[APP][Pro] Solcast - Solar Forecasts

You’re correct it looks like the counter is behaving ok now. Only the first update after first setup gave this error.

Hi @Pieterv123, I just realized strange behavior of Forecast TODAY - updated last time 24 days ago :wink:

Just in case you see anything in the logs - 0953c047-308a-418d-a5d4-6d51d782c49a

Did you make a flow for the midnight fetch at 02 AM as described in the first post?

I actually use your integration for maybe more then year and never used automatic polling, have so far set only midnight fetch and not 02AM fetch (+ several others within API limit). So that’s the cause, missing manual fetch at 02AM, later fetch will not update it ?

Maybe to prevent misunderstanding - all values get updated except of Forecast TODAY

Based on this experience I also asked (begged) support for some extra api calls for a second string. Unfortunately they didn’t want to raise it. There are many free users and server load is getting to high… :unamused:
They are thinking about a subscription model for extra calls. To investigate if users are interested they have a form

As example:

The “Fetch midnight” is used once in the morning to get the daily forecast (I think ist must be later than 2am CET).
The other Fetch is used to update today remaining forecast.

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Thanks Ronny - even at midnight, I used only Solcast update, never called Midnight update, will update the flows then.

update indeed Midnight update fetch (action card) updated the forecast TODAY (even when I launched it now 1PM…)

Thanks, answered - not sure if it’s right strategy to target hobbyist though…

Yes you can use it during the day, but the values are not correct then. (only once per day)
Forecast today should be triggered before sunrise, to have a good comparison with your actual solar data. By experience in Europe 0200 AM is a good time.

I disabled the automatic update because for people in different timezones and daylight savings, it is more complicated to make an accurate update.

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Yep, as I mentioned, I never used it, just missed the point with new Action card (Fetch midnight data) required when updated to new version v3.5.0

I’m using it to calculate values from both strings and based on this triggering actions - so sort of manage effective expected solar energy vs. expected consumption vs trying to minimize battery cycle, the rest is for me only kind of FYI. So eg. in case of sufficient solar power, I start water heating sooner to use directly the energy for the heating instead of taking power from battery… later for car charging and during night maximise use of battery and to have sort of backup / battery fully charged…

Somehow OT, but there is a solution for solar forecasts of multiple strings: you could request global tilted radiation data from open meteo and simply multiply it by your panel area and panel efficiency. Use of the open meteo api is free for up to 10,000 calls a day (in words: ten thousand) and totally straight forward. I use it to calculate predictions for my two strings for the upcoming days. Let me know if you are interested in some details.

Example: Prognosis for the remaining yield of the current day (“Prognose Restertrag”)

Example: Prognosis of the next three days

Example: Prognosis for the next 24 hours


Can you elaborate on this one please ? It’s like UVI index, or ?

It’s just that: global tilted radiation. See here. You have to enter your latitude, longitude and the tilt and azimuth of your panels (at the top of the page).

API URL is below the chart.

Once you got the values, just multiply by your panel area and efficiency and you’re done. If you have multiple strings, just make one request per string, multiply by the respective area and efficiency and add all up.


Might be clearly solution if the “hobbyist” part of SolCast will be paid … thank you for sharing !

Maybe method to think about for @Pieterv123 ? :grinning:

This prognosis would give the ability to calculate max. PV production during noon. This would allow an easy check if you should stop battery charging in the morning to charge over noon to collect production from the panels that the inverter is not able to convert.

Kind of. Those GTI values are average values over a given time over a given area. Especially on days with a few clouds your actual values vary A LOT. On the other hand, your average actual values will fit quite nicely the average prognosed values even on those days.

I have this implemented here already, but it’s not that straight forward and you should never delay battery charging until the last moment. My battery level of the last seven days looks like this:

You see it discharging during the night, then staying the same for a few hours until early afternoon, and finally quickly charging up to the max level necessary (currently around 80%) before discharging starts again 1-2 hours later.

If you want to manually activate/deactivate something like this during certain seasons, it’s easy to implement. If you want it fully automated throughout the year, it’s really challenging. I’m planning on sharing my code, but right now it’s not yet feature complete, especially during the winter time (prioritised charging is missing, house consumption is necessary without heat pump consumption, etc.).

When I find the time I’ll start with a How-to for the visualisation of the PV yield prognosis on one of the upcoming weekends. It’s one of the two major requisites for a sophisticated battery dis-/charging strategy. The other is house consumption and prediction thereof, which I haven’t completely solved yet.

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You should have a look at EMHASS


Makes a forecast of your consumption, uses solar data and dynamic prices to make a plan on how to use the battery

Can you please share advanced flows making use of this? I’m trying to make optimal use of my solar power by swithing on devices based on solar over production based on load & priority (like pool pump, warm water, washing machine, etc). On Facebook they pointed me to this script which can for sure help, but some examples would be really usefull.

I installed Solcast today, added my API and Resource Key but get an API error in Homey. I have removed the app, reinstalled it, added API and Resource Key and rebooted Homey but I keep getting the API error. Am I missing something, new to Homey.

I have no examples for an advanced flow