The method
How Sunnix calculates
When a company sends you an estimate or a proposal with Sunnix, the prices are theirs. The maths — how much the system produces, how much energy you use, how much you save and how many years it takes to pay back — is done by Sunnix, always the same way.
How much it produces
From the exact spot on the roof or the ground, with tilt, orientation and system losses, production comes from PVGIS, the European Commission's service.
How much energy you use
With the bills, the maths runs hour by hour over nine years of real weather at that spot, with consumption by time band (F1, F2, F3) and with the battery if there is one. Without bills an average share for the type of customer is used, and next to the number it says «average assumption».
How much you save
The energy you use is worth what you pay for it: your bill's price if there is one, otherwise the Italian average of €0.29/kWh. What you send to the grid is worth the GSE's dedicated withdrawal: €0.1/kWh, €0.085/kWh in the South.
How many years to pay back
The maths goes year by year for 20 years. Panels lose 0.5% of production a year, and there are maintenance and a battery refresh in year twelve. For a home the energy price stays at today's; for a company it grows 2% a year, the average growth measured in Italy between 2008 and 2025 (Eurostat). The proposal says which of the two it used. Replacing the inverter is not included, and the proposal says so.
Why the company can't change them
The company chooses the products and the prices. The energy price and the self-consumption share it can't move: if a proposal set them by hand, instead of the «Calculated by Sunnix» badge you'll read «The company's assumptions».
What no estimate knows