PVCalc vs SunStem

PV Calc helps homeowners understand whether solar makes financial sense — before calling a single installer. Enter your location and home profile, and the app instantly estimates: • How much solar you need based on your actual electricity usage • Annual energy production from real PVGIS satellite data (EU JRC) • Installation cost after federal and Hawaii state tax credits • Payback time based on your current electricity tariff • Monthly financing options How it works Solar irradiance data is pulled live from the PVGIS v5.2 API (European Commission Joint Research Centre), covering worldwide locations. The app uses your home profile — bedrooms, cooling type, water heater, EVs, and pool — to estimate your consumption and recommend the right system size. Panel types : Choose Budget (300W), Standard (400W), or Premium (500W) panels to see how panel choice affects system size, roof area, and cost. Use PV Calc to compare system sizes, understand your payback timeline, and walk into installer meetings informed.

SunStem is an offline solar and battery calculator for RVs, vans, boats and cabins. Build a saved system profile, then estimate battery runtime, solar yield, reserve risk and safer system sizing on iPhone or iPad. CALCULATE BATTERY RUNTIME - Compare load, solar and usable battery capacity - Forecast the next charge window and hours to the reserve floor - Work offline from a saved profile and local inputs SIZE AN OFF-GRID SYSTEM - Review battery, PV, MPPT, inverter, wire and fuse planning outputs - Check voltage drop, cold Voc and fuse-versus-wire safety gates - See assumptions and deterministic calculations from the native core AUDIT THE NEXT SEVEN DAYS - Scan daily reserve risk from saved load and solar assumptions - See what to shed, when to charge and why the risk changed - Export facts for a trip partner, installer or hardware review No cloud account is required before first value. SunStem provides planning estimates and field-review evidence, not engineering certification. It does not control chargers, inverters or BMS hardware. Background or unattended hardware monitoring is not promised in this release.