Also several digits. The payback period of the correctly calculated solar installation draws up 6-8 years. But even this is in the absence of accounting for the constant rise in price of gas, that is, in 8 years the system justifies itself and evokes net profit. Satisfactory investment for private individuals. Legal entities (they have absolutely different tariffs) will pay off solar collectors much more. And for a long time it is possible to outline economic recoils, to give numbers, … much easier to observe European neighbors. Who, and they understand the cost of money. And we have to know!