Energy After Losses

Formula

Description

This formula calculates the usable energy output after accounting for conversion losses. It applies to any energy conversion process: charging a battery, converting solar energy, running a motor, or transferring power through a cable. The energy lost is Ein × (1 - η), which typically becomes waste heat. When chaining multiple conversion stages, multiply each stage's efficiency to get the total system efficiency, then apply it to the input energy.

Variables

• Eout — Usable output energy (Wh)
• Ein — Total input energy (Wh)
• η — Conversion efficiency (0 to 1)

Practical Notes

In a solar-to-battery system, you might have panel efficiency (20%), charge controller efficiency (95%), and battery charge/discharge efficiency (90%), giving an overall η of 0.20 × 0.95 × 0.90 = 0.171, meaning only 17.1% of solar energy is ultimately available.