Built by a working field technician, not a software company. FieldWatt is the offline field toolkit for utility scale solar: commissioning and O&M crews on 1500 volt DC plants with central inverters, single axis trackers, and a controls layer nobody has 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 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 by site and export a whole job packet as one PDF.
CREW SITE LOG, OPTIONAL
Off until you enable it. Geofences up to twenty 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. 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; 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 current period ends; manage or cancel in your Apple account settings. Any unused portion of the free trial is forfeited when you purchase.
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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.
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