How the estimate is built
The saving is the sum of five rows in three buckets. Each bucket only credits what the one before it left off, so the rows never double-count.
All amounts are gross, including 19 % VAT.
What is left out on purpose
Grid fees, metering charges, levies and taxes are the same whoever supplies the electricity. They appear on both sides of the comparison and cancel, so Bucket 1 compares supplier components only. Counting them would inflate both bills without changing the difference. Feed-in revenue is not part of the estimate. For households with PV the result is therefore conservative.Bucket 1: better plan conditions
When the customer does not enter their current tariff, the calculator compares against the market benchmark below. The result is marked as an estimate. When the customer enters their current tariff, the base fee is taken as entered (without grid and metering base fee), and the regional grid fee, levies and taxes are subtracted from their all-in energy price before comparing.Bucket 2: §14a EnWG
A household qualifies with at least one controllable device: an EV wallbox, a heat pump, or a battery above the power threshold listed under defaults and thresholds.- Module 1 is read directly from the plan’s quote for the customer’s grid operator. It is a fact about their bill, not an estimate.
- Module 3 compares the operator’s static grid fee against a blend of the operator’s own low, standard and high window rates, weighted by the window shares listed below. Operators only have to apply time-variable rates in some quarters, so the saving is scaled by the share of the year the schedule is active.
Bucket 3: optimization
Each part of the household’s consumption gets its own reduction on the spot share of the price. An EV can move almost all of its charging into cheap hours, base load hardly any. The household’s optimization rate is the consumption-weighted average of those reductions.Consumption
The customer enters base load (or picks a household size), plus each asset’s consumption. EV consumption is distance x consumption per 100 km x home charging share. With PV, every component is scaled down by the self-sufficiency share, so the mix and with it the optimization rate stay the same.Values and sources
Partners integrating the API get the same calculation from
POST /plans/{id} /savings, available from API version 2026-09-08.gauss. Its response carries
the five rows, the optimization rate and the §14a eligibility described above.Market benchmark
The energy price benchmark is normalized to 3,500 kWh per year.
Optimization
Optimization rate by household
The optimization rate is the consumption-weighted average of the spot reductions above, computed with the default consumption figures below. Real households get the rate their own mix earns.Time-variable grid fees (Module 3)
The calculator prices Module 3 on the grid operator’s published schedule. The fallback rates below are national averages, used only where no postcode is known yet. They never replace a missing operator schedule.