Funding
This site is funded exclusively through advertising. It sells nothing and brokers nothing.
The model
The only planned source of revenue is clearly labelled display advertising. There are no paid placements in calculation results, no lead sales to installation companies, and no commissions for brokered offers.
Current status
At present, no advertising is embedded. As soon as that changes, ads will be labelled as such and this page will be updated.
What advertising must not do
Advertising has no influence on calculation logic, results, warnings or editorial decisions. The full calculation path is disclosed on every calculator page — anyone can verify that no result depends on an advertising partner.
What this site is not
Not a comparison portal, not an offer broker, not a shop. If a calculator concludes that a system is not worth it, it says so — there is no business model that needs a different answer.