Renewable Energy & Efficiency

Renewable energy calculators and formulas for solar, battery storage, and equipment efficiency metrics. Includes solar panel output, battery capacity, and system efficiency calculations.

12Formulas

All levels Difficulty

Updated Oct 2026

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Fundamental

Solar Panel Quantity & PV Array Sizing Calculator

Multiple

Fundamental

SEER to EER Conversion (Air Conditioner Efficiency)

EER = SEER × 0.875 (approximate) · EER = -0.02 × SEER² + 1.12 × SEER - 0.5 (more precise)

Fundamental

Solar Panel Energy Output Estimate

Energy Output = Panel Area * Solar Irradiance * Efficiency * Performance Ratio

Fundamental

Specific Energy Consumption

SEC = Energy Consumed(kWh) / Output (units)

Fundamental

Lighting Lumen Efficacy

η = Luminous Flux(lm) / Power(W)

Fundamental

Coefficient of Performance (COP)

COP = Useful Heat/Cooling Output / Work Input

Fundamental

Energy Efficiency Ratio (EER)

EER = Cooling Output (BTU/hr) / Power Input (W)

Fundamental

Battery Backup Time Calculator

t = Ah / I_load

Fundamental

Battery Energy (Watt-Hours)

Wh = V × Ah

Fundamental

Battery Capacity (Amp-Hours)

Ah = I × t

Fundamental

Number of Solar Panels Needed

N = Total Load Energy / (Panel Output × Sun Hours)

Fundamental

Solar Panel Power Output

P = Irradiance × Area × Efficiency