Independent energy/ CALCULATOR

Measured solar self-consumption and household solar share

Reconcile matched AC generation, gross export and gross import to distinguish two solar percentages in a grid-connected home without storage.

AC solar generation during the intervalkWhPositive interval energy, not panel kWp, instantaneous kW or a lifetime total. Use the same start/end times as both grid records.

Gross electricity exported to the gridkWhSeparate export energy for that interval, not solar generation or an estimated payment. It cannot exceed generation in this no-storage, single-generator model.

Gross electricity imported from the gridkWhSeparate imported energy, not the import-minus-export billing balance. Zero is valid if some solar electricity was used locally.

Solar electricity used directly on site

250.00 kWh

Household electricity in the interval

700.00 kWh

Self-consumption: share of solar generation

41.7 %

Solar share of household electricity

35.7 %

One grid-connected household, PV as the only generator, no battery or vehicle discharge; matched AC kWh records at compatible measuring points. Losses between these points are neglected. Positive generation and household demand are required for both percentages. No hourly profile, peak power, bill, savings or outage autonomy is calculated. Do not force incompatible meter records to agree.

HOW IT WORKS

The calculation

Direct solar use = AC generation − grid export; demand = direct solar use + grid import; self-consumption = 100 × direct solar use / generation; solar share = 100 × direct solar use / demand

Source and further reading

SMA Sunny Home Manager — Energy Balance (definitions; English)

Worked example

600 kWh generation, 350 kWh export and 450 kWh import give 250 kWh direct solar use and 700 kWh household demand: 41.7% self-consumption, but 35.7% solar share. With zero export and the same 450 kWh import, self-consumption is 100% while solar share is only 57.1%. These are hypothetical inputs, not targets.

Understand the inputs.

Use matched generation, import and export records to distinguish solar self-consumption from the solar share of household electricity, without a battery.

Read the guide

FROM ESTIMATE TO ACTION

Use the result, not just the number.

Match three separate AC energy records

Use generation, gross export and gross import in kWh for the same start and end times. Subtract each cumulative register separately; record gaps, resets, timezone and units. Net billing balances, DC yield, kWp and instantaneous kW are not substitutes. Read authorized existing displays only; do not open equipment or change settings. A battery, another generator or vehicle discharge needs a different balance.

Check the two denominators

600 kWh generation, 350 kWh export and 450 kWh import give 250 kWh direct use and 700 kWh demand. Dividing by 600 gives 41.7%; by 700 gives 35.7%. Generation must be positive and export cannot exceed it. If all generation is exported and import is zero, demand is zero and its solar share is undefined: this input is rejected, not converted into a false percentage.

Compare useful demand, not independence promises

With 600 kWh generation, zero export and 450 kWh import, self-consumption is 100% but solar share only 57.1%. At the same 700 kWh demand, hypothetical 250 kWh export and 350 kWh import give 58.3% and 50.0%; load shifting is not proven to achieve this. Compare weather and useful loads. Energy totals establish neither hourly matching, outage backup, savings nor battery size.

Inputs to verify

AC solar generation during the interval (kWh): Positive interval energy, not panel kWp, instantaneous kW or a lifetime total. Use the same start/end times as both grid records.
Gross electricity exported to the grid (kWh): Separate export energy for that interval, not solar generation or an estimated payment. It cannot exceed generation in this no-storage, single-generator model.
Gross electricity imported from the grid (kWh): Separate imported energy, not the import-minus-export billing balance. Zero is valid if some solar electricity was used locally.

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