[Enhancement] Account for Sun-Window angle for sun triggers

[itsamejoshab]

With my blinds, I found the sun elevation itself to be inadequate to control when blinds should trigger. It depends on what way your window faces.

I have this code which you might find useful and incorporate into this blueprint.

You ask the user for 2 things:

• win_azi the azimuth of the window
• win_ele the elevation of the window
• sun_ele_threshold the threshold of elevation where sun disappears at horizon

In this example I get the sun attributes from another integration, but the math to calculate my helper is all written out for you. win_azi I got from google earth.

        {% set deg2rad = pi/180 %}

        {% set sun_azi = state_attr('sun.sun', 'azimuth') | int %}
        {% set sun_ele = state_attr('sun.sun', 'elevation') | int %}

        {% set sun_x = cos(sun_azi*deg2rad)*cos(sun_ele*deg2rad) %}
        {% set sun_y = sin(sun_azi*deg2rad)*cos(sun_ele*deg2rad) %}
        {% set sun_z = sin(sun_ele*deg2rad) %}

        {% set win_azi = 232.68 %}
        {% set win_ele = 0 %}
        {% set sun_ele_threshold = 5 %}

        {% set win_x = cos(win_azi*deg2rad)*cos(win_ele*deg2rad) %}
        {% set win_y = sin(win_azi*deg2rad)*cos(win_ele*deg2rad) %}
        {% set win_z = sin(win_ele*deg2rad) %}

        {% set dot = sun_x*win_x + sun_y*win_y + sun_z*win_z %}
        {% set norm_win = sqrt(win_x**2 + win_y**2 + win_z**2) %}
        {% set norm_sun = sqrt(sun_x**2 + sun_y**2 + sun_z**2) %}
        {% set cos_sim = dot/(norm_win*norm_sun) %}

        {% set ang_sim = 1 - acos(cos_sim)/pi %}
        {{ ((cos_sim * 100) | round(0)) if (sun_ele > sun_ele_threshold and cos_sim > 0 ) else 0 }}

This gives you a basis to measure how directly the sun is looking into the window. Higher means more direct.

Next, I use a binary sensor to compare this number to a threshold which a user would set, in my case I chose 30.

    - name: "Kitchen Window Sun"
      state: >
        {% if (states('sensor.sun_window_ang_similarity')|float(default=0.0) > 30) %}
            true
        {% else %}
            false
        {% endif %}

This was a very satisfying way to control the blinds, better than just elevation.

[hvorragend]

I also considered this at the very beginning: #3
I know the formula and have always followed the other ideas. The same goes for Adaptive Cover Integration.

I'll have to think about it. The problem is that I also have to provide support for it and debugging becomes more difficult.

[gandy92]

Having essentially one large combined kitchen/dining/living room with windows facing to east, south and west, I'd highly appreciate this feature. I'm currently switching over to home assistant from another home automation software where I've implemented sun shading in a way that the covers just go down far enough to block direct sunlight from getting through the glass, allowing for an always well lit room while keeping the heat out.
For me, it would already help a lot if it was possible to provide my own function (template?) that yields the currently best cover position for sun protection. Or is this already possible by providing the correct helper to one of the many configuration options?