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The calculation, down to the panel

For those who have their figures to hand. Fill in what you know and leave the rest: every field has a usable starting value.

Your consumption

Consumption per yearkWhThis is on your annual statement.Share you use during the day%A digital meter shows day and night separately.

Additional loads

These come on top of your consumption above. Leave empty what you do not have.

Electric driving: kilometres per yearkmCar consumption per 100 kmkWhShown on the on-board computer. Add about 10% for charging losses.Do you charge at home during the day?Electric cookingkWhIf you do not know, leave it empty: it is then already in your annual consumption.Heat pump or water heaterkWh

The installation

Number of panelsPower per panelWpThe SunPower P7 we install is 460 Wp, the Denim 455 Wp.Roof orientationShare of your daytime use that coincides with sunshine hours%An assumption. If you work from home or run the washing during the day, set it higher.

Home battery

CapacitykWhUsable cycles per yearAn assumption: in winter there is too little surplus to fill the battery every day.Amount for the battery€

Smart energy management (Jullix)

Your capacity tariff per kW per year€Only in Flanders. Without this figure, we do not include that saving.Expected reduction of your monthly peakkWAmount for the energy management€

Tariffs and amounts

Day tariff€Everything included. An assumption, not a tariff of ours.Night tariff€Feed-in tariff€Amount of the quote for the panels€

Your installation

— kWp

generates — kWh per year

Total consumption with everything included	—
Used directly yourself	—
Via the battery in the evening	—
To the grid	—

Electricity you do not buy	—
Payment for feed-in	—
Lower monthly peak	—
Total per year	—

Pays for itself after

—

Fill in the amounts from your quote.

Have it recalculated for your roof Book a site visit yourself Call 02 486 93 02

How we calculate

The rules behind this calculation

Yield: number of panels × power × the yield per kWp from PVGIS for Lembeek, with 14% system losses and a 35-degree roof pitch.
What you use directly yourself: the share of your daytime use that coincides with sunshine hours, and never more than what the panels generate at that moment.
The battery takes from the surplus what you use in the evening and at night, limited by the capacity times the number of cycles per year, with 10% loss on charging and discharging.
Energy management is counted here only for the item on your grid bill: a lower monthly peak times your capacity tariff (in Flanders). What energy management gains on top of that from dynamic hourly prices depends on your contract and is deliberately left out.
What is not included: maintenance, an inverter replaced after fifteen years, panel degradation, and interest if you borrow.

Anything marked as an assumption can be changed. The result remains an estimate on paper: only a site visit tells us how your roof really is.