First, check what your actual yield is. Note: You should not rely on your annual energy bill, but instead look at the data from your inverter(s). The amount of energy returned to the grid is always much lower than the amount of energy produced by the solar panels.

Next, compare the yield with what was stated in your quote. In the quote you received from Zonnefabriek, an estimated annual yield was mentioned. This provides you with a reference value for what the yield should approximately be.

If the yield seems disappointing or you notice a significant decrease over the years, check here for possible reasons and what we can do about it.