Note: Anyone who would like to support me is welcome to make a small donation: Donate. Thank you very much.

FAQ - Frequently Asked Questions

What does the service "Solarprognose/Solarprediction" offer?

We offer a prediction of the production of your solar system. It is displayed as a chart and table. The kilowatthours per day and the power in kilowatt is displayed in an overview graph and in daily graphs. The prediction can also be queried via a simple API.

How to add items?

Go to the "Manage" menu item. Click on it then click on "Create Items". Now you can create a location, plant, inverter or a module field.


    • You can select a location by clicking on the map.
    • But you can also search for your city/village in the "Select Location"-field.
    • As a third option you can directly enter latitude and longitude, then you have to click on the blue "Autofill form..." button.
  1. You can then select if this item should be public, this means accessible for everyone who knows the id.
  2. Then press the green "Save" button at the end of the form.


  1. At first you have to select a location. If you have been redirected to the plant form because you have added a location just before, then this is already done.
  2. Then you have to enter a name.
  3. You can then enter a "Max Power" of your system, if you don't know it enter the Kilowattpeak (kWp) of your modules.
  4. The field "System Losses" is optional, enter e. g. 15 for 15 % system losses.
  5. Press the "Save" button to save it.


  1. Here you have to select a plant where the inverter belongs to.
  2. Then enter a name and its maximum power, but this can be empty.
  3. Press the "Save" button to save it.

Module Field

  1. Select the inverter, then enter a name, e. g. "house roof", then the azimuth of the roof and the slope in degree. At last enter the Kilowattpeak (kWp) of the module field.
  2. The "Power Mpp Temperature Coefficient" is optional, enter e. g. -0.49 %, see in the datasheet of your modules for your value.
  3. Press the "Save" button to save it.
Are the modules sometime shaded?
You can define this per module field.
  1. In the Overview page scroll to the module fields and click the button.
  2. Then click the blue button "Power Constraint (Shadow)".
  3. Now you can enter per month and per hour how many percent of the module field don't see the sun.
  4. If you're completed press the "Save Changes" button.

You're done

You can now go to Overview and click on the Prediction button of the location (or plant, inverter or module field).