Forecast.Solar provides data based on your location, the declination and orientation of your solar panels.

Solar production

The weather based solar production forecast, historic averages and clear sky optimum provides watt powers and kilo watt energy data.


The weather forecast provide sky coverage amount, textual weather condition and icon URL, temperature and some wind information.
(Professional account)


Draw a daily solar production forecast chart with simple Javascript snippets.
(Professional account)

Solar production forecast and weather forecast data are provided for up to 7 days with a resolution of 1 hour down to 15 minutes.

If you then checked the documentation and you like it, register an account for more features.

Restful API

The API can deliver responses in JSON, XML and CSV

The Swagger compatible API definition is available in YAML.

Example: Get solar production estimate

You can easy build and test the required URLs with the Swagger-UI.



Response (professional account, 15 minutes resolution)

    "result": {
        "watts": {
            "2019-06-22 05:15:00": 17,
            "2019-06-22 05:30:00": 22,
            "2019-06-22 05:45:00": 27,
            "2019-06-29 20:15:00": 14,
            "2019-06-29 20:30:00": 11,
            "2019-06-29 20:45:00": 7
        "watt_hours": {
            "2019-06-22 05:15:00": 0,
            "2019-06-22 05:30:00": 6,
            "2019-06-22 05:45:00": 12,
            "2019-06-29 20:15:00": 2545,
            "2019-06-29 20:30:00": 2548,
            "2019-06-29 20:45:00": 2550
        "watt_hours_day": {
            "2019-06-22": 2626,
            "2019-06-23": 2918,
            "2019-06-24": 2526,
            "2019-06-25": 2866,
            "2019-06-26": 2892,
            "2019-06-27": 1900,
            "2019-06-28": 2199,
            "2019-06-29": 2550
    "message": {
        "type": "success",
        "code": 0,
        "text": ""

You can direct draw chart for solar production estimate using the Forecast.Solar widget.

(Professional account)

Chart for the geographical midpoint of Germany at  51°9'N,10°27'E  with a declination of 37°, looking south with 10 kilo watt peak installated.


Without given title or subtitle, no title is printed and the subtitle defaults to date


Title with date placeholder, no subtitle is printed

It is also possible to show charts of the historic average data and the theoretic data for clear sky conditions.
Todays historic average production

Title without date placeholder, subtitle defaults in this case to the date

Todays theoretical clear sky production

No title given but subtitle with placeholder

Please refer to the documentation for details and check also the example page.
The Script URL was build with: https://api.forecast.solar/demo-key/chart/51.15/10.45/37/0/10
Account models
You should consider to register an account for more features, compare plans in detail.


No registration required, free for life.

Best for users without loggers to get a quick idea about coming solar production.


Registration with a valid email required, access with personal API key, free trial of 14 days.

Best for users with loggers to integrate the data automatic.


Registration with a valid email required, access with personal API key, free trial of 14 days.

Best for business users with more than one plant and/or loggers to integrate the data automatic.


Registration with a valid email required, access with personal API key, free trial of 14 days.

—— coming soon ——
Support channels
An Issue tracker and a Slack channel are available for support.
Forecast your Solar production

With the increasing share of photovoltaics in the electricity market, the importance of Solar energy forecasts. These are an important tool for the integration of Solar power into existing network structures.

The production of solar power is dependent on external influences on which man has no or only limited influence. For example, Season, time of day, weather (eg ambient temperature, clouds, air turbidity).

A solar day covers the global energy supply for eight years.

Predictions about the availability of solar-generated electricity in the future support private power management, but are of great importance, above all, for commercial solar power generators and network operators.

Copyright © 2015-2021Knut Kohl | All rights reserved. | Photos: Flickr