Savings

The Savings page shows how much heat the sun puts into your tank, and how much gas, money and CO₂ that saves.

What you see#

• Totals for This month, This year and Since the first reading: the solar heat in kWh, the money saved, the gas in m³ and the CO₂ in kg.
• A chart of the solar yield, Per day, Per month or Per year.
• The installation details we calculate with. If it says "default", you have not entered that value yet. Edit lets you change them.

If you have more devices, switch with Other device.

How we estimate it#

We look at how much warmer your tank gets while the collector pump runs. That heat comes from the sun, and your boiler would otherwise have had to make it. From that follows how much gas you didn't burn, what that saves at your gas price and how much CO₂ it is.

That is why the installation details matter: your tank volume, boiler efficiency and gas price. The closer they are, the better the estimate. The exact calculation is on the page itself, under How we calculate. Amounts are in euros.

Why it is an estimate#

There is no heat meter in your installation. We work from the tank temperatures and the state of the pump. As a result:

• The estimate tends to be on the low side. If you draw hot water while the sun shines, that heat is not counted.
• Another heat source sometimes counts. If your boiler heats the tank while the collector pump runs, we count that as yield.
• It depends on your tank volume. If that is wrong, so is the yield.

If it says "Partial estimate", some tank readings were missing for a while. The actual yield is then probably a little higher.

When there is no estimate#

For an estimate your circuit needs a solar collector, a temperature sensor in the tank and a collector pump. If one is missing, the page says which. We don't estimate savings for a swimming pool yet.