Methodology
Make the estimate inspectable.
The planner exposes its inputs and uses conservative first-pass assumptions so the result can become a product-specification checklist.
Core equations
Daily energy: appliance watts × hours of use.
Battery baseline: daily energy × reserve days ÷ usable depth of discharge ÷ conversion allowance.
Solar baseline: daily energy ÷ planning sun hours ÷ conservative system-loss allowance.
Inverter baseline: simultaneous peak load plus headroom; startup behavior must be checked separately.
Evidence sources
PVWatts V8 model and API inputs
Location-aware production modelling inputs, outputs, and weather-data metadata.
Open source ↗PVWatts calculator cautions
Model uncertainty and interpretation guidance.
Open source ↗U.S. Department of Energy solar planning guide
Planning sequence, site constraints, energy use, and professional assessment context.
Open source ↗System Advisor Model
Reference modelling platform for more detailed technical and financial analysis.
Open source ↗Scope
The tools support early planning. Equipment data sheets, site conditions, mounting, wiring, protection, permits, and local requirements must be verified for the actual installation.