New
Open calculator →Complete System Designer
Build a preliminary panel, inverter and battery shopping list from your energy needs.
Free planning tools
Solar calculators that lead to practical decisions
Estimate system size, storage, inverter capacity, payback and more. Results are educational estimates—not a substitute for a site assessment or licensed electrical design.
Design a complete system →Choose a calculator
Popular
Open calculator →Point Insolation Lookup
Estimate solar resource and annual PV output for any coordinates.
Solar ROI & Payback
Estimate savings, payback period and long-term return.
Panel Count
Turn monthly electricity use into an estimated array size and panel count.
Battery Sizing
Estimate battery capacity from critical loads and desired backup time.
New
Open calculator →Battery Runtime
See how long a known battery can power a selected load.
Inverter Sizing
Estimate continuous and surge inverter requirements.
Solar vs Generator
Compare fuel-generator operating costs with solar and storage.
Appliance Cost
Estimate what an appliance costs to run from the grid.
Monthly Bill Estimator
Estimate a power bill from usage and rate assumptions.
Peak Load Analyzer
Identify simultaneous loads and likely demand spikes.