Energy After Losses
Eout = Ein × η
Quick answer
This calculator solves Eout = Ein × η for Output Energy. With Input Energy 1.1 kWh, Efficiency 50 %, the result is 0.55 kWh. It solves in 3 directions, so you can enter the values you have and get the one you need.
Calculator
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.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| Eout | Output Energy | Wh | µJ, mJ, J, kJ, Wh, kWh |
| Ein | Input Energy | Wh | µJ, mJ, J, kJ, Wh, kWh |
| eta | Efficiency | — | —, % |
Step by step
- 1. What you know: Input Energy 1.1 kWh, Efficiency 50 %
- 2. The relation: Eout = Ein × η
- 3. Substitute: Ein = 1.1 kWh, eta = 50 %
- 4. Result: Output Energy = 0.55 kWh
Worked examples
Minimum range
Given: Input Energy 7.92 kJ, Efficiency 2.5 %
Result: Output Energy = 0.198 kJ
Low range
Given: Input Energy 22 Wh, Efficiency 25 %
Result: Output Energy = 5.5 Wh
Typical
Given: Input Energy 1.1 kWh, Efficiency 50 %
Result: Output Energy = 0.55 kWh
High range
Given: Input Energy 11 kWh, Efficiency 0.8
Result: Output Energy = 8.8 kWh
Maximum range
Given: Input Energy 110 kWh, Efficiency 8
Result: Output Energy = 880 kWh
Solving for each variable
Solve for Output Energy
Input Energy 7.92 kJ, Efficiency 2.5 % → 0.198 kJ
Solve for Input Energy
Output Energy 3.6 kJ, Efficiency 2.5 % → 40 Wh
Solve for Efficiency
Output Energy 3.6 kJ, Input Energy 7.92 kJ → 45.45 %
How Output Energy changes with Input Energy
| Input Energy (input) | Output Energy (result) |
|---|---|
| 110 Wh | 55 Wh |
| 0.275 kWh | 137.5 Wh |
| 0.55 kWh | 0.275 kWh |
| 0.825 kWh | 0.4125 kWh |
| 1.1 kWh | 0.55 kWh |
| 1.65 kWh | 0.825 kWh |
| 2.2 kWh | 1.1 kWh |
| 4.4 kWh | 2.2 kWh |
| 7.7 kWh | 3.85 kWh |
| 11 kWh | 5.5 kWh |
The same result in other units
| Unit | Value |
|---|---|
| J | 1980000 |
| kJ | 1980 |
| Wh | 550 |
| kWh | 0.55 |
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<p><a href="https://vbatpower.com/formulas/energy-efficiency/">Energy After Losses</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate Energy After Losses?
Use Eout = Ein × η. With Input Energy 1.1 kWh, Efficiency 50 %, Output Energy works out to 0.55 kWh.
What is the formula for Energy After Losses?
The formula is Eout = Ein × η. This formula calculates the usable energy output after accounting for conversion losses.
How do you find Input Energy when you know the other values?
Rearrange for Input Energy: with Output Energy 3.6 kJ, Efficiency 2.5 %, Input Energy is 40 Wh.
How do you find Efficiency when you know the other values?
Rearrange for Efficiency: with Output Energy 3.6 kJ, Input Energy 7.92 kJ, Efficiency is 45.45 %.
What units does Energy After Losses use?
Output Energy is shown in J, kJ, Wh, kWh. Values are held in SI base units internally, so you can mix prefixes without converting by hand.
Related Concepts
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