Forecast.Solar

The Forecast.Solar integrationIntegrations connect and integrate Home Assistant with your devices, services, and more. [Learn more] estimates how much energy your solar panels will produce, using the Forecast.Solar service. The forecast combines the location, orientation, and size of your panels with historic averages and weather data, so you can plan ahead and use your own solar energy as efficiently as possible.

For example, you could use the forecast to decide whether you will produce enough solar energy in the next hour to run the washing machine, or whether to charge your electric vehicle from the sun tomorrow instead of from the grid overnight.

Prerequisites

Forecast.Solar uses data from the EU Photovoltaic Geographical Information System, which covers almost the entire world. Your panels need to be in a location that this tool covers.

To create a forecast, the integration needs a few details about your solar setup:

• Location: The latitude and longitude of your panels. You can enter fixed coordinates or follow your Home Assistant home location. Following the home location keeps the forecast up to date when your home moves, for example, with panels on a camper van, motorhome, or boat.
• Declination: The tilt of your panels in degrees. A value of 0 means the panels lie flat, facing straight up, and 90 means they stand fully upright. You can enter a fixed tilt or select a sensor that reports it.
• Azimuth: The compass direction the panels face, on a 360-degree scale. 0 is north, 90 is east, 180 is south, and 270 is west. You can enter a fixed direction or select a sensor that reports it, such as a compass.
• Total Watt peak power: The combined maximum power of all your panels, in Watt peak. Add up the peak power of every panel in the group to get this value.

Configuration

To add the Forecast.Solar service to your Home Assistant instance, use this My button:

Setup has two steps. In the first step, you choose where the location and the panel angles come from:

The second step asks only for what you chose in the first step. For each angle, you enter either a fixed value or a sensor, never both.

When you select a sensor, the form checks its current state:

• If the sensor doesn’t exist, it isn’t accepted, and the form shows The selected sensor doesn’t exist.
• If the state isn’t a number or is out of range, it isn’t accepted.
• A sensor that is unavailable or unknown is accepted.
• A sensor that has no state yet is accepted only if Home Assistant already knows about it, for example, when its integration hasn’t finished loading.

When you reconfigure a plane, sensors it already uses aren’t checked again. A sensor that is briefly unusable doesn’t stop you from changing other settings.

If you rename a sensor’s entity ID, the plane keeps using it automatically.

Changing the location

Reconfiguring the integration only changes the location. To change the location:

1. Go to Settings > Devices & services and select Forecast.Solar.
2. Select Reconfigure. Your current choice is already selected.
3. Select one of the following, then select Submit:
   • Follow the Home Assistant location, for homes that move such as campers or boats: Applies right away.
   • Enter fixed coordinates: Shows the latitude and longitude, pre-filled with the current coordinates or your Home Assistant home location, so you can change them.

To change the angles or power of a plane, reconfigure the plane instead. See Reconfiguring a plane.

Configuration options

After setup, you can fine-tune the forecast. Go to Settings > Devices & services, select the Forecast.Solar integration, and then select the cogwheel (Configure).

Adding multiple planes

A plane is a group of panels that share the same orientation. If your setup has panels facing different directions, such as an east-west roof, you can add each orientation as a separate plane within the same integration.

Adding more than one plane requires a paid Forecast.Solar account. See Using a Forecast.Solar account. You can configure up to four planes, and the integration combines their data into a single set of sensors, taking your inverter size into account if you set one.

Adding a plane uses the same two steps as setup, without the Location choice. When a plane uses a sensor, its title shows the sensor’s entity ID, for example 30° / sensor.roof_azimuth / 5100W. If you rename the sensor’s entity ID, the title follows. If you give the plane your own title, it is kept.

To add a plane:

1. Go to Settings > Devices & services and select Forecast.Solar.
2. Select Add plane.

Reconfiguring a plane

Reconfiguring a plane also uses the same two steps, without the Location choice. It starts with the plane’s current choices selected and its current values filled in. This is also how you switch an angle between a fixed value and a sensor.

To reconfigure a plane:

1. Go to Settings > Devices & services and select Forecast.Solar.
2. Next to the plane, select the three dots menu, then select Reconfigure.

Using a Forecast.Solar account

You can use the public Forecast.Solar service for free, but the data has a lower resolution, the forecast updates less often, and you can configure only a single plane.

If you would like more frequent updates or want to add multiple planes, you can sign up for one of their plans. The Personal Plus tier and above let you configure up to four planes.

To use your account, add the API key in the integration’s configuration options, as described under Configuration options.

Tweaking the estimations

A forecast will never perfectly match what your panels produce, because it is based on weather and historical data rather than the power you actually generate. Even so, you can make it more accurate for your situation in a few ways:

• Fine-tune the Azimuth and Declination if the real orientation of your panels differs slightly from what you first entered, or select a sensor for either so it follows a moving or adjustable mount. To change these, reconfigure the plane.
• Set a damping factor between 0 and 1 for the morning and the evening if your panels catch some shade early or late in the day. A value of 0 applies no damping; higher values lower the forecast more. For example, if trees shade your panels in the morning but not in the evening, set the morning damping factor above 0 and leave the evening damping factor at 0. Adjust the value over time by comparing the forecast with your actual production.
• Set the inverter size if your inverter can deliver less power than your panels can produce together, so the forecast does not exceed what your inverter can handle.

