with the 156 percent rule plus ambient and fill derates (690.8) • Fuse and OCPD checks against module series fuse limits (690.9) • Voltage drop for long field runs, copper and aluminum • Insulation resistance pass thresholds by system voltage (IEC 62446) • Expected output and performance ratio • Commissioning checks: measured versus expected Voc and Isc with irradiance gates Every result shows the formula, the worked steps, and the code citation for your selected NEC year (2017, 2020, 2023, or 2026). THE REFERENCE LIBRARY, FREE • Central inverter fault codes across brands, each with the safe response • DC combiner O&M: blown fuse localization, thermal scans, torque • Tracker procedures and common failure modes • PLC status lights, Modbus and RS 485 troubleshooting, DNP3, SunSpec, register map gotchas • SCADA tag quality, power plant controller behavior, and telling a real fault from a comms artifact • ANSI protection device numbers and relay target reading • Field metering cheat sheet with irradiance minimums GUIDED TROUBLESHOOTING Decision trees for an inverter offline, an underperforming block, a ground fault, and a device that dropped out of SCADA. Safety critical findings render red with a stop work posture. The app never advises a blind reset. SITE PAPERWORK TO CLEAN PDFS LOTO permits, energized electrical work permits, switching orders, JHA tailboards, arc flash checks, combiner and inverter commissioning records, tracker PM, work orders, and field safety checklists. Photos, signatures, crew sign in, and autofill from your company, crew, and site profiles. Group everything by site and export a whole job packet as one PDF. CREW SITE LOG, OPTIONAL Off until you enable it. Geofences up to twenty saved sites and logs arrivals and departures around the clock, including overnight, so there is no button to forget. Needs the Always location permission. Email the daily log to the office, or paste a company automation URL and every entry and exit posts as it happens. Events stay on this phone until you send them. A crew consent form is included in Site Forms. RECEIPT TRACKER Scan a receipt and on device text recognition reads the vendor, amount, date, and category. Tag the job number and who sent it in, then email a PDF copy to the office and to yourself. Offline sends queue until you find signal. BUILT FOR THE FIELD • Bright high visibility theme for direct sunlight, plus a dark theme • Big tap targets and readable numbers, made for gloves • No account, no ads, no analytics, nothing collected about you; your data stays on your device SUBSCRIPTION DETAILS The free tier includes the full reference library with search, the voltage drop calculator, and unit conversions. FieldWatt Pro unlocks everything else: $6.99 monthly, $49.99 annually with a 7 day free trial for first time subscribers, or a one time $99.99 lifetime purchase. Payment is charged to your Apple account at confirmation of purchase. Subscriptions renew automatically unless cancelled at least 24 hours before the end of the current period; manage or cancel anytime in your Apple account settings. Any unused portion of the free trial is forfeited when you purchase. Privacy Policy: https://thrasherapps.com/fieldwatt/privacy.html Terms of Use: https://thrasherapps.com/fieldwatt/terms.html Support: https://thrasherapps.com/fieldwatt/support.html FieldWatt is a field aid, not a substitute for the NEC, NFPA 70E, the PE stamped drawings, the AHJ, or manufacturer manuals. Safety critical work requires a qualified person. ## Key features - NEC compliant calculators with worked steps - Central inverter fault code reference - Guided troubleshooting decision trees - Site paperwork generation (LOTO, permits, checklists) - Receipt scanning and expense tracking - Offline functionality with no cell signal required ## Pricing and in-app purchases Base price: Free. **Subscriptions** | Subscription | Price | Period | | --- | --- | --- | | Pro Monthly | $6.99 | per month | | Pro Annual | $49.99 | per year | **One-time purchases** | Purchase | Price | Type | | --- | --- | --- | | Pro Lifetime | $99.99 | one-time | ## Recent user reviews (1 of 1) All indexed reviews: https://appshunter.io/ios/app/fieldwatt-solar-pv-toolkit/id6787932579/reviews.md ### 5/5 — Great app *2026-08-11* Very helpful in the field. All in one app. Saves time and money. ## Frequently asked questions about FieldWatt ### What is FieldWatt? FieldWatt is an offline field toolkit designed for utility scale solar technicians. It offers calculators for NEC compliance, a reference library for inverter faults and O&M procedures, guided troubleshooting, and site paperwork generation. ### Does FieldWatt work offline? Yes, FieldWatt is built to work offline. All necessary data and tools are included within the app, allowing it to function in remote field locations with no cell signal. ### What kind of calculations does FieldWatt offer? FieldWatt provides calculators for string size with temperature corrections, DC conductor sizing, fuse and OCPD checks, voltage drop, insulation resistance, and expected output/performance ratio. Each calculation shows the formula, steps, and relevant code citations. ### Can FieldWatt help with site paperwork? Yes, FieldWatt can generate site paperwork such as LOTO permits, energized electrical work permits, switching orders, JHA tailboards, arc flash checks, commissioning records, and safety checklists. It allows for photos, signatures, and can export a complete job packet as a PDF. ### How does the receipt tracker work in FieldWatt? The receipt tracker uses on-device text recognition to read vendor, amount, date, and category from scanned receipts. You can tag receipts with job numbers and sender information, then email PDF copies to the office or yourself. This feature also works offline. ### What are the subscription plans for FieldWatt? FieldWatt offers a Pro Monthly plan for $6.99 and a Pro Annual plan for $49.99. These plans likely unlock premium