European Inverter Efficiency
η_EU = weighted average of partial-load efficiencies
Quick answer
This calculator solves η_EU = 0.03×η₅ + 0.06×η₁₀ + 0.13×η₂₀ + 0.10×η₃₀ + 0.48×η₅₀ + 0.20×η₁₀₀ for Euro Efficiency. With η at 5% load 1.1, η at 10% load 2.35, η at 20% load 23.5 %, η at 30% load 5, η at 50% load 11 %, η at 100% load 11, the result is 2.957.
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Formula
Description
The European efficiency is a weighted-average inverter efficiency that accounts for the fact that solar inverters rarely operate at full power. The weighting factors reflect the typical irradiance distribution in central European climates, where partial-load conditions dominate. The 50% load point receives the highest weight (48%) because inverters spend the most time near this operating point. This metric gives a more realistic picture of annual energy harvest than the peak efficiency, which only occurs at one specific operating point.
Variables
- η_EU — Weighted European efficiency (0-1 or %)
- η₅ — Efficiency at 5% of rated power
- η₁₀ — Efficiency at 10% of rated power
- η₂₀ — Efficiency at 20% of rated power
- η₃₀ — Efficiency at 30% of rated power
- η₅₀ — Efficiency at 50% of rated power
- η₁₀₀ — Efficiency at 100% of rated power
Practical Notes
Modern string inverters achieve European efficiencies of 96-98%. The CEC (California Energy Commission) efficiency uses different weights optimized for sunnier climates. Microinverters and power optimizers have slightly lower peak efficiency but can improve system-level efficiency by reducing mismatch losses from shading or panel variation.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| eta_eu | Euro Efficiency | — | —, % |
| eta5 | η at 5% load | — | —, % |
| eta10 | η at 10% load | — | —, % |
| eta20 | η at 20% load | — | —, % |
| eta30 | η at 30% load | — | —, % |
| eta50 | η at 50% load | — | —, % |
| eta100 | η at 100% load | — | —, % |
Step by step
- 1. What you know: η at 5% load 1.1, η at 10% load 2.35, η at 20% load 23.5 %, η at 30% load 5, η at 50% load 11 %, η at 100% load 11
- 2. The relation: η_EU = 0.03×η₅ + 0.06×η₁₀ + 0.13×η₂₀ + 0.10×η₃₀ + 0.48×η₅₀ + 0.20×η₁₀₀
- 3. Substitute: eta5 = 1.1, eta10 = 2.35, eta20 = 23.5 %, eta30 = 5, eta50 = 11 %, eta100 = 11
- 4. Result: Euro Efficiency = 2.957
Worked examples
Minimum range
Given: η at 5% load 5.5 %, η at 10% load 11.8 %, η at 20% load 1.18 %, η at 30% load 25 %, η at 50% load 0.55 %, η at 100% load 0.55
Result: Euro Efficiency = 14.79 %
Low range
Given: η at 5% load 0.55, η at 10% load 1.18, η at 20% load 11.8 %, η at 30% load 2.5, η at 50% load 5.5 %, η at 100% load 5.5
Result: Euro Efficiency = 1.479
Typical
Given: η at 5% load 1.1, η at 10% load 2.35, η at 20% load 23.5 %, η at 30% load 5, η at 50% load 11 %, η at 100% load 11
Result: Euro Efficiency = 2.957
High range
Given: η at 5% load 1.76, η at 10% load 3.76, η at 20% load 37.6 %, η at 30% load 8, η at 50% load 17.6 %, η at 100% load 17.6
Result: Euro Efficiency = 4.732
Maximum range
Given: η at 5% load 17.6, η at 10% load 37.6, η at 20% load 3.76, η at 30% load 80, η at 50% load 1.76, η at 100% load 176
Result: Euro Efficiency = 47.32
How Euro Efficiency changes with η at 5% load
| η at 5% load (input) | Euro Efficiency (result) |
|---|---|
| 11 % | 2.928 |
| 27.5 % | 2.933 |
| 0.55 | 2.941 |
| 0.825 | 2.949 |
| 1.1 | 2.957 |
| 1.65 | 2.974 |
| 2.2 | 2.99 |
| 4.4 | 3.056 |
| 7.7 | 3.155 |
| 11 | 3.254 |
The same result in other units
| Unit | Value |
|---|---|
| 2.957 | |
| % | 295.7 |
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<p><a href="https://vbatpower.com/formulas/inverter-eff-euro/">European Inverter Efficiency</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate European Inverter Efficiency?
Use η_EU = 0.03×η₅ + 0.06×η₁₀ + 0.13×η₂₀ + 0.10×η₃₀ + 0.48×η₅₀ + 0.20×η₁₀₀. With η at 5% load 1.1, η at 10% load 2.35, η at 20% load 23.5 %, η at 30% load 5, η at 50% load 11 %, η at 100% load 11, Euro Efficiency works out to 2.957.
How do you calculate eu solar inverter weighted efficiency calculation?
Rearrange for Euro Efficiency: with η at 5% load 0.55, η at 10% load 1.18, η at 20% load 11.8 %, η at 30% load 2.5, η at 50% load 5.5 %, η at 100% load 5.5, Euro Efficiency is 1.479.
What is eu efficiency solar inverter?
Rearrange for Euro Efficiency: with η at 5% load 1.1, η at 10% load 2.35, η at 20% load 23.5 %, η at 30% load 5, η at 50% load 11 %, η at 100% load 11, Euro Efficiency is 2.957.
How do you calculate euro efficiency of solar inverters?
Rearrange for Euro Efficiency: with η at 5% load 0.55, η at 10% load 1.18, η at 20% load 11.8 %, η at 30% load 2.5, η at 50% load 5.5 %, η at 100% load 5.5, Euro Efficiency is 1.479.
What is the formula for European Inverter Efficiency?
The formula is η_EU = 0.03×η₅ + 0.06×η₁₀ + 0.13×η₂₀ + 0.10×η₃₀ + 0.48×η₅₀ + 0.20×η₁₀₀. The European efficiency is a weighted-average inverter efficiency that accounts for the fact that solar inverters rarely operate at full power.
What units does European Inverter Efficiency use?
Euro Efficiency is shown in , %. Values are held in SI base units internally, so you can mix prefixes without converting by hand.
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