You can change the damping factors and inverter size at any time under Configuration options. For more background on damping, see the Forecast.Solar damping documentation.

Supported functionality

The integration provides sensors that you can show on a dashboard or use in automations.

The following sensors are enabled by default:

• Estimated energy production - today: Total estimated production for today, in kWh.
• Estimated energy production - remaining today: Estimated production still to come today, in kWh.
• Estimated energy production - tomorrow: Total estimated production for tomorrow, in kWh.
• Estimated energy production - this hour: Estimated production for the current hour, in kWh.
• Estimated energy production - next hour: Estimated production for the next hour, in kWh.
• Estimated power production - now: Estimated power being produced right now, in Watt.
• Highest power peak time - today: The time of the highest expected power peak today.
• Highest power peak time - tomorrow: The time of the highest expected power peak tomorrow.

The following sensors are disabled by default. Enable them in the user interface if you want to use them:

• Estimated power production - in 1 hour: Estimated power production one hour from now, in Watt.
• Estimated power production - in 12 hours: Estimated power production twelve hours from now, in Watt.
• Estimated power production - in 24 hours: Estimated power production twenty-four hours from now, in Watt.

Using the forecast in the Energy dashboard

If you track your solar panels in the Energy dashboard, you can pair them with Forecast.Solar. The solar production graph then shows the forecasted production alongside what your panels actually generate, so you can see at a glance whether the day is living up to its prediction.

To add the forecast:

1. Go to Settings > Dashboards > Energy.
2. Under Solar panels, select your solar production entry. If you have not set one up yet, see integrating your solar panels first.
3. Turn on the solar production forecast option and select Forecast.Solar.
4. Save your changes.

The Energy dashboard now overlays the expected production on your solar graph.

List of actions

The Forecast.Solar integrationIntegrations connect and integrate Home Assistant with your devices, services, and more. [Learn more] provides the following actions. Each link below opens a dedicated page with examples, parameters, and a step-by-step UI walkthrough.

• Get forecast (forecast_solar.get_forecast) Returns the solar production forecast from Forecast.Solar.

For an overview of every action across all integrations, see the actions reference.

Examples

Automation: Act on a high solar forecast for tomorrow

This example sends a notification when the estimated energy production for tomorrow rises above 10 kWh.

alias: "High solar forecast tomorrow"
triggers:
  - trigger: numeric_state
    entity_id: sensor.energy_production_tomorrow
    above: 10
actions:
  - action: notify.send_message
    target:
      entity_id: notify.my_device
    data:
      message: "More than 10 kWh of solar production is forecast for tomorrow."

Automation: Act at the solar production peak

This example sends a notification at today’s forecast highest-power-peak time.

alias: "Forecast.Solar production peak"
triggers:
  - trigger: time
    at: sensor.power_highest_peak_time_today
actions:
  - action: notify.send_message
    target:
      entity_id: notify.my_device
    data:
      message: "The forecast solar production peak has started."

Data updates

How often the forecast updatesData polling is the process of querying a device or service at regular intervals to check for updates or retrieve data. By defining a custom polling interval, you can control how frequently your system checks for new data, which can help optimize performance and reduce unnecessary network traffic. [Learn more] depends on your Forecast.Solar account:

• Free accounts update every hour.
• Accounts with an API key update every 30 minutes.

Because Forecast.Solar limits how often the forecast can be requested, the integration reads your declination and azimuth sensors at each scheduled update, not the moment they change.

When the integration follows your Home Assistant home location, a change to that location refreshes the forecast right away. To stay within the Forecast.Solar rate limit, a location that keeps changing, such as on a moving camper, refreshes the forecast at most once per update interval.

The forecast always remains an estimate based on weather and historical data, not a measurement of the power your panels actually produce.

Known limitations

• The free service offers a lower data resolution, updates less often, and supports only a single plane. More frequent updates and multiple planes require a paid Forecast.Solar account.
• Your panel location must be covered by the EU Photovoltaic Geographical Information System.
• Declination and azimuth sensors are read at each scheduled forecast update, not the moment they change. See Data updates.
• A selected sensor is never replaced by a fixed value. If a sensor can’t be read after setup, the forecast keeps using its last reading and logs a warning once. When the sensor can be read again, the next forecast update uses its new value. The last reading isn’t kept across a restart or a reload of the integration. If the sensor still can’t be read at that point, setup retries. See Setup keeps retrying because of a sensor under Troubleshooting.

Troubleshooting

Removing the integration

This integration follows standard integration removal. No extra steps are required.

To remove an integration instance from Home Assistant

1. Go to Settings > Devices & services and select the integration card.
2. Next to the entry you want to remove, select the three dots menu. Then, select Delete.
   • Depending on the integration, the entries are listed under one of the following headings:
     • Devices
     • Hubs
     • Services
     • Integration entries
3. To confirm, select Delete.
   • Home Assistant also deletes the devices and entities of the entry.
4. If Home Assistant asks you to restart, restart Home Assistant.
5. If Home Assistant asks whether to also delete the application credentials, select Remove or Keep.
   • If you keep them, Home Assistant uses them automatically when you add the integration again.
   • To delete them later, refer to Deleting application credentials.