Feedback
What users reported to us, what we checked and what we did with it. Without names or addresses.
We favour no one. No supplier or installer pays us, and every supplier is calculated with the same rules. A report only changes something if it makes the calculation or the explanation better for everyone.
Something not right? Report it with ‘Is this not right?’ in the calculator or via contact.
08-10-2026 Calculating without hourly data
Report: A reaction on Reddit: without quarter-hourly or hourly data the calculation is guesswork. The annual statement does not tell you whether someone is at home during the day or charges the car at night.
What we checked
- Even with last year's hourly data, the future remains an estimate: different weather, different prices, no more net metering. What matters is the best possible model.
- The calculator already worked through every hour with the real hourly prices and the measured weather, asked separately how many days the car is at home during the day and when it charges, and with solar panels calibrated to the feed-in on the statement.
- Without solar panels the calculator could only compare the total: there was no figure that showed the daily rhythm.
- Next to the hourly meter of a home with solar panels, an electric car and a dynamic contract, the model charged the car during the day, while the meter showed it happened at night. An east-facing roof also peaked too late, and a high, flat night-time load was missing.
What we did
- Behind ‘Not right’ you can now also enter the off-peak consumption from your statement. With it the calculator calibrates how much of your consumption falls at night, even without solar panels.
- The model was adjusted to that meter: charging in the cheapest hours only when the car is at the charger, the solar peak of an east- or west-facing roof at the right hour, a field for the base load, and weeks away per month. Charging has one more choice: controlled by the supplier.
- On /export you can (beta, for now with one supplier) download your hourly consumption. With a tick box you send it to us, so we can test the model against more meters.
Not yet
- We do not use your own hourly data as input: we use hourly meters to test the model.
- Public holidays do not yet count in the off-peak rate.
- The calculator works per hour, not yet per quarter hour.
08-10-2026 Smart control of a heat pump water heater
Report: A user controls their heat pump water heater on solar surplus and low prices and asked whether the calculator takes that into account.
What we checked
- The calculator only shifted the hot water of a heat pump (a quarter of its use). A separate water heater was part of the total use and followed the normal daily pattern.
- With a hybrid heat pump that quarter was counted too, even though the hot water then comes from the gas boiler.
What we did
- Under heat pump the calculator now asks where your hot water comes from: the heat pump, the gas boiler, a heat pump water heater or an electric water heater.
- A smart-controlled water heater heats up on solar surplus and otherwise in the cheapest hours of the day; step 3 shows what that saves.
Not yet
- The calculator works per hour, not yet per quarter hour.
08-10-2026 Feed-in hard to find
Report: A user could not find where to enter feed-in, also not at a negative price.
What we checked
- The calculator does not ask for your feed-in but works it out: per hour, from what the solar panels generate and what you use yourself. The questions did not say so.
- At a negative price, the choice to simply keep feeding in was called ‘If the supplier does so’. That does not read as ‘no’.
What we did
- ‘What did you have in the past year?’ now says that the calculator works out your feed-in from your solar panels.
- The choice at a negative price is now called ‘No, unless the supplier curtails’.
Not yet
- The calculator uses Dutch rules and rates, not Belgian ones.
08-10-2026 Charging with a dynamic contract
Report: A user with a dynamic contract charges the car at home much more cheaply than the calculator works out.
What we checked
- We redid the calculation with the input that came with the report: charging at home in the cheapest hours, the car at home during the day on two working days.
- The calculator was already charging the car in the cheapest hours. Charging at home came to about 15 to 16 cents per kWh. Almost 15 cents of that is fixed: energy tax and the supplier’s purchase surcharge, with VAT. Everyone with a dynamic contract pays those.
- We found no calculation error. The difference lay in what had not been filled in: the charge point with MID meter (the ERE payment made a difference of about € 300 per year here) and the supplier’s payment for smart charging. In addition, apps often show only the hourly price, without energy tax.
What we did
- For the car, the calculator now asks whether your charge point has a MID meter, with the ERE payment you would otherwise miss.
- Under ‘Not right’ in the first step, the calculator asks whether the charge point with MID meter and the payment for smart charging are correct.
- The page on how the calculator works now explains why charging costs in an app look lower.
Not yet
- The calculator does not yet know which charge points and cars each supplier can charge smartly. It assumes this works with every dynamic contract.