Free Solar Engineering & Sizing Tools
Automate design calculations, electrical compliance, and operational sizing. Built for solar engineers, installers, and project managers.
Off-Grid Solar System Sizing
Size your solar array, lithium or lead-acid battery bank, charge controller, and inverter based on daily Wh load demand.
Wire Sizer & Voltage Drop
Determine optimal AWG wire sizing and voltage drop percentage based on conductor lengths, current, and NEC compliance guidelines.
Solar Panel String Sizer
Calculate optimal series and parallel string counts based on minimum/maximum inverter voltages and local extreme temperatures.
Grid-Tie ROI & Payback
Calculate return on investment (ROI), payback schedules, and 25-year cumulative savings for residential net-metered solar.
Tilt & Azimuth Optimizer
Find the perfect slope angle and azimuth orientation for your solar panels based on latitude to maximize annual yield.
Conduit Fill Sizing
Ensure physical conduit selections conform to code limits based on wire counts, wire gauges, and conduit types.
Ampacity Correction
Adjust current carrying capacity of PV conductors based on ambient temperature and conduit wire-fill correction factors.
Solar Permit Drawing Checklist
Interactive checklist that validates whether a plan set meets common AHJ requirements. Select state/AHJ type, mark items pass/fail, and export PDF reports.
Battery Autonomy
Deeper calculator for batteries that accounts for temperature coefficients and custom depth of discharge curves.
PV Watts Production Model
Estimate annual grid-connected solar production and grid offset potential for any address in the United States.
Solar Shading & Derating
Calculate annual energy loss from tree cover, roof obstructions, soil accumulation, and hot temperature derating.
Wind Load Racking Estimator
Approximate wind pressure forces on pitched and flat roof solar mounts using general structural safety equations.
Interconnection Checklist
Track regulatory compliance checklist for local utility agreements, net metering applications, and utility shut-off switch setups.
Inrush Current Surge Sizer
Size inverter systems for starting heavy motor loads like well pumps and air conditioners to prevent overcurrent shutdowns.
PV Yield Degradation Modeler
Calculate projected system production year-over-year based on standard module degradation parameters (e.g., 0.5% yearly decay).
Carbon Offset Calculator
Convert solar generation metrics into equivalent metrics for trees planted, cars removed, and metric tons of CO₂ avoided.
Financing Comparison
Compare cash purchases, solar loans, and Power Purchase Agreements (PPAs) based on long-term net savings metrics.
Grounding Conductor Sizer
Determine appropriate bare copper wire gauges for solar array frames and grounding electrode paths under NEC 250.