Add electricity price forecast visualization

[valexi7]

Is your feature request related to a problem? Please describe.
Currently, evcc shows the current electricity price but does not support displaying future electricity price forecasts.
For users with dynamic electricity contracts, upcoming price information would help with manual charging decisions.

Describe the solution you'd like
Add support for displaying electricity price forecast data in evcc.

The forecast should be provided through a dedicated forecast sensor containing future hourly electricity prices. evcc could then display the forecast alongside the current electricity price, similar to the existing solar forecast visualization.
Example data source:
https://sahkovatkain.web.app/index_en.html

Describe alternatives you've considered
Using external tools such as Home Assistant dashboards to display electricity price forecasts separately from evcc.

Additional context
In Finland and other Nord Pool areas, day-ahead electricity prices are available in advance.
Combining electricity price forecast with existing solar forecast visualization would provide a better overview of upcoming energy availability and costs.

[github-actions]

This already exists in evcc. If you configure a tariffs.grid (and optionally tariffs.feedin) provider, evcc shows a price forecast chart right next to the solar forecast — see assets/js/components/Forecast/PriceChart.vue and assets/js/components/Forecast/GridDetails.vue. It renders forecasted min/avg/max grid price and (for tariffs that expose it) a feed-in curve, using whatever hourly/quarter-hourly slots the configured tariff returns.

For Finland/Nord Pool day-ahead prices specifically, the entsoe tariff (tariff/entsoe.go) covers the FI bidding zone, and elering (tariff/elering.go) also supports Nord Pool areas including Finland. Configuring either as tariffs.grid should give you the hourly forecast in the UI without any code changes.

Docs: https://docs.evcc.io/docs/reference/configuration/tariffs

If you've already configured a tariff and are not seeing the forecast, please share your tariffs: config section and the evcc version/log so we can look into a possible display bug — otherwise this looks like a documentation/discoverability question rather than a missing feature.

🤖 Generated with Claude Code

[valexi7]

@github-actions Bad bot! We can only configure single tariff sensor for spot buying price. Secondary forecast sensor should be configurable.

[StefanSchoof]

There is the merged tariff https://github.com/evcc-io/evcc/blob/f7af0bbe6ae24a0e223adbcd548c0e76ee64259f/tariff/merged.go

[andig]

Price forecast is already displayed.

We can only configure single tariff sensor for spot buying price.

Seems your config is wrong. Just configure forecast instead of current price. Usually both are combined by adding the required fees and taxes on top of the spot price.