Electricity and cost
Tariff, kWh, appliance runtime and EV charging estimates.
SpecCalc Hub
Technical calculation guides
Short technical guides that explain formulas, assumptions, limits, and safer interpretation of calculator output.
Where to start
Start with the guide that matches the decision you are trying to check. For example, read 'Estimate Electricity Cost' before calculating a bill, or 'UPS Runtime Limits' before buying a backup unit. Open the related calculator from the card. For high-risk electrical topics, use the guide as a preliminary explanation and verify final decisions with a qualified professional.
Batteries and UPS
Wh, Ah, DoD, UPS VA limits, power factor and runtime caveats.
Cables and voltage drop
Preliminary voltage-drop and wire-size interpretation without final installation claims.
Solar systems
Peak sun hours, panel sizing and simple payback limitations.
Motors
Motor and inverter context where nameplate data and professional review matter.
Important calculators
How to estimate electricity cost from watts and hours
A practical guide to kWh, tariff, runtime, and realistic limits.
Energy cost starts with kWh: convert watts to kilowatts, multiply by time, then multiply by tariff.
Electricity Cost CalculatorWhat peak sun hours mean for solar sizing
Why solar sizing depends on local solar resource, losses, and coverage target.
Peak sun hours compress daily solar irradiance into equivalent full-power hours.
Solar Panel Size CalculatorBattery runtime basics: Wh, Ah, DoD, and efficiency
How to translate battery labels into usable energy and runtime.
Ah becomes Wh only after multiplying by voltage.
Battery Runtime CalculatorUPS runtime: why real runtime differs from simple math
UPS batteries, runtime curves, power factor, and aging explained.
Manufacturers often publish runtime charts because efficiency changes with load.
UPS Runtime CalculatorInverter sizing: continuous load, surge, and margin
Why surge loads and power factor matter before buying an inverter.
Motors, compressors, and pumps can need much more power at startup.
Inverter Size CalculatorEV home charging cost and time explained
SOC, charging efficiency, tariff, and charger power in one model.
Charging from 20% to 80% adds 60% of usable battery capacity.
EV Home Charging Cost CalculatorSolar payback: what simple payback does and does not say
Use simple payback as a first estimate, not as investment advice.
Net cost divided by annual savings gives a simple payback estimate.
Solar Payback CalculatorVoltage drop basics and safety limits
How voltage drop estimates work and why they do not prove code compliance.
Longer runs and smaller conductors create higher voltage drop.
Voltage Drop CalculatorWhy wire size estimate is not final cable selection
Voltage-drop-based sizing is only one part of cable selection.
A conductor can pass a voltage-drop estimate and still fail ampacity or installation rules.
Wire Size Estimate CalculatorPrivacy-first calculators: what SpecCalc does not store
No accounts, no saved calculations, no lead forms, and no calculator inputs in analytics.
Calculator inputs are processed client-side in the MVP.
Electricity Cost CalculatorFAQ
Are these guides final engineering advice?
No. They explain assumptions and estimate methods only.
Should I read the guide before using a calculator?
For high-risk topics, yes. It helps avoid common interpretation mistakes.