Array layout board
Drop panels in portrait or landscape rows, carve series strings and parallel groups, and see Voc, Vmp, Isc, and Imp totals refresh as topology changes. Sketch a roof plane or ground rack without leaving the desk.
GridWatt String Desk
PV string workstation · Offline
GridWatt String Desk
Lay out the array, lock the strings inside the inverter window, size the DC run—and walk away with a permit-ready one-sheet. Offline electrical fit for rooftops, ground mounts, and cabin builds.
Workshop-precise
Copper-and-slate craft for array math—not a marketplace, not a bill estimator.
40+Residential panel SKUs offline
15String & hybrid inverters
9 toolsFrom layout board to one-sheet
100%On-device — no account required
Workstation benches
Inverter fit check
Match strings to a string or hybrid inverter with pass/warn/fail on MPPT min–max, startup voltage, max input current, and max Isc—including cold-Voc and hot-Vmp cases.
Temperature derate lab
Cold mountain, temperate, hot desert, or custom cell temps. Panel coefficients recalculate design Voc/Vmp so the layout is honest before you buy hardware.
DC wire & fuse desk
One-way run length, copper or aluminum, conduit grouping—get gauge suggestions, % voltage drop at design current, and DC OCPD sizes from a built-in ampacity table.
Permit one-sheet
Printable summary with array thumbnail, string map, wire schedule, equipment list, and derate assumptions—share via Share Sheet or save PDF.
Configuration compare
Park two named array plans side-by-side on electrical fit, voltage drop, and panel count so the safer string topology wins before checkout.
Built for the string, not the sales pitch
Productivity tool for homeowners, apprentices, and off-grid builders who need electrical fit—not lead gen.
GridWatt String Desk is an interactive PV string-design workstation for homeowners sketching a roof, apprentices learning series/parallel math, and DIY off-grid builders who need more than a napkin sketch. Place panels in portrait or landscape, split them into strings and parallel groups, and watch live Voc, Vmp, Isc, and Imp totals move with every edit.
Climate presets and panel coefficients derate cold Voc and hot Vmp before you commit. Pick a string or hybrid inverter and get pass/warn/fail on MPPT voltage, startup, input current, and max Isc. Enter run length and metal type for gauge, voltage-drop, and OCPD suggestions. Compare two named designs side-by-side, then export a shareable one-sheet with string map, wire schedule, and equipment list—no accounts, no marketplace, no bill forecasts.
Illustrative marketing figures; not App Store metrics.