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[APP] Solcast - Solar Forecasts

Solcast - Solar Forecasts

Homey app using the Solcast API to get solar forecasts customized for your location and installation

You can download the app here: Solcast


The app will download every half hour the latest solar forecast with the current forecasted value, and the next 1, 2 and 3 hours.
Every night at Midnight, it will download the accumulated forecasts for Today and Tomorrow.

Every 5 minutes you can upload your current solar production to fine-tune the prediction model of your solcast forecast. (see below instructions to setup the flows)


You could use the app to switch on electric appliances or charge a car or battery based on the forecast solar power, to maximize self-consumption.
You can compare the daily forecast with your actual production.


Sign up your solar installation at Solcast Toolkit
You have to setup the ‘Free’ Home PV owner account (hobbyist) which gives you (currently) 50 API calls a day.
Fill in all the exact details of your solar installation.

Setup the Solcast app

You have to provide your API-key and Resource ID to get the app working.
API Key can be found under - Your name - Your API key
Resource ID can be found if you click on your location on the main screen.

Upload functionality

The app can upload your PV output every 5 minutes to improve the model.
The upload needs to have your PV output in kW!, most of the solar apps use watt, so you have to divide the output by 1000.
I also use the app Insight Trends to make an average of the output.

See in the 2nd comment, my example flows.

You can check if the upload was successful by going to:

Support topic

For support please use the official support topic on the forum.


If you appreciate the app: Buy me a Beer]
@athom a Homey Pro is always appreciated :slight_smile:


The Solcast api has a max of 50 calls a day, and the data is only available every 30 minutes.
The upload minimum is 5 minutes.

To Do

  • Different #API calls
  • Setup flows



  • Initial release

Flows for upload

  1. Calculate trend

  1. Set variable and divide by 1000

  1. Upload every 5 minutes during the day

Cool and cool app. BTW you can replace the “after sunrise” and “before sunset” conditions with “it is day” (het is overdag).


1 Like

The app is now in the app store


How do you use the information in the end, apart from uploading to SolCast and better their predictions? I’ve intrested in getting ideas on how to set charge levels of my ESS battery system depending on what predicted solar levels there is for next day. But when looking into the flows that I can enable it only seems to be forecast now is greated than or less than … The forecast now I assume is the next hour? Not the next day? Since I’m looking for ways to charge the ESS battery bank from grid during nighttime when the forecast says low sun probability for the next day.


The app will get following data:
At midnight:

  • total forecasted production today
  • total forecasted production next day

Every half hour

  • solar power now (W)
  • cumulated solar power next hour
  • cumulated solar power next 2 hours
  • cumulated solar power next 3 hours

I use the app to charge my Solaredge battery at night (during off-peak hours) when not enough solar is forecasted.

You can use the half hour predictions to start for example a washing machine, dryer, … if you know that it will consume for example 2KW during 2 hours, you could match this with the Solcast forecast

The app has limited flows built-in, but by using logic, you can do everything.

Example flow to charge battery (dutch)

Thanks found it