features or increased functionality beyond the free offering. ### Is FieldWatt suitable for all solar installations? FieldWatt is specifically designed for utility scale solar technicians working on 1500-volt DC plants with central inverters and single-axis trackers. It focuses on the controls layer and components commonly found in these larger installations. ### Does FieldWatt have ads? No, FieldWatt does not contain advertisements. The description explicitly states 'no ads' and 'nothing collected about you', indicating an ad-free experience. ## Version history (last 5 releases) ### 1.2.4 — 2026-08-24 INVERTER FAULT CODES The library now covers Ingeteam Ingecon Sun, sixteen alarms from 0001H through 8000H, each with what the alarm means and then an ordered list of what to check. Grid voltage and frequency trips start by correlating the timestamp across the plant, because one inverter tripping alone means something completely different from all of them tripping together. High DC input voltage starts with ambient temperature and time of day, since the classic cause is a cold clear morning lifting string open circuit voltage past the inverter maximum, which is a string sizing conversation rather than a fault. Branch faults carry the warning that consecutive failures escalate to a fatal error, so repeated resetting makes things worse. POWER ELECTRONICS FREESUN Two entries on the HEC series. The GFDI entry matters most: on a grounded pole installation the only permitted earth point is inside the inverter through the GFDI, and a second grounded connection anywhere else silently defeats it, so the plant looks protected and is not. Their own caution label states that normally grounded conductors may be ungrounded and energised when a ground fault is showing. The second covers the insulation monitor, whose service life Power Electronics defines in trips rather than years, with replacement due after 100 ground faults that tripped it. ### 1.2.3 — 2026-08-22 ARC FLASH, BUILT ON NFPA 70E Arc flash guidance now follows NFPA 70E from 50 volts up: justification for energized work, the energized work permit, and the shock risk assessment, surfaced where you need them. For utility scale DC, the app is explicit about where the category method stops. The NFPA 70E arc flash PPE category tables for DC systems span 100 to 600 volts, so a 1500 volt array sits above the range those tables cover. On those plants the app points you to an incident energy analysis rather than a category, because that is what the standard actually requires at that voltage. BYPASS DIODE DIAGNOSTICS String Voc shortfall now gives you both readings side by side: roughly one third of a module Voc for a single shorted bypass diode, since a diode spans one substring and a typical crystalline module carries three, and a full module Voc for a whole module shorted out or bypassed. The size of the shortfall is how you decide how far to hunt, so both numbers appear together in the commissioning calculator, on the reference entry, and in the warning text. REFERENCE LIBRARY 2026.08.4 The down versus unreachable procedure leads with its scope. The distinction earns its keep for autonomous devices that keep running their part of the plant without communication: inverters, tracker controllers, protective relays, revenue meters. For a device that cannot act without its controller, a VFD taking speed commands being the usual example, it is the same problem either way, and if the drive did not already react to loss of command, that is your finding. Dwell time is answered with a method for working it out on the plant in front of you, rather than a fixed number that does not survive contact with a different site. Plus a short agreement on first launch covering what the app is and is not. Accept once and it is gone. ### 1.2.2 — 2026-08-21 You can now tell me what to add next. Settings has a new option that opens an email straight to me. If a calculation is wrong, a code is missing, or there is something this app should do and does not, that is the fastest way to say so. I read all of it, and I would rather be corrected than keep shipping something wrong. ### 1.2.1 — 2026-08-17 Reference library update. New section on PV plan sets and drawings, covering how to read one line and three line diagrams. The down versus unreachable procedure now covers switch side checks, including port status and pinging from the switch or engineering station, and explains how to work out a sensible dwell time for your own site rather than guessing at one. Two corrections. The bypass diode Voc shortfall is now one third of a module rather than a whole module, and arc flash and torque values follow the published thresholds. ### 1.2 — 2026-08-15 Redeem a code If you have been given an access code, you can now redeem it inside the app rather than hunting for it in the App Store. Reference library update 2026.08.2 New entries on reading a plan set: the order that saves time, title blocks and which drawing governs, the one line diagram, the three line diagram, array layout and string diagrams, and conductor and raceway schedules. Handed a drawing set and told to find a combiner, this is the part nobody writes down. ## More apps by Chris Thrasher - [DropTubeBuilder: Fuel Tanks](https://appshunter.io/ios/app/droptubebuilder-fuel-tanks/id6740597739) - [Lava Dash](https://appshunter.io/ios/app/lava-dash/id6742521742) - [StreakQuest](https://appshunter.io/ios/app/streakquest/id6743329674) - [BlockThrasher: Neon Puzzle](https://appshunter.io/ios/app/blockthrasher-neon-puzzle/id6746172717) - [TrialMate: Attorney Case Prep](https://appshunter.io/ios/app/trialmate-attorney-case-prep/id6748589882) - [Side Work Tax](https://appshunter.io/ios/app/side-work-tax/id6782625305) All apps by Chris Thrasher: https://appshunter.io/developer/1790762521 ## Related topics [chris thrasher](https://appshunter.io/ios/topics/chris-thrasher) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-27.*