The method

How Sunnix calculates.

When a company sends you an estimate or a quote 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.

The method in numbers

  • 20 yearsof maths, year by year
  • 0.5%of production lost by the panels each year
  • €0.29per kWh, the Italian average without bills
  • 9 yearsof real weather, hour by hourwith the bills
  • How much it producesFrom 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 useWith 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 saveThe 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 backThe 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 quote says which of the two it used. Replacing the inverter is not included, and the quote says so.
  • If the company changes them, you see itThe company chooses the products and the prices. The energy price and the self-consumption share start from Sunnix’s: if the company changes them, instead of the «Calculated by Sunnix» badge you’ll read «The company's assumptions», on the page and in the PDF.

What no estimate knows

The site visit confirms it.

Nearby obstacles, the state of the roof, the electrical system: an estimate can’t see them. That’s why the real price comes after the site visit.

One year's weather moves production by a few points, consumption changes with habits, tariffs with the market. That's why every number carries where it comes from.