Solar shelf

Solar calculators for panels, batteries, wiring, backup power, and ROI.

Plan solar loads, panel count, series/parallel strings, wire gauge, battery storage, inverter size, charge controllers, RV/van systems, roof fit, tilt, generator backup, and payback without saving or sending your numbers anywhere.

Start with loads →Find a solar tool

Panels · MPPT · Wiring

Batteries · Inverters · Backup

Browser-only math

Educational planning utilities only — confirm electrical code, permits, roof constraints, fusing, wire ratings, battery limits, utility rules, and equipment manuals before buying or installing a solar system.

Solar sizing workflow

Choose the right solar calculator

Solar sizing works best as a sequence: load first, production second, storage third, then wiring, mounting, and economics. These tools are split so each assumption is easier to test.

Start from real loads

Estimate daily Wh/kWh, running watts, and surge demand before choosing any equipment.

Load Calculator Battery Bank Inverter Size

Size panels and MPPT

Convert daily energy demand into panel count, string voltage, array current, and charge controller rating.

Panel Count Series / Parallel Charge Controller

Check wiring and batteries

Estimate voltage drop, usable battery runtime, and high-current battery-to-inverter cable sizing.

Solar Wire Gauge Battery Runtime Battery Cable

Plan install and economics

Check panel fit, tilt assumptions, backup runtime, and payback before committing to a quote or parts list.

Roof Area Tilt Angle Payback / ROI

Combine the system

Use the combined off-grid and RV/van calculators when the whole package needs a fast sanity check.

Off-Grid System RV / Van Solar Generator Backup

Planning assumptions

What to know before using the solar tools

Start conservative

Use winter sun, measured loads, realistic losses, and a safety margin when the result drives an off-grid or backup-power purchase.

Check each component

A panel count can look right while string voltage, charge controller limits, wire drop, battery current, or roof fit still fails.

Verify before buying

Electrical code, permits, fuses, disconnects, roof structure, weather, battery chemistry, and manufacturer limits can override a calculator estimate.

Calculator finder

Find a solar calculator

Curated starting points

Search by goal, topic, or unit. Results update locally in your browser.

SolarSolar Load CalculatorEstimate daily energy use, running watts, and surge demand before sizing panels, batteries, and inverter.SolarSolar Panel Count CalculatorFind how many solar panels you need from daily kWh, peak sun hours, panel watts, and losses.SolarSolar Panel Series / Parallel CalculatorCheck solar panel string voltage, current, watts, cold Voc, and MPPT limits.SolarSolar Wire Gauge / Voltage Drop CalculatorEstimate solar DC wire gauge, voltage drop, watts lost, and round-trip resistance.SolarSolar Battery Bank Size CalculatorSize a solar battery bank from daily kWh, autonomy days, voltage, depth of discharge, and battery Ah.SolarSolar Inverter Size CalculatorEstimate inverter continuous watts and surge rating for off-grid, RV, cabin, and backup loads.

Popular tools

Start with a useful one

These are the calculators people are most likely to need first.

How to use this shelf

Best for

Use this shelf to plan solar loads, panels, batteries, inverters, controllers, wire, roof area, backup runtime, and payback before buying hardware.

Choose the right tool

Start with load, then size panels and battery. After that, check inverter, controller, wire, roof fit, and payback so one component is not isolated.

Verify before acting

Check sun hours, shading, derating, fusing, wire ampacity, voltage drop, battery limits, roof constraints, permits, code, and equipment manuals.

Suggested workflow: A practical solar workflow is: estimate loads, choose autonomy, size array and battery, validate electrical limits, then compare cost and payback.

Solar Load Calculator

Estimate solar daily load, running watts, and surge watts before sizing panels, batteries, inverter, and backup power.